Stochastic phase space methods for non-equilibrium systems
Lead Research Organisation:
University College London
Department Name: Physics and Astronomy
Abstract
The aim is to explore and expand the scope of phase space methods for simulating the behaviour of many-body quantum systems out of equilibrium.
As an initial project I will be looking for KPZ behaviour within the OPO regime of polaritons in semiconductor microcavities using existing code for the truncated Wigner simulation of this system. This is to serve the dual purpose of familiarising myself with the methods and how they are implemented computationally as well as answering an open question posed by my group's previous research.
Further projects will then involve exploring related phase space methods, such as positive P, to go beyond what is accessible to the truncated Wigner approximation to study non-classical effects in non-equilibrium many-body quantum systems, such as polariton lattices.
As an initial project I will be looking for KPZ behaviour within the OPO regime of polaritons in semiconductor microcavities using existing code for the truncated Wigner simulation of this system. This is to serve the dual purpose of familiarising myself with the methods and how they are implemented computationally as well as answering an open question posed by my group's previous research.
Further projects will then involve exploring related phase space methods, such as positive P, to go beyond what is accessible to the truncated Wigner approximation to study non-classical effects in non-equilibrium many-body quantum systems, such as polariton lattices.
Organisations
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509577/1 | 01/10/2016 | 24/03/2022 | |||
| 1814201 | Studentship | EP/N509577/1 | 01/10/2016 | 25/03/2021 | Alexander Ferrier |
| Description | Using our Truncated Wigner simulations, we produced the first numerical evidence of the 2D Kardar-Parisi-Zhang (KPZ) universality in the optical parametric oscillator (OPO) regime of exciton-polaritons in semiconductor microcavities. The KPZ universality encompasses the universal behaviour of a number of out-of-equilibrium systems, such burning paper, growing interfaces in liquid crystals, and growing cell colonies. However, useful experimental platforms for studying the KPZ universality in two dimensions are rare and highly sought after. Our numerical results open up the possibility of using the microcavity polariton OPO, a well established and highly controllable experimental platform, for studying the physics of the 2D KPZ universality. Using the example of the driven-dissipative Bose-Hubbard model, we demonstrated that positive-P method allows for exact scalable simulations open quantum systems in cases where the dissipation is sufficiently strong. It is not in general possible to simulate large many-body quantum systems on a classical computer, so finding a method that can achieve this for some subset of situations opens up deeper theoretically study of many cases where it was not otherwise possible. Open quantum systems, i.e. those with dissipation to the environment, encompass many of the experimental platforms currently at the forefront of investigations into quantum technologies and quantum simulation, particularly those that utilise light, which is difficult to perfectly confine within the system. While coupling of the system to the external environment can result in decoherence of quantum correlations within the system, it also can be exploited to allow the state of the system to be more easily prepared and measured. Increasing the range of situations in which it is possible to simulate these open quantum systems on a computer can greatly aid in both the understanding of them and their development for practical uses. |
| Exploitation Route | Our theoretical results on the 2D KPZ universality in the polariton OPO enable confirmation of those results in actual experiments. A number of research groups globally already perform polariton OPO experiments and our results provide a recipe by which this platform can be used to investigate the 2D KPZ universality. With our investigations into the positive-P method, we hope to encourage and facilitate the use of this method to study open quantum systems by other research groups. Furthermore, the use of the positive-P method as a computational tool in collaboration with experimental research may aid in investigating the properties of and developing applications for various kinds of open quantum system. |
| Sectors | Digital/Communication/Information Technologies (including Software),Electronics,Other |