Metastable criticality and the super Tonks-Girardeau gas

TL;DR

This paper studies a highly excited 1D Bose gas with attractive interactions, revealing metastability, unique excitation structures, and critical behavior akin to a Luttinger liquid, with implications for experimental probing.

Contribution

It demonstrates the metastability of an out-of-equilibrium attractive 1D Bose gas and characterizes its correlation functions and excitation spectrum within the Luttinger liquid framework.

Findings

Relaxation processes are suppressed, leading to long-lived metastable states.

Dynamical correlation functions show enhanced umklapp correlations and new excitation branches.

The system exhibits critical behavior with power-law decay of correlations.

Abstract

We consider a 1D Bose gas with attractive interactions in an out-of-equilibrium highly excited state containing no bound states. We show that relaxation processes in the gas are suppressed, making the system metastable on long timescales. We compute dynamical correlation functions, revealing the structure of excitations, an enhancement of umklapp correlations and new branches due to intermediate bound states. These features give a clear indication of the attractive regime and can be probed experimentally. We observe that, despite its out-of-equilibrium nature, the system displays critical behaviour: correlation functions are characterised by asymptotic power-law decay described by the Luttinger liquid framework.