Turbulent relaxation to equilibrium in a two-dimensional quantum vortex gas

Reeves, Matthew T., Goddard-Lee, Kwan, Gauthier, Guillaume, Stockdale, Oliver R., Salman, Hayder, Edmonds, Timothy, Yu, Xiaoquan, Bradley, Ashton S., Baker, Mark, Rubinsztein-Dunlop, Halina, Davis, Matthew J. and Neely, Tyler W. (2022) Turbulent relaxation to equilibrium in a two-dimensional quantum vortex gas. Physical Review X, 12 (1). ISSN 2160-3308

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Abstract

We experimentally study emergence of microcanonical equilibrium states in the turbulent relaxation dynamics of a two-dimensional chiral vortex gas. Same-sign vortices are injected into a quasi-two-dimensional disk-shaped atomic Bose-Einstein condensate using a range of mechanical stirring protocols. The resulting long-time vortex distributions are found to be in excellent agreement with the mean-field Poisson-Boltzmann equation for the system describing the microcanonical ensemble at fixed energy H and angular momentum M. The equilibrium states are characterized by the corresponding thermodynamic variables of inverse temperature β and rotation frequency ω. We are able to realize equilibria spanning the full phase diagram of the vortex gas, including on-axis states near zero-temperature, infinite temperature, and negative absolute temperatures. At sufficiently high energies the system exhibits a symmetry breaking transition, resulting in an off-axis equilibrium phase at negative absolute temperature that no longer shares the symmetry of the container. We introduce a point vortex model with phenomenological damping and noise that is able to quantitatively reproduce the equilibration dynamics.We experimentally study emergence of microcanonical equilibrium states in the turbulent relaxation dynamics of a two-dimensional chiral vortex gas. Same-sign vortices are injected into a quasi-two-dimensional disk-shaped atomic Bose-Einstein condensate using a range of mechanical stirring protocols. The resulting long-time vortex distributions are found to be in excellent agreement with the mean-field Poisson-Boltzmann equation for the system describing the microcanonical ensemble at fixed energy H and angular momentum M. The equilibrium states are characterized by the corresponding thermodynamic variables of inverse temperature β and rotation frequency ω. We are able to realize equilibria spanning the full phase diagram of the vortex gas, including on-axis states near zero-temperature, infinite temperature, and negative absolute temperatures. At sufficiently high energies the system exhibits a symmetry breaking transition, resulting in an off-axis equilibrium phase at negative absolute temperature that no longer shares the symmetry of the container. We introduce a point vortex model with phenomenological damping and noise that is able to quantitatively reproduce the equilibration dynamics.

Item Type: Article
Additional Information: Acknowledgements: We thank E. Kozik, N. Proukakis, and T. Simula for useful discussions. M. T. R. and T. W. N. thank the Institute for Nuclear Theory (INT) at the University of Washington for its kind hospitality and stimulating research environment at the INT-19-1a workshop, during which some of this research was undertaken. This research was supported in part by the INT’s U.S. Department of Energy Grant No. DE-FG02- 00ER41132. This research was supported by the Australian Research Council (ARC) Centre of Excellence for Engineered Quantum Systems (EQUS, CE170100009), and ARC Discovery Projects Grant No. DP160102085. This research was also partially supported by the Australian Research Council Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET, Project No. CE170100039) and funded by the Australian Government. G. G. acknowledges the support of an Australian Government Research and Training Program Scholarship. X. Y. acknowledges the support from NSAF with grant No. U1930403 and NSFC with Grant No. 12175215. T. W. N. acknowledges the support of Australian Research Council Future Fellowship No. FT190100306. Computing support was provided by the Getafix cluster at the University of Queensland.
Uncontrolled Keywords: physics and astronomy(all),4* ,/dk/atira/pure/subjectarea/asjc/3100
Faculty \ School: Faculty of Science > School of Mathematics
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Depositing User: LivePure Connector
Date Deposited: 07 Feb 2022 10:30
Last Modified: 22 Oct 2022 17:32
URI: https://ueaeprints.uea.ac.uk/id/eprint/83314
DOI: 10.1103/PhysRevX.12.011031

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