Ultimate stability of active optical frequency standards

Abstract

Active optical frequency standards provide interesting alternatives to their passive counterparts. Particularly, such a clock alone continuously generates highly-stable narrow-line laser radiation. Thus a local oscillator is not required to keep the optical phase during a dead time between interrogations as in passive clocks, but only to boost the active clock's low output power to practically usable levels with the current state of technology. Here we investigate the spectral properties and the stability of active clocks, including homogeneous and inhomogeneous broadening effects. We find that for short averaging times the stability is limited by photon shot noise from the limited emitted laser power and at long averaging times by phase diffusion of the laser output. Operational parameters for best long-term stability were identified. Using realistic numbers for an active clock with ${}^{87}$Sr we find that an optimized stability of ${\sigma }_y(\tau )\approx 4\times 10^{-18}/\sqrt{\tau [\mathrm{s}]}$ is achievable.

arXiv comment15 pages

References in corpus (17)

• Optical clock intercomparison with $6\times 10^{-19}$ precision in one hour
• Resolving the gravitational redshift within a millimeter atomic sample
• Ultra-stable optical clock with two cold-atom ensembles
• Prospects for a mHz-linewidth laser
• Real-time geopotentiometry with synchronously linked optical lattice clocks
• Quantum Synchronization of Two Ensembles of Atoms
• Nuclear Spin Effects in Optical Lattice Clocks
• On the measurement of frequency and of its sample variance with high-resolution counters
• Hyperfine quenching of the metastable ${}^3{P}_{0,2}$ states in divalent atoms
• Lasing in the superradiant crossover regime
• Lattice-induced photon scattering in an optical lattice clock
• Engineering Quantum States of Matter for Atomic Clocks in Shallow Optical Lattices
• Active optical frequency standard using sequential coupling of atomic ensembles
• Cavity-QED determination of the natural linewidth of the ${}^{87}$Sr millihertz clock transition with 30$\mu$Hz resolution
• Superradiant lasing in inhomogeneously broadened ensembles with spatially varying coupling
• Stability analysis for bad cavity lasers using inhomogeneously broadened spin-1/2 atoms as gain medium
• Continuous multi-step pumping of the optical clock transition in alkaline-earth atoms with minimal perturbation

Cited by in corpus (4)

• Modeling of a continuous superradiant laser on the sub-mHz ${}^1$S${}_0\to {}^3$P${}_0$ transition in neutral strontium-88
• Nanoscale Mirrorless Superradiant Lasing
• A superradiant two-level laser with intrinsic light force generated gain
• Superradiant active optical atomic clocks: motivations and current challenges