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A: Fachverband Atomphysik

A 29: Precision Spectroscopy of Atoms and Ions IV (joint session A/Q)

A 29.3: Vortrag

Freitag, 10. März 2023, 11:45–12:00, F303

An aluminum ion clock with 1.1× 10⁻¹⁸ estimated systematic uncertainty — •Johannes Kramer^1,2, Fabian Dawel^1,2, Marek Hild^1,2, Lennart Pelzer¹, Kai Dietze^1,2, Steven A. King³, Nicolas Spethmann¹, and Piet O. Schmidt^1,2 — ¹QUEST Institute for Experimental Quantum Metrology, Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany — ²Leibniz Universität Hannover, 30167 Hannover, Germany — ³Oxford Ionics Limited, Begbroke OX5 1PF, United Kingdom

A single trapped ²⁷Al⁺ ion is an excellent frequency reference for an optical clock, as it is largely insensitive to external field shifts. Achieved inaccuracies are below the 10⁻¹⁸ level and thus make aluminum clocks promising candidates for a re-definition of the SI second and enable for cm-scale height measurements in relativistic geodesy. We estimated the systematic uncertainty budget of PTB’s Al⁺ clock using a single ⁴⁰Ca⁺ ion as a sensor. Included in the analysis are shifts by black body radiation, collisions with background gas molecules, residual kinetic energy from uncompensated micromotion and the ac Zeeman shift caused by fast oscillating magnetic fields. The latter shift is mainly induced by the applied radio frequency used to trap the ion. Measurements show that these fields are in the range of a few 10 µT in our trap and are therefore a non-negligible contribution to the systematic frequency uncertainty budget.