Speed of ion-trap quantum-information processors - art. no. 042305

We investigate theoretically the speed limit of quantum gate operations for ion trap quantum information processors. The proposed methods use laser pu lses for quantum gates that entangle the electronic and vibrational degrees of freedom of the trapped ions. Two of these methods are studied in detail and for both of them the speed is limited by a combination of the recoil f requency of the relevant electronic transition, and the vibrational frequen cy in the trap. We have experimentally studied the gate operations below an d above this speed limit. In the latter case, the fidelity is reduced, in a greement with our theoretical findings.