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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.

• Organic Semiconductor Centre

An exciting research opportunity is available to investigate the precise molecular mechanisms through which the brain regulates appetite, using advanced real-time imaging techniques and neuronal culture systems. In particular, this project aims to investigate the role of Melanocortin Receptor Accessory Protein 2 (MRAP2) in the trafficking and signal transduction of the melanocortin 4 receptor (MC4R), which is crucial for regulating hunger and energy balance in the brain. Using advanced single cell imaging and functional fluorescence microscopy, the study will track MC4R dynamics in live neurons and assess changes in receptor expression and intracellular signaling in response to MRAP2. The findings could provide insights into the mechanisms underlying obesity and potential interventions for its prevention.

Applicants should hold, or expect to achieve, a 2:1 honours degree (or equivalent) in Biology, Biochemistry, Neuroscience or a related discipline.

This project has been awarded IBANS Research Bursary of £1000 for research expenses. For further details on the project and informal enquiries please look at the web page of the Institute for Behavioural and Neural Sciences and contact Dr Javier Tello (jt65@st-andrews.ac.uk) and Dr Paolo Annibale (pa53@st-andrews.ac.uk).

Quantum state sharing (QSS) [1-3] is a quantum communication protocol that splits quantum information between a number of parties such that the information is inaccessible unless a large enough group of them work together. In the same category as other protocols such as quantum teleportation, this protocol uses quantum entanglement to ensure the protocol can be provably secure. As the security is based on immutable laws of physics, such protocols cannot be hacked and so provide a crucial building block for a future quantum internet.
 Our group has previously shown the simplest form of this protocol to be secure, in which the quantum information is split between 3 parties with 2 of them needing to work together to reconstruct it [4]. In this project, you will look at how to employ this protocol for a broader scope of applications.
Our protocol uses quantum continuous variables (CV), like position and momentum of harmonic oscillator, or amplitude and phase of light. But such implementations are not restricted to the optics realm. Recently, a number of CV quantum communication protocols were implemented using microwaves [5]. Our protocol has just been implemented by the same group who performed the work [5] and the manuscript is in preparation. 
We want to continue this collaboration and to evolve it towards quantum blind computation [6] and possibly also error correction [7], where QSS serves as a building block.

[1] R. Cleve, D. Gottesman, and H.-K. Lo, Phys. Rev. Lett. 83, 648 (1999)
[2] T. Tyc and B. C. Sanders, Phys. Rev. A 65, 042310 (2002)
[3] M. Hillery, V. Buzek, and A. Berthiaume, Phys. Rev. A 59, 1829 (1999)
[4] C. Wilkinson, M. Thornton, and N. Korolkova, Phys. Rev. A 107, 062401 (2023)
[5] K. Fedorov et al, Science Advances 7, eabk0891 (2021); Nature Communications 15, 7544 (2024)
[6] N. Liu, T. Demarie, S-H. Tan, L. Aolita, J. Fitzsimons, Phys. Rev. A 100, 062309 (2019)
[7] M. Lassen, M. Sabuncu, A. Huck, J. Niset, G. Leuchs, N. J. Cerf and U. L. Andersen, Nature Photonics, 4, 700 (2010).

• Quantum Information Group

As all fields and particles, light obeys the Heisenberg uncertainty principle for position and momentum. If the uncertainty of the position is larger or smaller than of the momentum, the state is called a momentum- or position- squeezed state. These 'squeezed states' can be produced with laser light in a relatively simple way.
The aim of the project is to design and construct a detector for these squeezed states of light and to test it in the laboratory. The detector employs an efficient photodiode and a low noise photocurrent amplifier.
Design blueprints for this type of detector are available as a starting point for the project. The aim is to build a detector that is more sensitive and has more bandwidth than existing solutions that will be used for guidance.
You should enjoy to engineer and built a device for a practical application.
The project will start with a review of previous work in the group and specific ideas in the literature about increasing the sensitivity of the detector. With the aid of the supervisor you will then develop a prototype design idea, which will be simulated on the computer. Once the simulation is successful, you will design the printed circuitboard (PCB) with the appropriate software and we will order the PCB and electronics components in. The detector will then be built in the electronics workshop in the department (or by the student) and tested in the laboratory for sensitivity, bandwidth and linearity. If time permits, we can test the detector with squeezed light.
At the end of the project you will have learned about quantum aspects of light, optical ``direct" detection, the simulation of electronics and practical implementation using PCB CAD software. You will be working in a state-of –the art laser facility.

References:
"Quantentomographische Charakterisierung gequetschter Zustände" (https://pure.mpg.de/rest/items/item_151309/component/file_151308/content) 
"Resonant photodetector for cavity- and phase-locking of squeezed state generation" (https://doi.org/10.1063/1.4966249)

• Experimental quantum optics

The cornerstone of quantum photonic technologies is generation, manipulation and harnessing for applications of quantum states of light. Quantum state engineering mainly relies on spontaneous parametric down-conversion (SPDC) and spontaneous four-wave mixing, where one or two pump photons spontaneously decay into an entangled photon pair, a biphoton. Both of these nonlinear effects require momentum conservation for the participating photons, which strongly limits the versatility of the resulting quantum states. Recent developments in planar optics, coined "flat optics", are mainly based on nonlinear metasurfaces with subwavelength thickness [1] or on thin, optically nonlinear films. This material solution not only enables the redesign of optical components into thin and multifunctional elements, allowing for improvements in footprint, system complexity and generating new optical functions. It also allows for the relaxation of the momentum conservation constraint in SPDC leading to increased spectral bandwidths of generated biphotons, to the rich angular-momentum spectrum, and to the generation of the multi-frequency entanglement [2]. Recently, entangled photon pairs have been generated also from thin nonlinear films [3]. Even richer system is liquid crystals, where additional control parameters are available and first results on entanglement generation has been reported [4].
In this project we will study the generation of multi-frequency entanglement in such systems and analyze the feasibility of creating particular cluster states on this basis: a linear three-qubit state, a Greenberger-Horne-Zeilinger state, and some more general graph state. At the core of this opportunity lies a fundamental idea of induced coherence, first developed in early 90-ies in the L. Mandel group [5], and recently re-invented for various quantum information applications [2, 6]. We will also identify the advantages and bottleneck points for application of cluster states generated from flat sources and benchmark them against state-of-art.

1. K. Wang, M. Chekhova, and Y. Kivshar, Metasurfaces for quantum technologies. Physics Today 75, 38 (2022), https://doi.org/10.1063/PT.3.5062
2. T. Santiago-Cruz, S. D. Gennaro, O. Mitrofanov, S. Addamane, J. Reno, D. Bethke, I. Brener, and M. V. Chekhova, Resonant Semiconductor Metasurfaces for Generating Complex Quantum States. Science 377, 991 (2022). https://doi.org/10.1126/science.abq8684
3. T. Santiago-Cruz, V. Sultanov, H. Zhang, L. A. Krivitsky, and M. V. Chekhova, Entangled photons from subwavelength nonlinear films. Optics Letters 46, 653 (2021). https://doi.org/10.1364/OL.411176
4. V. Sultanov et al, Tunable entangled photon-pair generation in a liquid crystal, Nature 631, 294 (2024).
5. X. Y. Zou, L. J. Wang, and L Mandel, Induced coherence and indistinguishability in Optical Interference. Phys. Rev. Lett. 67, 318 (1991).
6. G. B. Lemos et al, Quantum imaging with undetected photons, Nature 512, 409 (2014).

• Quantum Information Group

We will consider quantum chain of bosonic modes coupled only through common dissipative Markovian reservoirs. One can show that this chain can simulate efficiently classically hard problems, such as multi-dimensional random walks or, alternatively, can be used in a new field of diffusive coherent photonics [1]. Furthermore, coherent chain of interacting quantum systems represents a wide class of physical objects that define the behavior of matter in different physical conditions. 
In this project we will focus on topological effects that can be created in such dissipatively coupled chains. Specifically, we will look for systems with PT- and anti-PT-symmetries. Parity-time (PT)-symmetric systems are a class of non-Hermitian systems characterized by real propagation constants. Non-Hermitian Hamiltonians are said to be PT symmetric provided that they commute with the parity-time (PT) operators. These Hamiltonians contain only real eigenvalues. PT-symmetry is equivalent to all eigenstates being eigenstates of the PT operator. Photonic PT-symmetric systems that also support topological states could be useful for shaping and routing light waves.
In the paper [2], authors show that anti-PT symmetry can be realized in dissipatively coupled optical systems similar to those described in [1]. Anti-PT symmetry, {PT, H} = 0, represents a generalization of PT symmetry (see e.g. [3] for parity-time symmetries in photonics).  The resulting anti-PT symmetry causes a spontaneous phase transition of the eigenstates (characterized by PT symmetry breaking), which significantly influences the eigenvalues as well as the transport properties.
Topologically bound modes are another interesting effect which can be created in binary optical waveguides with anti-PT symmetry [4]. In [4], the anti-PT-symmetric arrays were realized by incorporating additional waveguides such that the effective coupling between waveguides is imaginary. Such systems were shown to experience two kind of transitions: transition of the global topological order and transition in the quantum phase. There are, as a result, two types of bound modes related to each of these transitions.
In the project, we will explore the possibility to realize interesting PT and anti-PT symmetry effects in a simple system of two dissipatively coupled modes, like a PhoG device described in [5], to investigate quantum noise evolution in different phases, and possibly extend it to the case of longer dissipatively coupled quantum chains.

1. S. Mukherjee, D. Mogilevtsev, G. Ya. Slepyan, T. H. Doherty, R. R. Thomson, N. Korolkova, Dissipatively Coupled Waveguide Networks for Coherent Diffusive Photonics. Nature Communications 8:1909 (2017).
2. Fan Yang, Yong-Chun Liu, and Li You, Anti-PT symmetry in dissipatively coupled optical systems. Phys. Rev. A 96, 053845 (2017).
3. S. K. Özdemir, S. Rotter, F. Nori and L. Yang. Parity-time symmetry and exceptional points in photonics. Nature Materials 18, 783 (2019).
4. Shaolin Ke, Dong Zhao, Jianxun Liu, Qingjie Liu, Qing Liao, Bing Wang, and Peixiang Lu, Topological bound modes in anti-PT-symmetric optical waveguide arrays. Optics Express Vol. 27, Issue 10, pp. 13858-13870 (2019).
5. M. Thornton, A. Sakovich, A. Mikhalychev, J. D. Ferrer, P. de la Hoz, N. Korolkova, D. Mogilevtsev: Coherent diffusive photon gun for generating non-classical states, Phys. Rev. Applied 12, 064051 (2019).

• Quantum Information Group

You will be working with a homebuilt clinostat, a prototype device that can simulate microgravity while supplying mammalian cells held under physiological conditions with nutrients or pharmacological stimuli. A clinostat is a device that simulates a microgravity environment. It can be used on living mammalian cells, bacteria or plant systems to monitor the effect of microgravity on biological systems, albeit its use is also documented in colloids, liquid crystals or granular materials[1,2]. 

The clinostat works by rotating a sample along a single axis (hereby defined as y) therefore changing periodically the direction of the gravity vector in both  of x and z, leading to a an average vectorial sum of zero over time along each of these two axes. Simply put, over time, gravity acts in all directions and sums to zero. The sample is still experiencing, instantaneously, a force; hence this is not equivalent to real microgravity (as achievable, for instance, on the International Space Station science platforms) but is a good approximation of microgravity. Nonetheless, for processes happening on timescales of minutes to hours, simulated microgravity has been shown to mimic several of the effects of real microgravity[3].

The concerted and finely regulated spatial-temporal interplay of several proteins at the cellular membrane, prominently cell membrane receptors, mediates how human cells respond to extracellular stimuli, generating a cascade of 2nd messengers known as
'downstream signaling'. In a project last year, supported by the European Space Agengy and the UK Space Agency, we demonstrated how altered gravity affects downstream signaling mediated by prototypical G protein-coupled receptors (GPCRs), a family of over 800 membrane proteins and prominent drug targets. We could show that the production of the 2nd messenger cAMP upon adrenergic stimulation is enhanced in hypergravity, and decreased in simulated microgravity, confirming earlier reports that had shown that cAMP homeostasis is affected in cellular organisms and single cells exposed to periods of altered gravity. Our hypothesis is that sub-diffraction limit disturbances in the membrane nanotopography of the signalling receptors are responsible. 
 
In this interdisciplinary project, combining hardware development, experiments at European Space Agency ground based facilities, advanced microscopy, cell biology and data analysis, we want to quantitatively extract the relationship between altered gravity and nanoscale membrane receptors arrangement. 

Our results have the potential for developing a research area that received only limited earlier attention in microgravity research, namely membrane nanotopography of signaling proteins, which connects to the role altered gravity has in
modulating pharmacology, which has broad impact towards manned flight and space exploration at large.

If you are interested, please approach or send an email to Dr. Paolo Annibale (pa53@st-andrews.ac.uk).

References

(1) Oluwafemi, Funmilola A., and Adhithiyan Neduncheran. "Analog and simulated microgravity platforms for life sciences research: Their individual capacities, benefits and limitations." Advances in Space Research 69.7 (2022): 2921-2929.

(2) Brungs, Sonja, et al. "Facilities for simulation of microgravity in the ESA ground-based facility programme." Microgravity science and technology 28.3 (2016): 191-203.

(3) Bathe-Peters, M., Sohail, I., Sirbu, A., Schneider, K., Patriarchi, T., Anilkumar, A., ... & Annibale, P. (2025). "Effects of altered gravity on adrenergic-mediated cAMP signalling in intact cells." bioRxiv, 2025-03.

• The Centre for Exoplanet Science
• The Centre of Biophotonics