Quantum Logic Spectroscopy of Molecular Ions

• Applicant: Professor Dr. Piet Oliver Schmidt
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2012 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 214284891

Molecules with their complex internal structure offer themselves for answering a variety of fundamental questions, such as the possible time-variation of fundamental constants or the existence of an electric dipole moment of the electron. The required precision spectroscopy of molecules was limited in the past by the lack of methods for laser cooling, state preparation and detection.In this project, universal methods for precision spectroscopy of molecular ions will be developed, with the goal to determine an improved upper bound for a change in the electron-to-proton mass ratio. The required techniques are based on coherent manipulation of internal and external degrees of freedom using laser pulses, developed originally for quantum information processing with trapped atomic ions. A “logic ion”, simultaneously trapped with the molecular ion, provides sympathetic laser cooling and is used for internal state preparation and detection. This will allow deterministic preparation of a single molecular ion in a specific ro-vibrational state and to perform precision spectroscopy on vibrational transitions. These transition frequencies are sensitive to a change in the electron-to-proton mass ratio. Through long-term comparisons with an atomic reference, such as an optical clock, an improved upper bound for the rate of change will be determined.

• DFG Programme: Research Grants