Biography

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.

• Flow Equations for Floquet Dynamics (TBC), S. J. Thomson, D. Magano & M. Schiró, in preparation.
• Many-Body Localisation in the Presence of Long-Range Couplings (TBC), S. J. Thomson & M. Schiró, in preparation.
• Dynamics of Disordered Quantum Systems Using Flow Equations, S. J. Thomson & M. Schiró, Euro. Phys. J. B (2020) 93: 22
• Quantum Quenches in Isolated Quantum Glasses Out Of Equilibrium, S. J. Thomson, P. Urbani & M. Schiró, arXiv:1904.03147
• Time Evolution of Many-Body Localized Systems with the Flow Equation Approach, S. J. Thomson & M. Schiró, Physical Review B: Rapid Communication 97, 060201R (2018)
• Measuring the Edwards-Anderson order parameter of the Bose glass: a quantum gas microscope approach, S. J. Thomson, L. S. Walker, T. L. Harte & G. D. Bruce, Physical Review A: Rapid Communication 94, 051601R (2016)
• The effects of disorder in strongly interacting quantum systems, S. J. Thomson, University of St Andrews PhD Thesis
• Bose and Mott glass phases in dimerized quantum antiferromagnets, S. J. Thomson & F. Krüger, Physical Review B: Rapid Communication 92, 180201R (2015)
• Replica symmetry breaking in the Bose glass, S. J. Thomson & F. Krüger, Europhysics Letters 108, 30002 (2014)
• Helical glasses near ferromagnetic quantum criticality, S. J. Thomson, F. Krüger & A. G. Green, Physical Review B 87, 224203 (2013)

For a full list, see Google Scholar or ORCiD. For code, data, research notes and other resources, see the Resources page.

Upcoming

• TBC

Recent presentations

• 4th July 2019, “Non-Equilibrium Dynamics of Quantum Glasses and Many-Body Localised Phases”, University Collge London / London Centre for Nanotechnology
• 21st May 2019, “Non-Equilibrium Dynamics of Quantum Glasses and Many-Body Localised Phases”, CPHT École Polytechnique, Palaiseau
• “Flow Equations for Many-Body Localisation: Dynamics and Dimensionality”, APS March Meeting 2019, Boston (USA)
• 19th November 2018, “Fluctuation-Induced Aging in a Mean-Field Quantum Glass”, DIM SIRTEQ Annual Conference, Institut d’Optique (poster)
• 8th November 2018, “Fluctuation-Induced Aging in a Mean-Field Quantum Glass”, Schiró Group Meeting, Collège de France
• 4th April 2018, “Flow Equations for Many-Body Localisation: Dynamics and Dimensionality”, Laboratoire de Physique Théorique, Université Paul Sabatier, Toulouse

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:

• 2012-2013
  • PH5004 Quantum Field Theory, individual student support
  • PH2011 Physics 2A (Physique 2A), 2 groups, 1 workshop
  • PH2012 Physics 2B (Physique 2B), 2 groups, 1 workshop

• 2013-2014
  • PH3061 Quantum Physics 2A, 4 groups
  • PH3082 Electromagnetism, 5 groups
  • PH2011 Physics 2A (Physique 2A), 1 workshop
  • PH2012 Physics 2B (Physique 2B), 1 workshop

• 2014-2015
  • PH5004 Quantum Field Theory, individual student support
  • PH3081 Mathematical Methods for Physicists, 2 groups
  • PH3061 Quantum Physics 2A, 1 group
  • PH3082 Electromagnetism, 4 groups
  • PH2011 Physics 2A, 1 workshop
  • PH2012 Physics 2B, 1 workshop

• 2015-2016
  • PH4040 Transferable Skills for Physicists, 1 group
  • PH5002 Masters Project in Theoretical Physics - together with Dr Graham Bruce and Dr Jonathan Keeling, I supervised MPhys student Liam Walker’s final year research project on quantum gas microscopes. Liam was later shortlisted for the Undergaduate Awards for his final project dissertation, and is now a PhD student with Prof Andrew Daley, University of Strathclyde.

• Prof. Laurent Sanchez-Palencia
• Dr Marco Schiró
• Dr Pierfrancesco Urbani
• Dr Frank Krüger
• Prof. Andrew Green
• Dr Graham D. Bruce
• Dr Tiffany L. Harte
• Mr Liam S. Walker

Twitter: @PhysicsSteve

• steven.thomson@polytechnique.edu
• Centre de Physique Théorique, École Polytechnique, Institut Polytechnique de Paris, Route de Saclay, Palaiseau, France