Speckle Imaging of Spin Fluctuations in a Strongly Interacting Fermi Gas

TL;DR

This paper introduces a novel speckle imaging technique to study spin and density fluctuations in a strongly interacting Fermi gas, revealing suppressed spin fluctuations due to pairing and enabling exploration of magnetic phases.

Contribution

The study presents a new in-situ speckle imaging method to measure spin and density fluctuations in Fermi gases across the BEC-BCS crossover.

Findings

Resolved a tenfold suppression of spin fluctuations below shot noise.

Measured compressibility and magnetic susceptibility from fluctuations.

Demonstrated applicability to magnetic phases in optical lattices.

Abstract

Spin fluctuations and density fluctuations are studied for a two-component gas of strongly interacting fermions along the BEC-BCS crossover. This is done by in-situ imaging of dispersive speckle patterns. Compressibility and magnetic susceptibility are determined from the measured fluctuations. This new sensitive method easily resolves a tenfold suppression of spin fluctuations below shot noise due to pairing, and can be applied to novel magnetic phases in optical lattices.