Nondestructive Control and Hyperfine Spectroscopy of Single Molecular Hydrogen Ions in a Penning Trap at AlphatrapHYBRID

As the simplest molecules, molecular hydrogen ions (MHI) are an excellent system for testing fundamental 
physics. In the Penning-trap setup Alphatrap [1], we have demonstrated a new method for quantum 
state control and nondestructive internal quantum state readout of a single HD+ ion in the rovibrational 
ground state, utilizing the continuous Stern-Gerlach effect [2,3]. Based on these techniques, we can 
perform high-precision spectroscopy on single MHI. Measurements on the hyperfine structure (HFS) of 
HD+ in the microwave regime, allow us to extract the bound g factor of the electron, as well as coefficients 
of the hyperfine Hamiltonian. The results can be compared with high-precision ab initio theory and are 
important for a better understanding of rovibrational spectroscopy performed on this ion species, from 
which fundamental constants, such as mp/me are determined to high precision [4].
We are currently extending our methods to single-ion rovibrational laser spectroscopy of MHI at infrared 
wavelengths. The development of these techniques is one of the required steps towards spectroscopy of 
an antimatter H2− ion for tests of matter-antimatter symmetry [5]. 

[1] S. Sturm et al., Eur. Phys. J. Spec. Top. 227, 1425–1491 (2019) 
[2] H. Dehmelt, Proc. Natl. Acad. Sci. USA 83, 2291 (1986)
[3] C. M. König et al., Phys. Rev. Lett. 134,163001 (2025)
[4] I. V. Kortunov, et al., Nature Physics vol 17, 569–573 (2021)
[5] E. Myers, Phys. Rev. A 98, 010101(R) (2018)

https://gsi-fair.zoom.us/j/63856816325
Meeting-ID: 638 5681 6325
Passcode: AP_Seminar
dial by phone
+496938079884,,63856816325#,,,,*8527227260# Deutschland
+496950500951,,63856816325#,,,,*8527227260# Deutschland