Inserting two atoms into a single optical micropotential
  We recently demonstrated that strings of trapped atoms inside a standing wave optical dipole trap can be rearranged using optical tweezers [Y. Miroshnychenko et al., Nature, in press (2006)]. This technique allows us to actively set the interatomic separations on the scale of the individual trapping potential wells. Here, we use such a distance-control operation to insert two atoms into the same potential well. The detected success rate of this manipulation is 16(+4/-3) %, in agreement with the predictions of a theoretical model based on our independently determined experimental parameters. 
Y. Miroshnychenko, W. Alt, I. Dotsenko, L. Foerster, M. Khudaverdyan,   D. Meschede, S. Reick, and A. Rauschenbeutel