Colliding clouds of strongly interacting spin-polarized fermions

TL;DR

This paper explains why two dilute, strongly interacting spin-polarized Fermi gas clouds bounce off each other, supported by hydrodynamic analysis and experimental agreement, indicating a metastable state with effective repulsion.

Contribution

It provides a hydrodynamic explanation for cloud bouncing in strongly interacting Fermi gases, revealing a metastable state with effective repulsive interactions.

Findings

Hydrodynamic analysis matches experimental observations.

Evidence for a metastable many-body state with effective repulsion.

Strong interactions lead to bouncing behavior in dilute Fermi gases.

Abstract

Motivated by a recent experiment at MIT, we consider the collision of two clouds of spin-polarized atomic Fermi gases close to a Feshbach resonance. We explain why two dilute gas clouds, with underlying attractive interactions between their constituents, bounce off each other in the strongly interacting regime. Our hydrodynamic analysis, in excellent agreement with experiment, gives strong evidence for a metastable many-body state with effective repulsive interactions.