Ultracold atoms in modulated standing light waves

Z. Wang

In this paper the model of ultracold atomic momentum spread in phase\|modulated accelerating standing light waves was investigated. This model shows a chaotic behaviour in the classical limit. This system of atoms displays the characteristic of dynamical localization ,but does not show strong suppression of diffusive motion for the same parameters as those in the corresponding classical model.

Roberto Onofrio, Luca Salasnich

Weiping Zhang, Daniel F. Walls

A vector quantum field theory is developed to describe the interaction of an ultracold atomic ensemble with a laser field. The ultracold atomic ensemble is composed of either bosonic atoms or fermionic atoms. The photon exchanges between different ultracold atoms result in a long-range interatom interaction. Under appropriate conditions, such a many-body interaction leads to an effective ``Kerr-type'' nonlinearity of atomic waves. In terms of the nonlinearity, we construct a general formalism of nonlinear atom optics for an ultracold atomic beam. Applying the formalism to the diffraction of an ultracold atomic beam composed of bosonic atoms by a standing-wave laser field, we find that the many-body nonlinearity induces self-phase and cross-phase modulation of diffracted atomic waves. As a result, a standing-wave laser acts as a nonlinear atomic grating which diffracts atoms in the same way as a nonlinear periodic medium diffracts photons.

Nathan E. Lundblad

Weiping Zhang, Daniel F. Walls

A quantum field theory of the interaction of a light wave with ultracold atoms is presented. Both the light wave and the atoms are treated as quantum fields. As an example, the authors apply the quantum field theory to the diffraction of ultracold atoms by a standing wave laser.

Gediminas Juzeliūnas, Patrik Öhberg