Speaker
Description
Molecular hydrogen ions (MHI), the simplest molecules, are three-body quantum systems composed of two simple nuclei and one electron. They are of high interest for fundamental physics and metrology because they provide the missing link between the fields of mass and g-factor measurements with Penning traps and spectroscopy of hydrogen-like atoms.
Similar to s-states in the hydrogen atom, the rovibrational energy levels of the MHI are shifted by the interaction between the sole electron and the finite-size nuclei because the electron's wavefunction is nonzero at the nuclei's positions. The shift can be calculated accurately [1].
Additionally, in states with nonzero rotational angular momentum, there occurs a shift due to the finite electric quadrupole moment of the deuteron. This shift is embedded in the hyperfine structure of rovibrational transitions.
Both above shifts cannot be measured directly in a simply way; they may be extracted from experimental data with the help of highly precise calculations of QED corrections to the rovibrational energies and of a precise theory of the hyperfine structure [2,3], respectively. Moreover, the results of precision experiments on other systems are required [4,5,6].
We discuss some of our results on this topic as well as the potential and the challenges for increased precision of the determination of charge radii and quadrupole moments in the coming years.
[1] D. T. Aznabayev et al., Phys. Rev. A 99, 012501 (2019)
[2] D. Bakalov et al., Phys. Rev. Lett. 97, 243001 (2006)
[3] S. Alighanbari et al., Nature 581, 152 (2020)
[4] M. Germann et al., Phys. Rev. Research 3 L022028 (2021)
[5] I. V. Kortunov et al., Nat. Phys. 17, 569 (2021)
[6] S. Alighanbari et al., subm.
