Magnetic inhibition of polarization-gradient laser cooling in σ₊-σ_- optical molasses

Xenon atoms are released from a magneto-optical trap and equilibrate in a one-dimensional, σ₊-σ_- optical molasses, along which a uniform magnetic field is applied. In the rest frame of the ‘‘corkscrew’’ pattern of laser polarization, the magnetic field induces a nonzero average atomic velocity. Introducing a moving molasses through a relative difference in the two laser-beam frequencies allows straightforward, accurate measurements of the molasses-frame velocity distribution over a large range of magnetic fields. The measurements reveal the loss of polarization-gradient cooling in fields higher than ∼0.2 mT, in quantitative agreement with theoretical predictions. © 1996 The American Physical Society.