Landau-Zener sweeps and sudden quenches in coupled Bose-Hubbard chains

TL;DR

This paper numerically studies the dynamics of strongly correlated bosons in a two-leg ladder under time-dependent biases, revealing effects like reduced particle transfer during slow sweeps and thermalization after quenches.

Contribution

It provides a detailed numerical analysis of Landau-Zener sweeps and quenches in coupled Bose-Hubbard chains, connecting experimental observations with theoretical insights.

Findings

Reduced inter-chain particle transfer during slow linear sweeps.

Rapid broadening of quasi-momentum distribution indicating low-energy excitations.

Momentum distribution relaxes to thermal equilibrium after large density quenches.

Abstract

We simulate numerically the dynamics of strongly correlated bosons in a two-leg ladder subject to a time-dependent energy bias between the two chains. When all atoms are initially in the leg with higher energy, we find a drastic reduction of the inter-chain particle transfer for slow linear sweeps, in quantitative agreement with recent experiments. This effect is preceded by a rapid broadening of the quasi-momentum distribution of atoms, signaling the presence of a bath of low-energy excitations in the chains. We further investigate the scenario of quantum quenches to fixed values of the energy bias. We find that for large enough density the momentum distribution relaxes to that of an equilibrium thermal state with the same energy.