Study of light-assisted collisions between a few cold atoms in a   microscopic dipole trap
  We study light-assisted collisions in an ensemble containing a small number (~3) of cold Rb87 atoms trapped in a microscopic dipole trap. Using our ability to operate with one atom exactly in the trap, we measure the one-body heating rate associated to a near-resonant laser excitation, and we use this measurement to extract the two-body loss rate associated to light-assisted collisions when a few atoms are present in the trap. Our measurements indicate that the two-body loss rate can reach surprisingly large values beta>10^{-8} cm^{3}.s^{-1} and varies rapidly with the trap depth and the parameters of the excitation light. 
A. Fuhrmanek, R. Bourgain, Y. R. P. Sortais and A. Browaeys
physics.atom-ph cond-mat.quant-gas quant-ph