Finite-Temperature Collective Dynamics of a Fermi Gas in the BEC-BCS Crossover

TL;DR

This paper experimentally investigates the collective dynamics of a strongly interacting Fermi gas across the BEC-BCS crossover, revealing hydrodynamic behavior and a temperature-dependent damping peak related to superfluidity.

Contribution

It provides the first detailed phase diagram of collisional properties and identifies a novel damping feature near the superfluid transition in a tunable Fermi gas.

Findings

Hydrodynamic behavior observed over a large interaction range.

Identification of a temperature-dependent damping peak.

Evidence of superfluid transition effects in damping behavior.

Abstract

We report on experimental studies on the collective behavior of a strongly interacting Fermi gas with tunable interactions and variable temperature. A scissors mode excitation in an elliptical trap is used to characterize the dynamics of the quantum gas in terms of hydrodynamic or near-collisionless behavior. We obtain a crossover phase diagram for collisional properties, showing a large region where a non-superfluid strongly interacting gas shows hydrodynamic behavior. In a narrow interaction regime on the BCS side of the crossover, we find a novel temperature-dependent damping peak, suggesting a relation to the superfluid phase transition.