Noise correlations of the ultra-cold Fermi gas in an optical lattice

TL;DR

This paper investigates how density noise correlations in an ultra-cold Fermi gas within optical lattices can distinguish between different quantum phases, including BCS, FFLO, and BP states, at various temperatures and dimensions.

Contribution

It provides a comparative analysis of noise correlations for multiple phases and explores their temperature dependence, especially in one-dimensional systems.

Findings

Noise correlations differ significantly among BCS, FFLO, and BP states.

Finite temperature effects can obscure phase detection.

One-dimensional systems show promising signals for FFLO state identification.

Abstract

In this paper we study the density noise correlations of the two component Fermi gas in optical lattices. Three different type of phases, the BCS-state (Bardeen, Cooper, and Schieffer), the FFLO-state (Fulde, Ferrel, Larkin, and Ovchinnikov), and BP (breach pair) state, are considered. We show how these states differ in their noise correlations. The noise correlations are calculated not only at zero temperature, but also at non-zero temperatures paying particular attention to how much the finite temperature effects might complicate the detection of different phases. Since one-dimensional systems have been shown to be very promising candidates to observe FFLO states, we apply our results also to the computation of correlation signals in a one-dimensional lattice. We find that the density noise correlations reveal important information about the structure of the underlying order parameter as well as about the quasiparticle dispersions.