Probing beyond the laser coherence time in optical clock comparisons

TL;DR

This paper introduces differential measurement protocols that enable optical clock comparisons beyond the laser coherence time, significantly improving measurement precision and reducing duration by over tenfold.

Contribution

It presents novel protocols for optical clock comparison that surpass laser coherence time limitations using phase-locked oscillators and numerical simulations demonstrating their effectiveness.

Findings

Protocols enable probe times longer than laser coherence time

Methods support Heisenberg-limited measurement precision

Reduce frequency ratio measurement durations by over ten times

Abstract

We develop differential measurement protocols that circumvent the laser noise limit in the stability of optical clock comparisons by synchronous probing of two clocks using phase-locked local oscillators. This allows for probe times longer than the laser coherence time, avoids the Dick effect, and supports Heisenberg-limited measurement precision. We present protocols for such frequency comparisons and develop numerical simulations of the protocols with realistic noise sources. These methods provide a route to reduce frequency ratio measurement durations by more than an order of magnitude.