Since the Nobel Prize in Chemistry in 2000 for the discovery and the development of conductive polymers, organic electronics has emerged as a promising technology for the development of a next generation of innovative and smart electro-optical functional devices. Despite the great potential of organic electronic materials and devices, organic light-emitting diodes (OLEDs) for display and lighting applications are currently the only technology that has reached the performance level suitable for a large-scale commercialization. Other organic electronic devices such as solar cells, photodetectors, field-effect transistors (FETs) and thermoelectric generators still need substantial research efforts to improve their properties and realize their full potential for a variety of applications including the Internet of Things, energy harvesting, healthcare and wearable electronics. 

Strong light-matter coupling has been explored in organic semiconductors leading to the observations of polariton condensation and high-efficiency polaritonic emission at room temperature [1]. In the recent years, a variety of novel organic optoelectronic device architectures has emerged to exploit the unique features of this strong coupling regime. This research has led to the demonstration of optically-pumped organic polariton lasers [2], highly efficient polaritonic OLEDs with narrow band emission [3], organic polaritonic photodetectors with spectrally extended responsivity [4] and polaritonic organic solar cells with reduced photon energy losses [5]. Few recent works have also suggested the possibility to use strong coupling for boosting the conductive properties of organic thin films [6]. While past research efforts to enhance organic electrical conductivity have been mainly focused on the development of novel materials, recent advances in nanostructured plasmonic metamaterials [7] allowing to control the strength of the light-matter interactions could open exciting and still unexplored opportunities to improve the conductive properties of organic electronic devices. 

The successful PhD candidate will investigate the influence of innovative plasmonic metamaterial nanostructures on the electrical and electro-optical properties of novel strongly-coupled organic electronic device architectures. The results will provide new important guidelines to boost electrical conductivity and open a completely new toolbox to improve the performance of organic optoelectronic devices. The student will learn and apply a broad range of organic device fabrication and characterization techniques, work in a state-of-the-art cleanroom and use a cryogenic probe station to study the temperature dependence of the electrical properties of organic electronic materials. This project represents a unique opportunity for a motivated PhD student to work at the forefront of an interdisciplinary and timely research topic, and to gain strong expertise in different areas of research, from the engineering and characterization of advanced organic electronic architectures to the photophysics of organic conjugated materials and the physics of plasmonic metamaterials. 

To be eligible, applicants should hold or expect to receive a minimum 2:1 Honours degree (or the international equivalent) in physics, material science or any related disciplines. The successful candidate should be highly motivated to undertake multidisciplinary research and demonstrate enthusiasm for research, the ability to think and work both independently and in team, excellent analytic and communication skills. Previous experiences in organic electronics will be considered advantageous. The student will work in a new laboratory at the School of Physics and Astronomy of the University of St Andrews, interacting with faculty members, postdoctoral researchers and other postgraduate students involved in the well-equipped Organic Semiconductor Centre. A PhD scholarship of the University of St Andrews is available for Home/EU and international students. Note that non-UK applicants must imperatively meet English language entry requirement (IELTS with a minimum overall score of 6.5 or the equivalent).  The scholarship will cover 3.5 years of stipend and fees, and the School will cover costs associated with any required visa. The position will remain open until a suitable candidate is found. 

Informal enquiries are welcome and should be made by email to Dr Jean-Charles Ribierre (jr43@st-andrews.ac.uk).

[1] J. Keeling, S. Kena-Cohen, Annu. Rev. Phys. Chem. 71, 435 (2020).
[2] S. Kena-Cohen, Nature Photon. 4, 371 (2010); M. Wei et al., Laser & Photon. Rev. 15, 2100028 (2021).
[3] A. Mischok et al., Nature Photon. 17, 393 (2023).
[4] E. Eizner et al., ACS Photon. 5, 2921 (2018).
[5] V.C. Nikolis et al., Nature Comm. 10, 3706 (2019).
[6] E. Orgiu et al., Nature Mater. 14, 1123 (2015) ; K. Nagarajan et al., ACS Nano 14, 10219 (2020), A. Thomas et al., https://arxiv.org/abs/1911.01459; F. J. Garcia-Vidal et al., Science 373, eabd0336 (2021).
[7] P. Wang et al., Chem. Rev. 122, 15031 (2022); P. Huo et al., Adv. Opt. Mater. 7, 1801616 (2019).  

The circumgalactic medium (CGM) that surrounds galaxies provides the fuel for them to grow, and the sink for them to stop growing. Quantifying and understanding the CGM is crucial for linking galaxy growth over cosmic time to the large web-like structures (Cosmic Web) in which they live, and thereby understanding how and why some galaxies continue to grow while others stop forming stars.  Cross-correlation between absorption systems detected in the spectra of background quasars with a foreground galaxy population have revealed important details about the CGM of galaxies. In this project, we will apply this method to unprecedentedly large samples of galaxies and background QSOs from the DESI survey (https://www.desi.lbl.gov). We will study the gas profiles around galaxies with different star formation histories, living in different environments, and in the filaments that feed them. This work will be supported by parallel analyses in simulations.

This project would be eligible for funding including: STFC DTP (Must be within STFC remit.)

 

In recent years there have been enormous advances in fabricating quantum devices from materials with unique and exotic properties. Such devices often combine several materials in a heterostructure, e.g., consisting of a superconductor and a semiconductor with strong spin-orbit interaction. Devices formed from a combination of unique materials enable the realisation of properties that are not easily achieved in a single material. Naturally, such devices present a huge potential for both new physics and future technological applications. However, to characterise these devices requires new probes and to predict novel phenomena demands new theoretical tools.

This project will investigate transport responses beyond Ohm's law. In other words, currents that are generated due to nonlinear orders in the electric field. Importantly, nonlinear transport coefficients often have intimate connections with the symmetries and the topological properties of a material or device. These connections make non-linear transport phenomena perfect for the detection of subtle electronic characteristics that are key for future applications of quantum technologies and also a fantastic playground for the interplay of symmetries and topology for novel quantum phenomena. Moreover, it was recently realised that similar nonlinear effects in superconductors can lead to the so-called superconducting diode effect, whereby a supercurrent can flow in one direction in a material or device, but there is a finite resistance in the opposite direction.

The main aims of this project will be to understand how the out-of-equilibrium nature of nonlinear transport effects and their connections to symmetry/topology can be exploited to create new probes. For instance investigating nonlinear effects in different types of qubits to realise new kinds of readout, with potentially higher fidelities. Also, for instance, considering how nonlinear effects can be used to investigate strongly correlated matter. To achieve these goals will require the use of both analytic techniques (Kelydsh/Green's function formalism) and computational techniques.

Further reading:

• Y Tokura and N Nagaosa, Nat. Comm. 9, 3740 (2018)
• HF Legg, M Rößler, et al., Nat. Nanotech. 17, 696–700 (2022)
• Y Wang, HF Legg, et al., PRL 128 (17), 176602 (2022)
• RMA Dantas, HF Legg, S Bosco, D Loss, J Klinovaja, PRB 107 (24), L241202 (2023)
• HF Legg, D Loss, J Klinovaja, PRB 106, 104501 (2022)
• HF Legg, K Laubscher, D Loss, J Klinovaja, PRB 108 (21), 214520 (2023)

This project would be eligible for funding including: EPSRC DTP (Must be within EPSRC remit.)

• The Centre for Designer Quantum Materials

 

In this project you will work towards building theoretical models of a chemical reaction happening inside a cavity. The cavity is able to confine electromagnetic radiation that can induce a transition between electronic or vibrational states of the molecule(s). However, even when the cavity is unpopulated with photons, vacuum fluctuations could still modify the eigenstates of the molecule-photon system, and in turn this may change the rates and outcome of a chemical reaction.

We recently invented a new technique for studying the dynamics of small open quantum systems, in which the dynamics of quantum system strongly coupled to one or more environments can be modelled. We have shown our method is extremely efficient and able to simulate a very wide range of models. We are now working on how we might extend these models to accurately capture the very large number of molecules that might be involved in a chemical reaction. By using and developing such techniques further, you will model the dynamics of the molecules inside a cavity, treating the cavity modes and molecular vibrations as strongly coupled environments.

We also plan to propose and describe experiments that aim to demonstrate cavity-induced chemical catalysis that are being performed by our collaborators and the Universities of Sheffield and Milan. These might include efforts to improve transport characteristics in a transistor, and altering the progress of an isomerization reaction.

Related literature:

PT-MPO techniques - the new methods we have developed to describe strongly coupling open systems:
[1] Strathearn et al. "Efficient non-Markovian quantum dynamics using time-evolving matrix product operators" Nature Comms. 9 3322 (2018)
[2] Fux et al. "Efficient exploration of Hamiltonian parameter space for optimal control of non-Markovian open quantum systems" Phys. Rev. Lett. 126 200401 (2021)
[3] Gribben, Rouse, Iles-Smith et al. "Exact dynamics of non-additive environments in non-Markovian open quantum systems" PRX Quantum 3 010321 (2022)
[4] Cygorek et al. "Numerically-exact simulations of arbitrary open quantum systems using automated compression of environments" Nature Physics 18 662 (2022)
Possible experimental demonstration of this kind of thing:
[5] Thomas et al. "Tilting a ground-state reactivity landscape by vibrational strong coupling" Science 363 615 (2019)
A model proposing a way in which reaction rates might be influenced by strong coupling:
[6] Campos-Gonzalez-Angulo et al. "Resonant catalysis of thermally-activated chemical reactions with vibrational polaritons" Nat Commun. 10 4685 (2019)
A recent demonstration, using molecules in cavities, of superabsorption, by our group and that of experimentalist collaborators:
[7] Quach et al. "Superabsorption in an organic microcavity: towards a quantum battery" Science Advances 8 eabk3160 (2022).

This project would be eligible for funding including: EPSRC DTP scholarships administered by the University.

There now exist a suite of different experimental techniques that can be used to image how the excitations of a quantum system change in both space and time. Such methods include transient absorption microscopy, which can probe features of above about 100 nm, and scanning tunnelling microscope luminescence, which can reach features that are smaller than a single molecule.

Such techniques are very exciting since they open a new window on how complex quantum mechanical processes work and what their function is in real devices. For example, they allow us to track how absorbed energy moves around in a solar cell, thus enabling us to design more efficient devices. In addition, imaging biomolecules in this way will allows us a greater understanding the fundamental mechanisms of life – and to probe the key role of non-equilibrium dynamics in biology.

It is vital then, to develop theoretical tools that are able to model the quantum dynamics of systems like molecules, which are typically strongly coupled to an environment of vibrational modes. Such open quantum systems undergo non-Markovian dynamics, in which the behaviour of a system cannot be predicted from its current state alone. What it has done in the past, too, affects what it will do in the future.

We have developed a set of ground-breaking new tools that enable the ultra-efficient modelling of such systems. Our tools are based on tensor networks, and are ideally suited for extracting the kinds of spatio-temporal information that modern experiments are now able to provide. In this project your aim will be to identify and model the signals that are generated in these experiments.

In the longer term, this work will help to identify better device designs for solar energy harvesting, In addition, we hope to understand how quantum allostery—i.e. signalling between different parts of a protein that triggers a biological function—works.

This PhD project will be jointly supervised by Prof Brendon Lovett and Dr Alex Chin, Sorbonne (Paris).

 Related literature:

Tensor network methods we we have developed to describe strongly coupling open systems:
[1] Lacroix, Dunnett, Gribben, Lovett, and Chin "Unveiling non-Markovian spacetime signaling in open quantum systems with long-range tensor network dynamics" Phys. Rev. A 104 052204 (2021)
[2] Strathearn et al. "Efficient non-Markovian quantum dynamics using time-evolving matrix product operators" Nature Comms. 9 3322 (2018)
[3] Fux et al. "Efficient exploration of Hamiltonian parameter space for optimal control of non-Markovian open quantum systems" Phys. Rev. Lett. 126 200401 (2021)
[4] Gribben, Rouse, Iles-Smith et al. "Exact dynamics of non-additive environments in non-Markovian open quantum systems" PRX Quantum 3 010321 (2022)
[5] Cygorek et al. "Numerically-exact simulations of arbitrary open quantum systems using automated compression of environments" Nature Physics 18 662 (2022)

Experimental methods probing spatio-temporal correlations:
[6] Kong et al. "Probing intramolecular vibronic coupling through vibronic-state imaging" Nature Comms. 12 1280 (2021)
[7] Zhu and Cheng "Transient absorption microscopy: Technological innovations and applications in materials science and life science" J. Chem. Phys. 152 020901 (2020)
[8] Pandya, et al. "Microcavity-like exciton-polaritons can be the primary photoexcitation in bare organic semiconductors" Nature Comms. 12 6519 (2021)

Allostery
[9] Leitner "Energy Flow in Proteins" Ann. Rev. Phys. Chem. 59 233 (2008)

This project would be eligible for funding including: EPSRC DTP scholarships administered by the University. 

Small "waste" solutes circulate the narrow space in between brain cells and are cleared through mechanisms not fully understood. This knowledge gap is partly due to the lack of techniques to study dynamic events such a complex space. Exciting advances in this field have recently shown that flow-mediated clearance is enhanced during sleep due to a major volume change in the extracellular space, facilitating the flow of the interstitial fluid. However, this process has only been characterised at a low spatial resolution while the physiological changes regulating this process occur at the nanoscale. Understanding flow circulation at high spatial resolution requires the development of nanoscale imaging techniques that can study the brain in living animals. The PhD project aims to understand how nanoscale changes in Aquaporin-4 arrays facilitate volume changes in the extracellular space of the brain, which in turn will regulate the clearance of soluble waste products. To achieve this, the successful PhD candidate will perform super-resolution imaging in brain slices and single-nanoparticle tracking in vivo to characterise key features of the so called "glymphatic" hypothesis. We are looking for an enthusiastic PhD student with a background in either physical or biological sciences, willing to work in an interdisciplinary environment studying the brain at the single-molecule level. Experience in biophysics and/or neurosciences will be advantageous. 

Relevant references:
Varela et al., "Optical structural analysis of individual α-synuclein oligomers". Angewandte Chemie International Edition, 4886-4890 (2018).
Godin et al., "Single-nanotube tracking reveals the nanoscale organization of the extracellular space in the live brain". Nature Nanotechnology, 12, 238?243 (2017).
Varela et al., "Targeting neurotransmitter receptors with nanoparticles in vivo allows single molecule tracking in brain tissue". Nature Communications, 7:10947 (2016).
Varela et al., "Single nanoparticle tracking of NMDA receptors in cultured and intact brain tissue". Neurophotonics, 3:41808 (2016).
Xie et al., "Sleep drives metabolite clearance from the adult brain". Science 342, 373-7 (2013).
Nicholson et al., "Brain Extracellular Space: The Final Frontier of Neuroscience". Biophysical Journal, 113, 2133?2142 (2017).

 

Photodynamic Therapy (PDT) is a treatment for cancer that involves light-activation of a photosensitiser and causes cell death by release of singlet oxygen and free radicals. The Scottish PDT Centre was established in Ninewells Hospital, Dundee in 2000 thanks to a generous donation from the Barbara Stewart Charitable Trust. Since its introduction in Dundee, over 2,000 treatments have been carried out. The photosensiters used for PDT also have the property that they fluoresce and so they can be used for photodiagnosis (PD), which is performed at the Scottish PDT Centre to direct the surgeon towards tissue that is likely to be cancerous.

The purpose of the proposed PhD program is to gain a fuller understanding of the interaction between the incident light and the tumour. Optimal treatment regimes have not been established. We would like to be able to model both PDT and PD. To assist in this, we propose to develop theoretical radiation transfer models using Monte Carlo techniques in order to simulate the incident light and the fluorescent emission. This will be done for the range of tissue types where PDT is performed in Dundee. This includes skin (the most accessible), the oral cavity, the brain and bladder.

The work will also find application in a wide range of other areas in the drive towards minimally invasive and highly targeted therapies. In addition to the PDT described above, the techniques can be applied to so-called ‘caged compounds’ that are a range of biologically active compounds that are activated with light. In order to apply such compounds within a therapeutic environment, understanding the light tissue interactions is of key importance.

Light distribution measurements will be made around a range of light delivery devices, including cylindrical diffusers and miniature balloons filled with light-scattering media. Further measurements will be carried out using optical fibres embedded in tissue samples and using ultrashort pulses to probe two-photon activation at depth within the body. Fluorescent emission spectra will also be measured using a specially constructed optical biopsy system.

This project provides many opportunities for the student to study PDT and other light activated therapies from theoretical, experimental, and clinical perspectives. There will be joint supervision from Dr Harry Moseley, who is Technical & Scientific Director of the Scottish PDT Centre and Honorary Reader at the University of Dundee, and Drs Tom Brown and Kenny Wood, who are Lecturers in the Department of Physics and Astronomy at the University of St Andrews. Dr Wood will supervise the theoretical aspects of the PhD (Monte Carlo radiation transfer), Dr Brown the experimental light tissue studies and Dr Moseley will supervise the clinical applications at Ninewells Hospital.

 

Raman spectroscopy is a powerful label-free method which can be used to identify the molecular composition of a wide variety of materials. In recent years, we have applied this to systems ranging from bacteria [1], amino acids [2] and epithelial and immune cells [3,4] through to food and drink [5,6].
We have pioneered new measure techniques with Raman Spectroscopy, including wavelength modulated Raman spectroscopy (WMRS) [3] which efficiently removes the auto-fluorescence from biological samples, such as cells or tissue, therefore hugely enhances the signal to noise level and its detection ability. We have also demonstrated the capability to perform Raman imaging through a single multimode optical fibre [7]. More recently, by careful tailoring of the input beam profile using an axicon, we have demonstrated an efficient method to decouple the Raman signals produced by a container and its contents, allowing us to measure the chemical signature of whiskies with no contribution from the glass bottle, without needing to open the bottle [5].
This project aims to perform Raman spectroscopy at greater depths within biological samples, by harnessing the techniques above, to answer important questions in the medical diagnosis capabilities of Raman spectroscopy.

The work will take place in the Optical Manipulation Group (www.opticalmanipulationgroup.com), whose interests also span from Biophotonics and the development of new tools for optical imaging at depth to optical trapping and manipulation of microparticles and optical metrology using laser speckle. In this highly collaborative environment, there is likely to be opportunities to contribute to research in these other areas.
This project may be offered as a co-tutelle degree where a significant component of the research would be undertaken at University of Adelaide.
For more details or enquires, contact Dr Graham D Bruce (gdb2@st-andrews.ac.uk) and Prof Kishan Dholakia (kd1@st-andrews.ac.uk).

[1] V. O. Baron, M. Chen, B. Hammarström, R. J. H. Hammond, P. Glynne-Jones, S. H. Gillespie and K. Dholakia. Real-time monitoring of live mycobacteria with a microfluidic acoustic-Raman platform. Commun. Bio. 3, 235 (2020)
[2] M. Chen, L. Strother, G. H. Doherty, and K. Dholakia. Optical analysis of homocysteine metabolites using vibrational spectroscopy. OSA Continuum 3,1958 (2020)
[3] L. Woolford, M. Chen, K. Dholakia and C. S. Herrington. Towards automated cancer screening: label-free classification of fixed cell samples using wavelength modulated Raman spectroscopy. Journal of Biophotonics 11, e201700244 (2018)
[4] R. K. Gupta, M. Chen, G. P. A. Malcolm, N. Hempler, K. Dholakia and S. J. Powis. Label-free optical hemogram of granulocytes enhanced by artificial neural networks. Opt. Express 27, 13706 (2019)
[5] H. Fleming, M. Chen, G. D. Bruce and K. Dholakia. Through-bottle whisky sensing and classification using Raman spectroscopy in an axicon-based backscattering configuration. Anal. Methods 12, 4572 (2020)
[6] N. McReynolds, J. M. Auñón Garcia, Z. Guengerich, T. K. Smith and K. Dholakia. Optical spectroscopic analysis for the discrimination of extra-virgin olive oil. Applied Spectroscopy 70, 1872 (2016)
[7] I. Gusachenko, M. Chen and K. Dholakia. Raman imaging through a single multimode fibre. Opt. Express 25, 13782 (2017)

This project would be eligible for funding including: EPSRC DTP; University of Adelaide co-tutelle.
 

This PhD thesis will investigate the structures and kinematics of protoplanetary disks using high resolution, sub-mm interferometric observations with the Atacama Large Millimeter Array (ALMA). Through programs like MAPS, exoALMA, and others, ALMA has consistently demonstrated the ability to detect "non-Keplerian" motions of the molecular gas in protoplanetary disks hosted by pre-main sequence stars. Many threads of evidence suggest that these motions are directly caused by (proto)planets embedded in the disk, however, there are other disk processes that could alter the Keplerian flow of gas. It is the goal of this project to explore these possibilities using high resolution observations of protoplanetary disks, as well as any ancillary information. In order to analyse the rich, Fourier-type datasets from ALMA, this project will develop and employ statistical and machine learning techniques concerning Bayesian inference and Regularized Maximum Likelihood Imaging (RML).

References:

• Zawadzki, Czekala, et al. (2023): Regularized Maximum Likelihood Image Synthesis and Validation for ALMA Continuum Observations of Protoplanetary Disks
• Izquierdo et al. (2023): The Disc Miner. II. Revealing gas substructures and kinematic signatures from planet-disc interaction through line profile analysis
• Molecules with ALMA at Planet-forming Scales (MAPS)
• exoALMA large program

 
This project would be eligible for funding including: STFC DTP.

 

Galaxy mergers are known to play a major role in the life history of galaxies by disrupting the stellar disk and quenching of star formation to turn star-forming disk galaxies into quiescent elliptical galaxies. While there is a long history of hydrodynamic simulations helping us to understand the physics that occurs during this tumultuous time in the life of a galaxy, recent evidence suggests that current-generation simulations have missed some key factors. In particular, observations of significant cold gas reservoirs in galaxies which have undergone a recent significant burst of star formation, indicate that the gas is not removed by strong winds, as assumed in the current generation simulations. Rather turbulence may play a role in reducing star formation efficiency, either triggered by the recent merger, stellar winds or a central active galactic nuclei. One key limitation in galaxy scale simulations is the spatial and temporal resolution. In this project we uniquely bring together the expertise of Dr. Rowan Smith in very high resolution galaxy-scale simulations of star-forming disks, and Prof. Vivienne Wild in the observational properties of recent galaxy mergers. We will create a brand new suite of colliding galaxy simulations at very high resolution, and compare this to standard low-resolution simulations. We will investigate the impact of resolution on the star formation history of the merged galaxy, and try to understand how cold gas can still be present while not forming stars. Ultimately our results will inform sub-grid physics to be included in future cosmological hydrodynamic simulations.  

References:
"The Cloud Factory I: Generating resolved filamentary molecular clouds from galactic-scale forces" (DOI: 10.1093/mnras/stz3328)
"Resolved Molecular Gas Observations of MaNGA Post-starbursts Reveal a Tumultuous Past" (DOI: 10.3847/1538-4357/ac9dee)
"Comparison of stellar populations in simulated and real post-starburst galaxies in MaNGA" (DOI: 10.1093/mnras/staa2358)

This project would be eligible for funding including: STFC DTP (Must be within STFC remit.) 

 

When monochromatic light strikes a rough surface it produces a distinctive grainy interference pattern called speckle. This disordered pattern is often thought of as detrimental to optical systems, and has historically been predominantly studied by optical engineers seeking to remove or reduce its effects. However, the interference pattern produced is extremely sensitive to changes of the properties of the light, the scattering medium and the environment, and has begun to see increased use as a tool to perform precision measurements in a compact setup.
For example, in St Andrews we have developed a state-of-the-art speckle wavemeter, by passing coherent light through an integrating sphere [1] or a step-index multimode fibre [2]. By tracking changes in the speckle with multivariate analysis techniques such as Principal Component Analysis [2] or Convolutional Neural Networks [3], we can track changes in wavelength on the attometre scale, and can extend our device to simultaneously measure the wavelength of multiple lasers [4]. Wavelength is not the only property of the light that can be tracked, and we also recently demonstrated precision measurement of the polarisation states of multiple laser beams [5].
In this project, you will develop new applications and new techniques for precision measurements with speckle. This will include simultaneous tracking of multiple properties of the light and testing the capability of speckle to measure environmental changes such as temperature and pressure in real-world environments and for trace-gas detection.
The work will take place in the Optical Manipulation Group (www.opticalmanipulationgroup.com), whose interests also span from Biophotonics and the development of new tools for optical imaging at depth to Raman spectroscopy for chemical sensing and optical trapping and manipulation of microparticles. In this highly collaborative environment, there is likely to be opportunities to contribute to research in these other areas. 
This project may be available as part of a co-tutelle agreement, where a significant portion of the research would be conducted at University of Adelaide.
For more details or enquires, contact Dr Graham D Bruce (gdb2@st-andrews.ac.uk).

[1] N. K. Metzger, R. Spesyvtsev, G. D. Bruce, B. Miller, G. T. Maker, G. Malcolm, M. Mazilu and K. Dholakia. Harnessing speckle for a sub-femtometre resolved broadband wavemeter and laser stabilization. Nature Communications 8, 15610 (2017)
[2] G. D. Bruce, L. O’Donnell, M. Chen and K. Dholakia. Overcoming the speckle correlation limit to achieve a fiber wavemeter with attometer resolution. Optics Letters 44, 1367 (2019)
[3] R. K. Gupta, G. D. Bruce, S. J. Powis and K. Dholakia. Deep learning enabled laser speckle wavemeter with a high dynamic range Laser and Photonics Reviews 14, 2000120 (2020)
[4] G. D. Bruce, L. O’Donnell, M. Chen, M. Facchin and K. Dholakia. Femtometer-resolved simultaneous measurement of multiple laser wavelengths in a speckle wavemeter. Optics Letters 45, 1926 (2020)
[5] M. Facchin, G. D. Bruce and K. Dholakia. Speckle-based determination of the polarisation state of single and multiple laser beams. OSA Continuum 3, 1302 (2020)

This project would be eligible for funding including: EPSRC DTP; University of Adelaide co-tutelle.
 

The goal of this PhD project is the exploration of novel ring-shaped atom traps for applications to quantum sensing. You will make use of techniques from the field of atomtronics, a new field at the frontier of matter-wave optics seeking to realize atomic circuits in which ultracold atoms are manipulated in versatile optical or magnetic traps. In particular, your work will be based on holographic optical traps, which are produced by diffracting a laser beam off a computer-controlled optical device, known as a Spatial Light Modulator (SLM). This apparatus offers unparalleled flexibility for the purpose of trapping and manipulating ultracold atoms. 

In this context, in this PhD project you will simulate the dynamics of a Bose-Einstein condensate confined in a ring trap and prepared in a vortex-anti vortex superposition. It has been theoretically proposed that this configuration can be used as an inertial sensor, e.g. to measure rotations, or as a magnetic field sensor [1,2]. In both cases, the external influence causes a precession of the BEC standing wave, which can be measured experimentally. In your project, you will use numerical simulations to optimise the preparation of condensate in the superposition state, study its evolution in the ring trap, and finally test the sensitivity of this device to external magnetic fields for realistic experimental parameters. This work is mostly computational, but some aspects will also be explored experimentally.

[1] S. Thanvanthri, K. T. Kapale and J. P. Dowling, "Ultra-stable matter-wave gyroscopy with counterrotating vortex superpositions in Bose-Einstein condensates", Journal of Modern Optics, vol. 59, no. 13, pp. 1180-1185 (2012). (doi: https://doi.org/10.1080/09500340.2012.702228)
[2] G Pelegrí, J Mompart and V Ahufinger, "Quantum sensing using imbalanced counter-rotating Bose-Einstein condensate modes", New J. Phys. 20 103001 (2018).  (doi: 10.1088/1367-2630/aae107)

 

The search for novel quantum states of matter in artificial thin-film structures, in which superconducting (S) and ferromagnetic (F) materials are juxtaposed, has reached an exciting and timely stage of development. In the last year a series of new landmark experimental results seem set to herald a period of rapid expansion of interest and activity in the field. This was the pioneering observation by several groups of spin-triplet supercurrents traversing relatively thick F layers [1-3], believed theoretically to be signatures of a novel equal-spin spin-triplet and possibly ‘odd frequency’ superconducting state. This achievement represent the culmination of several years of breakthrough experiments [1-7] in a field whose modern era began almost most a decade ago, with the experimental discovery of Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) [8] type states in S-F-S structures [10]. What both the FFLO [8] and the odd-frequency pairing phenomena [9] have in common is that they were predicted to occur theoretically in bulk systems [8,9] but only in state-of-the-art artificial thin-film structures were they finally demonstrated to exist [1-7,10-13]. Modern thin-film growth and large area lithographic patterning open-up an enormous range of further possibilities for engendering novel quantum states of matter via the controlled interaction S and F order on the nanoscale. This capability also offers the promise of designing and engineering hybrid metamaterials (in a similar spirit to electromagnetic metamaterials) with tailored quantum properties. Concurrently there is enormous interest in spintronics, the manipulation of electronic spin for application in novel electronic devices. The structures investigated within this programme marry the fields of mesoscopic superconductivity, novel strongly correlated electron physics and spintronics. By introducing quantum coherence phenomena into spintronic types devices, this also opens up the possibility of non-locality and entanglement, with possible application long-term in quantum computation.

Professor Steve Lee leads an EPSRC funded Critical Mass Grant award (St Andrews, Leeds, Bath, Royal Holloway, ISIS, with partners in PSI ( Swizterland), Cambridge, and Leiden ) that underpins an international research programme that brings together a team with a wide range of relevant expertise to explore the physics of such systems. We make use of some of the most powerful probes in condensed matter physics (scattering and surface probe techniques) in order to throw new light onto the physics of artificial S-F metamaterials, with particular emphasis on spatially–resolved measurements. This combines with state-of-the-art facilities for materials growth and patterning and world leading instrumentation for measurement. The programme is also informed by cutting-edge theory. There are significant opportunities for research students within this collaboration, with excellent access to world leading research facilities (such as Diamond, ISIS, ILL, PSI, SLS). Due to the strong interactions between nodes there is also significant scope for student mobility in order to enhance training and experience. This is all underpinned by access to excellent graduate training bot via the SUPA Graduate School and the additional benefits of the Doctoral Training Centre in condensed matter physics based at St Andrews, Edinburgh and Heriot Watt.

[1] J.W.A. Robinson et al., Science 329 59 (2010).
[2] T.S. Khaire et al., PRL 104, 137002 (2010).
[3] M.S. Anwar et al., PRB 82, 100501 (2010).
[4] R.S. Keizer et al., Nature 439 825 (2006).
[5] J. Wang et al., Nat. Phys. 6 389 (2010).
[6] I. Sosnin et al., PRL 96 157002 (2006).
[7] D. Sprungmann et al., PRB 82, 060505 (2010).
[8] P. Fulde and R.A. Ferrell, PRB 135 A550 (1964); A.I. Larkin and Y.N. Ovchinnikov, Zh. Eksp. Teor. Fiz. 47, 1136 (1964).
[9] V.L. Berezinskii, JEPT Lett. 20, 287 (1974).
[10] V.V. Ryazanov et al., PRL 86, 2427 (2001); T. Kontos et al., PRL 89, 137007 (2002).
[11] A.I. Buzdin et al., JETP Letters 35, 178 (1982)
[12] F.S. Bergeret et al., PRL 86, 4096 (2001); Rev. Mod. Phys. 77, 1321 (2005).
[13] M. Eschrig et al., PRL 90, 137003 (2003); M. Eschrig and T. Löfwander, Nature Phys. 4 138 (2008).

This project is offer in conjunction with Prof. Amir Yacoby at Harvard.

In this project, we aim to bridge the gap between two fields in which huge progress has been made over the past twenty years.In mesoscopic physics, the aim is to work with samples that are specially fabricated so that their physical size becomes comparable with one or more of the fundamental length scales of the underlying physics. In a metal this might be the mean free path, and in a superconductor it might be the coherence length or the penetration depth. So far, the vast majority of research into mesoscopic physics has been performed on traditional materials in which the electron-electron interactions are relatively weak. In parallel with these developments, equally rapid progress has been made on research into new materials with very strong electron-electron interactions, which lead to high quasiparticle masses and an exciting variety of metallic, superconducting and magnetic ground states. For technical reasons the two fields have advanced in parallel, with little cross-fertilisation of ideas and techniques. The goal of this jointly supervised project is to combine the different expertise of our two groups to bring strongly interacting electrons into the mesoscopic regime. You will work both in St Andrews and at the spectacular new Harvard Nanoscience Center, performing pioneering experiments on the fabrication and measurement of correlated electron mesoscopic devices.

(Jointly affiliated to both University of St Andrews and Max Planck Institute for the Chemical Physics of Solids, Dresden)

There is rapidly growing interest in indoor photovoltaics because of their potential in the huge technology field of the Internet of Things (IoT) [1]. IoT refers to a smart network of internet connected electronic and electrical devices which can communicate with each other and respond promptly. Wireless sensors, requiring only µW-mW range of electrical power for their efficient functioning, are the most fundamental components in these smart devices. By 2025, there will be more than 75 billion IoT connected devices with half of the components to be installed inside the buildings (web reference). Sustainably powering these sensors is a huge challenge. Light energy from artificial light sources such as white LEDs and fluorescent lamps are ubiquitous inside the building and can be converted to electricity using the photovoltaic effect, to autonomously power IoT sensors. Among the various photovoltaic technologies available today such as silicon, dye sensitised, hybrid perovskites and organic photovoltaics (OPVs), the latter one is very promising as they are scalable, flexible, conformable and possess excellent optoelectronic properties suitable for efficient light-harvesting [2, 3]. Furthermore their wider band gap than most other photovoltaic materials, makes them better matched to the spectrum of indoor lighting, which is very different from the sun.
The first generation of organic photovoltaics (OPVs) mainly used fullerene-based acceptors and the power conversion efficiency (PCE) of the corresponding bulk-heterojunction (BHJ) devices levelled off around 10% under 1 Sun irradiance (100 mW/cm²). However, with the emergence of non-fullerene acceptors, the PCE of the analogous organic solar cells are soaring towards 20% [4]. These non-fullerene acceptor based BHJs are particularly interesting for indoor OPVs, because of their tunable bandgap, low open-circuit voltage loss, high absorption coefficient in the visible range and demonstrated maximum PCE of ~ 30% under indoor illumination (< 1 mW/cm²). However, this demonstrated efficiency is only half of the theoretically predicted maximum PCE value.
In this PhD project, you will explore the bandgap tuning of NFA based organic solar cells to maximise the spectral overlap of their absorption with the emission spectra of indoor light sources. You will also explore bulk and buried interface engineering to reduce the recombination losses, maximise the carrier extraction and push the PCE of indoor OPVs closer to its theoretically predicted value. The kinetics of photogenerated carriers will be studied using time-resolved photoluminescence (TR-PL) with measurements of transient photovoltage (TPV), transient current (TPC) and impedance spectroscopy measurements to further understand device operation and guide the improvement of low-intensity indoor light harvesting. You will have the opportunity to conduct the proposed research in a very supportive research environment with access to a breadth of advanced device fabrication and characterisation facilities.

References:
[1]  Mathews et al  Joule (2019) 6 1415
[2]  Hedley et al  Chem. Rev. (2017) 117 796
[3]  Mainville et al ACS Energy Lett. (2020) 5 1186
[4]  Feng et al Adv. Mater. (2021) 33 2100830

This project would be eligible for funding including: EPSRC DTP scholarships administered by the University.

• Energy Harvesting Research Group
  
  

Super Resolution Microscopy (SRM) is a broad class of microscopy techniques collectively aimed at breaking the fundamental limit imposed on fluorescence imaging due to the diffractive nature of light. Recent advances in SRMs have enabled nanometre and sub-nanometre resolution imaging of protein complexes in their native cellular environments. However, these methods remain severely limited in the size and number of complexes they can image; hence, improved methods are needed to image the widely sized intracellular protein complexes at a structural and ultra-structural level.

As part of this PhD project, you will develop a range of instrument automation, processing, and analysis tools to image structurally heterogeneous and disease-implicated protein complexes at molecular resolution with the aim of mapping the ultra-structural diversity of misfolded protein aggregates in mice and human brain samples of neurodegeneration. This opportunity will allow you to develop expertise in super resolution imaging, computer vision, and deep learning tools for biological imaging. As part of your training, you will be extensively exposed to the expansive fields of neurodegeneration and ultra-sensitive immunological assaying. Towards the end of the PhD, you will develop an all-rounded skill set that is in high demand across academia and industry.

Intrinsically Disordered Proteins (IDPs) regulate a wide range of biological processes by assembling into flexible complexes that escape (ultra) structural imaging using existing methods, such as Cryogenic Electron Microscopy (CryoEM), being heterogeneous. SRM can image single protein complexes but at a lower resolution. By pushing the resolution of SRM towards molecular scales, the (ultra) structure of flexible protein assemblies can be resolved at a single assembly level, allowing the structural basis of many biological processes and diseases to be studied.

The Danial Lab, situated at the School of Physics and Astronomy within the University of St Andrews, pioneers technical advancements aimed at advancing single-molecule fluorescence microscopy for ex vivo and in situ structural imaging. Within this pursuit, the lab wishes to accommodate researchers boasting diverse expertise, spanning from optical engineering and software development to biochemistry and assay development. Together, they would collaborate to unravel the structural and molecular foundations of human brain disorders. Accessible resources include cutting-edge single molecule microscopes that are fit-for-purpose as well as powerful workstations hosting the most advanced GPUs.

We are looking for a talented individual with strong and demonstrated expertise in Python programming (front-to-back end) as well as instrument automation applied to fluorescence imaging. The ideal candidate should demonstrate a strong enthusiasm for acquiring new skills at the forefront of biophotonics and neurodegeneration and the stamina to develop major software with wide impact.

For enquiries, please send an email (including a CV and an open-source repository of prior work) to Dr John S H Danial (jshd1@st-andrews.ac.uk).

This project would be eligible for funding including: PhD studentship committed by School of Physics and Astronomy.

• Centre of Biophotonics  

 

Hyperbolic metamaterials [1] are anisotropic metal/dielectric plasmonic nanostructures that exploit the basic dispersion relation of waves to manipulate light at the nanoscale and control light-matter interactions. They have rapidly gained an important role in nanophotonics due to their applications in sub-wavelength imaging, spontaneous emission engineering and sensing. Their main limitations come from their light propagation losses and their multiple-step fabrication processes. Recently, hyperbolic dispersion relation was found in a few solution-processed organic thin films [2]. These materials showed lower optical losses than plasmonic structures and could substantially enhance the spontaneous emission of light-emitting molecules placed near their interface. To fully exploit their potential, it is now essential to establish their structure-property relationship and provide new molecular guidelines to improve and tune their optical properties in the visible and near infrared spectral range.  

This PhD project in collaboration with a French CNRS laboratory aims to relate the structural and optical properties of new organic thin films that show hyperbolic relation dispersion. The experimental techniques required for this study include organic thin film fabrication by solution-processing and thermal evaporation, variable-angle spectroscopic ellipsometry, steady-state and time-resolved optical spectroscopy, attenuated total internal reflection and x-ray diffraction techniques. This project is challenging but represents a unique opportunity for a motivated PhD student to work at the forefront of an interdisciplinary and timely research topic. The expertise gained during this project will place the PhD student in a favorable position to pursue a scientific career either in academia or industry.

Strong coupling of photons and excitons has been observed in organic wavelength-scale microcavities and is of strong interest for both fundamental science devoted to light-matter interactions and a wide range of photonic applications.[3] Past research efforts to enhance the charge carrier mobilities of OFETs have been mainly focused on the development of novel organic semiconductors, the optimization of their molecular organization in the films and the improvement of the device architecture.[4] However, few recent works have suggested the possibility to use strong coupling for boosting the conductive properties of organic thin films.[5,6]  

To be eligible, applicants should hold or expect to receive a minimum 2:1 Honours degree (or the international equivalent) in physics, material science, physical chemistry or any related disciplines. The successful candidate should be highly motivated to undertake multidisciplinary research and demonstrate enthusiasm for research, the ability to think and work both independently and in team, excellent analytic and communication skills. Previous experiences in organic optoelectronics and photophysics of organic semiconductors will be considered advantageous. The student will work in a new laboratory at the School of Physics and Astronomy of the University of St Andrews, interacting with faculty members, postdoctoral researchers and other postgraduate students involved in the well-equipped Organic Semiconductor Center. A PhD scholarship funded by the Leverhulme Trust Foundation is available for Home/EU and international students. Note that non-UK applicants must meet English language entry requirement (IELTS with a minimum overall score of 6.5 or the equivalent). The scholarship will cover 3.5 years of stipend and fees, and the School will cover costs associated with any required visa. The position will remain open until a suitable candidate is found.

Informal enquiries are welcome and should be made by email to Dr Jean-Charles Ribierre (jr43@st-andrews.ac.uk)

[1] A. Poddubny et al. Nat. Photon. 7, 948 (2013); P. Wang et al., Chem. Rev. 122, 15031 (2022) ; P. Huo et al., Adv. Opt. Mater. 7, 1801616 (2019) ; A. Aigner et al., LSA 11, 9 (2022); K. J. Lee et al. Nat. Mater. 16, 722 (2017) ; K. J. Lee et al., Nano Lett. 18, 1476 (2018).
[2] Y. U. Lee et al. ACS Photon. 6, 1681 (2019) ; Y. U. Lee et al. Adv. Opt. Mater. 6, 1701400 (2018); M. J. Kim et al., Adv. Opt. Mater. 9, 2101091 (2021).

This project would be eligible for funding including: Leverhulme Trust Foundation.

Light-emitting polymers are promising materials for lasers because they combine novel optoelectronic properties with simple fabrication. In addition to being flexible, they have high gain and broad emission spectra. So far, the broad emission spectra have been used to make lasers that can be tuned over a range of wavelengths.
However, broad emission spectra open up another very interesting possibility, namely the possibility of generating short light pulses. This follows from the uncertainty principle DEDt>h/4p. A very short light pulse (small Dt) must contain a range of energies (wavelengths) of light (large DE). Light-emitting polymers can lase over a large range of wavelengths, and so have the potential to generate femtosecond light pulses. This project will explore generating short light pulses from these materials by a range of techniques, and particularly by the process of modelocking in which the phase of different modes is locked together such that their interference gives a train of short light pulses. This new type of laser would be compact, lightweight and generate short light pulses at a range of wavelengths in the visible region of the spectrum.

As part of a generously-funded Leverhulme research project, we seek an ambitious and motivated PhD student to join a research initiative aimed at investigating how the electronic structure and collective states of thin-film correlated oxides evolve with direct control over their material composition.
This is motivated by the recent discovery of superconductivity in thin-film nickel-based oxides when their structure is transformed from the perovskite to the so-called infinite layer form [1], upon removal of some of their oxygen atoms. This points to an enormous potential for tuning the electronic properties of thin-film oxides by active control of their oxygen stoichiometry, and utilising this to stabilise new collective phases.
You will develop routes to enable direct electronic structure measurements of such samples using our state-of-the-art laser-based angle-resolved photoemission spectroscopy (ARPES) and integrated molecular-beam epitaxy growth setup in St Andrews, as well as utilising measurements at leading synchrotron facilities in Europe and internationally. You will join a highly collaborative research group (https://www.quantummatter.co.uk/king) with broad interests across strongly correlated and spin-orbit coupled electronic materials.[2-7]

The position is available immediately, funded at the standard UK rate. Applications will be considered until the position is filled.
For further information, or to discuss specific research possibilities, please contact pdk6@st-andrews.ac.uk.  

[1] D. Li et al., Nature 572, 624 (2019)
[2] V. Sunko et al., Nature 549, 492 (2017) 
[3] J. Riley et al. Nature Physics 10, 835 (2014)
[4] M.S. Bahramy et al., Nature Materials 17, 21 (2018)
[5] V. Sunko et al., Science Adv. 6, eaaz0611 (2020)
[6] E. Abarca Morales et al., Phys. Rev. Lett. 130, 096401(2023)
[7] B. Edwards et al., Nature Mater. 22, 459 (2023)

This project would be eligible for funding including: Leverhulme Trust Foundation.

• The Centre for Designer Quantum Materials

 

Additional supervisor: Dr Nicholas Boardman nfb@st-andrews.ac.uk

This project will investigate the mechanisms behind star-formation cessation ('quenching') in distant galaxies, using the upcoming MOONRISE spectroscopic survey. MOONRISE observations will be taken with the MOONS instrument, due to be installed in the Very Large Telescope in Chile.
 
Observations of the nearby Universe have revealed galaxies with a range of properties: some galaxies (such as our own Milky Way) continue to form stars, while others appear to have quenched many billions of years ago. Probes into the nature of quenching have however been inconclusive from nearby galaxies, with data separately argued to support 'fast' (< 1Gyr) or 'slow' (~few Gyr) quenching. The student will work towards solving the nature of quenching, by analysing many thousands of distant galaxy spectra from the MOONRISE survey. Through detailed spectral analysis, the student will probe the stellar populations and gas of galaxies located billions of light-years away, viewing deep into the Universe's past.

References:
Cirasuolo et al. 2020: MOONS: The New Multi-Object Spectrograph for the VLT
Maiolino et al. 2020: The Main MOONS GTO Extragalactic Survey
Wild et al. 2020: The star-formation histories of z ~ 1 post-starburst galaxies
Peng et al. 2015: Strangulation as the primary mechanism for shutting down star-formation in galaxies
Leung et al. 2024: Chemical evolution of post-starburst galaxies: implications for the mass-metallicity relation

This project would be eligible for funding including: STFC DTP (Must be within STFC remit.) 

 

WEAVE is a brand new spectrograph for the William Herschel Telescope in the Canary Islands, currently completing commissioning. WEAVE IFU's very large field of view and extensive wavelength range makes it ideal for studying the detailed formation history of local galaxies, via spatially resolved kinematics, star formation histories and chemical properties. This project will focus on local post-starburst galaxies. These are a particularly interesting and unusual class of galaxies, which are apparently caught in a transition phase between gas-rich star-forming disks and gas-poor quiescent elliptical galaxies. The process(es) that cause this transition for the galaxy population as a whole are poorly constrained, and this is one of the key questions currently being addressed in the field of extra-galactic astronomy. Simulations reveal that the strong radial gradients observed in many post-starburst galaxies are hard to recreate, and are hugely sensitive to Active Galactic Nuclei feedback prescriptions assumed, making them ideal observational targets to better understand the processes triggering this transition in the local Universe.  

References:
Post-starburst galaxies in SDSS-IV MaNGA
Comparison of stellar populations in simulated and real post-starburst galaxies in MaNGA
Galaxy mergers can rapidly shut down star formation
The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation

Note: this project will only be offered if commissioning of the WEAVE instrument is successful and initial data is available for analysis at the start of the PhD project.

This project would be eligible for funding including: STFC DTP (Must be within STFC remit.) 

 

Extensive layers of diffuse ionized gas are observed in the Milky Way and other galaxies. This project will study the structure, ionization, heating, and dynamics of diffuse ionized gas using our newly developed radiation hydrodynamics codes that incorporate feedback processes including photoionisation, stellar outflows, and supernovae. Output from our 3D rad-hydro simulations will be compared with emission line observations of the diffuse ionised gas.

Star formation is a fundamental process in astrophysics. Stars ended the cosmic dark ages, re-ionised the Universe and created all the heavy elements via stellar nucleosynthesis. In galaxies the process of star formation represents a continuous cycle of matter – known as the baryon cycle. Dense gas is gathered in molecular clouds (so-called because they mainly consist of molecular hydrogen), and these then fragment gravitationally to form stars. The most massive of these stars will die in supernovae explosions, which inject thermal and kinetic energy as well as chemically enriched gas back into their surroundings. This continuous transfer of gas and energy between stars and the interstellar medium is a major internal driver of galactic structure and its subsequent evolution.

Unfortunately, our view of the star forming interstellar medium has previously been limited to our local environment in the Milky Way. This makes it hard to understand if, and how, star formation depends on environment (e.g., in galactic bars or spirals, at the galactic centre or in the outer galaxy). For the first time it is now possible to study the ISM at the scales of individual molecular clouds in nearby galaxies thanks to the PHANGS (Physics at High Angular resolution in Nearby GalaxieS) surveys using ALMA (Leroy et al. 2021) and the JWST (Lee et al. 2023). To fully utilise this resource, we need a set of observational predictions and metrics for comparison to understand the importance of galactic environment and different physical forces in determining star formation within galaxies. This project will create such diagnostics by generating synthetic observations using our groups "Cloud Factory" (Smith et al. 2020) simulations of isolated galaxies. These unique models simulate resolved star forming clouds embedded in a realistic galaxy environment. The project would have scope to go down either a more theoretical/numerical or observational path depending on the skills and interests of the student, and the PhD student would become a member of the international PHANGs collaboration.

This project would be eligible for funding including: STFC DTP. (Must be within STFC remit.)

 

Most stars form in clusters, where energetic feedback from massive (proto)stars – including outflows, ionization, heating, and winds – shapes the environment and impacts accretion. The relative importance of different feedback processes is a key outstanding issue in our understanding of massive star formation.

The aim of this project is to conduct a large-scale observational study of the role and physics of feedback in young massive (proto)clusters, using ALMA and Jansky Very Large Array (VLA) observations of "Extended Green Objects (EGOs)". The PhD project will focus on imaging and analyzing ALMA observations of the EGO-10, a sample of typical young, massive star-forming regions that exist in a specific evolutionary state where active outflows dominate their infrared appearance.

This project would be eligible for funding including: STFC DTP (Must be within STFC remit.)

 

This project is to develop models of resolved star formation on galactic scales. This will involve modelling a full galactic potential and how it drives the formation of molecular clouds and the onset of gravitational collapse and star formation. feedback from ionisation and supernova will be included to assess molecular cloud lifetimes and star formation efficiencies.

Many gravitational microlensing events involve binary (or multiple) systems, which can be any combination of stars, stellar remnants, brown dwarfs, and planets. Yet, there is quite a lack of systematic studies on what microlensing observations can tell us about the demographics of such systems. This now becomes an even more promising topic as not only photometric but also astrometric microlensing signatures are observed.

This project can take different directions in line with the main interests of the student, where specific questions could include a) the overlapping mass regime between planets and brown dwarfs, b) close binaries, or c) the yet unresolved question why so few binary-source events have been identified (with potential implications on the derivation of planet population statistics).

This project would be eligible for funding including: STFC DTP scholarships administered by the University. (Must be within STFC remit.)

While high-mass stars (M>8 M_sun) are known to form in stellar clusters and associations, the physics of how (and even whether) the formation of a high-mass star is intrinsically linked to the formation of a surrounding cluster remain unclear. A key limitation has been that testing cluster formation models requires being able to directly compare predicted and observed structures over the extent of a cluster-forming cloud. To address this, this project will bring together the expertise of Dr Claudia Cyganowski in ALMA observations of high-mass star-forming regions and the expertise of Dr Rowan Smith in high-resolution star formation simulations to compare new deep, large-scale ALMA mosaics of a forming stellar protocluster with synthetic observations of custom simulations. The PhD project will include imaging and analysis of ALMA data, multiwavelength analysis including existing VLA datasets, and analysis of and comparison with simulations, with the balance of these elements depending on the interests of the student. 

This project would be eligible for funding including: STFC DTP (Must be within STFC remit.)

Galaxy formation and evolution is an enormously complex process, with many important yet interlinked physical processes at play. One of the key questions we are grappling with, is why some galaxies stop forming stars, while others continue until the present day. Astronomers are using a wide range of data and models to constrain all the relevant physical processes, to try to disentangle which are the most important as a function of e.g. stellar mass and redshift.

Traditionally, when extracting the physical properties of galaxies (such as star formation histories) from their observed spectra, we treat galaxies as independent entities. This prevents us from building in important prior information that we can glean by viewing the entire population together. For example, a population of galaxies called "post-starburst" galaxies have been caught in the act of switching off their star formation. We can fit their spectra to reveal physical properties such as the number of stars born during the starburst, the age of the burst and the rate of decline. But post-starbursts must be fundamentally linked to the starburst population that we observe in the same datasets – for which we can obtain accurate instantaneous star formation rates. Putting this information together would allow us to better constrain the properties of both sets of galaxies.

Over the past year, the team in St Andrews have developed a Hierarchical Bayesian approach to spectral fitting. So far, applying it to individual local galaxies with spatially resolved data in SDSS/MaNGA, we have uncovered brand new insights into the causes of starbursts. In this project we will move one step further, applying the method to a complete population of galaxies. We will use our Hierarchical Bayesian approach to build a data-driven model of galaxy quenching, and then compare this to state-of-the-art cosmological simulations, to find out which aspects of the simulations need improving. Starting with well understood datasets such as from the SDSS in the local Universe, and COSMOS at cosmic noon, we will prepare for the brand new MOONS instrument on the VLT, which should start observing in 2025 to collect spectra for 100,000's of galaxies between 1 < z < 3 where the properties of the local galaxy population appears to be determined.

This project will suit a student with strong mathematical ability, and an interest in astronomical statistics, but also a predominantly data-driven student interested in extracting the most information possible from observational astronomical datasets.

This project would be eligible for funding including: STFC DTP (Must be within STFC remit.) 

Supervisor: Dr Ryan MacDonald  (ryanjmac@umich.edu)

One of the most significant research directions in modern astronomy is the search for atmospheres on rocky planets orbiting other stars. Establishing the prevalence of thick atmospheres on extrasolar rocky worlds is a frontier with profound implications for understanding planetary formation, atmospheric chemistry, and the habitability of terrestrial worlds throughout our galaxy. With the powerful spectroscopic capabilities of the James Webb Space Telescope (JWST), we finally have the sensitivity to characterise rocky exoplanet atmospheres.

The rocky exoplanets JWST is now observing generally orbit M Dwarf stars, due to the significantly higher signal-to-noise ratio compared to larger Sun-like stars. However, M Dwarf stars pose many challenges to atmospheric retention for close-in rocky exoplanets, due to their extreme-UV radiation and frequent flaring. Consequently, these worlds have experienced a significantly different stellar history and irradiation environment compared to the solar system. A further complication in searching for rocky planet atmospheres around M Dwarf stars arises from stellar surface inhomogeneities (e.g. starspots). These surface inhomogeneities can imprint spectral signatures in exoplanet spectra that can mimic or overwhelm atmospheric absorption features. Our drive to detect rocky exoplanet atmospheres is therefore confronted by our limited ability to accurately model the emergent spectra of M Dwarf stars.

This project will extend a state-of-the-art Bayesian modelling code to model JWST spectra of M Dwarfs and their orbiting rocky worlds. You will develop a new framework for jointly inferring properties of rocky exoplanets and their host M Dwarf stars. Alongside your model development, you will have access to cutting-edge JWST observations of some of the highest-profile rocky exoplanet systems, including spectra of the TRAPPIST-1 system, through joining several international collaborations. The ultimate goal of your project will be to enrich our understanding of M Dwarf active regions and search for clear evidence of rocky exoplanet atmospheres.

As a PhD Candidate, you will have the opportunity to use your ingenuity and passion to make major advances in exoplanetary science. This project will enable you to become a leader at the interface of theoretical and observational astronomy and at the intersection of stellar and exoplanet astronomy. You will become an expert in some of the most important foundational techniques of modern astrophysics, including radiative transfer, Bayesian analysis, and high-performance computing. By the end of your PhD, you will be a highly proficient astrophysicist equipped with the knowledge and skills to formulate and pursue your own independent research directions.

References:

• Rackham et al., 2023, The Effect of Stellar Contamination on Low-resolution Transmission Spectroscopy: Needs Identified by NASA's Exoplanet Exploration Program Study Analysis Group 21 – RASTI, 2, 148.
• Moran et al., 2023, High Tide or Riptide on the Cosmic Shoreline? A Water-rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ 486b from JWST Observations – ApJL, 948, L11.
• MacDonald, 2023, POSEIDON: A Multidimensional Atmospheric Retrieval Code for Exoplanet Spectra – JOSS, 8(81), 4873.
• Madhusudhan, 2018, Atmospheric Retrieval of Exoplanets – Springer, Handbook of Exoplanets

This project would be eligible for funding including: STFC DTP (Must be within STFC remit).

 

Determining the demographics of cool planets by means of microlensing is one of the key science goals of NASA's Nancy Grace Roman Space Telescope mission. Already the much smaller data rate of the most advanced ground-based surveys poses a key challenge for the modelling of the detected gravitational microlensing events. The major bottleneck to be overcome is the reliance on human judgement in the data analysis process. Any scalable solution not only needs to be fully-automated ("data-in-model-out"), but also needs to take into account the specific statistics of time-series observations, with their correlated noise and non-Gaussian distribution of measurements. This results in a complex Bayesian interference problem involving an intricate high-dimensional parameter space.

This project would be eligible for funding including: STFC DTP scholarships administered by the University. (Must be within STFC remit.)

Two fundamental unanswered questions in star formation are: (1) how, precisely, do high-mass stars (M>8 M_sun) acquire their mass? and (2) what produces the very high multiplicity fraction of high-mass (O and B type) main-sequence stars?  Some recent models suggest that the answers to both questions may be linked to the structure and (in)stability of accretion discs around high-mass protostars, which are less well-understood than their low-mass counterparts.  This PhD project will focus on the imaging and analysis of high-resolution ALMA observations of a small sample of discs around high-mass protostars, to study disc structure and stability, search for signatures predicted by models of "bursty" or episodic accretion and constrain the level of multiplicity present in the early stages of high-mass star formation. 

This project would be eligible for funding including: STFC DTP (Must be within STFC remit.) 
 

Holographic traps are a new kind of optical traps for neutral atoms which are promising for a wide range of applications, e.g. quantum information processing and quantum simulation. They are produced by diffracting a laser beam off a computer-controlled optical device, known as a Spatial Light Modulator (SLM). This apparatus offers unparalleled flexibility in the choice of trapping geometry, and different experiments can be done simply by reconfiguring the SLM. In this PhD project you will work on:

- Double well traps for confined atom interferometry, which is promising for the development of sensitive devices (see [1] for a review).

- Ring-shaped atom guides (see [2] and [3]), which can be used to observe superfluid motion of a Bose-Einstein condensate, e.g. persistent current states. BECs in these geometries and the study of their critical velocities (where superflow stops) have very important technological applications in sensing devices, such as superconducting quantum interference devices (SQUIDs). Moreover, theoretical proposals have been put forward in which coherent superposition of different BEC flows can be used as qubits.

[1] http://rmp.aps.org/abstract/RMP/v81/i3/p1051_1
[2] http://prl.aps.org/abstract/PRL/v106/i13/e130401
[3] http://lanl.arxiv.org/abs/1008.2140

Evaporative cooling is an essential stage in the creation of Bose-Einstein condensates (BECs) in atomic gases. Recently we suggested [1] that holographic optical traps can be used to increase the evaporation efficiency, leading to larger BECs. In this PhD project you will implement this scheme, which will result in a simplified apparatus for the productions and subsequent manipulation of BECs.

[1] http://pra.aps.org/abstract/PRA/v84/i5/e053410

Halide perovskite semiconductors possess many excellent optoelectronic properties making them suitable for a variety of devices such as solar cells, light-emitting diodes and photodetectors. Recently it has been shown that some family of these materials shows ferroelectricity and piezoelectric properties. Ferroelectric materials possess spontaneous polarization even in the absence of an external electric field and find applications in memory devices, energy harvesting, and radiofrequency and microwave devices. The piezoelectric properties would enable the development of ambient mechanical energy harvesters to self-power the small electronic components in the Internet of Things (IoT) and wearable electronics (WE). Even though halide perovskite semiconductors have been thoroughly explored for solar cell applications, their other energy harvesting applications are little explored.
In the proposed project, hybrid perovskite-based thin films will be investigated for their ferroelectric and piezoelectric properties. The ferroelectric properties will be explored using the P-E loop (polarisation-electric field) and piezo-force microscopy (PFM) method. Piezoelectric charge coefficient will be optimized as a function of different halide perovskite compositions to maximise the output power. The project would mainly involve the optimisation of ferroelectric and piezoelectric properties and develop the composition with the optimized properties towards a thin-film based ambient mechanical energy harvester to generate useful electricity to power small electronic components such as temperature sensors applicable to the IoT systems.
References:
1.    Kim et al Energy Environ. Sci., 2020, 13, 2077—2086
2.    Wilson et al APL Mater. 2019, 7, 010901

This project would be eligible for funding including: University Scholarship.

• Energy Harvesting Research Group

Angle-resolved photoemission spectroscopy (ARPES) provides arguably the most direct experimental probe of the electronic structure of crystalline solids, yielding the dispersions of electronic bands, and providing a sensitive momentum-resolved probe of many-body interactions in the solid [1]. Typically, however, ARPES has required the preparation of large-area near-perfect single crystals, dramatically limiting its applicability. Through the development of schemes for focussing vacuum ultraviolet and soft x-ray photon beams, it has recently become possible to perform ARPES measurements with a sub-micron probe, alleviating many of these restrictions, and opening a new form of microscopy where ARPES can be used to provide electronic contrast [2-4], or even to allow performing ARPES measurements from operating devices [4,5]. We are applying this method to study spatially-varying electronic structures at, for example, surfaces of metal-intercalated transition-metal dichalcogenides [3] and delafossite oxides [4,6], as well as to probe mesoscopic systems.
We seek motivated PhD students to join our work in this area, with interests in the study of spatial-dependent electronic structures of topical quantum materials; the development of data-driven approaches for the analysis of the 4D data sets obtained, including incorporating machine learning methods; and/or the development of our lab setup for spin-resolved ARPES incorporating microfocus laser sources to enable to a new generation of micro-spin-ARPES experiments. These projects require good experimental and computational skills, and would benefit from prior knowledge of Python. As part of this project, you will also undertake experiments at national and international facilities. Thus, a willingness to travel is an essential prerequisite.
For further information, or to discuss specific research possibilities, please contact pdk6@st-andrews.ac.uk. 

[1] King et al., Chemical Reviews 121, 2816 (2021)
[2] Rotenberg and Bostwick, J. Synchrotron Radiation https://doi.org/10.1107/S1600577514015409
[3] Edwards et al., Nature Mater. 22 (2023) 459
[4] Yim et al., Nature Commun. 15 (2024) 8098
[4] Hofmann, AVS Quantum Sci. 3, 021101 (2021)
[5] Nguyen et al., Nature 572 (2019) 220
[6] Sunko et al., Nature 549 (2017) 492

This project would be eligible for funding including: EPSRC DTP (Must be within EPSRC remit.)

• The Centre for Designer Quantum Materials

 

Visible light communication is an emerging field that aims to deliver high-bandwidth wireless data through solid-state (LED) lighting. A key challenge in developing this optical version of WiFi is to make optical detectors that have very fast response, are very sensitive, and can receive data signals from any angle. This project aims to develop the next generation of receiver technologies for wireless optical communications.

The project will develop optical data receivers based on luminescent polymer films. Photonic nanostructures embedded within the fluorescent film will modify the radiative lifetime and direction of the light emission to collect and concentrate incoming optical signals onto a fast silicon detector. The student will design novel optical antennas, and fabricate these using thin film deposition and nanoimprint lithography. Working with collaborators at the University of Oxford, these components will be combined with silicon photomultiplier detectors to assess their performance in optical data links.

1. "Optical antennas for wavelength division multiplexing in visible light communications beyond the étendue limit", Manousiadis, P., Chun, H., Rajbhandari, S., Vithanage, D., Malyawan, R., Faulkner, G., Haas, H., O'Brien, D. C., Collins, S., Turnbull, G. A. & Samuel, I. D. W., Advanced Optical Materials 1901139 (2019).
2. "Wide field-of-view fluorescent antenna for visible light communications beyond the étendue limit”, Manousiadis, P., Rajbhandari, S., Mulyawan, R., Vithanage, C. D. A., Chun, H., Faulkner, G., O'Brien, D. C., Turnbull, G. A., Collins, S. & Samuel, I. D. W., Optica 3, 702 (2016).

• Organic Semiconductor Optoelectronics research group
  
  

In many unconventional superconductors, magnetism and superconductivity occur in close proximity to each other - which is surprising given that they are usually considered mutually exclusive properties of a material. This is also true for the iron pnictide superconductors, where in several materials magnetism and superconductivity appear to coexist from macroscopic measurements. In this project, you will take an atomic scale view at the magnetic order and the superconducting properties using low temperature spin-polarized scanning tunneling microscopy[1]. Combining images of the magnetic order with a characterization of superconductivity from tunneling spectroscopy will allow to establish whether magnetism and superconductivity coexist microscopically, or whether they are really competing. These results provide important benchmarks for theory, and may help to establish an understanding of superconductivity in these materials.

You will be using bespoke low temperature scanning tunneling microscopes, which are installed in a new ultra-low-vibration facility at the University of St Andrews.

[1] Enayat et al., Science 345, 653 (2014).

Many quantum materials exhibit complex magnetic orders, which often are sensitive to external stimuli, such as magnetic field or doping, making them in principle interesting for many technological applications. Characterization of the spatial structure of the magnetic order has mostly been done through Neutron scattering, which however average over a macroscopic sample volume. Spin-polarized scanning tunneling microscope provides real space images of magnetic order at the atomic scale, thereby providing new insights into the spatial structure of the complex magnetic orders. In this project, you will use low temperature scanning tunneling microscopy in a vector magnetic field to characterize the magnetic structure of quantum materials. The studies will aim to establish the surface impact on the magnetic order, knowledge which is critical for technological exploitation and interfacing to other materials, but also to provide a microscopic picture of the magnetic order which will help to identify the dominant contributions to the magnetic interactions in the material. We are in particular interested in metamagnetic phases, where the external magnetic fields can drive phase transitions in the material.

You will be using bespoke low temperature scanning tunneling microscopes, which are installed in a new ultra-low-vibration facility at the University of St Andrews.

[1] Enayat et al., Science 345, 653 (2014).
[2] Singh et al., Phys. Rev. B 91, 161111 (2015).
[3] Trainer, et al., Rev. Sci. Instr. 88, 093705 (2017).

Strongly interacting electron systems are one of the best hosts for study of the quantum many-body problem. Experimental discoveries made in the past decade show that, in the cleanest materials, a variety of subtle collective states form at low temperatures. Some of these are metallic but involve the development of a preferred direction, driven not by the crystal symmetry but by the electron-electron interactions themselves. To study anisotropic responses like these, careful experiments are necessary – they can easily be missed if the correct probes are not used. Many of the states discovered so far have a coupling to externally applied magnetic fields, so these fields can be used to ‘train’ the systems’ response functions. This has highlighted the need to develop better and better ‘vector magnets’ in which the field vector can be changed via computer-controlled energisation of multiple superconducting coils. On this project you will have access to world-leading instruments capable of generating 1, 1 and 9 tesla along the x, y and z axes. This will enable you to study transport and thermodynamic quantities that cannot be accessed in standard instruments. Using this unique instrumentation, you will have the chance to investigate a range of the most exciting new strongly correlated materials in a fast-moving field of modern research.

(Jointly affiliated to both University of St Andrews and Max Planck Institute for the Chemical Physics of Solids, Dresden)

The concepts of symmetry and symmetry breaking cut across all sub-fields of physics. Whether crystal symmetry in solids, gauge symmetry in superconductors or time reversal symmetry in ferromagnets, we have become used to defining phases of matter in terms of order parameters associated with symmetry breaking. However, not all collective quantum states can be fully characterised in terms of their symmetries. In some systems phases are classified in terms of their topological characteristics. Although this has been known for several decades, it was thought to apply in highly restricted circumstances. Exciting and rapid developments over the past five years have shown that these topologically characterised phases are likely to be much more widespread than first thought, and that, in the long term, it may be possible to exploit their properties in adventurous new technologies. Although progress has been rapid, fascinating theoretical questions remain, not least the interplay between symmetry and topology. The field is also ripe for experimental study. Superconductors are among the most fascinating candidates for topological systems. A host of intriguing theoretical proposals exist, but the extent to which they are observable in practice has yet to be determined. This project is concerned with investigating candidate topological superconductors, using a combination of the world-leading experimental facilities in St Andrews, Dresden and Cornell. The project is ambitious, and would be best suited to a candidate with both experimental and theoretical aptitude.

(Jointly affiliated to both University of St Andrews and Max Planck Institute for the Chemical Physics of Solids, Dresden)

Metamaterials (MMs) are man made materials with engineered optical properties. They are made assembling their artificial atoms at a scales much smaller than that of light, so as to appear homogenous. They are at the basis of very thought provoking proposals, including super imaging and cloaking applications. In the group of Synthetic Optics we have developed a large portfolio of fabrication techniques for one- and two-dimensional MMs.

The aim of this project is to develop the fabrication protocol and applications of three-dimensional MMs obtained with a bottom up approach. The student will combine the extraordinary physical and optical properties of silica based aerogels with the flexibility of the design of nanoplasmonics to realise effective materials with bespoke optical behaviour. The aerogel is an ultra light material with refractive index close to unity and thermally more insulating than air. Combining these features with the field enhancement offered by infiltrated metallic nano particles is specially suited to address nonlinear effects at ultra-low powers.

This challenging but rewarding project requires a thorough understanding of the physics involved and the experimental rigour to fabricate and test the MMs, but offers the student the chance to learn a broad range of design, fabrication and experimental techniques.

The aim of this project is to investigate experimentally the influence of broken inversion symmetry on superconductivity in a variety of non-centrosymmetric (NCS) materials. Most crystalline metals have a structure that maps onto itself exactly under inversion of spatial coordinates. Such materials are termed “centrosymmetric” and when they become superconducting, the spatial part of the Cooper pair wavefunction must have a definite parity, i.e. inversion simply multiplies it by ±1. This imposes restrictions also on the spin configuration within the Cooper pair. By contrast, in non-centrosymmetric superconductors where the crystal structure breaks inversion symmetry, such restrictions do not apply. Amongst the properties predicted for non-centrosymmetric superconductors are mixed spin-singlet/spin-triplet pairing, enhanced critical fields and spatially modulated superconducting states. Whilst unusual superconducting properties have been detected in a number of NCS materials, there is relatively little firm experimental evidence linking these to the lack of inversion symmetry; for example only in very few cases has a substantial triplet component of the order parameter been firmly established.

The project will be focused on NCS superconductors where the electronic correlations are weak, since these offer the chance to isolate the role of the broken inversion symmetry. The experiments will focus on using low temperature scanning tunneling microscopy and spectroscopy to establish the structure of the superconducting order parameter and study the influence of defects of different dimensionalities on the superconducting properties.

Ultraviolet light, in particular UVC wavelengths in the range 200nm to 280nm, has a long history as a disinfectant including for water purification and preventing the spread of airborne pathogens such as measles and tuberculosis. With the current COVID-19 pandemic there has been renewed interest in UVC technologies to prevent the airborne spread of the virus. Due to safety concerns, traditional "upper room" UVC devices that operate at a wavelength of 254nm must be shielded from people and provide a beam of UVC light above head height. Airborne viruses are inactivated as they pass through the UVC beam. Recently new technologies operating at shorter UVC wavelengths around 222nm are coming to market. These devices are believed to be safe for use around humans because the outermost layers of the skin and eyes prevent the shorter UVC wavelengths penetrating and causing harm. Such devices that are safe to use around humans may provide a new way for preventing the airborne spread of not just the current coronavirus, but also other deadly pathogens such as influenza and drug resistant hospital acquired infections. This PhD project will study the use of both traditional 254nm and new 222nm UVC technologies in a range of settings including hospitals, care homes, schools, transportation, and the retail sector. Theoretical studies will combine three dimensional simulations of air flow and the spread of virus particles along with Monte Carlo simulations to predict the UVC light distribution within rooms and public spaces. The resulting simulations will allow the design of optimal UVC installations for inactivating viruses in areas with differing amounts of natural and mechanical ventilation.

 

An important area in biophysical research is how transmembrane proteins that mediate drug responses, such as G Protein-Coupled Receptors (GPCRs), can tune their function in response to changes in the biophysical organization of cellular membranes. We and others observed that curved membranes are known to be associated with GPCR segregation, possibly resulting in signalling compartmentalization, i.e. the ability of cells to integrate or distinguish often-converging stimuli within their picoliter volume (Bathe-Peters et al. 2021; Rosholm et al. 2017; Kockelkoren et al. 2024) (Sirbu et al. 2024).

Within the last years, thanks to generous funding from the Leverhulme Trust, we have established a platform to achieve nanoscale control on receptors localization and local membrane environment, exploiting advanced nanostructured substrates produced in the School's cleanroom facility. When combining these substrates with advanced fluorescence spectroscopy approaches, that allow monitoring receptors localization, dynamics, interactions and overall function, we have now a powerful platform to conduct single cell pharmacology studies with profound biophysical insight.

At the same time, interpretation of this wealth of microscopy and spectroscopy data, requires innovative and original approaches to extract quantitative information, ultimately towards the development of an automated screening platform.

We are seeking a highly motivated candidate with a strong foundation in quantitative data analysis and coding (Python, Matlab or Java), to join our effort and lead the data acquisition aspect of our project. In this role, the successful applicant will acquire microscopy data in modalities ranging from single molecule tracking to biosensors readout using resonance energy transfer, while working to establish a robust data analysis pipeline to pinpoint the nanoscale spatial-temporal dynamics of cellular signals.

The PhD position will provide an ideal opportunity to receive training in a wide range of cutting-edge techniques spanning biophysical imaging, instrument development and data analysis methods, by using the state-of-the-art facilities and by working in an interdisciplinary and multicultural team within one of UK leading Universities. The successful candidate will have the opportunity to join a vibrant student life, engage in student-led outreach and science dissemination activities, and benefit from the training offered by the Scottish University Physics Alliance network. This set of inter-disciplinary skills and training will place the PhD candidate in an excellent position to pursue a career in the academic or private sectors.

Applicants should have a degree in Physics, Biomedical Engineering, or related disciplines. Previous experience in image analysis is considered advantageous, and a solid background in quantitative data analysis is critical. 

The position is funded for a duration of 3.5 years, providing a maintenance fellowship according to UKRI rates. 

The position is available for immediate start. Informal enquiries are welcome and should be made by email to Dr Paolo Annibale (pa53@st-andrews.ac.uk). The project for this thesis is funded by Dr Paolo Annibale's Leverhulme grant 'Bottom-up nanoscale control of compartmentalized cellular signaling: geometry and finesse'.

[1] Bathe-Peters, M., P. Gmach, H. H. Boltz, J. Einsiedel, M. Gotthardt, H. Hubner, P. Gmeiner, M. J. Lohse, and P. Annibale. 2021. 'Visualization of beta-adrenergic receptor dynamics and differential localization in cardiomyocytes', Proc Natl Acad Sci U S A, 118.
[2] Kockelkoren, G., L. Lauritsen, C. G. Shuttle, E. Kazepidou, I. Vonkova, Y. Zhang, A. Breuer, C. Kennard, R. M. Brunetti, E. D'Este, O. D. Weiner, M. Uline, and D. Stamou. 2024. 'Molecular mechanism of GPCR spatial organization at the plasma membrane', Nat Chem Biol, 20: 142-50.
[3] Rosholm, K. R., N. Leijnse, A. Mantsiou, V. Tkach, S. L. Pedersen, V. F. Wirth, L. B. Oddershede, K. J. Jensen, K. L. Martinez, N. S. Hatzakis, P. M. Bendix, A. Callan-Jones, and D. Stamou. 2017. 'Membrane curvature regulates ligand-specific membrane sorting of GPCRs in living cells', Nat Chem Biol, 13: 724-29.
[4] Sirbu, A., M. Bathe-Peters, J. L. M. Kumar, A. Inoue, M. J. Lohse, and P. Annibale. 2024. 'Cell swelling enhances ligand-driven beta-adrenergic signaling', Nat Commun, 15: 7822.

• Sir James Mackenzie Institute for Early Diagnosis
• The Centre of Biophotonics

 

Raman spectroscopy is a powerful label-free method which can be used to identify the molecular composition of a wide variety of materials. In recent years, the Optical Manipulation Group have pioneered new measure techniques with Raman Spectroscopy, including wavelength modulated Raman spectroscopy (WMRS) [1] which efficiently removes the auto-fluorescence from samples, and shaping the input beam profile to decouple the Raman signals produced by a container and its contents [2]. This allows us to measure the chemical signature of whiskies with no contribution from the glass bottle, without needing to open the bottle [3].

Performing chemical profiling inside turbid media remains a challenge. When light traverses a turbid medium, multiple scattering takes place and the light exiting the medium forms a granular interference pattern called speckle. This disordered pattern is often thought of as detrimental to optical measurements. However, we have recently shown that the interference pattern produced is extremely sensitive to changes of the properties of the light, the scattering medium and the environment. In particular, we have shown that by tracking changes in the speckle with multivariate analysis techniques such as Principal Component Analysis [4,5] or Convolutional Neural Networks [6], we can measure changes in wavelength on the attometre scale.

This project aims to perform Raman spectroscopy at greater depths within highly scattering samples, by harnessing the techniques of speckle metrology. This will be utilized in applications ranging from biophotonics to security.

The work will take place in the Optical Manipulation Group, whose interests also span from Biophotonics and the development of new tools for optical imaging at depth to optical trapping and manipulation of microparticles and optical metrology using laser speckle. In this highly collaborative environment, there is likely to be opportunities to contribute to research in these other areas.

This project may be offered as a co-tutelle degree where a significant component of the research would be undertaken at University of Adelaide.
For more details or enquires, contact Dr Graham D Bruce (gdb2@st-andrews.ac.uk).

[1] V. O. Baron, M. Chen, B. Hammarström, R. J. H. Hammond, P. Glynne-Jones, S. H. Gillespie and K. Dholakia. Real-time monitoring of live mycobacteria with a microfluidic acoustic-Raman platform. Commun. Bio. 3, 235 (2020)
[2] G. E. Shillito,  L. Mcmillan, G. D. Bruce and K Dholakia. To focus-match or not to focus-match inverse spatially offset Raman spectroscopy: a question of light penetration. Opt. Express 30, 8876-8888 (2022)
[3] H. Fleming, M. Chen, G. D. Bruce and K. Dholakia. Through-bottle whisky sensing and classification using Raman spectroscopy in an axicon-based backscattering configuration. Anal. Methods 12, 4572 (2020)
[4] N. K. Metzger, R. Spesyvtsev, G. D. Bruce, B. Miller, G. T. Maker, G. Malcolm, M. Mazilu and K. Dholakia. Harnessing speckle for a sub-femtometre resolved broadband wavemeter and laser stabilization. Nature Communications 8, 15610 (2017)
[5] G. D. Bruce, L. O'Donnell, M. Chen and K. Dholakia. Overcoming the speckle correlation limit to achieve a fiber wavemeter with attometer resolution. Optics Letters 44, 1367 (2019)
[6] R. K. Gupta, G. D. Bruce, S. J. Powis and K. Dholakia. Deep learning enabled laser speckle wavemeter with a high dynamic range Laser and Photonics Reviews 14, 2000120 (2020)

This project would be eligible for funding including: EPSRC DTP (Must be within EPSRC remit.). Applied Photonics CDT (Requires industrial partner to commit funding.  See https://cdtphotonics.hw.ac.uk/.)

• The Centre of Biophotonics

 

This PhD project extends the groundbreaking research of Wei et al. (2022) [1] on room temperature polariton condensates, focusing on their application in lattices within organic microcavities specifically for analogue Ising machine (AIM) applications. The candidate will explore the potential of these lattices to mimic the Ising model in statistical mechanics, a promising approach for solving complex optimization problems. The project combines experimental and theoretical approaches to uncover new insights into analogue quantum simulation at room temperature.

Organic polaritons, as quasiparticles formed by the strong coupling of electromagnetic waves with electronic excitations in organic materials, merge the characteristics of photons and excitons, leading to a unique state of light and matter. This fusion enables their use in ultrafast applications, novel light sources, and analogue computing. Polariton condensation, a quantum phenomenon occurring typically at low temperatures, involves polaritons accumulating in a single quantum state, akin to a Bose-Einstein condensate, and exhibiting properties like superfluidity and coherent light emission. Our research focuses on creating polariton condensates at room temperature in organic semiconductor microcavities [2]. We achieved the trapping of these condensates in one- and two-dimensional optical potentials through a tunable optical method [1], observing quantized states of a harmonic oscillator at room temperature. Here we are extending this to lattices for the development of tunable polariton simulators [3].

References:
[1] M. Wei, W. Verstraelen, K. Orfanakis, A. Ruseckas, T. C. H. Liew, I. D. W. Samuel, G. A. Turnbull, and H. Ohadi, Optically Trapped Room Temperature Polariton Condensate in an Organic Semiconductor, Nat Commun 13, 1 (2022).
[2] M. Wei, S. K. Rajendran, H. Ohadi, L. Tropf, M. C. Gather, G. A. Turnbull, and I. D. W. Samuel, Low-Threshold Polariton Lasing in a Highly Disordered Conjugated Polymer, Optica, 6, 1124 (2019).
[3] N. Stroev and N. G. Berloff, Analog Photonics Computing for Information Processing, Inference, and Optimization, Advanced Quantum Technologies 6, 2300055 (2023).

Contact Information: Principal Investigators: Hamid Ohadi (ho35@st-andrews.ac.uk), Ifor Samuel (idws@st-andrews.ac.uk), Graham Turnbull (gat@st-andrews.ac.uk)

The position is fully funded, including tuition, stipend, and research expenses. Start Date: August 2024.

 

When light is confined on the nanoscale it is possible to observe light-matter interactions that are not normally observed in bulk materials. One example is the strong coupling of photons and excitons in wavelength-scale microcavities, in which the modes of the cavity couple with the exciton to make a hybrid light-matter state called a polariton [1,2]. Polaritons can form a Bose-Einstein condensate [3], and we have demonstrated low threshold polariton lasers [4].
Organic semiconductors are particularly interesting for the study of polaritons because their excitons have binding energies much greater than the thermal energy at room temperature. This means that polaritonic phenomena that are restricted to low temperature in other materials are readily observed at room temperature in organic semiconductors. The purpose of this project is to explore aspects of room temperature polaritons in organic semiconductors. First, the possibility of using strong light-matter coupling to tune the energy levels of organic semiconductors will be explored. Then the effects of polaritons being delocalised will be studied.  Normally excitons in organic semiconductors are localised and can only travel a few nanometers. However polaritons are delocalised and so may access a much larger volume. Finally these two strands of work will be combined to make sensors that are both selective and sensitive. The selectivity will arise from the tuning of energy levels, and the sensitivity from polaritons being delocalised.

[1] C. Weisbuch et al., Phys. Rev. Lett. 69, 3314 (1992)
[2] D.G. Lidzey et al., Nature 395, 53 (1998)
[3] J D Plumhof, T Stöferle, L Mai, U Scherf & R F Mahrt, Nature Materials 13, 247–252 (2014)
[4] Rajendran, S. K., Wei, M., Ohadi, H., Ruseckas, A., Turnbull, G. A. & Samuel, I. D. W.  Advanced Optical Materials. 7, 1801791 (2019)

 

This project will use (and futher develop) our new radiation hydrodynamics codes to syudy the effects of stellar feedback on the structure, dynamics, and star formation rates in star forming regions (parsec sizescales) and the interstellar medium (kiloparsec sizescales). Feedback processes that are readily incorporated into our codes include photoionisation, radiation pressure, dust heating, stellar outflows, and supernovae. In addition to studying these processes in star forming regions, the new numerical codes are also applicble to numerical studies of galactic outflows and the impact of feedback processes and leakage of ionising radiation into the intergalactic medium.

Informal enquiries to Kenny Wood: kw25@st-andrews.ac.uk

Biologists have compelling evidence that in addition to biochemical signals, mechanical forces have a major impact on a wide range of processes in cell biology, with examples ranging from cell migration and cell growth to the spreading of cancer and the differentiation of stem cells. However, there is at present a shortage of suitable tools to measure the force exerted by a cell which often is well below 1nN (i.e., < 10^-6 N (!)).

By developing a novel optical micro-cavity-based sensor technology, the Gather Lab seeks to overcome current limitations in measuring cellular forces and – for instance – investigate the mechanics involved in the formation and the growth and repair of nerve cells.

The basic working principle of our sensors is to detect shifts in the resonance frequency of a micro-cavity due to mechanical forces applied by cells cultured on the sensor. These shifts can be detected with high spatial and temporal resolution and the forces at play are then computed from this by a finite element method.

A PhD in the field of cellular mechanics provides you with a broad, interdisciplinary skill set: You will learn and apply a range of micro- and nano-fabrication methods and work in a state-of-the-art cleanroom. You will use different types of optical spectroscopy and work with atomic force microcopy. You will receive hands-on training in cell culturing techniques and perform studies of e.g. stem cell differentiation.

The project is part of an international collaboration with leading scientists at Harvard Medical School and University of Cambridge which is funded by the Human Frontier Science Program, the leading funding institution for interdisciplinary and international collaborative research into complex biological systems.  

Water is one of the most miraculous gifts to humankind. Our present-day lifestyle, industrialization, farming practices, medical care and warfare activities have given rise to a wide range of contaminants of emerging concerns (CECs). They enter our environment through various pathways, accumulate leading to hazardous effects on ecological and human health.  Optical chemical sensors have a huge potential in sensitive, convenient, cost-effective and real-time environmental monitoring of pollutants. They make use of optical parameters like absorbance; Raman spectrum; and fluorescence intensity, wavelength, lifetime and quantum yield for detection of contaminants. Variation in any of these parameters in presence of specific contaminants gives detectable optical signals for detection.

This project, will develop trace optical sensors for industrial contaminants, and pharmaceuticals in water bodies. Experimental work will include clean-room fabrication of thin-film sensors, optical characterisation of their response to different contaminants, and testing the sensors in real-world environments.

EPSRC DTP (Must be within EPSRC remit.)

• Organic Semiconductor Centre

Transition metal oxides host a wide range of physical properties and functionalities, making them an ideal platform for implementing potential future devices. The aim of this project is to establish novel ways to manipulate the local properties of transition metal oxides by using a scanning tunneling microscope to enable writing device structures at the atomic scale into the surface of the material. To establish the properties of these written device structure, you will first use scanning tunneling spectroscopy, but later also explore possibilities to contact the written structures macroscopically to study transport through these and enable actual device operation. While initial studies will be performed on bulk material, at later stages of the project, thin-film samples grown by reactive oxide molecular beam epitaxy will be used.

HOYS is a long-term project to monitor young stars with small telescopes around the world. The database contains data from seven years, with several hundred million brightness measurements for about 10000 young stars. We are using this enormous dataset to study rotation, activity, accretion in young stars, as well as disk structures related to planet formation. We also have the ability to look at eclipsing binaries or pulsations. The project is led by the University of Kent, for examples of what can be achieved with this dataset, please check hoys.space. Our own telescopes in St Andrews are contributing images to the database. For this PhD project we will use the database, as well as new observations with our own telescopes. In particular, we want to focus on the shortest timescales of minutes to hours, which are so far not covered by the existing observations. The project will involve hands-on observing as well as processing and understanding large photometric datasets.

This project would be eligible for funding including: STFC DTP. (Must be within STFC remit.) 

• Centre for Exoplanet Science

 

We are seeking ambitious and motivated PhD students to join a major research initiative aimed at investigating the electronic structure and collective states of two-dimensional quantum materials. The remarkable electronic, optical, and structural properties of graphene, a single atom-thick layer of carbon, has spurred enormous interest in atomically-thin materials. We have recently pioneered a universal method to fabricate high-quality and large-area epitaxial monolayers of 2D chalcogenides [1]. In turn, this advances new routes to study their electronic structure and collective states using state-of-the-art spectroscopic probes [2,3]. In this project, you will work to exploit these advances to develop a tuneable platform for studying electronic interactions in 2D materials. You will work to develop novel 2D heterostructures, creating hybrid materials with control over their superconducting, magnetic and/or charge-ordering instabilities. You will investigate the potential of moiré superlattices as a powerful route to further control the correlated ground states of these systems, and seek to understand how these can be tuned using electrostatic gating approaches, similar to that utilised in field-effect transistors. The work undertaken will build on the group’s existing activity in the study of bulk and monolayer transition-metal dichalcogenides [https://www.quantummatter.co.uk/king; e.g. 2-7], and ultimately aims to develop new routes towards the "on-demand" control of the quantum many-body system underpinning the physical properties of 2D quantum materials.  Projects are available working on materials fabrication and on spectroscopic studies of their electronic structure. These projects will make extensive use of the unique facilities of the Centre for Designer Quantum Materials in St Andrews, with integrated facilities for molecular-beam epitaxy growth, glove-box-based mechanical exfoliation, and in situ spectroscopy. Further ARPES, spin-resolved ARPES and time-resolved ARPES may be performed at international facilities, further increasing the possibilities to probe the electronic structure and many-body interactions of the materials synthesized. 
For further information, or to discuss specific research possibilities, please contact pdk6@st-andrews.ac.uk. 

This project would be eligible for funding including: NextGenTech CDT (requires 50% matched funding); EPSRC DTP (must be within EPSRC remit); Committed studentship from the Centre to match a funded grant.

• The Centre for Designer Quantum Materials

 

Artificial designer heterostructures of correlated electron systems open up a wide range of exciting possibilities for the creation of new materials. The atomic-layer-by-atomic-layer deposition now achievable in thin films gives a unique potential to manipulate the properties of this still poorly explored new class of materials, ultimately allowing the creation of new phases with properties difficult to attain in bulk compounds [1]. St Andrews has recently opened a new dedicated MBE growth facility with the aim of exploiting the possibilities of such tailored materials.

This new class of materials, however, poses a key challenge to experimentalists interested in such basic thermodynamic properties as specific heat and magnetisation. The extremely low ‘thermal mass’ of such materials compared to bulk systems ultimately requires the development of a new bespoke set of experimental tools for measurement. To bring the paradigm of such fundamental thermodynamic measurements to nanoscale thin films is the key aim of a new research program established at the University of St Andrews of which you will be a key member. During your PhD you will contribute to the development of these new tools with the aim to applying them to the study of designer quantum materials spanning phenomena such as superconductivity, novel (topological) Dirac- and Weyl- systems and (quantum) spin liquids.

[1] J. Mannhart and D. Schlom, Science 327, 1607 (2010).

 

Pulsed dipolar spectroscopy (PDS) forms a sub set of electron paramagnetic resonance (EPR) spectroscopic experiments. PDS exploits the long range dipole-dipole coupling between paramagnetic centres and this allows for the extraction of nanometre scale distances and distributions. The application of these measurements to biomacromolecules, such as nucleic acids and proteins, is a small but important area of the field of structural biology.
 
You will receive training, and therefore become an independent researcher, in:
  1. preparing biomacromolecule samples;
  2. running advanced PDS measurements;
  3. analysing data for its relevance to finding the answers to questions in structural biology.
 
The work will be carried out in fully equipped biological laboratories, and using our state-of-the-art commercial and home-built EPR spectrometers.
 
Given the interdisciplinary nature of this work a scientific background (for example a degree in physics, chemistry or biology) and an enthusiasm for the project are required.
 
You will make full use of the further academic and transferrable skills training on offer, and you will have the option to take part in public engagement and teaching activities.
 
Contact the supervisor Dr Janet Lovett directly for more information, and see https://www.st-andrews.ac.uk/~jel20/

Magnetic resonance is the broad term for techniques that exploit the fundamental and fascinating property of spin. Electron paramagnetic resonance (EPR) spectroscopy is where the spin being used or probed is from a paramagnetic centre, i.e. electron spins. The electron interacts with the environment and the result is that EPR spectroscopy measures details of that environment.
In this project you will apply existing, and develop bespoke, EPR experiments to a range of open questions about the properties of materials. These materials will range from biomolecules and in particular proteins, to semiconductors for solar cells. You will work primarily with Dr Janet Lovett, but also collaborate with other researchers. For example, in the St Andrews School of Physics and Astronomy this will include Professor Graham Smith and Dr Lethy Jagadamma.
Through your project you will have a chance to develop methodologies alongside the pure developments of the EPR experiments. For example, ways to investigate the effect of temperature and pressure on the folding landscapes of proteins, measured using EPR spectroscopy techniques such as DEER. 
Other biological questions that you will use the EPR methods to answer are likely to be related to protein-protein interactions and structural changes with impact on the fields of protein repair, antibiotic resistance and cellular calcium dynamics.
The EPR equipment is based in the School of Physics and Astronomy and supplemented by equipment in the School of Chemistry. We currently have X-band CW and pulsed spectrometers, Q-band pulsed (with a recent successful grant proposal providing a second soon) and also our home-built world-leading and continuously developed W-band spectrometer, HiPER. You will have access to preparation laboratory space as needed, and this includes well-equipped biology labs. 
Please see https://www.st-andrews.ac.uk/~jel20/.

Entry Requirements: At least a UK 2:1 honours degree or equivalent. This is mostly likely to be in Physics, Chemistry or Biochemistry but applications from associated degrees are welcome. Prior knowledge of magnetic resonance, biology or semiconductors is not required, but a willingness to learn about these methods and applications is a necessity.

Closing date: 4 January 2025 for standard admissions, but later applications may be considered until the position is filled dependent on available funding.

Funding: The School of Physics and Astronomy at the University of St Andrews has a range of funding opportunities for both UK and international students. For more information please visit https://www.st-andrews.ac.uk/physics-astronomy/prospective/pgr/.

How To Apply: please visit https://www.st-andrews.ac.uk/physics-astronomy/prospective/pgr/ to find further information on applying for this project.

 

Defects in two-dimensional materials have recently attracted a lot of interest as they have been shown to have quantum features like single atoms: they have well-defined energy levels, and once excited they can emit one photon at a time. These characteristics are crucial for quantum technologies such as quantum memories and single-photon sources. Coupling the emission from these defects to photonic cavities allows mapping their quantum states to photons which can then be transported and stored, as well as using them as high brightness single-photon sources.

In this project, we are aiming to use carbon defects in hexagonal boron nitride layers as quantum emitters. You will fabricate single-photon sources by placing these defects inside high quality optical Fabry-Perot cavities, and couple their emission to optical fibers. You will study the quantum operation of the device by mapping the photon statistics of the coupled light.

Reference:  Koperski, M. et al. "Midgap radiative centers in carbon-enriched hexagonal boron nitride" PNAS 117, 13214 (2020)

It has been known for a long time that magnetic impurities induce bound states in superconductors [1] but only in recent years it was realised that lining up such states [2] can lead to a twist in the resulting wave function that is known as a changed topological index. The study of such topological states has by now become a highly active field of research. A strong promotor is the rather recent insight that any quantum technology will have to rely on some form of topological states. In this PhD project we will investigate how topological properties appear at interfaces or magnetic structures embedded on superconductors, in a set-up where a strict dimensional decoupling as considered by most approaches is not possible. This will build on our recent work [3]. A particular emphasis will be given to interactions between the states generated by the interaction between the magnetic scatterers and the superconductor, and to particular instabilities that can lead to novel quantum phases.

[1] L. Yu, Acta Phys. Sin. 21, 75 (1965); H. Shiba, Prog. Theor. Phys. 40, 435 (1968); A. I. Rusinov, JETP Lett. 9, 85 (1969).
[2] F. Pientka, L. I. Glazman, and F. von Oppen, Phys. Rev. B 88, 155420 (2013); S. Nadj-Perge, I. K. Drozdov, J. Li, H. Chen, S. Jeon, J. Seo, A. H. MacDonald, B. A. Bernevig, and A. Yazdani, Science 346, 6209 (2014).
[3] C. J. F. Carroll and B. Braunecker, arXiv:1709.06093.

Quantum simulation offers the possibility to create physical phenomena that are hard to access or control otherwise. Notorious is particularly many-body physics with strong correlations. Remarkably some types of such physics can be created in dissipative quantum circuits, in which the type of correlation physics appears through a nonlinear interaction of the electron transport with electromagnetic environment fluctuations. For weakly transmitting conductor such physics is understood since a long time [1]. But the potential of the quantum simulation appears only for highly transmitting circuits in which the transmission time is comparable with the environment's reaction time, called the dynamical Coulomb blockade regime, for which much less is known. Although for specific conditions important advances have been made over the last years [2], recent experimental progress has shown that there is still much unclear especially when there is strong backaction of the environment [3]. In this PhD project we will access this physics through analytical and numerical non-perturbative many-body modelling, including bosonisation [4] and recently developed mappings on scattering boundary value problems [5].

[1] G.-L. Ingold and Y. Nazarov, in Single Charge Tunneling ed. by H. Grabert and M. H. Devoret, Ch. 2 (Plenum, 1992).

[2] K. A. Matveev, D. Yue and L. I. Glazman, Phys. Rev. Lett. 71, 3351 (1993); L. W. K. Molenkamp, Flensberg and M. Kemerink, Phys. Rev. Lett. 75, 4282 (1995). Y. V. Nazarov, Phys. Rev. Lett. 82, 1245 (1999); M. Kindermann and Y. V. Nazarov, Phys. Rev. Lett. 91, 136802 (2003); I. Safi and H. Saleur, Phys. Rev. Lett. 93, 126602 (2004); D. S. Golubev, A. V., Galaktionov and A. D. Zaikin, Phys. Rev. B 72, 205417 (2005).

[3] F. D. Parmentier, A. Anthore, S. Jezouin, H. le Sueur, U. Gennser, A. Cavanna, D. Mailly and F. Pierre, Nat. Phys. 7, 935 (2011); A. Anthore, Z. Iftikhar, E. Boulat, F. D. Parmentier, A. Cavanna, A. Ouerghi, U. Gennser, and F. Pierre, Phys. Rev. X 8, 031075 (2018).

[4] J.-R. Souquet, I. Safi, and P. Simon, Phys. Rev. B 88, 205419 (2013).

[5] B. A. Muzykantskii and Y. Adamov, Phys. Rev. B 68, 155304 (2003); B. Muzykantskii, N. d'Ambrumenil, and B. Braunecker, Phys. Rev. Lett. 91, 266602 (2003); J. Zhang, Y. Sherkunov, N. d'Ambrumenil, and B. Muzykantskii, Phys. Rev. B 80, 245308 (2009); B. Braunecker, Phys. Rev. B. 73, 075122 (2006).

Organic semiconductors based on light-emitting conjugated polymers are attracting considerable interest in semiconductor physics and are emerging as exceptional 'plastic-like' materials for optoelectronic applications including displays, lasers and solar cells. We have recently reported the first single-molecule studies regarding the conformation of individual polymer chains in organic solvents commonly used for device fabrication [1-3]. Now, in this project, we aim to combine single-molecule super-resolution spectroscopy with magnetic tweezers to apply force to the polymer chain. By merging these techniques, we will be able to stretch the polymer chain at will and understand in more detail how the conformation of the polymer chain impacts its light-emission properties. Importantly, we will apply for the first-time super-resolution imaging methods to resolve, beyond the diffraction limit, the structure of the polymer chain as a function of applied force. The results will help to develop new solution-processing methods that improve device performance. The project is a collaboration between the groups of Prof Ifor Samuel and Dr Carlos Penedo.

[1] Dalgarno, Paul A., Christopher A. Traina, J. Carlos Penedo, Guillermo C. Bazan, and Ifor D. W. Samuel. (2013) Solution-Based Single Molecule Imaging of Surface-Immobilized Conjugated Polymers. J. Am. Chem. Soc. 135 (19): 7187–93.
[2] Tenopala-Carmona, F.,  Fronk, S., Bazan, G., Samuel, I. D. W., Penedo, J.C. (2018) Real-time observation of conformational switching in single conjugated polymer chains. Sci. Advances, 4: eaao5786.
[3] Brenlla, A., Tenopala-Carmona, F., Kanibolotsky, A. L., Skabara, P., Samuel, I. D. W., Penedo, J.C. (2019) Single-Molecule Spectroscopy of Polyfluorene Chains Reveals β-Phase Content and Phase Reversibility in Organic Solvents. Matter, 1, 1399–1410.

No real-world quantum system is truly isolated. This means the dynamics of a quantum system cannot be fully captured by just solving its Schrödinger equation, and instead different approaches need to be developed. If the coupling to an environment is strong, as it often is in solid state or molecular systems, it is not even possible to predict a system's future evolution with a model that only depends on the present time. Rather, the full history of how a system has interacted in the past is needed to know what it will do in the future.

Such 'non-Markovian' behaviour is notoriously difficult to simulate. However, in recent years we have developed a suite of groundbreaking new algorithms to tackle this challenge. In particular, we use tensor network approaches to capture the influence of the  environment on a system efficiently. This has opened up a new world of predictive power.

In this project, we will exploit and combine powerful features from different and currently complementary tensor network methods and apply them to particular real-world problems. In particular, we will be interested in cases where one or two particles in the environment dominate the effect on the open system, over a broad background of the rest. This might, for example, allow us to design molecular systems that have more efficient energy transfer, and so impact on the future developments in solar cell technology.

This PhD project will be jointly supervised by Prof Brendon Lovett and Prof Erik Gauger (Heriot Watt University).

Related literature:

PT-MPO techniques - the new methods we have developed to describe strongly coupling open systems:
[1] Strathearn et al. "Efficient non-Markovian quantum dynamics using time-evolving matrix product operators" Nature Comms. 9 3322 (2018)
[2] Fux et al. "Efficient exploration of Hamiltonian parameter space for optimal control of non-Markovian open quantum systems" Phys. Rev. Lett. 126 200401 (2021)
[3] Gribben, Rouse, Iles-Smith et al. "Exact dynamics of non-additive environments in non-Markovian open quantum systems" PRX Quantum 3 010321 (2022)
[4] Cygorek et al. "Numerically-exact simulations of arbitrary open quantum systems using automated compression of environments" Nature Physics 18 662 (2022)

Our studies of the quantum mechanics of light harvesting in molecular systems:
[5] A. Fruchtman et al. Phys. Rev. Lett. 117 203603 (2016)
[6] K.D.B. Higgins, et al. J. Phys. Chem. C 121 20714 (2017)
[7] K.D.B. Higgins, et al. Nature Communications 5 4705 (2017)

This project would be eligible for funding including: EPSRC DTP scholarships administered by the University.

The generation of indistinguishable single photons on demand is a key requirement for many kinds of future quantum technologies, such as secure communication and optical quantum computing [1]. Being able to make coherent quantum light sources in solid state systems would enable us to create on-chip photonic circuits that would enable this technology. It is therefore of the utmost importance to understand what effect a solid state environment has on the fidelity of emitted photons.

In this project, you will exploit and developing a groundbreaking new technique our group has created for simulating open quantum systems [2]. Based on a combination of Feynman's path integrals [3,4] and matrix product states [5], it has already enabled calculations impossible by more traditional means. You will study how the technique might be used to calculate the photon correlation functions that characterise a single photon source, in the presence of a strongly-coupled environment of vibrational modes of the crystal. You will go on to study how a photonic cavity might be used to improve the performance of such a device.

[1] I. Aharonovich. D. Englund and Milos Toth, Nature Photonics 10 631 (2016)
[2] A. Strathearn, P. Kirton, D. Kilda, J. Keeling, and B. W. Lovett, Nature Communications 9 3322 (2018)
[3] R. P. Feynman, and F. L. Vernon, Jr., Ann. Phys. 24 118 (1963)
[4] N. Makri and D. E. Makarov. The Journal of Chemical Physics J. Chem. Phys. 102 4600 (1995)
[5] R. Orús, Annals of Physics 349 117 (2014)

Structured light is used in imaging, communication and optical micromanipulation to increase resolution, data capacity and optimise optical traps. At the single photon level, structured light offers the perfect system to study fundamental light-matter interaction such as the transfer of linear and angular momentum to microscopic objects. This theoretical study looks at the links between quantum technology and optical micromanipulation. More precisely, coherent electromagnetic radiation can take many forms in general. Indeed, any scattering and interaction of a light field with its environment will change the beam profile and the properties of the light field involved. These effects can be calculated numerically and sometimes analytically by solving the classical Maxwell’s equations. One class of solutions of Maxwell’s equations are the optical eigenmodes that constitute a natural representation of electromagnetic scattering events. These eigenmodes are orthogonal to each other and are useful to optimise beam properties such as linear and angular momentum transfer to microparticles. This is particularly interesting when designing structured illumination for optical micromanipulation, coherent control, single pixel imaging super resolution microscopy and spectroscopy. This project aims at expanding our initial research looking at the use of optical eigenmodes in the context of single photons and quantum optics. The project has a numerical and a theoretical component that together should enable the results to be applicable to experimentally relevant cases.

The worldwide emergence and rapid spread of Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused more than 700,00 deaths and infected more than 20 million people worldwide, putting healthcare systems at the border of collapse and the entire economy into recession. Compared to other members of the SARS family, including SARS-CoV and MERS (Middle East Respiratory Syndrome), SARS-CoV-2 exhibits a higher transmission rate and evades the human immune system more efficiently [1-3].The first step in viral infection is the attachment of the viral particle to the surface of the host cell, subsequently enter endosomes, and eventually fusing viral and lysosomal membranes. Understanding how SARS-CoV-2 infects cells is a high priority and the first opportunity to develop intervention strategies. In this project, we aim to investigate how SARS-CoV-2 enters the host cell by fusing its viral envelope to the host cell membrane. We will develop a combination of biomimetic proteo-liposomes and single-molecule super-resolution microscopy methods to dissect each step of the membrane fusion mechanism in real time [4]. The project is in collaboration with Dr. Juan Varela at the School of Biology.

The student will be immersed in a motivating learning environment and will engage in group meetings with biologists, biophysicists, and microscopy experts to discuss any challenge along the PhD. Overall, the project will provide a unique across-disciplines background that will enable the student to develop a successful scientific career in both academy and industry.

Additional information about our research groups can be found at:
https://www.st-andrews.ac.uk/~singlemol/singlemol.html
https://synergy.st-andrews.ac.uk/neurophotonics/
https://biology.st-andrews.ac.uk/biophotonics/

References:
[1] Rossi, G. A., Sacco, O., Mancino, E., Cristiani, L. & Midulla, F. Differences and similarities between SARS-CoV and SARS-CoV-2: spike receptor-binding domain recognition and host cell infection with support of cellular serine proteases. Infection (2020) doi:10.1007/s15010-020-01486-5.
[2] Cai, Y. et al. Distinct conformational states of SARS-CoV-2 spike protein. Science (2020) doi:10.1126/science.abd4251.
[3] Shang, J. et al. Cell entry mechanisms of SARS-CoV-2. PNAS 117, 11727–11734 (2020).
[4] Yoon, T.-Y., Okumus, B., Zhang, F., Shin, Y.-K. & Ha, T. Multiple intermediates in SNARE-induced membrane fusion. Proceedings of the National Academy of Sciences 103, 19731–19736 (2006).

The Synthetic Optics group (www.st-andrews.ac.uk/physics/synthopt) in the School of Physics and Astronomy at the University of St Andrews has a large portfolio of research projects aimed at designing and exploiting light matter interactions at the nanoscale. The range of applications targeted is equally wide and includes the development of advanced materials, nonlinear and complex photonic and biophotonics applications. All these strands converge in the newly funded project AMPHIBIANS, which aims at developing a novel biophotonic platform based on the all optical manipulation of photonic metasurfaces in microfluidic environments. This experimental PhD project will focus on the design and fabrication of the photonic metasurfaces.

The current trend in biophotonics is to try and replicate the same ease and precision that our hands, eyes and ears offer at the macroscopic level, e.g. to hold, observe, squeeze and pull, rotate, cut and probe biological specimens in microfluidic environments. The bidding to get closer and closer to the object of interest has prompted the development of extremely advanced manipulation techniques at scales comparable to that of the wavelength of light. However, the fact that the optical beam can only access the microfluidic chip from the narrow aperture of a microscopic objective limits the versatility of the photonic functions that can be realized.

AMPHIBIANS aims to introduce a new biophotonic platform based on the all optical manipulation of flexible photonic metasurfaces. These artificial two-dimensional materials have virtually arbitrary photonic responses and have an intrinsic exceptional mechanical stability. This cross-disciplinary project, bridging photonics, material sciences and biology, will enable the adoption of the most modern and advanced photonic designs in microfluidic environments, with transformative benefits for microscopy and biophotonic applications at the interface of molecular and cell biology.

This experimental project is a unique opportunity for a motivated individual to work at the forefront of a cross-disciplinary and timely topic. The project is challenging but highly rewarding as it gives to the student the opportunity to learn different and highly valued skills, from the advanced design of nanophotonic devices, to the fabrication and characterisation of metasurfaces in the visible range and their applications to biological problems.

The detection of hydrogen gas is important in many industries (petrochemical, civil nuclear, transport etc) due to its highly flammable nature. This need is likely to grow in the near future as hydrogen is used as the fuel of choice in many applications to reduce greenhouse gas emissions. Typically, hydrogen is detected using technologies reliant on chemical interactions with a catalytic material to oxidise the hydrogen to generate a signal. These technologies can be limited by their lack of selectivity and susceptibility to catalytic poisoning by commonly occurring chemicals. They also require a minimum oxygen content to function.

There is a need to have a compact optical solution that is selective, reliable, and able to operate in harsh environments, possibly without the presence of oxygen.

Raman spectroscopy has the capability to selectively detect hydrogen. However due to the extremely low signal levels for the Raman scattering process this technique is yet to be widely commercialised. Some progress has been made for open path detection using sensitive single photon avalanche diodes (SPAD) to detect the extremely small signals, but this methodology is not applicable for confined spaces or sealed vessels where a more compact solution is required. An alternative way to boost the sensitivity of the Raman signal would be to use the evanescent wave effects employed by surface enhanced Raman (SERS). SERS substrates are readily available for use with liquid analytes, particularly for biological specimens. However, these have a limited life, are often single use and require a suitable Raman microscope to measure the SERS signal.

A similar SERS effect should be possible using slotted photonic crystal waveguides (SPCW). These can be fabricated using semiconductor technology and could eventually lead to a full Raman-on-a-chip device.

This project would use models to predict the most suitable semiconductor substrate and excitation wavelength to use for SERS on an SPCW. The design would then be fabricated using the state-of-the-art facilities at St Andrews and tested to demonstrate the ability to detect hydrogen.

The student will be working at the University of St Andrews, supervised by the group of Synthetic Optics, within the School of Physics and Astronomy. The student will have access to the nanofabrication facilities, including multiple cleanrooms, electron beam and optical lithography systems, material deposition such as sputterer, evaporators, etc. Characterisation facilities include scanning electron microscopes, optical setups from the visible to near infrared spectral regions, and material characterisation, e.g. profilometry and ellipsometry. The student will also be part of the wider photonics research environment in the School of Physics and Astronomy, with a cohort of approximately 100 staff and students.

The School of Physics and Astronomy at the University of St Andrews has Juno Champion status (Institute of Physics) which reflects its commitment to family friendly policies and creating a work environment of benefit to all staff and students.
It has flexible and part time working policies for staff and features guidelines for full time vs part time study for students.
The supervision team are happy to discuss these with candidates when desired.

• Synthetic Optics

In addition to carrying genetic information, the flexibility and dynamics of RNA molecules allows them to fold into specific structures that dictate their fate and role in many crucial biological processes. Traditional structure determination methods such as X-ray, NMR or cryo-EM generate exquisitely resolved static 3D-structures, but they cannot be applied to study the structure of long and dynamic RNA sequences. The first step to determine the structure of long RNA molecules is to be able to discriminate stretches of single-stranded RNA from secondary and tertiary folded segments. Super-resolution optical imaging of long DNA sequences using fluorescence intercalators or fluorescently labelled DNA-binding proteins has been recently demonstrated as a tool to reveal the structure of the duplex DNA. In contrast, the application of super-resolution imaging of RNA sequences has been limited to detecting their presence, but not their structure, using in-situ hybridization or the incorporation of fluorescent aptamers within the RNA sequence. Current intercalator-based methods used commonly for DNA staining cannot discriminate between single- or duplex nucleic acid sequences, therefore they have limited application to image RNA structure. Our aim is to develop super-resolution structural imaging of RNA molecules, using a novel approach combining fluorescently labelled single-strand binding proteins (SSBs) and super-resolution optical imaging.
The stochastic binding of fluorescently labelled SSBs to the nucleic acid single strand sequences can be considered as a point accumulation for imaging nanoscale topography (PAINT) method that uses a protein-based reporter instead of a short DNA sequence (DNA-PAINT) [1]. Because the interaction of the SSB protein with the RNA is not sequence specific, SSB stochastic binding will light up the entire single-strand RNA sequence which is desirable for many applications. Thus, the combination of SSB-PAINT and super-resolution will allow, for the first time, to discriminate entire single-strand RNA regions from duplex RNA segments, which is currently impossible, and monitor transcriptional processes with an unprecedented spatial resolution.

Additional information about our research group can be found at:
https://www.st-andrews.ac.uk/~singlemol/singlemol.html
https://biology.st-andrews.ac.uk/biophotonics/

[1] Schnitzbauer et al, Super-resolution microscopy with DNA-PAINT. Nature Protocols, 12, 1198 (2017).

 

Organic light-emitting diodes (OLEDs) are novel type of LEDs in which electroluminescence is generated by plastic-like organic molecules. OLEDs are at the heart of modern smart phone displays and are likely to become the dominant technology for computer screens and large area TVs in the future. In addition, OLEDs are considered for general illumination, an area where efficiency is of key importance. While OLEDs can operate with close to 100% internal electron-to-photon conversion efficiency, typically less than 20-25% of the generated light is extracted into the surrounding air; the rest is trapped in waveguided modes and eventually lost to absorption.

Various strategies have been proposed to improve light extraction from OLEDs. Very recently controlling the average orientation of the electroluminescent molecules inside an OLED has been identified as a promising avenue. However, accurate measurement of molecular orientation is difficult and it remains unclear how molecular orientation can be controlled efficiently. Within this project, these challenges will be approached by making use of different spectroscopic and computational methods. Provided certain formal criteria are met, the student can benefit from placement with a major commercial developer of OLED materials and technology.

Further reading:
[1] A Graf, P Liehm, C Murawski, S Hofmann, K Leo, M C Gather, "Correlating the transition dipole moment orientation of phosphorescent emitter molecules in OLEDs to basic material properties", Journal of Materials Chemistry C 2, 10298 - 10304 (2014).
[2] C Murawski, P Liehm, K Leo, M C Gather, "Influence of cavity thickness and emitter orientation on the efficiency roll-off of phosphorescent organic light-emitting diodes", Advanced Functional Materials 24, 1117-1124 (2014)
[3] P Liehm, C Murawski, M Furno, B Lüssem, K Leo, M C Gather, "Comparing the emissive dipole orientation of two similar phosphorescent green emitter molecules in highly efficient organic light-emitting diodes", Applied Physics Letters 101, 253304 (2012).

Nanoplastic pollution in aquatic environments has emerged as a pressing global environmental crisis [1]. These particles, defined as plastic fragments smaller than 1 µm, are pervasive in oceans, rivers, and even drinking water. Originating from the degradation of larger plastic debris, nanoplastics possess the alarming ability to penetrate biological barriers, posing risks to marine life and human health [2]. They also act as nucleation sights for the establishment of bacterial or algal colonies which can cause significant change to marine ecosystems. Traditional detection methods are inadequate for addressing the scale and complexity of nanoplastic pollution, due to vanishingly small signals from such small objects in low concentrations. This is particularly challenging in field settings, highlighting the need for innovative solutions.
Building on recent advancements by our groups, specifically the successful isolation of microparticles using micron-scale optical traps on a microscope slide [3], this project aims to develop an innovative, miniaturized on-chip diagnostic system. This system will integrate multiplexed optical trapping with micromirrors for precise particle isolation, enhanced Raman spectroscopy through high-efficiency micromirrors and optimized laser wavelengths, and AI-driven analysis for rapid chemical structure detection. The novelty lies in translating lab-bound technologies into a portable, field-deployable format capable of high-throughput, real-time nanoplastic detection (size and composition) across diverse environments.

[1] Cai, H. et al. Analysis of Environmental Nanoplastics: Progress and Challenges. Chemical Engineering Journal, 410, 128208 (2021).
[2] Shi, C. et al. Emergence of Nanoplastics in the Aquatic Environment and Possible Impacts on Aquatic Organisms. Science of The Total Environment, 906, 167404 (2024)
[3] Plaskocinski, T.; Arita, Y.; Bruce, G. D.; Persheyev, S.; Dholakia, K.; Di Falco, A.; Ohadi, H. Laser Writing of Parabolic Micromirrors with a High Numerical Aperture for Optical Trapping and Rotation. Applied Physics Letters, 123, 081106 (2023).

This project would be eligible for funding including: EPSRC DTP (Must be within EPSRC remit.) 

Black holes can be understood in a simple picture: Imagine a river flowing towards a waterfall with ever increasing flow speed. Also imagine fishes in the river swimming upstream. At some position in the river the maximum speed of the fish will equal the flow speed and all fish beyond that "point of no return" will be flushed into the waterfall. Here the flow speed corresponds to the gravity of a black hole and the point of no return to the event horizon.
Arguably the most facinating aspects of astronomical black holes is the emission of Hawking radiation from the event horizon, an intriguing quantum effect combining gravity, thermodynamics and quantum mechanics.

Unfortunately, the astrophysical Hawking radiation is far too weak to ever being detected directly. Recently, however, we have invented a method to create moving artificial event horizons with short pulses in optical fibers. Moreover, the expected Hawking radiation is strong enough to be detectable with single photon coincindence counting.

The idea of the PhD programme is the calculation, detection, and characterization of this elusive Hawking radiation for the first time. The work has already gained momentum in our group and a setup is built using optical pulses of just a few cycles pulse length. In addition we will explore further quantum field theory effects in curved spacetime.

• Experimental quantum optics
• Quantum optics and information

Optical phenomena in biological structures have fascinated mankind for centuries and biological materials with optical functionality are currently a major topic of research. In the future, photonic devices may indeed be based on natural or genetically engineered optical function.

Recently, we developed a biological laser - a device based on a single living cell genetically programmed to produce the fluorescent protein GFP. The laser is biocompatible and biodegradable, and thus offers unique physical and biological properties not shared by any existing device.

However, so far our biolasers require an artificial resonator and an external pump source. This project is aimed at gaining a better understanding of lasing and stimulated emission in biological materials and at developing new avenues to biolasers. For example, this can include the study of bio-assembled resonators based on naturally occurring structures, photophysical investigations aimed explaining why fluorescent proteins are such efficient laser materials, or the development of biocompatible nanolasers.

The project is inter-disciplinary, involving photonics, laser physics, genetic engineering, proteomics, and material science and adequate training in these fields will be provided within the school and through external collaborators.

Further reading
[1] M C Gather, S H Yun, "Single-cell biological lasers", Nature Photonics 5, 406-410 (2011)
[2] M T Hill, M C Gather, "Advances in Small Lasers", Nature Photonics 8, 908-918 (2014) (Review paper)
[3] M C Gather, S H Yun, "Bio-optimized energy transfer in densely packed fluorescent protein enables near-maximal luminescence and solid-state lasers", Nature Communications 5, 5722 (2014)
[4] C P Dietrich, S Höfling, M C Gather, "Multi-state lasing in self-assembled ring-shaped eGFP microcavities", Applied Physics Letters 105, 233702 (2014)

 

Organic Light Emitting Diodes (OLEDs) are novel optoelectronic devices with potential applications ranging from displays (e. g. in smart phones or for flexible screens) to general illumination. In contrast to conventional LEDs, OLEDs are based on plastic-like organic materials. Thus, they can be mechanically flexible and are believed to offer improved biocompatibility.

In this project, micro-displays based on >200,000 individual OLEDs, each smaller than a single biological cell, are used as a platform for advanced studies in cell biology. Potential applications include lens-free, low-cost, continuous microscopy of cells and structured illumination for optogenetic studies. Optogenetics is a technique which allows controlling the biological activity of genetically modified cells by exposure to light. Over the past decade, the technique has greatly improved the understanding of various fundamental processes in biology, in particular in neuroscience. OLED micro-displays may enable optogenetic experiments, like stimulating growth or movement of neurons, with improved temporal and spatial control, higher degree of parallelization and over longer times than currently possible.

This project is highly interdisciplinary involving photonics and materials science but also cell biology and genetics. Training will be provided in all these aspects from within my group and through collaboration with the School of Biology and external collaborators at University of Cambridge and Harvard Medical School.

Further reading:
[1] L Fenno, O Yizhar, K Deisseroth (2011). The development and application of optogenetics. Annual Review of Neuroscience 34 (1), 389-412. DOI: 10.1146/annurev-neuro-061010-113817.
[2] B Geffroy, P Le Roy, C Prat (2006). Organic light-emitting diode (OLED) technology: materials, devices and display technologies. Polym. Int. 55 (6), 572-582. DOI: 10.1002/pi.1974.
[4] G Miller (2006). Shining new light on neural circuits. Science 314 (5806), 1674-1676. DOI: 10.1126/science.314.5806.1674.

 

We are seeking a PhD student to work in the Experimental Quantum Optics group of Dr. Friedrich Koenig (QuOpStAndrews) at St Andrews.

The project in St. Andrews is the implementation of "quantum simulators" in optical fibers, laboratory systems that can simulate situations of black hole interactions. These situations are notoriously difficult to observe directly in black holes and often impossible to calculate due to their non-perturbative nature.

Solitons in optical fibres efficiently simulate optical black holes by the event horizon. The wave equation in the frame of the pulse follows an effective fluid metric, i.e. the nonlinear refractive index curves otherwise straight light trajectories similar to a curvature of spacetime in General Relativity. Once perturbed, analogues and black holes both relax through the emission of characteristic waves, whose "fingerprint-like" frequency is independent of the initial perturbation. The PhD project is to measure this frequency experimentally and to find the classical and quantum correlations between soliton (black hole) oscillations and light characteristically radiated by the soliton. This simulator allows to experimentally address and verify ideas based on recent quantum technologies which are not possible to experiment with otherwise and might serve as a stepping stone to quantum gravity. We laid out the theoretical work in [1-3].

The research is part of the consortium of leading scientists from seven UK-based research organisations located in St Andrews, Cambridge, King's College London, Newcastle, Nottingham, University College London and Royal Holloway University London (more at qsimfp).

The ideal candidate should hold a first or upper second class degree in physics and have an interest in experimental nonlinear optics and quantum optics. The project also involves: pulsed laser systems, optical fibres, homodyne detection, quantum field theory, general relativity. 

[1] C. Burgess, et al., Phys. Rev. Lett. 132, 053802 (2024).
[2] C. Burgess and F. Koenig, Frontiers Physics 12 (2024).
[3] S. S. Baak and F. Koenig, New J. Phys. 27, 015001 (2025).

This project would be eligible for funding including: EPSRC DTP (Must be within EPSRC remit.)

• Experimental quantum optics

We are seeking an ambitious and motivated PhD student to join an EPSRC-funded project which seeks the adventurous goal of "designer magnetism", based around the flexibility and functionality offered by 2D magnetic materials. Of fundamental importance in its own right, but also as a platform to create targeted spintronic functionality, interfacing different van der Waals materials and magnets together promises almost limitless possibilities for tuning magnetic interactions and ordering tendencies and for realising new quantum states and phases. 
You will join an EPSRC-funded project which is working to develop an integrated approach to achieve this via the synthesis and spectroscopic characterisation of such 2D magnetic van der Waals heterostructures. We seek a PhD student to focus on advancing the spectroscopic investigation of these systems, probing their electronic structure in both k-space and real space, and developing routes to probe their magnetic order and excitations on the atomic scale. This project will make extensive use of the unique integrated materials synthesis and spectroscopy (STM, spin- and laser-ARPES) facilities of the Centre for Designer Quantum Materials in St Andrews, and builds on the host groups' experience in the study of 2D materials, of atomic-scale magnetic imaging, and of understanding and modelling their electronic structures [e.g. 1-5]. We seek a candidate who is interested to work collaboratively within and between these groups. 
For further information, or to discuss specific research possibilities, please contact pdk6@st-andrews.ac.uk or gpw2@st-andrews.ac.uk.

[1] Kushwaha et al. arXiv:2409.00189 (2024)
[2] Feng et al., Nano. Lett. 18 (2018) 4493
[3] Enayat et al., Science 345 (2014) 653
[4] Riley et al., Nature Physics 10 (2014) 835
[5] Edwards et al., Nature Materials 22 (2023) 459

This project would be eligible for funding including: EPSRC DTP (must be within EPSRC remit); Committed studentship from the Centre to match a funded grant.

• The Centre for Designer Quantum Materials

 

Decoherence, the enemy of any quantum processing, is the uncontrolled decay of a well defined quantum superposition. It occurs because any quantum system is always embedded in a wider environment with a macroscopic number of degrees of freedom. The interaction with these degrees of freedom causes a destructive interference and a nicely prepared quantum superposition dissipates somewhere in the environment. Large efforts are thus made throughout the world to isolate the system from its environment, to use special driving protocols that reverse some of the destructive interference, etc.

However, the concept of "bad" can also be reversed into something "good". It is indeed interesting to ask how exactly decoherence builds up, if we can use this to learn something about the system and the environment, and even if there is a way to use this knowledge for quantum information processing. Indeed the quantum fluctuations that eventually turn into decoherence initially build up an entanglement with the environment. The main questions underlying this PhD project are how this happens, how it can be followed in time, and if we can use it in a controlled way.

As a first example we have worked out in detail how a spin decays in a metal [1]. The stationary properties of such a system are known since very long and the analysis of the thermal decay is on the basis of magnetic resonance techniques such as NMR or MRI. However, mostly left aside was the regime of very short time scales in which the spin and a part of the metallic environment have a joint coherent evolution, and in which coherent excitations in the metal act back on the spin dynamics. The coherent many-body effect of a local excitation, such as from a spin flip, on the environment runs under the name of orthogonality catastrophe or Fermi edge singularity, is on the basis of the Kondo effect, and we have worked on extending the techniques to access this physics for various situations over many years. In [1] we have now set up the approach allowing us to systematically investigate the backaction on the spin as well. This proposed PhD work will build on these foundations and make the transition to including strongly correlated many-body environments. The goal is to provide a framework for the characterisation of correlated systems through probing localised spins, which is de facto an extension of the foundations of NMR to strongly interacting systems in which temporal correlations are as important as the spatial correlations that alone are addressed in current theories. Through the tremendous progress made in material design, low temperature physics and quantum control such a theoretical foundation is becoming more and more necessary.

[1] S. Matern, D. Loss, J. Klinovaja, B. Braunecker, Phys. Rev. B 100, 134308 (2019) [arXiv:1905.11422]

A triumph of 20th century condensed matter physics is the understanding of the phases of matter, arising from interacting many body problems in thermal equilibrium. However, not all matter is in equilibrium, and the understanding of matter out of equilibrium is far less developed. To develop our understanding of this, it is necessary both to develop new theoretical techniques, and to identify clean experimental systems where these approaches can be tested against known problems.

Ultracold atoms have provided an excellent test-bed for simulating canonical models in equilibrium, and can be adapted to probe non-equilibrium physics. In particular, ultracold atoms placed in optical cavities can be used to prepare and control non-equilibrium states of matter. Specifically, these experiments involve driving by scattering a pump laser into the optical cavity, leading to cavity mediated interactions between atoms, accompanied with collective dissipation processes. While experiments on atoms single mode cavities have been studied extensively, experiments on multimode cavities are only just beginning. These have the potential to transform the kinds of behaviour one can study.

Our theoretical group collaborates closely with the experimental group of Prof. Benjamin Lev (Stanford) who have built a multimode optical cavity that can produce tunable-range atomic interactions [1,2], and are now in the position to use this to explore novel states of matter [3]. Several ideas in this direction have been proposed, including paradigmatic models of phase transitions in one-dimensional systems [4] and Hopfield associative memories[5].

This PhD will explore a number of these topics; we will work in close collaboration with the Lev group in Stanford, so the precise projects will be determined in order to match ongoing and future experiments. We will make use of a variety of analytical and numerical techniques, potentially including matrix product state calculations. A key focus will be consider seriously the nature of the non-equilibrium states of matter that arise in such a context.

[1] "Tunable-Range, Photon-Mediated Atomic Interactions in Multimode Cavity QED" V.D. Vaidya, Y. Guo, R.M. Kroeze, K.E. Ballantine, A.J. Kollar, J. Keeling, and B.L. Lev, Phys. Rev. X 8 011002 (2018)
[2] "Sign-Changing Photon-Mediated Atom Interactions in Multimode Cavity Quantum Electrodynamics" Y. Guo, R.M. Kroeze, V.D. Vaidya, J. Keeling, and B.L. Lev, Phys. Rev. Lett. 122 193601 (2019)
[3] "An optical lattice with sound" Y. Guo, R.M. Kroeze, B.P. Marsh, S. Gopalakrishnan, J. Keeling, B.L. Lev, Nature 599 211 (2021)
[4] "Photon-Mediated Peierls Transition of a 1D Gas in a Multimode Optical Cavity" C. Rylands, Y. Guo, B.L. Lev, J. Keeling, and V. Galitski, Phys. Rev. Lett. 125 010404 (2020)
[5] "Enhancing Associative Memory Recall and Storage Capacity Using Confocal Cavity QED" B.P. Marsh, Y. Guo, R.M. Kroeze, S. Gopalakrishnan, S. Ganguli, J. Keeling, and B.L. Lev, Phys. Rev. X 11 021048 (2021)

This project would be eligible for funding including: EPSRC DTP scholarships administered by the University.
 

Topological quantum phases have risen to a very active field of research recently, triggered mostly by the realisation that "ordinary" semiconductor nanostructures can be fine tuned to exhibit topological properties which are very attractive for quantum information storing and processing. With the link to semiconductors a major step forward has been taken towards a quantum technological implementation of such states, yet to obtain robust and scalable quantum systems the requirement of fine tuning has to be dropped.

Self-sustained topological phases provide such stable and robust systems, and exhibit a multitude of fascinating new physical properties that emerge as an effect of strongly interacting particles in a condensed matter system. We have already demonstrated that such phases spontaneously appear in hybrid magneto-electronic systems in one dimension [1-5]. Yet in 1D the number of topological states is restricted, and to obtain more exotic topological states extensions to higher dimensions must be made. It is, however, mandatory to maintain then the 1D self-sustaining mechanisms to avoid producing only conventional phases [6].

In this PhD project, we will take a systematic approach towards such self-sustained topological phases by enhancing the complexity of the systems step by step while maintaining full control over the strongly correlated electron state. We will investigate the influence of the lattice structure (square, honeycomb, kagome), anisotropies and frustration, as well as the crucial renormalisation of the system properties by electron interactions.

[1] B. Braunecker, P. Simon, and D. Loss, Phys. Rev. Lett. 102, 116403 (2009) [arXiv:0808.1685]
[2] B. Braunecker, P. Simon, and D. Loss, Phys. Rev. B 80, 165119 (2009) [arXiv:0908.0904]
[3] B. Braunecker and P. Simon, Phys. Rev. Lett. 111, 147202 (2013) [arXiv:1307.2431]
[4] B. Braunecker and P. Simon, Phys. Rev. B 92, 241410(R) (2015) [arXiv:1510.06339]
[5] C. J. F. Carroll and B. Braunecker arXiv:1709.06093
[6] P. Simon, B. Braunecker, and D. Loss, Phys. Rev. B 77, 045108 (2008) [arXiv:0709.0164]

Rydberg excitons are giant atomic-like particles with macroscopic dimensions, long lifetimes and large interaction. Following their discovery in 2014, there is great interest to use them for modeling quantum phenomena. However, their control is still not achieved. Here, we aim to control and arrange them in ordered lattices to realise new quantum matter.

Excitons are the quantum particles in semiconductors. Excitons are bound electrons and holes, like the hydrogen atom and similarly have discrete energy levels. Much like atoms, excitons can be excited to high states with the electron now at much larger orbits than the ground state. This highly excited state is called the Rydberg exciton. Excitons tend to repel each other due to their Coulomb interaction. Because of the large size of Rydberg excitons this interaction strength becomes orders of magnitude larger [1], making them a suitable candidate for nonlinear quantum physics. By confining these excitons between two mirrors, light can strongly interact with them to form new particles called polaritons. In this project, we aim to realise tunable optical lattices of Rydberg polaritons, bringing them a step closer to quantum applications such as quantum simulations and quantum computers.

Rationale behind the proposed research – Lattices of Rydberg atoms have recently emerged as a successful demonstrator platform for quantum information [2]. Experimental realisation of Rydberg atoms, however, require incredibly sophisticated, expensive, and huge labs, which make their future large-scale adaptation less feasible. This problem can be solved by using Rydberg excitons where the semiconductor nature of Rydberg excitons allows them to be miniaturised on a chip, and to be used in a similar fashion to our current computer processors. Despite their recent discovery, however, lattices of Rydberg excitons are still not demonstrated. Here, by demonstrating optical lattices of Rydberg polaritons we are taking this important step towards the realisation of a solid-state quantum simulator. The medium-term aim of this project is the proof-of-principle demonstration of quantum correlations in lattices of Rydberg polaritons. The long-term aim is to use these controlled quantum correlations to build a solid-state quantum simulator using which complex problems can be solved exponentially faster than the classical computers [3].

Background – Most studies with excitons in semiconductors are limited to the lowest two energy levels. This is because the binding energy of excitons in most semiconductors is small. Recently, it has been shown recently [4,5] that cuprous oxide, can host giant Rydberg excitons, because of its large binding energy (Ry ≃100meV, 25 times larger than GaAs). Cuprous oxide is an abundant nontoxic direct-bandgap semiconductor. Rydberg excitons like Rydberg atoms are highly excited states, and they can extend to hundreds of lattice sites, as large as a micron. This is 1000 times larger than that of traditional semiconductors. The macroscopic dimensions of these "superatoms" allow their confinement for quantum technologies using current optical methods, where the wavelength of light is a few hundred nanometres and comparable to the size of the excitons. Furthermore, the effective size and interaction of these particles can be enhanced even further by coupling the Rydberg excitons to optical cavities to form polaritons [6]. Polaritons can be patterned and controlled much easier by lasers. Applying a nonresonant laser at higher energies than the bandgap can create an electron-hole plasma that inhibits the creation of polaritons [7], thereby forming an effective potential where the particles can be confined, while below the bandgap it creates a potential due to the AC Stark effect. The optical approach here allows an on-the-fly lattice of polaritons, with tunable interactions for studying emergent quantum phases.

[1] J. Heckötter, V. Walther, S. Scheel, M. Bayer, T. Pohl, and M. Aßmann, Asymmetric Rydberg Blockade of Giant Excitons in Cuprous Oxide, Nat. Commun. 12, 3556 (2021).
[2] M. Saffman, T. G. Walker, and K. Mølmer, Quantum Information with Rydberg Atoms, Rev. Mod. Phys. 82, 2313 (2010).
[3] C. S. Adams, J. D. Pritchard, and J. P. Shaffer, Rydberg Atom Quantum Technologies, J. Phys. B At. Mol. Opt. Phys. 53, 012002 (2019).
[4] T. Kazimierczuk, D. Fröhlich, S. Scheel, H. Stolz, and M. Bayer, Giant Rydberg Excitons in the Copper Oxide Cu2O, Nature 514, 343 (2014).
[5] K. Orfanakis, S. K. Rajendran, H. Ohadi, S. Zielińska-Raczyńska, G. Czajkowski, K. Karpiński, and D. Ziemkiewicz, Quantum Confined Rydberg Excitons in Cu2O Nanoparticles, Phys. Rev. B 103, 245426 (2021).
[6] K. Orfanakis, S. K. Rajendran, V. Walther, T. Volz, T. Pohl, and H. Ohadi, Rydberg Exciton–Polaritons in a Cu2O Microcavity, Nat. Mater. 21, 7 (2022).
[7] J. Heckötter, M. Freitag, D. Fröhlich, M. Aßmann, M. Bayer, P. Grünwald, F. Schöne, D. Semkat, H. Stolz, and S. Scheel, Rydberg Excitons in the Presence of an Ultralow-Density Electron-Hole Plasma, Phys. Rev. Lett. 121, 097401 (2018).
[8] G. Muñoz-Matutano et al., Emergence of Quantum Correlations from Interacting Fibre-Cavity Polaritons, Nat. Mater. 18, 213 (2019).

Polaritons are quasiparticles resulting from strong coupling between matter and light. Strong coupling occurs for photons confined in a microcavity, so that rather than photon emission being an irreversible loss process, photons that are emitted into the cavity can subsequently coherently excite the material again. This leads to new normal modes, polaritons. [1]

Historically, much of the work on these quasiparticles made use of strong coupling to electronic excitations in inorganic semiconductors, such as GaAs or CdTe. However, recently there has been a lot of interest in polaritons formed from a wide variety of materials, including organic molecules (ranging from small molecules to organic polymer chains), as well as very recent developments for materials such as transition metal dichalcogenides, and hybrid organic-inorganic perovskites. These molecular systems have very strong matter-light coupling, and so the physics can be seen at room temperature. [1,2,3]

One significant area of research concerns polariton condensation and lasing. Polaritons are bosons, and so Bose-Einstein condensation can be (and has been) seen. Because polaritons are part photon, they have a very low effective mass, leading to a very high transition temperature, indeed with organic materials, this can occur up to room temperature.

Another area of increasing experimental interest is in using strong coupling to change material properties. In the context of organic molecules, this has included the idea of changing chemical reaction rates by strong coupling.

This PhD position will be to explore theoretically models that capture the specific physics of a given material system, and ask how the physics of these materials affects, and is affected by, strong coupling to light. We will look both at the physics of Bose-Condensation, as well as modelling other possible applications of strong matter-light coupling to change material properties. We will make use of a variety of analytical and numerical techniques. For examples of relevant recent work from our group see Refs. [4,5,6].

[1] "The new era of polariton condensates" D.W. Snoke and J. Keeling, Phys. Today 70 54 (2017)
[2] "The road towards polaritonic devices" D. Sanvitto and S. Kena-Cohen, Nat. Mater. 15 1061 (2016)
[3] "Bose-Einstein Condensation of Exciton-Polaritons in Organic Microcavities" J. Keeling and S. Kéna-Cohen, Annu. Rev. Phys. Chem. 71 435 (2020)
[4] "Multimode Organic Polariton Lasing" K.B. Arnardóttir, A.J. Moilanen, A. Strashko, P. Törmä, and J. Keeling, Phys. Rev. Lett. 125 233603 (2020)
[5] "Crescent states in charge-imbalanced polariton condensates" A. Strashko, F.M. Marchetti, A.H. MacDonald, and J. Keeling, Phys. Rev. Lett. 125 067405 (2020)
[6] "Efficient non-Markovian quantum dynamics using time-evolving matrix product operators" A. Strathearn, P. Kirton, D. Kilda, J. Keeling, and B.W. Lovett, Nat. Commun. 9 3322 (2018)

This project would be eligible for funding including: EPSRC DTP scholarships administered by the University.
 

We are conducting a multi-faceted observational program to characterise brown dwarfs, including those with masses comparable to giant planets. Most of these objects form like stars, some will be ejected planets – but the exact formation mechanism are unclear. We use a range of ground-based and space telescopes covering the entire electromagnetic spectrum. The PhD project will focus on identifying brown dwarfs with NIRCam at the JWST. We want to develop a better understanding on how to distinguish brown dwarfs from other astrophysical sources, and then apply those criteria to archival and newly acquired NIRCam data, including images taken for completely different purposes. This will hopefully lead to improved samples in a range of environments, enabling discussions of the mass function and brown dwarf evolution. The same principle idea could be applied to the large-scale optical data from the Vera Rubin Observatory down the road.

This project would be eligible for funding including: STFC DTP. (Must be within STFC remit.) 

• Centre for Exoplanet Science

 

The world is increasingly using low-power, electronic devices in myriad ways, including sensors for the Internet of Things (IoT), where billions of objects are connected to the internet to make a smart network. Powering these billions of devices sustainably is a huge challenge. This project aims to develop novel indoor photovoltaic systems based on hybrid perovskites to sustainably power the wireless sensors in IoT [1]. Considering the huge number of sensors going to be in IoT applications, using an electrical grid or battery to power them will consume even more electricity and pose an environmental issue. By recycling electrical energy used for indoor lighting - which is otherwise lost - to power these innumerable sensors will improve the nation’s energy security. This will help the rapid growth of IoT, revolutionise the communication, health care and well-being facilities of communities.

Hybrid perovskites are a relatively new family of materials providing a framework to bind organic and inorganic components to a molecular composite and possess exceptional optoelectronic properties [2]. In the history of photovoltaics, no other light-harvesting material system has ever triggered research attention and promising avenues to harness solar energy similar to hybrid perovskites. Within a decade, these perovskite solar cells have made an amazing advancement from 3.81% of power conversion efficiency in 2009 to 25.2% today. However, in these materials so far, their excellent photovoltaic property under sunlight has only been extensively explored, leaving opportunities for alternate energy-harvesting such as ‘indoor photovoltaics’ [3].  Through the proposed research, the knowledge gap in the fundamental material and device physics of hybrid perovskites under indoor light conditions will be filled and efficient indoor photovoltaics to sustainably power IoT sensors will be developed. There would be ample opportunities to interact with the industries as well since the project involve many industry collaborations.

[1] Peters et al Joule (2019) 3 P1415
[2] Jena et al Chem. Rev. (2019) 119 3036
[3] Jagadamma et al Sol. Energy Mater. Sol. Cells (2019) 201 110071

• Energy Harvesting Research Group