Abstract

Laser cooling of atoms has been demonstrated in the past few years with a large variety of methods¹. All these methods rely on spontaneous emission to dissipate an atom’s internal energy, thereby subjecting the atom to a recoil velocity of ħk/M (k the wave vector of the light and M the atomic mass) in a random direction. This heating process has limited the minimum temperature that may be reached with most laser cooling methods to about ten times the single photon recoil temperature k_BT_rec = (ħk)²/2m. Temperatures below the recoil limit were obtained in one spatial dimension for helium atoms using velocity-selective coherent population trapping², and for sodium atoms using stimulated Raman transitions³.

© 1993 Optical Society of America