Cooling Moves Beyond Optical Molasses

Physicists at Stanford University in Stanford, Calif., reported the 3-D degenerate Raman sideband cooling of cesium atoms to 290 nK and a phase-space density nearly three orders of magnitude higher than that produced with the free-space optical molasses technique. Their study appears in the Jan. 17 issue of Physical Review Letters.

The researchers prepared 3 x 10⁸ cesium atoms in a magneto-optical trap at room temperature. A 3-D far-detuned optical lattice from a 100-mW distributed Bragg reflector diode laser induced degenerate Raman transitions in the sample, which yielded a phase-space density nλ³_dB = 1/500 at a density of 1.1 x 10¹¹ cm^-3.