# Direct laser cooling to Bose-Einstein condensation in a dipole trap

## TL;DR

This paper demonstrates a laser cooling method to produce Bose-Einstein condensates in a dipole trap, enabling rapid quantum degenerate gas creation without evaporative cooling.

## Contribution

The authors introduce a laser cooling technique that achieves Bose-Einstein condensation directly in a dipole trap, bypassing traditional evaporative cooling.

## Key findings

- Condensation achieved with 2.5×10^4 atoms at 0.6 μK after 1.4 s of cooling.
- Temperatures below the recoil limit were reached.
- Careful tuning of trap parameters is essential at high densities.

## Abstract

We present a method for producing three-dimensional Bose-Einstein condensates using only laser cooling. The phase transition to condensation is crossed with $2.5 {\times} 10^{4}$ $^{87}\mathrm{Rb}$ atoms at a temperature of $T_{\mathrm{c}} = 0.6\ \mu\mathrm{K}$ after 1.4 s of cooling. Atoms are trapped in a crossed optical dipole trap and cooled using Raman cooling with far-off-resonant optical pumping light to reduce atom loss and heating. The achieved temperatures are well below the effective recoil temperature. We find that during the final cooling stage at atomic densities above $10^{14}\ \mathrm{cm}^{-3}$, careful tuning of trap depth and optical-pumping rate is necessary to evade heating and loss mechanisms. The method may enable the fast production of quantum degenerate gases in a variety of systems including fermions.