Criterion for remote clock synchronization with Heisenberg-scaling accuracy

We propose a quantum method to judge whether two spatially separated clocks have been synchronized within a specific accuracy sigma. If the measurement result of the experiment is clearly a nonzero value, the time difference between two clocks is smaller than sigma; otherwise, the difference is beyond sigma. Upon sharing the 2N-qubit bipartite maximally entangled state in this scheme, the accuracy of judgment can be enhanced to sigma similar to pi/[omega(N + 1)]. This criterion is consistent with Heisenberg scaling, which can be considered as the beating standard quantum limit; moreover, the unbiased estimation condition is not necessary. In particular, we demonstrate that this scheme is still feasible when suffering the loss of qubits.OpticsPhysics, Atomic, Molecular & ChemicalSCI(E)EI7ARTICLE5null8