University of St Andrews
School of Physics and Astronomy
PhD positions for a start in 2018 are still available, and details
are listed here.
We are theoretical condensed matter physicists interested in many-body
and interaction effects
in systems that are attractive for future quantum technology.
Our current activities involve:
Topological states by self-organisation transitions in interacting low-dimensional conductors.
New physics achievable with Majorana bound states in condensed matter systems.
Generation and detection of entanglement in nanostructures.
For details on our recent activities click here.
Latest papers of the group
Entanglement in 3D Kitaev spin liquids
S. Matern, M. Hermanns
J. Stat. Mech.: Theor. Exp. P063101 (2018)
Quantum spin liquids are highly fascinating quantum liquids in which the spin degrees of freedom fractionalize.
An interesting class of spin liquids are the exactly solvable, three-dimensional Kitaev spin liquids. Their
fractionalized excitations are Majonara fermions, which may exhibit a variety of topological band
structures—ranging from topologically protected Weyl semi-metals over nodal semi-metals to systems with
Majorana Fermi surfaces. We study the entanglement spectrum of such Kitaev spin liquids and verify that it is
closely related to the topologically protected edge spectrum. Moreover, we find that in some cases the entanglement
spectrum contains even more information about the topological features than the surface spectrum, and thus provides
a simple and reliable tool to probe the topology of a system.
Continuum description for sub-gap states at ferromagnetic and spiral ordered magnetic chains in two-dimensional superconductors
C. J. F. Carroll, B. Braunecker
We consider sub-gap bands induced in a two-dimensional superconductor by a densely packed chain of magnetic moments with ferromagnetic
or spiral alignments. We show that crucially all wavelengths must be taken into account in the calculation of the sub-gap properties,
and that in particular gap closings can occur at high momentum due to a mix of Shiba type and magnetic scattering states. The sub-gap
bands are always connected to the bulk bands such that it is impossible to single out a fully one-dimensional subband as required for
distinct topological properties. To obtain the latter a finite spacing between the impurities needs to be reintroduced such that by zone
folding the bands can disconnect from the continuum.