All-optical production of 7Li Bose-Einstein condensation using Feshbach resonances

TL;DR

This paper demonstrates an all-optical method to produce 7Li Bose-Einstein condensates by utilizing Feshbach resonances to tune interactions, achieving rapid condensation within 3 seconds of evaporation.

Contribution

It reports the first observation of two new Feshbach resonances in 7Li and uses a broad resonance for efficient all-optical Bose-Einstein condensation.

Findings

Two new Feshbach resonances observed at 831 G and 884 G.

Bose-Einstein condensation achieved in less than 3 seconds.

Broad resonance enables efficient evaporation in optical traps.

Abstract

We show an all-optical method of making 7Li condensate using tunability of the scattering length in the proximity of a Feshbach resonance. We report the observation of two new Feshbach resonances on |F = 1;mF = 0> state. The narrow (broad) resonance of 7 G (34 G) width is detected at 831 +- 4 G (884 +4 -13 G). Position of the scattering length zero crossing between the resonances is found at 836 +- 4 G. The broad resonance is shown to be favorable for run away evaporation which we perform in a crossed-beam optical dipole trap. Starting directly form the phase space density of a magneto-optical trap we observe a Bose-Einstein condensation threshold in less than 3 s of forced evaporation.