Topology of quantum systems out of equilibrium
Lead Research Organisation:
University of Cambridge
Department Name: Physics
Abstract
In this project, we study the non-equilibrium properties of quantum systems with topologically non-trivial properties. The broad aim is to understand how the phenomenology of topological phases in equilibrium changes once non-equilibrium dynamics is introduced, which includes periodic driving, quantum quenches, and external noise. Using both archetypical models and more general theoretical tools, we will address questions relating to the key signatures of topological phases, including the fate of topological invariants, and the experimental observables generally associated with topological non-triviality. In addition, we will look for new phenomena which are not seen in equilibrium phases, with a focus on quantities which can be measured in ultracold atom exeriments, in which coherent quantum dynamics can be accessed.
Organisations
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509620/1 | 01/10/2016 | 30/09/2022 | |||
| 1948689 | Studentship | EP/N509620/1 | 01/10/2017 | 31/03/2021 | Maximillian McGinley |
| Description | It is well understood that certain quantum systems can exhibit novel phases of matter known as topological phases. We have theoretically investigated how these systems behave when subjected to some external time-dependent perturbations, which drives them far from equilibrium. We found that there are some systems for which the useful `topological' properties familiar from studies of equilibrium systems will persist when driving is added. In contrast, there are some phases which are spoiled by the addition of non-equilibrium phases. We have exhaustively classified exactly which phases are / are not robust in this sense. In turn, we considered how this fragility to non-equilibrium driving affects the properties of these phases that makes them potentially useful in quantum technologies. In particular, we demonstrated that these unstable phases will suffer from issues if they are to be used as a basis for a topologically protected quantum memory. |
| Exploitation Route | Our findings are somewhat surprising given the conventional wisdom that all topological phases are equally well `protected'. We expect that our non-equilibrium classification of topological phases can be used by future researches to immediately identify systems that may suffer from issues related to non-equilibrium effects, e.g. in open systems. |
| Sectors | Other |