BCS pairing in a trapped dipolar Fermi gase

TL;DR

This paper investigates the BCS pairing transition in a trapped polarized dipolar Fermi gas, analyzing how trap geometry and dipole interactions influence the critical temperature and phase diagram, revealing optimal conditions for superfluidity.

Contribution

It provides a detailed analysis of the effects of trap aspect ratio and dipole interaction strength on the BCS transition in trapped dipolar Fermi gases, including phase diagram derivation.

Findings

Transition temperature decreases with trap aspect ratio.

Existence of an optimal trap geometry for highest critical temperature.

Critical dipole strength depends on trap anisotropy.

Abstract

We present a detailed study of the BCS pairing transition in a trapped polarized dipolar Fermi gas. In the case of a shallow nearly spherical trap, we find the decrease of the transition temperature as a function of the trap aspect ratio and predict the existence of the optimal trap geometry. The latter corresponds to the highest critical temperature of the BCS transition for a given number of particles. We also derive the phase diagram for an ultracold trapped dipolar Fermi gases in the situation, where the trap frequencies can be of the order of the critical temperature of the BCS transition in the homogeneous case, and find the critical value of the dipole-dipole interaction energy, below which the BCS transition ceases to exist. The critical dipole strength is obtained as a function of the trap aspect ratio. Alternatively, for a given dipole strength there is a critical value of the trap anisotropy for the BCS state to appear. The order parameter calculated at criticality, exhibits nover non-monotonic behavior resulted from the combined effect of the confining potential and anisotropic character of the interparticle dipole-dipole interation.