Enhanced correlations due to ballistic transport

TL;DR

This paper studies how density correlations evolve in a 1D gas of hard-core particles expanding into empty space, revealing algebraic decay at large times regardless of initial temperature, using exact and hydrodynamic methods.

Contribution

It provides analytical and numerical analysis of density correlations during expansion, highlighting temperature-independent algebraic decay and applying quantum generalized hydrodynamics.

Findings

Correlations decay algebraically at large times

Results are consistent across zero and finite temperature

Analytical and numerical methods agree well

Abstract

We investigate the nature of density-density correlations in a 1D gas of hard-core particles initially prepared at equilibrium (either at zero or finite temperature) on a semi-infinite line and subsequently let to expand into the other (initially empty) half of the system. Using a combination of analytical techniques based on exact methods and asymptotic hydrodynamic approaches, we discuss the behavior of the gas as its initial temperature varies, and back up our derivations with numerical exact diagonalization of the model. Our findings reveal that, irrespective of the initial temperature, the non-equilibrium behavior of density-density correlations at sufficiently large times is characterized by algebraic decay. Furthermore, we provide analytical results based on quantum generalized hydrodynamics that match with the numerical data both at zero and finite temperature.