Pairing in population imbalanced Fermion systems

TL;DR

This study uses Quantum Monte Carlo simulations to explore the pairing mechanisms in imbalanced one-dimensional fermionic systems, revealing the robustness of the FFLO phase across different conditions and its experimental detectability.

Contribution

The paper provides the first detailed phase diagram of imbalanced fermionic systems with attractive interactions, highlighting the stability of the FFLO phase at higher temperatures and polarizations.

Findings

FFLO phase persists at higher temperatures with increased polarization

The phase diagram maps the stability regions of different phases

FFLO phase is detectable in current ultra-cold atom experiments

Abstract

We use Quantum Monte Carlo (QMC) simulations to study the pairing mechanism in a one-dimensional fermionic system governed by the Hubbard model with attractive contact interaction and with imbalance between the two spin populations. This is done for the uniform system and also for the system confined in a harmonic trap to compare with experiments on confined ultra-cold atoms. In the uniform case we determine the phase diagram in the polarization-temperature plane and find that the "Fulde-Ferrell-Larkin-Ovchinnikov" (FFLO) phase is robust and persists to higher temperature for higher polarization. In the confined case, we also find that the FFLO phase is stabilized by higher polarization and that it is within the range of detection of experiments currently underway.