Tobias Wilken

TL;DR: This work reports a substantially different approach to comb generation, in which equally spaced frequency markers are produced by the interaction between a continuous-wave pump laser of a known frequency with the modes of a monolithic ultra-high-Q microresonator via the Kerr nonlinearity.

TL;DR: It is shown that tracking complex, time-varying systematic effects in the spectrograph and detector system is a particular advantage of laser frequency comb calibration, and this technique promises an effective means for modeling and removal of such systematic effects to the accuracy required by future experiments to see direct evidence of the universe's putative acceleration.

TL;DR: The 1S-2S transition frequency in atomic hydrogen via two-photon spectroscopy on a 5.8 K atomic beam is measured, with improvement to a fractional frequency uncertainty of 4.2 × 10(-15) arises mainly from an improved stability of the Spectroscopy laser, and a better determination of the main systematic uncertainties.

TL;DR: The calibration of an astronomical spectrograph with a short-term Doppler shift repeatability of 2.5 cm s−1 is reported, which should make it possible to detect Earth-like planets in the habitable zone of star or even to measure the cosmic acceleration directly.

TL;DR: The frequency of the extremely narrow 1S-2S two-photon transition in atomic hydrogen is measured using a remote cesium fountain clock with the help of a 920 km stabilized optical fiber with a relative uncertainty of 4.5×10(-15).