Phase Coherence of Strongly Interacting Bosons in One-Dimensional Optical Lattices

TL;DR

This study combines experiments and tensor-network simulations to analyze phase coherence in strongly interacting one-dimensional Bose gases in optical lattices, revealing temperature effects and thermalization inhibition.

Contribution

It provides a comprehensive analysis of phase coherence across various lattice depths, incorporating experimental data and advanced simulations to understand thermal effects.

Findings

Good agreement with zero-temperature theory at deep lattices.

Finite-temperature effects become significant at shallower lattices.

Inhibition of thermalization leads to low-entropy quantum states at large lattice depths.

Abstract

Ultracold Bose gases in one-dimensional optical lattices constitute an important benchmark problem in the study of strongly interacting many-body quantum phases. Here we present a combined experimental and theoretical study of their phase-coherence properties over a wide range of lattice depths. Experimentally, we extract the single-particle correlation function directly from the measured momentum distribution. Theoretically, we perform tensor-network simulations of the Bose-Hubbard model that incorporate all relevant experimental parameters. For deep lattices well within the Mott insulator regime, the experimental results are in good agreement with the expected zero-temperature behavior, with only small temperature-dependent corrections. As the lattice depth is reduced, finite-temperature effects become increasingly important. We find that the experimental data are quantitatively described by an effective temperature extracted from the tensor-network simulations, and that this effective temperature decreases markedly with increasing lattice depth. Rather than indicating actual cooling, we interpret this behavior as evidence of inhibition of thermalization caused by the formation of Mott domains that suppress heat transport. Counterintuitively, the inhibition of thermalization favors the preparation of an effectively low-entropy quantum gas in the trap center for large lattice depths.