Production of a degenerate Fermi gas of metastable helium-3 atoms

Most of this book discusses Fermi gases composed of alkali atoms. Since the first realization of a degenerate K Fermi gas in 1999, Li has been the only other fermionic atom to be cooled below the Fermi temperature. In this contribution we will discuss our recent results on cooling fermionic He below the Fermi temperature. This has not been performed with ground state He, but with He in the metastable 2 S1 state, which has an internal energy of 20 eV. Helium atoms in this metastable state are denoted by He* and have a lifetime of ∼ 8000 s, which is infinite for all practical purposes. He* atoms can be efficiently cooled with laser light at 1083nm and samples of ∼ 10 atoms of either isotope can be confined in a magneto-optical trap (MOT) at temperatures around 1mK. The density in a He* MOT is limited to ∼ 4 × 10 cm due to large losses associated with Penning ionization (PI) and associative ionization (AI):