Quantum effects in atomic reflection

(Received 29 April 1994, received in final form 15 September 1994, accepted 23 September 1994)

Abstract
In this paper we consider the effects of spontaneous emission on the problem of atomic reflection from an optical evanescent travelling wave. The atoms are assumed to be travelling so slowly that the external degrees of freedom of the atom need to be treated quantum mechanically. Spontaneous emission is modelled using a fully quantum mechanical model based on the quantum Monte Carlo technique which includes the effects of atomic recoil. The results of the simulation are compared with a semi-classical Monte Carlo simulation in which the atomic motion is treated classically and the internal state of the atom is assumed to follow the light-induced quasipotentials adiabatically between spontaneous emission events. The spontaneous emission leads to a broadening of the momentum distribution of the outgoing wave packet and mechanisms for this broadening are discussed.