Precision measurement and compensation of optical Stark shifts for an ion-trap quantum processor -: art. no. 143602

Using optical Ramsey interferometry, we precisely measure the laser-induced ac-Stark shift on the S(1/2)-D(5/2) quantum bit transition near 729 nm in a single trapped (40)Ca(+) ion. We cancel this shift using an additional laser field. This technique is of particular importance for the implementation of quantum information processing with cold trapped ions. As a simple application we measure the atomic phase evolution during a n x 2pi rotation of the quantum bit.