A cryogenic sapphire resonator oscillator with 10−16 mid-term fractional frequency stability

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