Time Accuracy for Superposition of Coherent States in Quantum Clock Synchronization

The analysis of accuracy for arbitrary number N copies of identical prepared samples has been performed based on Bayesian framework. The time accuracies for even superposition of coherent states (SCSs) and odd SCSs could only achieve standard quantum limit for average photon number n (or α ²) is larger. The accuracies are also deduced from the approach of Cramér-Rao bound. It can be seen from the comparison that the accuracies derived from two methods in agreement with each other when n is large. The even SCSs could provide higher precision than classical coherent states in the interval 0.7≤n≤3.