An ultrastable silicon cavity in a continuously operating closed-cycle cryostat at 4 K

TL;DR

This paper demonstrates a silicon cavity laser system operating continuously at 4 K with unprecedented stability and linewidth, advancing the development of ultrastable lasers for optical clocks.

Contribution

It presents a silicon cavity laser system at 4 K with significantly improved stability and linewidth, showing technical readiness for next-generation ultrastable lasers.

Findings

Achieved $1 imes 10^{-16}$ instability at 1542 nm

Median linewidth of 17 mHz at 4 K

Ten-fold improvement over previous systems

Abstract

We report on a laser locked to a silicon cavity operating continuously at 4 K with $1 \times 10^{-16}$ instability and a median linewidth of 17 mHz at 1542 nm. This is a ten-fold improvement in short-term instability, and a $10^4$ improvement in linewidth, over previous sub-10 K systems. Operating at low temperatures reduces the thermal noise floor, and thus is advantageous toward reaching an instability of $10^{-18}$, a long-sought goal of the optical clock community. The performance of this system demonstrates the technical readiness for the development of the next generation of ultrastable lasers that operate with ultranarrow linewidth and long-term stability without user intervention.