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arXiv · 2007.08935

Cumulant theory of the unitary Bose gas: Prethermal and Efimovian dynamics

V. E. Colussi·H. Kurkjian·M. Van Regemortel·S. Musolino·J. van de Kraats·M. Wouters·S. J. J. M. F. Kokkelmans
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Abstract

We study the quench of a degenerate ultracold Bose gas to the unitary regime, where interactions are as strong as allowed by quantum mechanics. We lay the foundations of a cumulant theory able to capture simultaneously the three-body Efimov effect and ergodic evolution. After an initial period of rapid quantum depletion, a universal prethermal stage is established characterized by a kinetic temperature and an emergent Bogoliubov dispersion law while the microscopic degrees of freedom remain far-from-equilibrium. Integrability is then broken by higher-order interaction terms in the many-body Hamiltonian, leading to a momentum-dependent departure from power law to decaying exponential behavior of the occupation numbers at large momentum. We find also signatures of the Efimov effect in the many-body dynamics and make a precise identification between the observed beating phenomenon and the binding energy of an Efimov trimer. Throughout the work, our predictions for a uniform gas are quantitatively compared with experimental results for quenched unitary Bose gases in uniform potentials.

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V. E. Colussi, H. Kurkjian, M. Van Regemortel, S. Musolino, J. van de Kraats, M. Wouters, S. J. J. M. F. Kokkelmans. 2021-02-10. Cumulant theory of the unitary Bose gas: Prethermal and Efimovian dynamics. https://doi.org/10.1103/physreva.102.063314

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