Erlangen 2018 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 40: Poster: Quantum Optics and Photonics III

Q 40.16: Poster

Tuesday, March 6, 2018, 16:15–18:15, Zelt West

Coupling individual Erbium ions to single telecom photons — •Lorenz Weiss, Natalie Wilson, Benjamin Merkel, and Andreas Reiserer — Max Planck Institute of Quantum Optics, Garching, Germany

Erbium ions in suited host crystals are promising candidates for large-scale quantum networks since they combine second-long ground state spin coherence times with coherent optical transitions at telecommunication wavelengths. Unfortunately, the extremely long lifetime of the excited state (14 ms) makes it difficult to spectrally resolve and control individual ions in order to harness them for quantum networks. To overcome this challenge, we employ Fabry-Perot cavities that contain micrometer-thin, erbium-doped yttrium orthosilicate (Y₂SiO₅) crystals. In initial experiments, we have observed a cavity finesse of 36 000. To achieve both a smaller mode volume and a higher resonator quality factor, we have then optimized both the sample surface roughness (below 0.2 nm rms) and the resonator size (to a few cubic wavelengths) by fabricating low-roughness depressions of small radius of curvature in fused silica. At cryogenic temperature, we thus expect to shorten the radiative lifetime of the optical transitions by three orders of magnitude via the Purcell effect. This will enable deterministic interactions between individual spins and single telecom photons, opening unique prospects for the realization of entanglement between spins over distances exceeding 100 km.