Decay of an ultracold fermionic lithium gas near a Feshbach resonance

TL;DR

This study investigates how an ultracold fermionic lithium gas's inelastic decay rates depend on magnetic fields near Feshbach resonances, revealing suppressed decay due to quantum statistics and providing insights into superfluidity conditions.

Contribution

It provides experimental data on decay resonances in fermionic lithium gases near Feshbach resonances, highlighting the role of Pauli exclusion in suppressing decay.

Findings

Decay resonances at 550 G and 680 G due to two-body collisions.

Decay suppression near Feshbach resonances compared to bosonic gases.

Longer lifetimes than expected for superfluid transition times.

Abstract

We studied the magnetic field dependence of the inelastic decay of an ultracold, optically trapped 6-Li gas of different spin compositions. The spin mixture of the two lowest hyperfine states showed two decay resonances at 550 G and 680 G due to two-body collisions, close to the predicted Feshbach resonance of the elastic s-wave collisions at 800 G. The rapid decay near Feshbach resonances found in bosonic gases was found to be suppressed by the Pauli exclusion principle. The observed lifetimes of several hundred milliseconds are much longer than the expected time for Cooper pair formation and the phase transition to superfluidity in the vicinity of the Feshbach resonance.