A Cryogenic Sapphire Resonator Oscillator with 1e-16 mid-term fractional frequency stability

TL;DR

This paper demonstrates a cryogenic sapphire oscillator achieving exceptional mid-term frequency stability below 2e-16 and long-term stability limited by a 1e-18/sqrt(tau) random walk, using advanced instrumentation and correlation techniques.

Contribution

It presents a cryogenic sapphire oscillator with record-breaking frequency stability and details the methods used to attain and verify this performance.

Findings

Frequency stability below 2e-16 near 1,000 s

Long-term Allan Deviation limited by 1e-18/sqrt(tau)

Use of sophisticated instrumentation and correlation methods

Abstract

We report in this letter the outstanding frequency stability performances of an autonomous cryogenique sapphire oscillator presenting a flicker frequency noise floor below 2e-16 near 1,000 s of integration time and a long term Allan Deviation (ADEV) limited by a random walk process of 1e-18/sqr(tau). The frequency stability qualification at this level called for the implementation of sophisticated instrumentation associated with ultra-stable frequency references and ad hoq averaging and correlation methods.