Properties of a Rarefied Fermi Gas with Attraction

Shun Uchino, Masahito Ueda

Iacopo Carusotto, Yvan Castin

Sergei Khlebnikov, Igor I. Tkachev

We consider phase separation in a nonequilibrium Bose gas with an attractive interaction between particles. Using numerical integrations on a lattice, we show that the system evolves into a state that contains drops of a Bose-Einstein condensate suspended in uncondensed gas. When the initial gas is sufficiently rarefied, the rate of formation of this quantum dew scales with the initial density as expected for a process governed by two-particle collisions.

Frédéric Chevy, Ch Salomon

Joseph M. Kinast

Vladimir A. Sautenkov

In this paper, our experimental studies of dipole-dipole interactions in excited resonance gases are discussed. In weakly excited gas the dipole broadening of optical transitions is proportional to its density N. A gas medium can be identified by its density N as rarefied gas, where dipole broadening of atomic transitions is much less than Doppler width, or as dense gas, where dipole broadening is much more than Doppler width. According to our experiments the dipole broadening in rarefied gas does not depend on the optical excitation. This behavior is in a good agreement with predictions of standard theory for impact atomic collisions. In excited dense gas we observed the strong reduction of the dipole broadening. These experimental results are not described by standard theory for impact collisions. We suggested a simple description of the optical properties for excited dense gas.