Clock synchronization using dichotomy based on polarization-entangled GHZ states

摘要

We propose a clock synchronization scheme using dichotomy based on polarization-entangled GHZ states. This scheme includes the first synchronization party (Alice), the second synchronization party (Bob) and the transmitter (Charlie). Alice and Bob are connected through a classical channel, Charlie and Alice are connected through a quantum channel, and Charlie and Bob are connected through a quantum channel and a classical channel. Charlie prepares a three-photon polarization entangled GHZ state and sends three photons to Alice, Bob and his own detector simultaneously. Alice, Bob, and Charlie then measure the polarization of the three photons. According to the properties of the GHZ state, Charlie can infer which of Alice and Bob performed the measurement first by comparing the measurement results with Bob, so as to adjust the optical delay line between himself and Alice. The GHZ state entanglement effect used in this scheme is a non-localized effect, which is "instantly" and can reach a higher accuracy than classical clock synchronization. The transmission of the optical signal is one-way, there is no requirement for the transmission speed of the signal in different directions and thus reduce the influence of the fiber during the transmission.