Mainz 2026 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 29: Precision Spectroscopy of Atoms and Ions IV (joint session A/Q)
A 29.1: Hauptvortrag
Donnerstag, 5. März 2026, 11:00–11:30, N 3
An optical clock with entangled trapped 40Ca+ ions. — •Kai Dietze1,2, Lennart Pelzer1,2, Bennet Benny1,2, Fabian Dawel1,2, Mirza A. Ali1,2, Derwell Drapier1, and Piet O. Schmidt1,2 — 1QUEST Institute for Experimental Quantum Metrology, Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany — 2Leibniz Universität Hannover, 30157 Hannover, Germany
Optical atomic clocks based on trapped ions reach fractional systematic uncertainties in the low 10−18 range. The statistical uncertainty, however, is typically limited by the quantum projection noise due to the small number of ions, requiring long averaging times to reach a comparable level in uncertainty. Entanglement-assisted interrogation schemes can lower this limit by providing a gain in signal-to-noise ratio. We discuss entanglement-based measurement schemes in the presence of spontaneous emission and magnetic-field fluctuations [2] and present our experimental realization of an optical clock employing two entangled 40Ca+ ions prepared in a decoherence-free subspace. We experimentally compare a classical correlated protocol with an entanglement enhanced protocol based on a magnetically insensitive multi-ion state, demonstrating lifetime-limited coherence times and their applicability within an optical clock comparison [2].
[1] T. Kielinski et al., Sci. Adv. 10, eadr1439 (2024)
[2] K. Dietze et al., arXiv:2506.11810 (2025)
Keywords: Optical atomic clocks; Trapped ions; Entanglement based measurements