Photoassociation dynamics in a Bose-Einstein condensate

Thomas Gasenzer

Institut für Theoretische Physik, Universität Heidelberg Philosophenweg 16, D-69120 Heidelberg, Germany

Photoassociation is, at present, the most promising technique for producing a Bose-Einstein condensate of molecules which also internally are in their, electronic and rovibrational, ground state. A dynamical many body theory of single color photoassociation in a Bose-Einstein condensate is presented. The theory describes the time evolution of a condensed atomic ensemble under the influence of an arbitrarily varying near resonant laser pulse, which strongly modifies the binary scattering properties. In particular, when considering situations with rapid variations and high light intensities the approach leads, in a consistent way, beyond standard mean field techniques. This allows to address the question of limits to the photoassociation rate due to many body effects which has caused extensive discussions in the recent past. Both, the possible loss rate of condensate atoms and the amount of stable ground state molecules achievable within a certain time are found to be stronger limited than according to mean field theory. The consequences of the finite lifetime of the resonantly coupled bound state are discussed in the two body as well as in the many body context.