All-optical production of ${}^6\textrm{Li}$ molecular BEC in excited hyperfine levels

TL;DR

This paper reports an all-optical approach to produce ${}^6 extrm{Li}$ molecular Bose-Einstein condensates in excited hyperfine states, achieving significant condensate fractions with minimal experimental constraints.

Contribution

The authors develop a refined all-optical method for creating ${}^6 extrm{Li}$ molecular BECs in excited hyperfine levels, simplifying the experimental setup and improving condensate fractions.

Findings

Achieved 36% condensate fraction with 9×10^4 atoms in the 1-2 hyperfine mixture.

Achieved 28% condensate fraction with 3.2×10^4 atoms in the 2-3 hyperfine mixture.

Method allows minimal constraints on subsequent experiments with optical access and simplified cooling system.

Abstract

We present an all-optical method for achieving molecular Bose-Einstein condensates of ${}^6\textrm{Li}$. We demonstrate this with mixtures in the lowest two (1-2), and second lowest two (2-3) hyperfine states. For the 1-2 mixture, we can achieve condensate fractions of 36\%, with $9\times10^4$ atoms at $0.05\textrm{ }\mu\textrm{K}$ temperature. For the 2-3 mixture, we have 28\% condensed with $3.2\times10^4$ atoms at $0.05\textrm{ }\mu\textrm{K}$ temperature. We use mostly standard methods, but make a number of refinements in the magnetic bias coils compared with earlier work. Our method imposes minimal constraints on subsequent experiments by allowing plenty of optical access while requiring only one high-vacuum chamber. We use an optical system designed around minimizing the number of active elements, and we can accomplish slowing and sub-Doppler cooling with a single tapered amplifier