Implementation of a nonlocal N-qubit conditional phase gate by single-photon interference

By virtue of single-photon interference, we present how to realize a nonlocal N-qubit conditional phase gate, which might be quite useful for the synthesis of arbitrary entangled quantum states of remote qubits required by distributed quantum information processing. Without considering photon loss, our scheme would work in a repeat-until-success fashion with an automatic feedback line added. Even by taking photon loss into consideration, only the success probability is affected, not the gate fidelity.