Hydrodynamic description of Hard-core Bosons on a Galileo ramp

TL;DR

This paper investigates the non-equilibrium dynamics of hard-core bosons in a one-dimensional optical lattice after trap removal and a linear potential ramp, revealing complex behaviors like Bloch oscillations and phase-dependent condensate dynamics.

Contribution

It introduces a hydrodynamical approach to describe the quantum evolution of hard-core bosons under a Galileo ramp, validated by exact numerical simulations, highlighting rich phase-dependent phenomena.

Findings

Observation of Bloch oscillations and self-trapped condensates

Identification of different dynamical regimes based on initial density

Demonstration of superfluid and Mott phase behaviors during expansion

Abstract

We study the quantum evolution of a cloud of hard-core bosons loaded on a one-dimensional optical lattice after its sudden release from a harmonic trap. Just after the trap has been removed, a linear ramp potential is applied, mimicking the so called Galileo ramp experiment. The non-equilibrium expansion of the bosonic cloud is elucidated through a hydrodynamical description which is compared to the exact numerical evolution obtained by exact diagonalization on finite lattice sizes. The system is found to exhibit a rich behavior showing in particular Bloch oscillations of a self-trapped condensate and an ejected particle density leading to two diverging entangled condensates. Depending on the initial density of the gas different regimes of Josephson-like oscillations are observed. At low densities, the trapped part of the cloud is in a superfluid phase that oscillates in time as a whole. At higher densities, the trapped condensate is in a mixed superfluid-Mott phase that show a breathing regime for steep enough potential ramps.