Cavity-enhanced spectroscopy of molecular quantum emitters

Rare earth ions in solid-state hosts are a promising candidate for optically
addressable spin qubits, owing to their excellent optical and spin
coherence times. Recently, also rare earth ion-based molecular complexes
have shown excellent optical coherence properties [1]. Due to
the long optical lifetime of the optical transition 5D0-7F0, an efficient
spin-photon interface for quantum information processing requires the
coupling of single ions to a microcavity. Open-access Fabry-Pérot fiber
cavities have been demonstrated to achieve high quality factors and
low mode volumes, while simultaneously offering large tunability and
efficient collection of the cavity mode [2]. Since the used molecular
quantum emitters require a cryogenic environment, the demands on
mechanical stability of the cavity setup have a high priority. To tackle
these challenges, we report on the development of a monolithic type
of cavity assembly, sacrificing some lateral scanning ability for the
purpose of significantly increasing the passive stability. We integrate
molecules into the cavity in the form of a crystalline thin film on a
macroscopic mirror and identify a sub-nanometer local surface roughness,
... mehr
sufficient to avoid excessive scattering loss. We report on first
studies of cavity-enhanced emission spectroscopy.
[1] Serrano et al., Nature, 603, 241-246 (2022)
[2] Hunger et al., New J. Phys 12, 065038 (2010)