Trapped fermion mixtures with unequal masses: a Bogoliubov-de Gennes approach

TL;DR

This paper investigates the ground state phases of trapped two-species fermion mixtures with unequal masses using the Bogoliubov-de Gennes formalism, revealing spatially modulated superfluidity near unitarity and its evolution with interaction strength.

Contribution

It provides a detailed analysis of spatial superfluid modulation and phase transitions in mass-imbalanced fermion mixtures using a Bogoliubov-de Gennes approach.

Findings

Superfluid order parameter is spatially modulated near unitarity.

Modulations diminish as attraction increases, leading to uniform superfluidity.

Entire mixture becomes locally unpolarized in the molecular limit.

Abstract

We use the Bogoliubov-de Gennes formalism to analyze the ground state phases of harmonically trapped two-species fermion mixtures with unequal masses. In the weakly attracting limit and around unitarity, we find that the superfluid order parameter is spatially modulated around the trap center, and that its global maximum occurs at a finite distance away from the trap center where the mixture is locally unpolarized. As the attraction strength increases towards the molecular limit, the spatial modulations gradually disappear while the Bardeen-Cooper-Schrieffer (BCS) type nonmodulated superfluid region expands until the entire mixture becomes locally unpolarized.