Freiburg 2024 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 21: Quantum Communication III
Q 21.5: Talk
Tuesday, March 12, 2024, 12:00–12:15, HS 3219
Spectroscopy and cavity-enhanced emission of Eu-based molecular systems — •Evgenij Vasilenko, Vishnu Unni C, Weizhe Li, Nicholas Jobbitt, Senthil Kuppusamy, Mario Ruben, and David Hunger — Karlsruhe Institute of Technology
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 REI-based molecular complexes have shown excellent optical coherence properties [1]. However, Eu ions have a long optical lifetime of the 5 D0-7F0 transition (T1,opt ms) and a low branching ratio (<1%), limiting single-ion experiments. Both issues can be solved by high-finesse fiber-based microcavities. We study Eu-doped molecular crystalline materials, including a Trensal complex that yields 7 min spin lifetime and a homogeneous linewidth of 2.8 MHz at 4.2 K [2]. On a single, macroscopic molecular crystal [Eu(Ba)4(pip)] [1], we measure narrow inhomogeneous linewidths, hour-long spin T1 and photon echoes at <1K. Steps to integrate molecular crystals into a fiber cavity at cryogenic operation are reported. Open-access 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 [3]. The results are important steps towards single-ion readout and control being necessary for scalable quantum registers.
[1] Serrano et al., Nature, 603, 241-246 (2022)
[2] Kuppusamy et al., J. Phys. Chem. C 127, 22 (2023)
[3] Hunger et al., New J. Phys 12, 065038 (2010)
Keywords: Rare-earth ions; Europium; Cryogenic ensemble spectroscopy; Molecular complexes; Fiber-based microcavities