Bonn 2025 – scientific programme

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A: Fachverband Atomphysik

A 32: Ultra-cold Plasmas and Rydberg Systems II (joint session A/Q)

A 32.5: Talk

Thursday, March 13, 2025, 15:30–15:45, HS PC

Ground State Cooling of a Single Beryllium Ion in a Superconducting Paul Trap — •Stepan Kokh, Vera M. Schäfer, Elwin A. Dijck, Christian Warnecke, José R. Crespo López-Urrutia, and Thomas Pfeifer — Max-Planck-Institut für Kernphysik, Heidelberg

Spectroscopy of ions and atoms for generalized King Plot analysis allows for the search of new physics, such as unknown particles or forces, using one of the most precisely measurable quantities, the transition frequency of an atom. Employing highly charged ions (HCI) greatly increases the number of available transitions through the different charge states [1]. This method requires high precision. Therefore, suppression of external perturbations is essential. Our superconducting Paul trap shields external fields by 57 dB, a level comparable to dedicated magnetically shielded rooms [2]. However, the current setup limits our secular frequencies due to thermal effects in the Paul trap resonator. Therefore, we operate only in an intermediate Lamb-Dicke regime at η = 0.84. We demonstrate how we nevertheless achieve ground-state cooling of a single beryllium ion with 80 % ground-state population in the given setup as a first step towards quantum logic spectroscopy of HCI.

[1] Nils-Holger Rehbehn, et al., Phys. Rev. Lett. 131, 161803 (2023) [2] Elwin A. Dijck, et al., Rev. Sci. Instrum. 94, 083203 (2023)

Keywords: Ground State Cooling; Highly Charged Ions; Paul Trap; Resolved Sideband Cooling