Conditional Phase Gate Using an Optomechanical Resonator

We investigated the characteristics of an optomechanical system, which could be a candidate for a conditional phase gate for optical qubits. Despite of the promising results of semiclassical treatment, we found significant deviations at the two-photon level in quantum mechanical treatment. We applied a recently developed input-output formalism for the description of the few-photon states of the radiation field. The obtained analytical results show a trade-off between the achievable conditional phase and the fidelity of the final state, which is in a good agreement with previous studies on systems based on the nonlinear Kerr effect.