Freiburg 2024 – scientific programme

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MO: Fachverband Molekülphysik

MO 10: Ultracold Molecules (joint session Q/MO)

MO 10.6: Invited Talk

Wednesday, March 13, 2024, 12:30–13:00, HS 1015

Quantum Logic Spectroscopy of the Hydrogen Molecular Ion — David Holzapfel, Fabian Schmid, Nick Schwegler, Oliver Stadler, Martin Stadler, Jonathan Home, and •Daniel Kienzler — Otto-Stern-Weg 1, 8093 Zurich, Switzerland

I will present our latest results, implementing pure quantum state preparation, coherent manipulation, and non-destructive state readout of the hydrogen molecular ion H₂⁺. The hydrogen molecular ion H₂⁺ is the simplest stable molecule, and its structure can be calculated ab-initio to high precision. However, challenging properties such as high reactivity, low mass, and the absence of rovibrational dipole transitions have thus far strongly limited spectroscopic studies of H₂⁺. We trap a single H₂⁺ molecule together with a single beryllium ion using a cryogenic Paul trap apparatus, achieving trapping lifetimes of 11 h and ground-state cooling of the shared axial motion [1]. With this platform we have recently implemented Quantum Logic Spectroscopy of H₂⁺. We utilize helium buffer-gas cooling to prepare the lowest rovibrational state of ortho-H₂⁺ (rotation L=1, vibration ν=0). We combine this with quantum-logic operations between the molecule and the beryllium ion for preparation of single hyperfine states and non-destructive readout, and demonstrate Rabi flopping on on several hyperfine transitions. Our results pave the way to high-precision spectroscopy studies of H₂⁺ which will enable tests of theory, metrology of fundamental constants, and an optical molecular clock.

[1] N. Schwegler, D. Holzapfel, M. Stadler, A. Mitjans, I. Sergachev, J. P. Home, and D. Kienzler, Phys. Rev. Lett. 131, 133003 (2023)

Keywords: Hydrogen Molecular Ion; Quantum Logic Spectroscopy; Molecular Ions; Quantum State Preparation; Spectroscopy