Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Jan. 6, 2022 at 2 p.m. only via Zoom

Prof. Dr. Peter van Loock
Institut für Physik

Dr. Lars von der Wense
Institut für Physik

Quantum Technologies for Molecular Precision Spectroscopy
Prof. Stefan Willitsch (Universität Basel)

The development of quantum technologies for molecules has remained a long-standing challenge due to the complexity of molecular systems. We have recently developed a quantum-non-demolition technique for the non-destructive detection of the internal quantum state of a single trapped molecular ion [1,2,3]. The method is based on the state-dependent coherent excitation of the motion of the molecular ion and subsequent measurement of the motional quantum state using a co-trapped atomic ion. This approach offers new perspectives not only for the detection, but also for the preparation and the manipulation of molecular quantum states on the single-particle level with a sensitivity several orders of magnitude higher compared to previously used destructive schemes. We present a characterisation of the technique using the homonuclear diatomic ion N2+ as an example and show how it can be used for non-invasive spectroscopic measurements on single molecules. We also discuss applications of this technique in the realm of precision molecular spectroscopy [4] using a newly established fibre network for the precise transfer of frequencies within Switzerland and their comparison to the Swiss primary standard at METAS.

References: [1] Z. Meir, G. Hegi, K. Najafian, M. Sinhal and S. Willitsch, "State-selective coherent motional excitation as a new approach for the manipulation, spectroscopy and state-to-state chemistry of single molecular ions”, Faraday Discuss. 217 (2019), 561. [2] M. Sinhal, Z. Meir, K. Najafian, G. Hegi and S. Willitsch, "Quantum non-demolition state detection and spectroscopy of single trapped molecules”, Science 367 (2020), 1213. [3] K. Najafian, Z. Meir, M. Sinhal and S. Willitsch, "Identification of molecular quantum states using phase-sensitive forces”, Nat. Commun. 11 (2020), 4470. [4] K. Najafian, Z. Meir and S. Willitsch, ”From megahertz to terahertz qubits encoded in molecular ions: theoretical analysis of dipole-forbidden spectroscopic transitions in N2+”, Phys. Chem. Chem. Phys. 22 (2020), 23083. [5] D. Husmann et al., “SI-traceable frequency dissemination at 1572.06 nm in a stabilized fiber network with ring topology”, Opt. Expr. 29 (2021), 24592.