Cooling a Bose gas by three-body losses

TL;DR

This paper demonstrates that three-body losses can be used to cool a 1D Bose gas, achieving a significant temperature reduction and providing theoretical insights into the cooling mechanism.

Contribution

First experimental demonstration of cooling via three-body losses in a 1D Bose gas with theoretical analysis supporting the findings.

Findings

Temperature drops up to a factor of four during losses

The ratio k_B T/(m c^2) remains close to 0.64

Theoretical models predict convergence towards 0.6 for this ratio

Abstract

We report the first demonstration of cooling by three-body losses in a Bose gas. We use a harmonically confined one-dimensional (1D) Bose gas in the quasi-condensate regime and, as the atom number decreases under the effect of three-body losses, the temperature $T$ drops up to a factor four. The ratio $k_B T/(m c^2)$ stays close to 0.64, where $m$ is the atomic mass and $c$ the sound speed in the trap center. The dimensionless 1D interaction parameter $\gamma$, evaluated at the trap center, spans more than two order of magnitudes over the different sets of data. We present a theoretical analysis for a homogeneous 1D gas in the quasi-condensate regime, which predicts that the ratio $k_B T/(mc^2)$ converges towards 0.6 under the effect of three-body losses. More sophisticated theoretical predictions that take into account the longitudinal harmonic confinement and transverse effects are in agreement within 30% with experimental data.