Special Seminar: Absolute Measurement of a THz Transition Frequency Referenced to a Magnetic Dipolar Transition in Ca+ ion
Special Seminar: Absolute Measurement of a THz Transition Frequency Referenced to a Magnetic Dipolar Transition in Ca+ ion
- Datum: 06.09.2022
- Uhrzeit: 11:00
- Vortragende: Dr. Caroline Champenois
- Aix-Marseille University, CNRS, Institute de Physique des Interactions Ioniques et Moléculaires, Marseille, France
- Ort: Max Planck Institute of Quantum Optics
- Raum: Hörsaal, Raum B 0.32 / New lecture hall, Room B 0.32
- Gastgeber: MPQ, Laser Spectroscopy Division
A three-photon Coherent Population Trapping is observed by the dark line it induces on the laser induced fluorescence of a laser-cooled Ca+ ion cloud. This dark line is referenced to a magnetic dipolar transition at 1.8 THz, between two fine-structure sub-state of a metastable state. We explore the performance of such a system for frequency metrology in the THz domain.
To that purpose, the three involved lasers are made phase coherent thanks to a phase-lock on the same optical frequency comb (OFC), that is locked on an ultra-stable laser, a home-made Ti:Sa laser. Absolute measurements of this transition frequency are made possible through comparison with an ultra-stable optical signal referenced to the SI second and delivered by an optical fibre link. The uncertainty in the measured frequencies is of the order of 100 Hz, limited by the experimental linewidth which can reach 10 kHz. Comparison with the best known value for this transition frequency shows shifts on the order of a kHz that will be discussed. Gaetan Hagel, Marie Houssin and Grégoire Vallet contributed to this research.