Spin-velocity correlations of optically pumped atoms

摘要

We present efficient theoretical tools for describing the optical pumping of atoms by light propagating atnarbitrary directions with respect to an external magnetic field, at buffer-gas pressures that are small enoughnfor velocity-selective optical pumping (VSOP) but large enough to cause substantial collisional relaxation ofnthe velocities and the spin. These are the conditions for the sodium atoms at an altitude of about 100 km thatnare used as guidestars for adaptive optics in modern ground-based telescopes to correct for aberrations due tonatmospheric turbulence. We use spin and velocity relaxation modes to describe the distribution of atoms innspin space (including both populations and coherences) and velocity space. Cusp kernels are used to describenvelocity-changing collisions. Optical pumping operators are represented as a sum of poles in the complexnvelocity plane. Signals simulated with these methods are in excellent agreement with previous experiments andnwith preliminary experiments in our laboratory.