Dr. Leonid Gerasimov, Quantum Technologies Center, MSU, St. Petersburg, Russia
Leuchs-Russell Auditorium, A.1.500, Staudtstr. 2
Location details

Abstract:

Long decoherence times are desired in quantum computational systems. In tightly focused far-off-resonant optical dipole trap (optical tweezers) for trapping of single cold rubidium atoms the trap lifetime of ~1-10 seconds may be achieved with temperature of atoms on the order of ~10-100\muK. But further cooling is needed to prevent an atomic qubit from being destroyed by decoherence on time scales much shorter than trap lifetime. We clarify the optimal conditions for the protocol of Raman sideband cooling (RSC) of a single atom confined with an optical tweezer. The protocol ultimately pursues cooling to a three-dimensional ground state of the confining potential. We show that the RSC protocol has to fulfill a set of critical requirements for the parameters of cooling beams and the excitation geometry to be effective in a most general three-dimensional configuration and for an atom having initial temperature between the recoil and the Doppler bounds. We perform a numerical simulation of the Raman passage for an example of an 85Rb atom taking into account the full level structure and all possible transition channels.