Efficient distributed controlled Z gate without ancilla single-photons via cross-phase modulation
Meng-Zheng Zhu, Liu Ye · Journal of the Optical Society of America B · 2014
A scheme is proposed to directly implement a controlled Z gate for two remote photonic qubits based on the weak cross-Kerr nonlinearity and intense coherent states of light. The distributed controlled Z gate can be used to achieve the remote creation of entangled states and can be extended to perform distributed quantum computation. The distinct advantage of the present scheme in contrast with the existing schemes is that ancilla single-photons are not needed. The total success probability and fidelity of the present controlled Z gate can approach unit in principle. We investigate photon losses of the qubus beam during the transmission and decoherence effects in the quantum gate caused by such photon losses. The scheme uses only basic tools in quantum optical laboratories and can be implemented in the regime of weak cross-Kerr nonlinearities. Therefore this makes us more confident in the feasibility of the proposed scheme.