Dr Steven J Thomson is a postdoctoral researcher at the Centre de Physique Théorique, École Polytechnique, working with Prof. Laurent Sanchez-Palencia. He has previously been a postdoctoral researcher at the Institut de Physique Théorique (CEA Paris-Saclay) and Collège de France, working with Dr Marco Schiró. His main research interests are the non-equilibrium dynamics of strongly correlated quantum systems in the presence of quenched random disorder, particularly many-body localisation and quantum glasses. He is currently particularly interested in developing cutting-edge numerical methods, with a focus on unitary flow techniques and tensor networks. He lives and works in Paris, France.
His PhD was supervised primarily by Dr Frank Krüger (UCL), with Dr Chris Hooley (St Andrews) as a second supervisor. During his PhD, he worked on disorder-induced phase reconstruction near ferromagnetic quantum critical points, spin density wave phases, fermionic nodal hypersufaces, ergodicity breaking in disordered bosonic systems, magnon glass phases in dimerised ferromagnets and collaborated with experimental physicists to design new protocols for quantum gas microscopes to measure exotic disordered phases of matter.
PhD, Theory of Condensed Matter, 2016
University of St Andrews and the Scottish Doctoral Training Centre in Condensed Matter Physics
MPhys Theoretical Physics (Hons), 2012
University of St Andrews
See my blog at Broken Symmetry for recent posts and other content.
Flow Equations for Many-Body Localisation - a powerful new method for studying localised quantum matter, capable of simulating large systems sizes (L>100) independent of their geometry or dimensionality, and able to access the dynamics of both local observables and correlation functions.
Localisation in Power-Law Random Band Matrices - even in one dimension, systems with long-range hopping can undergo an Anderson transition which turns out to have many interesting properties, and is an excellent test bed system for the development of tools for the study of many-body localisation.
Isolated Mean-Field Quantum Spin Glasses - providing a tractable window into the dynamics of disordered quantum systems in the thermodynamic limit, mean-field quantum glasses can be studied with a Schwinger-Keldysh framework. Numerically solving the Kadanoff-Baym equations allows us to access the dynamics of these systems and examine the effects of thermal and quantum fluctuations in great detail.
Transport Dynamics of the Sachdev-Ye-Kitaev Model - a fully-connected model of interacting Majorana fermions, the Sachdev-Ye-Kitaev model is an example of a disordered system which thermalises extremely quickly. It also has intriguing connections to black holes and quantum gravity: studying the non-equilibrium dynamics of this model allows us to simultaneously investigate both quantum glasses and quantum black holes.
Ergodicity Breaking in the Bose Glass - the Bose glass is a Griffiths phase that exists in the disordered Bose-Hubbard model, and is essentially a Mott insulator with rare disconnected superfluid ‘puddles’. This phase displays curious non-ergodic effects in its ground state (including replica symmetry breaking), and is believed to display many-body localisation on its excited states. It is also accessible with quantum gas microscopes: this is a particularly interesting model in that it can be studied from a large variety of angles, both theoretically and experimentally, yet a large number of important questions remain unanswered.
Quantum Gas Microscopy for Imaging Disordered Quantum Matter - one of the most powerful experimental tools in recent decades, the ability to image individual atoms in an optical lattice allows us an unprecedented view into the quantum heart of matter. A particularly interesting use for quantum gas microscopes is the investigation of disordered systems, where they can be used to directly image some of the most beguiling and complex quantum phases known to modern physics.
In 2018 I obtained the maître de conferences teaching qualification in France (required to become a lecturer in a French university), however I do not yet have a teaching position. During my time at the University of St Andrews, I was involved in teaching/tutoring/demonstrating the following courses: