A Degenerate Bose-Fermi Mixture of Metastable Atoms

TL;DR

This paper reports the creation of a quantum degenerate mixture of metastable helium-3 and helium-4 atoms, enabling high-precision studies of quantum gases with potential applications in quantum atom optics.

Contribution

First demonstration of simultaneous quantum degeneracy in a metastable Bose-Fermi mixture of helium isotopes using sympathetic cooling.

Findings

Achieved over 10^6 atoms of each isotope at sub-microkelvin temperatures.

Fermionic degeneracy parameter T/Tf=0.45 indicating strong quantum degeneracy.

Enabled detection of individual metastable atoms with sub-nanosecond resolution.

Abstract

We report the observation of simultaneous quantum degeneracy in a dilute gaseous Bose-Fermi mixture of metastable atoms. Sympathetic cooling of helium-3 (fermion) by helium-4 (boson), both in the lowest triplet state, allows us to produce ensembles containing more than 10^6 atoms of each isotope at temperatures below 1 micro-Kelvin, and achieve a fermionic degeneracy parameter of T/Tf=0.45. Due to their high internal energy, the detection of individual metastable atoms with sub-nanosecond time resolution is possible, permitting the study of bosonic and fermionic quantum gases with unprecedented precision. This may lead to metastable helium becoming the mainstay of quantum atom optics.