Kinetically constrained dynamics in quantum gases

• Applicants: Dr. Mari Carmen Bañuls; Professor Igor Lesanovsky
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas ; Theoretical Condensed Matter Physics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 499180199

This project aims to break new ground in the understanding of complex dynamics that is displayed by kinetically constrained quantum systems. These are many-body models which were originally conceived in the study of classical glassy systems in which relaxation can become so slow that the stationary state cannot be reached on experimentally accessible time scales. They are often formulated in terms of spin ensembles, where the change of the state of a given spin is conditioned on the presence of a particular spin configuration within its neighbourhood. The understanding of quantum generalisations of kinetically constrained systems is still in its infancy, partly due to the fact that studying quantum mechanical systems becomes exponentially more costly with growing size, when compared with their classical counterpart. In this project we will construct and analyse quantum many-body systems with kinetic constraints and propose experimental realisations for them. We will on the one hand utilise advanced numerical methods, based on tensor networks, which will shed light on the connection between relaxation dynamics of kinetically constrained spin systems and the spectral properties of their dynamical generator as well as the time evolution of spatio-temporal quantum and classical correlations. On the other hand, we will develop and put into use a framework for the investigation of dynamical phase transitions, which is based on large deviation methods and the concept of time-integrated order parameters. Moreover, we will formulate and analyse kinetically constrained models which will be experimentally realised within our Research Unit, and which are based on a cold atomic quantum gas involving two species. We expect that our research results will lead to a significant advance in our understanding of relaxation processes in open and closed quantum matter as well as in the characterisation of complex dynamical phases. Moreover, our work will yield novel numerical and analytical tools which will benefit the research community as a whole.

• DFG Programme: Research Units
• Subproject of: FOR 5522: Quantum thermalization, localization, and constrained dynamics with interacting ultracold atoms
• International Connection: United Kingdom
• Cooperation Partner: Professor Dr. Juan P. Garrahan