Quench dynamics of a strongly interacting resonant Bose gas

Abstract

We explore the dynamics of a Bose gas following its quench to a strongly interacting regime near a Feshbach resonance. Within a self-consistent Bogoliubov analysis we find that after the initial condensate-quasiparticle Rabi oscillations, at long time scales the gas is characterized by a nonequilibrium steady-state momentum distribution function, with depletion, condensate density and contact that deviate strongly from their corresponding equilibrium values. These are in a qualitative agreement with recent experiments on Rb85 by Makotyn, et al. Our analysis also suggests that for sufficiently deep quenches close to the resonance the nonequilibrium state undergoes a phase transition to a fully depleted state, characterized by a vanishing condensate density.Comment: 4 pages, 5 pdf figure

Nonequilibrium states of a quenched Bose gas

“…Of particular relevance here is a theoretical analysis of the JILA experiment by Yin and Radzihovsky [1] who, in the spirit of Bogoliubov mean-field theory, divided the Bose gas at zero temperature into a quantum system of Bogoliubov quasiparticles and a condensate of number density n c , which is treated as a dynamical mean field (as opposed to a fixed constant as done by Natu and Mueller [50]). We explore this same topic using this same approach.…”

“…It was unclear which dominates until recently when a JILA experiment on 85 Rb by Makotyn et al [2] firmly established that the three-body loss rate is much slower than the equilibration rate. This pleasant surprise opens the door to the possibility of exploring the rich physics underlying strongly interacting Bose gases [29][30][31][32][33][34][35][36][37] and has motivated, together with experimental works such as [43], a flurry of theoretical studies concerning quenched nonequilibrium dynamics [1,[44][45][46][47][48][49].…”

“…Yin and Radzihovsky [1] recently developed a self-consistent extension of a Bogoliubov theory, in which the condensate number density nc is treated as a mean field that changes with time, in order to analyze a JILA experiment by Makotyn et al…”

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Yin and Radzihovsky [1] recently developed a self-consistent extension of a Bogoliubov theory, in which the condensate number density nc is treated as a mean field that changes with time, in order to analyze a JILA experiment by Makotyn et al[2] on a 85 Rb Bose gas following a deep quench to a large scattering length. We apply this theory to construct a closed set of equations that highlight the role ofṅc, which is to induce an effective interaction between quasiparticles.

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Dynamics of correlations in a quasi-two-dimensional dipolar Bose gas following a quantum quench

“…In this section we compare our "static" treatment of the time-dependent Bogoliubov approximation [54] of Sec III to a fully self-consistent Bogoliubov treatment of the dynamics, developed by Lin and Radzihovski [45], where we let the condensate density fluctuate in time according to:…”