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A: Fachverband Atomphysik

A 12: Poster I

A 12.30: Poster

Dienstag, 7. März 2023, 16:30–19:00, Empore Lichthof

Towards a compound ²⁷Al - ⁴⁰Ca and multi-ion ⁴⁰Ca clock — •Lennart Pelzer¹, Johannes Kramer^1,2, Kai Dietze^1,2, Fabian Dawel^1,2, Marek Hild^1,2, Victor Martinez-Lahuerta², Klemens Hammerer², and Piet O. Schmidt^1,2 — ¹Physikalisch-Technische Bundesanstalt, 38116 Braunschweig — ²Leibniz Universität Hannover, 30167 Hannover

Optical atomic clocks based on a single aluminium ion reach a record fractional frequency systematic uncertainty below 10⁻¹⁸. This outstanding precision allows for applications like relativistic geodesy on the cm-level and helps to tighten the bounds for physics beyond the standard model. But single ion clocks are impeded by their low signal-to-noise ratio and require therefore long averaging times. Even state-of-the-art laser stabilization is not sufficient to enable lifetime-limited interrogation of ²⁷Al⁺. Thus, pre-stabilization of the clock laser via a ⁴⁰Ca⁺ multi-ion reference could further improve the coherence time of the laser and thus increase the interrogation time on ²⁷Al⁺. Here we present the status of PTB’s ²⁷Al⁺ clock and the implementation of a multi-ion Ca⁺ reference based on dynamical decoupling. The estimated error budget of 1 × 10⁻¹⁸ of the ²⁷Al⁺ clock is based on measurements using a ⁴⁰Ca⁺ ion as a sensor. A continuous dynamic decoupling scheme is used to suppress inhomogeneous broadening from quadrupole and tensor ac Stark shifts in multi-ion ⁴⁰Ca⁺ crystals. Simultaneous suppression of first order Zeeman shifts allows interrogation of the crystal close to its natural lifetime limit.