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

TL;DR

This paper introduces a finite-temperature hydrodynamic model for 1D Bose gases, explaining frequency doubling in breathing-mode oscillations after a trap quench, supported by numerical simulations.

Contribution

It develops a hydrodynamic approach for finite-temperature 1D Bose gases and applies it to analyze momentum-space oscillations, extending the theory's applicability.

Findings

Frequency doubling depends on quench strength and initial temperature.

Hydrodynamic predictions align with finite-temperature c-field simulations.

The approach describes finite-temperature dynamics in momentum space.

Abstract

We develop a finite-temperature hydrodynamic approach for a harmonically trapped one-dimensional quasicondensate and apply it to describe the phenomenon of frequency doubling in the breathing-mode oscillations of its 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. We find that the frequency doubling is governed by the quench strength and the initial temperature, rather than by the crossover from the ideal Bose gas to the quasicondensate 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.