Cooling a Fermi gas with three-body recombination near a narrow Feshbach resonance

TL;DR

This paper demonstrates that three-body recombination near a narrow Feshbach resonance can cool a Fermi gas by selectively removing high-energy atoms, offering a novel cooling mechanism for atomic systems.

Contribution

It reveals a counter-intuitive cooling effect of three-body recombination in a Fermi gas near a narrow Feshbach resonance, supported by a theoretical model.

Findings

Cooling occurs when the threshold energy exceeds 3/2kBT.

Optimal cooling is achieved at a threshold energy around 3kBT.

Three-body recombination can be used as a cooling method for complex atomic systems.

Abstract

Three-body recombination is a phenomenon common in atomic and molecular collisions, producing heating in the system. However, we find the cooling effect of the three-body recombination of a 6Li Fermi gas near its s-wave narrow Feshbach resonance. Such counter-intuitive behavior is explained as follows, the threshold energy of the quasi-bounded Feshbach molecule acts as the knife of cooling, expelling the scattering atoms with selected kinetic energy from the trap. When the threshold energy happens to be larger than 3/2kBT, each lost atom in the three-body recombination process has more than 3kBT energy which results in cooling. The best cooling is found with the threshold energy set at about 3kBT, consistent with a theoretical model. The three-body recombination induced cooling raises potential applications for cooling complex atomic systems.