Continuous-wave laser system for precision experiments with single molecular ions

• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: Funded in 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 460457764

The system will enable novel quantum optics and spectroscopy experiments. Specifically, a new, general method for molecular ion spectroscopy is to be demonstrated, characterized and developed to a high degree of precision. A series of investigations in fundamental physics will then be carried out.The method is based on the use of a specially configured Penning trap, ALPHATRAP, in the Dr. S. Sturm / Prof. K. Blaum at the Max Planck Institute for Nuclear Physics (MPI-K) in Heidelberg. Individual molecular ions can be loaded into this trap and cooled to kinetic energies in the Kelvin range. Due to the strong spatial confinement of the movement, sideband-resolved laser vibrational spectroscopy is expected to be possible. In particular, the Penning trap enables the non-destructive detection of the electron spin state of the molecular ion. In molecules, both the g-factor and the hyperfine structure depend on the state of rotation and vibration. By utilizing this effect, it is in principle possible to carry out vibrational spectroscopy in a non-destructive manner.In order to examine the general procedure in detail, the heteronuclear hydrogen molecular ion HD+ and the homonuclear H2+ are chosen as test molecular ions. These are ideal objects to be investigated, as they can be theoretically treated ab initio and for which experimental precision results from radio frequency traps are already available. In addition, the precision measurements aimed for enable far-reaching results in fundamental physics.Three study topics will be pursued:1. Demonstration and characterization of non-destructive vibrational spectroscopy on a single molecular ion in a Penning trap.2. Extremely-high-resolution and precisely reproducible vibrational frequency measurements on the H2+ molecular ion in a Penning trap. The aims are (1) performing a new test of Lorentz invariance, preparatory studies towards future tests of (2) CPT invariance (comparison of the vibrational frequency of H2+ with that of anti-H2+), (3) of the temporal constancy of the proton-to-electron mass ratio, and (4) of the constancy of the antiproton-to-positron mass ratio.3. Precision measurements on the quantum mechanical three-body problem in a magnetic field: test of QED, determination of fundamental constants (mass ratios, g-factors, quadrupole moment, Rydberg constant) and search for hypothetical new forces between protons and between protons and deuterons.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Dauerstrich-Lasersystem für Präzisionsexperimente an einzelnen Molekülionen
• Instrumentation Group: 5700 Festkörper-Laser
• Applicant Institution: Heinrich-Heine-Universität Düsseldorf
• Leader: Professor Stephan Schiller, Ph.D.