Rapid sympathetic cooling to Fermi degeneracy on a chip

TL;DR

This paper demonstrates rapid production of a degenerate Fermi gas of 40K using a microfabricated magnetic trap, achieving faster cooling than traditional methods and providing insights into the underlying collision dynamics.

Contribution

It introduces a simple microtrap-based method for sympathetic cooling of fermions, significantly reducing the time to reach Fermi degeneracy and analyzing collision cross-section behavior.

Findings

Achieved Fermi degeneracy of 40K in six seconds.

First demonstration of sympathetic cooling in a microtrap.

Measured temperature dependence of 40K-87Rb cross-section.

Abstract

Neutral fermions present new opportunities for testing many-body condensed matter systems, realizing precision atom interferometry, producing ultra-cold molecules, and investigating fundamental forces. However, since their first observation, quantum degenerate Fermi gases (DFGs) have continued to be challenging to produce, and have been realized in only a handful of laboratories. In this Letter, we report the production of a DFG using a simple apparatus based on a microfabricated magnetic trap. Similar approaches applied to Bose-Einstein Condensation (BEC) of 87Rb have accelerated evaporative cooling and eliminated the need for multiple vacuum chambers. We demonstrate sympathetic cooling for the first time in a microtrap, and cool 40K to Fermi degeneracy in just six seconds -- faster than has been possible in conventional magnetic traps. To understand our sympathetic cooling trajectory, we measure the temperature dependence of the 40K-87Rb cross-section and observe its Ramsauer-Townsend reduction.