Alan L. Migdall, Harold J. Metcalf, William D. Phillips
We propose an optical Maxwell demon which efficiently captures, concentrates, and damps the kinetic motion of sodium atoms in a gas cell. A bath of radiation tuned just below resonance can prove to be a very viscous medium for atoms. We propose to use this effect to produce and concentrate very slow atoms in a vapor cell. Our bath of radiation consists of three orthogonally intersecting pairs of counterpropagating laser beams. Each beam is tuned about half of the natural linewidth below the resonance transition frequency. (Because of the hyperfine splitting of the Na ground state, two separate frequencies are used.) Atoms which enter the intersection region with velocities less than ~15 m/s (for 1-cm diam beams) are quickly damped to ~0.5 m/s. Thereafter, the velocity is randomized in a characteristic time of ~10 μs. The atoms will then execute diffusive motion in this photon bath, escaping only after many seconds. Since the effusion time for atoms to enter the intersecting beam demon is much shorter than the diffusion time out of it, the demon acts to collect and concentrate the slow atoms into a cold, dense, central gas superposed on the hot, rarified, background gas.
Annual Meeting Optical Society of America•Jan 1, 1985•0 citations