VELOCITY-SELECTIVE RESONANCES AND SUB-DOPPLER LASER COOLING

We describe several one-dimensional sub-Doppler laser-cooling experiments that cool Rb to finite and zero velocities in a magnetic field and polarization gradients. We then present a physical picture that unifies these measurements in terms of coherent two-photon velocity-selective resonances (VSR) between atomic ground-state sublevels (including Raman resonances). We propose several sub-Doppler cooling schemes without fields or without polarization gradients, based on VSR between nondegenerate ground states.