Delehaye, Marion

Date:   Wednesday, Mar. 20, 2019
Time:   15:00
Place:   ETH Zurich, Hönggerberg, HPF G 6
Host:    Laura Corman

Metrology with compact ion clocks and superradiant lasers

Marion Delehaye
CNRS - FEMTO-ST, Besançon, France

Time and frequency can now be measured with impressive precision. This has been emphasized by the recent redefinition of SI units that linked most physical quantities to the SI second. FEMTO-ST in Besançon, in partnership with SYRTE Paris Observatory, has maintained a long-lasting knowledge in ultra-stable oscillators for time and frequency metrology.
In this talk, I will present the ultra-stable time and frequency activities of FEMTO-ST, with a special focus on our two most recent experiments: a compact optical clock and a superradiant laser. The aim of the compact optical clock project is to realize a clock with a fractional frequency stability of 10^-14 τ^-1/2 for a total volume below 500 L, including vacuum cell, optics and electronics. Such a compact clock would be part of the growing European optical clocks network that already triggers new applications in a large variety of domains, ranging from relativistic geodesy to fundamental science. Ion frequency standards are well suited for compact optical clocks. We thus develop a compact optical ¹⁷¹Yb⁺ clock on a chip. I will report on the experimental apparatus and current status.
The ultra-stable ytterbium superradiant laser project at FEMTO-ST has started only very recently. It is based on pioneering work made by Thompson group at JILA on a superradiant strontium experiment. Ultracold atoms are trapped in an ultra-stable Fabry-Perot cavity operated in the so called “bad-cavity regime”. When atoms are pumped into the excited state of the clock transition, superradiance leads to emission of ultra-stable laser light, with an expected fractional frequency stability of order 10^-18 τ^-1/2, ten times better than the current best optical clocks and with unprecedented miniaturization possibilities.