Pairing and Phase Separation in a Polarized Fermi Gas

TL;DR

This paper reports the observation of pairing and phase separation in a polarized Fermi gas, revealing how superfluid and normal phases coexist and how critical polarization depends on interaction strength, with implications for exotic matter phases.

Contribution

It provides experimental evidence of phase separation in polarized Fermi gases and measures the universal parameter 5, aligning with recent theoretical predictions.

Findings

Observation of pairing in polarized Fermi gas

Identification of a critical polarization for phase separation

Measurement of the universal parameter 5 = 0.54 (5)

Abstract

We report the observation of a pairing in a number polarized two-component gas of atomic fermions. Beyond a critical polarization, the gas separates into a superfluid paired core surrounded by a shell of normal unpaired fermions. The critical polarization diminishes with decreasing attractive interaction. We also measure the parameter \beta = 0.54 (5) describing the universal energy of a strongly interacting Fermi gas, and find good agreement with most recent theory. These results are relevant to predictions of exotic new phases of quark matter and of strongly magnetized superconductors.