Anomalous Transport in the Superfluid Fluctuation Regime

TL;DR

This paper investigates how superfluid fluctuations near the transition affect particle and spin transport in a one-dimensional fermionic system, revealing conductance enhancement and suppression phenomena consistent with recent ultracold atom experiments.

Contribution

It provides a theoretical analysis of transport properties influenced by superfluid fluctuations, highlighting their impact on conductance in a ballistic regime.

Findings

Particle conductance is strongly enhanced by superfluid fluctuations.

The conductance plateau becomes blurred due to bosonic pair transport.

Spin conductance is suppressed due to additional wire resistance.

Abstract

Motivated by a recent experiment in ultracold atoms [ S. Krinner et al., Proc. Natl. Acad. Sci. U.S.A 113, 8144 (2016)], we analyze transport of attractively interacting fermions through a one-dimensional wire near the superfluid transition. We show that in a ballistic regime where the conductance is quantized in the absence of interaction, the conductance is renormalized by superfluid fluctuations in reservoirs. In particular, the particle conductance is strongly enhanced and the plateau is blurred by emergent bosonic pair transport. For spin transport, in addition to the contact resistance the wire itself is resistive, leading to a suppression of the measured spin conductance. Our results are qualitatively consistent with the experimental observations.