Person:

Sadeghpour, Hossein

We use accurate ab initio and quantum scattering calculations to demonstrate that the maximum He3 spin polarization that can be achieved in spin-exchange collisions with potassium (K39) and silver (Ag107) atoms is limited by the anisotropic hyperfine interaction. We find that spin exchange in Ag-He collisions occurs much faster than in K-He collisions over a wide range of temperatures (10–600 K). Our analysis indicates that measurements of trap loss rates of S2 atoms in the presence of cold He3 gas may be used to probe anisotropic spin-dependent interactions in atom-He collisions.

We present a rigorous quantum study of spin-exchange transitions in collisions of the alkali-metal atoms with H3e in the presence of an external magnetic field. Using accurate ab initio interaction potentials, we obtain refined estimates for the Fermi contact interaction constants for complexes of Na, K, and Rb atoms with H3e . Ab initio calculations show that the Fermi contact interaction in Li-H3e varies more slowly with internuclear distance than predicted by the atomic model [R. M. Herman, Phys. Rev. 37, A1062 (1965)]. The calculated spin-exchange rate constants for Na, K, and Rb atoms in a gas of H3e are in good agreement with experimental data. Our calculations demonstrate that at a temperature of 0.5 K, collision-induced spin exchange of the alkali-metal atoms occurs at a very slow rate of ˜10-22cm3/s , suggesting potential applications in cryogenic cooling, precision spectroscopy, and quantum optics.