Finite-temperature hydrodynamics for one-dimensional Bose gases: Breathing-mode oscillations as a case study

Isabelle Bouchoule (1) , S S Szigeti (2) , M J Davis (3) , K V Kheruntsyan (2)

1 Laboratoire Charles Fabry / Optique atomique
2 School of Mathematics and Physics [Brisbane]
3 University of Utah, Department of Biology

We develop a finite-temperature hydrodynamic approach for a harmonically trapped one-dimensional quasi-condensate and apply it to describe the phenomenon of frequency doubling in the breathing-mode oscillations of the quasicondensate momentum distribution. The doubling here refers to the oscillation frequency relative to the oscillations of the real-space density distribution, invoked by a sudden confinement quench. By constructing a nonequilibrium phase diagram that characterises the regime of frequency doubling and its gradual disappearance , we find that this crossover is governed by the quench strength and the initial temperature, rather than by the equilibrium-state crossover from the quasicondensate to the ideal Bose gas regime. The hydrodynamic predictions are supported by the results of numerical simulations based on a finite-temperature c-field approach, and extend the utility of the hydrodynamic theory for low-dimensional quantum gases to the description of finite-temperature systems and their dynamics in momentum space.

Domaines: Gaz Quantiques [cond-mat.quant-gas]

Isabelle Bouchoule, S S Szigeti, M J Davis, K V Kheruntsyan. Finite-temperature hydrodynamics for one-dimensional Bose gases: Breathing-mode oscillations as a case study. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 2016, 94, pp.051602(R). ⟨10.1103/PhysRevA.94.051602⟩. ⟨hal-01422001⟩