Damagnetization cooling of a gas

TL;DR

This paper demonstrates a novel cooling method for ultracold gases using demagnetization driven by inelastic dipolar collisions, significantly increasing phase space density without atom loss, and potentially enabling quantum degeneracy.

Contribution

Introduces demagnetization cooling of ultracold gases via inelastic dipolar collisions, a technique that can be extended to other dipolar systems for quantum degeneracy.

Findings

Increased phase space density by an order of magnitude

Achieved cooling with nearly no atom loss

Potential to reach quantum degeneracy

Abstract

We demonstrate demagnetization cooling of a gas of ultracold $^{52}$Cr atoms. Demagnetization is driven by inelastic dipolar collisions which couple the motional degrees of freedom to the spin degree. By that kinetic energy is converted into magnetic work with a consequent temperature reduction of the gas. Optical pumping is used to magnetize the system and drive continuous demagnetization cooling. Applying this technique, we can increase the phase space density of our sample by one order of magnitude, with nearly no atom loss. This method can be in principle extended to every dipolar system and could be used to achieve quantum degeneracy via optical means.