Thermal Phase Fluctuations in Narrow Superfluid Rings

TL;DR

This study investigates thermal phase fluctuations in ultracold fermionic superfluid rings using matter-wave interference, revealing how correlation length and coherence are affected by density, coupling, and boundary conditions, with implications for quantum circuit applications.

Contribution

It provides experimental insights into phase fluctuations in superfluid rings, demonstrating the effects of density, coupling, and boundary conditions on coherence in ultracold quantum gases.

Findings

Correlation length decreases with density

Increased coupling enhances coherence

Boundary conditions influence phase fluctuations

Abstract

Using matter-wave interference, we have investigated thermal phase fluctuations in narrow coplanar, concentric rings of ultracold fermionic superfluids. We found that the correlation length decreases with number density, consistent with theoretical expectations. We also observed that increasing the coupling between the rings leads to greater overall coherence in the system. The phase fluctuations increased with a change from periodic to closed boundary conditions as we applied a potential barrier at one point in a ring. These results are relevant for the implementation of proposals to utilize ultracold quantum gases in large and elongated circuit-like geometries, especially those that require deterministic preparation and control of quantized circulation states.