Clock Synchronization with Weakly Correlated Photons

TL;DR

This paper demonstrates clock synchronization using weakly correlated photons over long distances with low optical loss, achieving low jitter and extending quantum synchronization methods beyond strongly correlated photon pairs.

Contribution

It introduces a novel synchronization scheme utilizing weakly time-correlated photons, expanding quantum clock synchronization capabilities.

Findings

Achieved 10 ns synchronization jitter over 25 hours

Successfully synchronized clocks over -102 dB optical loss

Developed a model for coherence peak success probability estimation

Abstract

Clock synchronization is necessary for communication and distributed computing tasks. Previous schemes based on photon timing correlations use pulsed light or photon pairs for their strong timing correlations. In this work, we demonstrate successful synchronization of crystal clocks using weakly time-correlated photons of 180 ns coherence time from a bunched light source. A synchronization timing jitter of 10 ns is achieved over symmetric -102 dB optical channel loss between two parties, over a span of 25 hours. We also present a model that gives better estimates to the coherence peak finding success probabilities under low signal.