SUBRECOIL RAMAN COOLING OF CESIUM ATOMS

We use velocity-selective Raman pulses generated by two diode lasers t o cool cesium atoms in 1 dimension to an r.m.s. of 1.2 mm/s. This is a bout 1/3 of the single-photon recoil velocity v(rec) = hk/M, where hk is the photon momentum and M the atom's mass. The corresponding effect ive temperature is a factor of 9 below the single-photon recoil temper ature given by k(B)T(rec)/2 = 1/2Mv(rec)(2). Because of the high cesiu m mass, this temperature is only (23 +/- 5) nanokelvin, the lowest 1D kinetic temperature reported to date.