Precision measurement and compensation of optical Stark shifts for an ion-trap quantum processor

Abstract

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 $n\times 2\ddot{I}€$ rotation of the quantum bit.

4 pages, 4 figures