Compression of cold atoms to very high densities in a rotating-beam blue-detuned optical trap

We propose and demonstrate a scheme for a blue-detuned optical dipole trap for cold atoms which consists of a single, rapidly rotating laser beam. We characterize a parameter range in which the optical potential can be accurately described by a quasistatic time-averaged potential. The trap is loaded with >10⁶ Rb atoms, and is then compressed adiabatically by a factor of 350 to a final density of 5×10¹³ cm^-3. A~4 times adiabatic increase in the peak phase-space density of the trapped atoms is obtained due to the change in the shape of the trap potential. The two-body elastic and inelastic collision rates of atoms in the compressed trap are determined.