What is nonlocal in counterfactual quantum communication

Willem M. de Muynck, Willy De Baere

张盛

Mary Bell, Shan Gao

Qi Guo, Liu‐Yong Cheng, Hong‐Fu Wang +1 more

We propose an alternative entanglement swapping scheme based on the principle of the counterfactual quantum communication, which demonstrates nonlocal entanglement swapping can be achieved by the operations of a third party. During the whole process, it is not needed to transmit any physical particles among the participants. Furthermore, all the entangled particles are not destroyed in the counterfactual entanglement swapping process, which means we can obtain two pairs of nonlocal entanglement at the same time, thus achieve high-efficiency entanglement distribution. The numerical analysis about the performance of the presented scheme shows that this counterfactual protocol can be implemented with high success probability and fidelity in the ideal asymptotic limit. The scheme may be meaningful for large-scale quantum communication network and quantum repeater.

Andrey Anatoljevich Grib, Waldyr A. Rodrigues

Zheng-Hong Li, Shang-Yue Feng, M. Al-Amri +1 more

The direct counterfactual quantum-communication protocol involving double-chained Mach-Zehnder interferometers requires a single-photon input. Here, we show that even with multiphoton light sources, including a strong coherent light source as input, the counterfactual communication can be achieved with success probability approaching unity in the ideal asymptotic limit. The path evolution of multiple photons is nonlocally controlled. Thus, information is transmitted without any photons, or any other auxiliary information carriers, appearing in the public transmission channel. The effect is quantum since quantum measurements are an essential requirement for this protocol. Furthermore, a modified scheme is proposed in which the number of interferometers is reduced.