Superfluid Phases of Dipolar Fermions in Harmonically Trapped Optical Lattices

TL;DR

This paper explores various superfluid phases of ultracold dipolar fermions in 2D optical lattices, revealing distinct pairing symmetries, phase diagrams, and spontaneous currents, with potential experimental detection methods.

Contribution

It introduces a comprehensive phase diagram of superfluid phases with different pairing symmetries considering many-body screening effects.

Findings

d-wave pairing is favored near half-filling

time-reversal-symmetry breaking superfluid occurs between other phases

spontaneous currents can be detected via Bragg spectroscopy

Abstract

We describe the emergence of superfluid phases of ultracold dipolar fermions in optical lattices for two-dimensional systems. Considering the many-body screening of dipolar interactions at intermediate and larger filling factors, we show that several superfluid phases with distinct pairing symmetries naturally arise in the singlet channel: local s-wave $(sl)$, extended s-wave $(se)$, d-wave $(d)$ or time-reversal-symmetry breaking $(sl + se \pm id)$-wave. We obtain the temperature versus filling factor phase diagram and show that d-wave pairing is favored near half-filling, that $(sl + se)$-wave is favored near zero or full filling, and that time-reversal-breaking $(sl + se \pm id)$-wave is favored in between. The inclusion of a harmonic trap reveals that a sequence of phases can coexist in the cloud depending on the filling factor at the center of the trap. Most notably in the spatial region where the $(sl + se \pm id)$-wave superfluid occurs, spontaneous currents are generated, and may be detected using velocity sensitive Bragg spectroscopy.