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By controlling the group velocity dispersion of a microresonator through proper shape design, scientists generate a comb whose central frequency can be tuned throughout the transparency window of the microresonator host material.

Shot noise originates from the discrete nature of optical field detection. By exploiting correlations in the shot-noise spectrum of optical pulse trains, scientists improve shot-noise-limited optical pulse timing measurements by several orders of magnitude. A photodetected pulse train timing noise floor at an unprecedented 25 zs Hz^−1/2 is reported.

A soliton microcomb as an astronomical spectrograph calibrator is presented. It can ultimately have a footprint of a few cubic centimetres, and reduced weight and power consumption, attractive for precision radial velocity measurement.

By pairing an octave-spanning terahertz microcomb with a terahertz Vernier microcomb, a continuous-wave laser at 871 nm is frequency divided to a radiofrequency clock output at 235 MHz. This laser is designed for frequency doubling to reach the ytterbium ion clock transition at 435.5 nm.

Laser frequency combs emit a spectrum of equally spaced peaks that can provide precise frequency references useful for astronomy. Here, the authors demonstrate a frequency comb using electro-optical modulation, which has a line spacing that is resolvable using grating spectrographs unlike the mode-locking approach.

Researchers demonstrate a microwave generator based on a high-Q optical resonator and a frequency comb functioning as an optical-to-microwave divider. They generate 10 GHz electrical signals with a fractional frequency instability of ≤8 × 10⁻¹⁶ at 1 s.

High-fidelity control and readout of a superconducting qubit is performed with a low-noise optical fibre link that delivers microwave signals directly to the millikelvin quantum computing environment.

The observation of soliton crystals in monolithic Kerr microresonators is reported. The physics of such resonators is explored in a regime of dense soliton occupation, offering a way to increase the efficiency of Kerr combs.

A network of optical atomic clocks based on three different atomic species is reported and their frequency ratios are measured with uncertainties at or below 8 × 10⁻¹⁸.

Scientists demonstrate a cavity-stabilized laser system with a reduced thermal noise floor, exhibiting a fractional frequency instability of 2 × 10⁻¹⁶. They use this system as a stable optical source in an ytterbium optical lattice clock to resolve an ultranarrow 1 Hz linewidth for the 518 THz clock transition. Consistent measurements with a clock instability of 5 × 10⁻¹⁶/√τ are reported.