Alternative scheme for a two-qubit conditional phase gate by adiabatic passage under dissipation

Abstract

We check a recent proposal (Goto and Ichimura 2004 Phys. Rev. A 70 012305) for a controlled phase gate through adiabatic passage under the influence of spontaneous emission and the cavity decay. We show a modification of the above proposal could be used to generate the necessary conditional phase gates in the two-qubit Grover search. Conditioned on no photon leakage either from the atomic excited state or from the cavity mode during the gating period, we numerically analyse the success probability and the fidelity of the two-qubit conditional phase gate by adiabatic passage. A comparison made between our proposed gating scheme and a previous one shows that Goto and Ichimura's scheme is an alternative and feasible way in the optical cavity regime for two-qubit gates and could be generalized in principle to multi-qubit gates.