Temperature of a laser-cooled trapped three-level ion

Abstract

We develop an expression for the final temperature achieved by laser cooling of a trapped three-level ion with the A configuration of states by employing an expansion in the photon momenta and degenerate perturbation theory. The special cases of low intensities or large detunings for the intermediate level are studied analytically. A cooling mechanism based on two-photon transitions with a simultaneous reorganization of the center-of-mass motion is isolated. The limit of the temperature is set either by the two-photon linewidth or by optical pumping between the long-lived states of the three-level system and may be extremely low.