Observation of Bose-Einstein Condensation of Molecules

TL;DR

This paper reports the first observation of Bose-Einstein condensation of molecules formed from fermionic lithium atoms, demonstrating a transition from BCS superfluidity to molecular BEC.

Contribution

It provides experimental evidence of molecular Bose-Einstein condensation from fermionic atoms near a Feshbach resonance, bridging BCS and BEC regimes.

Findings

Bose-Einstein condensate of up to 900,000 molecules observed

Condensate identified by bimodal density distribution

Achieved at temperatures below 600 nK

Abstract

We have observed Bose-Einstein condensation of molecules. When a spin mixture of fermionic Li-6 atoms was evaporatively cooled in an optical dipole trap near a Feshbach resonance, the atomic gas was converted into Li_2 molecules. Below 600 nK, a Bose-Einstein condensate of up to 900,000 molecules was identified by the sudden onset of a bimodal density distribution. This condensate realizes the limit of tightly bound fermion pairs in the crossover between BCS superfluidity and Bose-Einstein condensation.