Ultra-stable laser with average fractional frequency drift rate below $5\times 10^{-19}/\mathrm{s}$

Abstract

Cryogenic single-crystal optical cavities have the potential to provide highest dimensional stability. We have investigated the long-term performance of an ultra-stable laser system which is stabilized to a single-crystal silicon cavity operated at 124 K. Utilizing a frequency comb, the laser is compared to a hydrogen maser that is referenced to a primary caesium fountain standard and to the ${}^{87}\mathrm{Sr}$ optical lattice clock at PTB. With fractional frequency instabilities of ${\sigma }_y(\tau )\le 2\times 10^{-16}$ for averaging times of $\tau =60\mathrm{s}$ to $1000\mathrm{s}$ and ${\sigma }_y(1\mathrm{d})\le 2\times 10^{-15}$ the stability of this laser, without any aid from an atomic reference, surpasses the best microwave standards for short averaging times and is competitive with the best hydrogen masers for longer times of one day. The comparison of modeled thermal response of the cavity with measured data indicates a fractional frequency drift below $5\times 10^{-19}/\mathrm{s}$, which we do not expect to be a fundamental limit.

References in corpus (2)

• Ultra-low-phase-noise cryocooled microwave dielectric-sapphire-resonator oscillators with 1 x 10^-16 frequency instability
• Adapting a Cryogenic Sapphire Oscillator for Very Long Baseline Interferometry

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• Universal formalism for data sharing and processing in clock comparison networks
• Development of a laser stabilized on an ultra-stable silicon cryogenic Fabry-Perot cavity for dark matter detection