Spin-orbit suppression of cold inelastic collisions of aluminum and helium
Colin B. Connolly, Yat Shan Au, Eunmi Chae, Timur V. Tscherbul, Alexei A. Buchachenko, Hsin-I Lu, Wolfgang Ketterle, and John M. Doyle
Accepted
We present a quantitative study of suppression of cold inelastic collisions by the spin-orbit interaction. We prepare cold ensembles of > 1011 Al(2P1/2) atoms via cryogenic buffer-gas cooling and use a single-beam optical pumping method to measure their magnetic (mJ-changing) and fine-structure (J-changing) collisions with ßhe atoms at millikelvin temperatures over a range of magnetic fields from 0.5 to 6 T. The experimentally determined rates are in good agreement with the functional form predicted by quantum scattering calculations using ab initio potentials. This comparison provides direct experimental evidence for a proposed model of suppressed inelasticity in collisions of atoms in 2P1/2 states [Phys. Rev. A 80, 040701 (2009)], which may allow for sympathetic cooling of other 2P1/2 atoms (e.g., In, Tl and metastable halogens).