Spin-charge separation effects in the low-temperature transport of 1D Fermi gases

TL;DR

This paper investigates how spin-charge separation manifests in the low-temperature transport of one-dimensional Fermi gases, revealing that it becomes evident only at low temperatures through distinct velocities and profiles.

Contribution

It analytically demonstrates the emergence of spin-charge separation at low temperatures in 1D Fermi gases using generalized hydrodynamics.

Findings

Signatures of spin-charge separation appear at low temperatures.

Profiles exhibit piece-wise constant forms at low temperatures.

Two decoupled Luttinger liquids describe the low-temperature regime.

Abstract

We study the transport properties of a one-dimensional spinful Fermi gas, after junction of two semi-infinite sub-systems held at different temperatures. The ensuing dynamics is studied by analysing the space-time profiles of local observables emerging at large distances $x$ and times $t$, as a function of $\zeta = x/t$. At equilibrium, the system displays two distinct species of quasi-particles, naturally associated with different physical degrees of freedom. By employing the generalised hy- drodynamic approach, we show that when the temperatures are finite no notion of separation can be attributed to the quasi-particles. In this case the profiles can not be qualitatively distinguished by those associated to quasi-particles of a single species that can form bound states. On the contrary, signatures of separation emerge in the low-temperature regime, where two distinct characteristic ve- locities appear. In this regime, we analytically show that the profiles display a piece-wise constant form and can be understood in terms of two decoupled Luttinger liquids.