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Q: Fachverband Quantenoptik und Photonik
Q 41: Poster – Quantum Technologies II & Laser Technology
Q 41.19: Poster
Wednesday, March 4, 2026, 17:00–19:00, Philo 2. OG
Towards ground state cooling of 115In+−172Yb+ Coulomb crystals — •Mouhamed-Omar Manai1,2, Ingrid M. Richter1, H. Nimrod Hausser1, Shobhit S. Dey1, Dongliang Cong1, Jonas Keller1, and Tanja E. Mehlstäubler1,2 — 1Physikalisch-Technische Bundesanstalt, Braunschweig, Germany — 2Leibniz Universität Hannover, Hanover, Germany
One of the major contributions to the error budget of state-of-the-art optical clocks is second-order Doppler shift, also referred to as time dilation (TD) shift. Ground-state (GS) cooling of the clock ions not only suppresses this TD shift as well as line broadening beyond what is achievable with Doppler cooling alone, but also allows for the manipulation of the motional state by single quanta.
Our multi-ion clock features a mixed-species Coulomb crystal trapped in a radiofrequency Paul trap [1]. Clock campaigns have been conducted with up to eight 115In+ clock ions, which are sympathetically cooled by twelve 172Yb+ ions. The systematic uncertainty in this configuration is at the 1 × 10−18 level, with TD shift being one of the limiting contributions.
We are currently implementing GS cooling on the 1S0 → 3P1 intercombination transition of In+, in an intermediate regime with a linewidth of γ = 360 kHz. This will allow for spectroscopic investigations of the TD shift, in turn allowing us to further reduce our clock uncertainty, along with tests of relativity.
[1] H. N. Hausser et al., Phys. Rev. Lett. 134, 023201 (2025)