The 27th International Conference on Atomic Physics

Towards a two-photon optical clock in calcium

19 Jul 2022, 17:00

1h 30m

Hart House (Hart House)

Poster presentation Precision measurement and tests of fundamental physics Poster session

Description

Two-photon transitions in neutral atoms are attractive candidates for the development of compact and portable optical clocks. Such clocks can be used to search for dark matter and dark energy, to build a gravitational wave telescope, to perform ultra-precise surveys of the earth's gravitational potential, and to serve as the foundation for the new definition of the SI second. The Doppler- and recoil-free nature of two-photon transitions eliminates the need for confinement of the atoms at ultracold temperatures. Clock precision of $\delta \nu /\nu \approx {10}^{-16}/\sqrt{\tau }$ can be achieved without the need for an optical lattice or ion trap, both of which would introduce Stark shifts. Although it was historically thought that large probe laser light shifts were inevitable due to the high laser power required to drive two-photon transitions, we have developed a system of magic polarization to eliminate this shift. We report on progress towards the observation of the $4s^2{}^1{S}_0\to 3d4s{}^1{D}_2$ two-photon clock transition at 915 nm in a cloud of freely-falling ${}^{40}$Ca atoms.