Quantum fluctuations of a resonantly interacting $p$-wave Fermi superfluid in two dimensions

TL;DR

This paper uses Gaussian pair fluctuation theory to study quantum fluctuations in a two-dimensional resonantly interacting p-wave Fermi superfluid, revealing significant renormalizations and non-analytic behaviors near the topological phase transition.

Contribution

It provides a detailed analysis of quantum fluctuations and their effects on physical properties across the BEC-BCS topological transition in 2D p-wave superfluids, highlighting non-analyticities.

Findings

Quantum fluctuations significantly renormalize the equation of state, sound velocity, and BKT temperature.

The BKT critical temperature peaks near the topological phase transition.

The system becomes a trivial Bose liquid in the BEC limit.

Abstract

Using the Gaussian pair fluctuation theory, we investigate quantum fluctuations of a strongly interacting two-dimensional chiral \textit{p}-wave Fermi superfluid at the transition from a Bose-Einstein condensate (BEC) to a topologically non-trivial Bardeen-Cooper-Schrieffer (BCS) superfluid. Near the topological phase transition at zero chemical potential, $\mu=0$, we observe that quantum fluctuations strongly renormalize the zero-temperature equations of state, sound velocity, pair-breaking velocity, and Berezinskii-Kosterlitz-Thouless (BKT) critical temperature of the Fermi superfluid, all of which can be non-analytic functions of the interaction strength. The indication of non-analyticity is particularly evident in the BKT critical temperature, which also exhibits a pronounced peak near the topological phase transition. Across the transition and towards the BEC limit we find that the system quickly becomes a trivial interacting Bose liquid, whose properties are less dependent on the interparticle interaction. The qualitative behavior of composite bosons in the BEC limit remains to be understood.