# Can three-body recombination purify a quantum gas?

## TL;DR

This paper demonstrates that three-body recombination can act as a purification mechanism in a quantum Bose gas, increasing the condensed fraction and reducing entropy, contrary to traditional views.

## Contribution

It reveals that three-body loss can enhance condensation and entropy reduction, showing a novel dynamical behavior in quantum gases.

## Key findings

- Three-body recombination can increase the condensed fraction in a Bose gas.
- The evolution of the condensate fraction depends on initial conditions, showing bifurcation behavior.
- The predicted effects are observable under realistic experimental conditions.

## Abstract

Three-body recombination in quantum gases is traditionally associated with heating, but it was recently found that it can also cool the gas. We show that in a partially condensed three-dimensional homogeneous Bose gas three-body loss could even purify the sample, that is, reduce the entropy per particle and increase the condensed fraction $\eta$. We predict that the evolution of $\eta$ under continuous three-body loss can, depending on small changes in the initial conditions, exhibit two qualitatively different behaviours - if it is initially above a certain critical value, $\eta$ increases further, whereas clouds with lower initial $\eta$ evolve towards a thermal gas. These dynamical effects should be observable under realistic experimental conditions.