Probing the Excitations of a Lieb-Liniger Gas from Weak to Strong Coupling

TL;DR

This study investigates the excitation spectrum of a one-dimensional Bose gas across different interaction strengths, revealing the significant role of hole-like excitations in its dynamical response through experimental and theoretical analysis.

Contribution

It provides the first comprehensive experimental and theoretical analysis of the excitation spectrum of a Lieb-Liniger gas from weak to strong coupling, highlighting the role of hole-like excitations.

Findings

Experimental Bragg spectroscopy matches integrability calculations across interaction regimes.

Hole-like excitations significantly influence the dynamical response.

The results confirm the unique excitation features of 1D Bose gases.

Abstract

We probe the excitation spectrum of an ultracold one-dimensional Bose gas of Cesium atoms with repulsive contact interaction that we tune from the weakly to the strongly interacting regime via a magnetic Feshbach resonance. The dynamical structure factor, experimentally obtained using Bragg spectroscopy, is compared to integrability-based calculations valid at arbitrary interactions and finite temperatures. Our results unequivocally underly the fact that hole-like excitations, which have no counterpart in higher dimensions, actively shape the dynamical response of the gas.