Detecting $\pi$-phase superfluids with $p$-wave symmetry in a quasi-1D optical lattice

TL;DR

This paper proposes an experimental method to realize and detect a novel $ ext{pi}$-phase $p$-wave superfluid in a quasi-1D optical lattice using cold Fermi gases, with measurable signatures and distinct symmetry properties.

Contribution

It introduces a new protocol for creating $ ext{pi}$-phase $p$-wave superfluids in cold atoms and analyzes their measurable characteristics.

Findings

Confirmation of $p$-wave symmetry in the pairing order parameter

Prediction of $ ext{pi}$-phase modulation in the superfluid state

Calculations of observable signals like time-of-flight and RF spectra

Abstract

We propose an experimental protocol to study $p$-wave superfluidity in a spin-polarized cold Fermi gas tuned by an $s$-wave Feshbach resonance. A crucial ingredient is to add a quasi-1D optical lattice and tune the fillings of two spins to the $s$ and $p$ band, respectively. The pairing order parameter is confirmed to inherit $p$-wave symmetry in its center-of-mass motion. We find that it can further develop into a state of unexpected $\pi$-phase modulation in a broad parameter regime. Measurable quantities are calculated, including time-of-flight distributions, radio-frequency spectra, and in situ phase-contrast imaging in an external trap. The $\pi$-phase $p$-wave superfluid is reminiscent of the $\pi$-state in superconductor-ferromagnet heterostructures but differs in symmetry and origin. If observed, it would represent another example of $p$-wave pairing, first discovered in He-3 liquids.