Clock synchronization by remote detection of correlated photon pairs

TL;DR

This paper introduces a method for synchronizing remote clocks using correlated photon pairs, eliminating the need for dedicated hardware or highly stable reference clocks, thus simplifying quantum communication systems.

Contribution

The paper presents a novel algorithm for clock synchronization via correlated photons that significantly relaxes reference clock accuracy requirements compared to prior methods.

Findings

Enables remote clock synchronization without dedicated hardware.

Reduces reference clock accuracy requirements by about 100,000 times.

Applicable to entanglement-based quantum key distribution schemes.

Abstract

We present an algorithm to detect the time and frequency difference of independent clocks based on observation of time-correlated photon pairs. This enables remote coincidence identification in entanglement-based quantum key distribution schemes without dedicated coincidence hardware, pulsed sources with a timing structure or very stable reference clocks. We discuss the method for typical operating conditions, and show that the requirement in reference clock accuracy can be relaxed by about 5 orders of magnitude in comparison with previous schemes.