# Demonstration of a time scale based on a stable optical carrier

## TL;DR

This paper presents a novel optical time scale using a stable optical carrier and cryogenic silicon cavity, achieving high long-term stability and outperforming existing microwave standards.

## Contribution

It introduces a new all-optical time scale architecture that combines a cryogenic silicon cavity with an optical clock, demonstrating superior stability over traditional methods.

## Key findings

- Estimated time error of 48±94 ps over 34 days
- Outperforms existing microwave time scales
- Capable of reaching stability below 10^-17 after months

## Abstract

We demonstrate a time scale based on a phase stable optical carrier that accumulates an estimated time error of $48\pm94$ ps over 34 days of operation. This all-optical time scale is formed with a cryogenic silicon cavity exhibiting improved long-term stability and an accurate $^{87}$Sr lattice clock. We show that this new time scale architecture outperforms existing microwave time scales, even when they are steered to optical frequency standards. Our analysis indicates that this time scale is capable of reaching a stability below $1\times10^{-17}$ after a few months of averaging, making timekeeping at the $10^{-18}$ level a realistic prospect.