Pseudogap phenomenon in an ultracold Fermi gas with a p-wave pairing interaction

TL;DR

This paper explores how a pseudogap forms and disappears in a p-wave interacting ultracold Fermi gas, revealing a non-monotonic dependence on interaction strength due to the anisotropic nature of p-wave pairing.

Contribution

It demonstrates the non-monotonic behavior of the pseudogap in p-wave Fermi gases and explains its origin from the momentum dependence of p-wave interactions, extending understanding beyond s-wave cases.

Findings

Pseudogap first appears with increasing interaction strength.

Pseudogap eventually disappears at strong coupling.

The behavior differs from s-wave interactions due to momentum dependence.

Abstract

We investigate single-particle properties of a one-component Fermi gas with a tunable p-wave interaction. Including pairing fluctuations associated with this anisotropic interaction within a $T$-matrix theory, we calculate the single-particle density of states, as well as the spectral weight, above the superfluid transition temperature $T_{\rm c}$. Starting from the weak-coupling regime, we show that the so-called pseudogap first develops in these quantities with increasing the interaction strength. However, when the interaction becomes strong to some extent, the pseudogap becomes obscure to eventually disappear in the strong-coupling regime. This non-monotonic interaction dependence is quite different from the case of an s-wave interaction, where the pseudogap simply develops with increasing the interaction strength. The difference between the two cases is shown to originate from the momentum dependence of the p-wave interaction, which vanishes in the low momentum limit. We also identify the pseudogap regime in the phase diagram with respect to the temperature and the p-wave interaction strength. Since the pseudogap is a precursor phenomenon of the superfluid phase transition, our results would be useful for the research toward the realization of p-wave superfluid Fermi gases.