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Hybrid quantum systems based on spin-ensembles coupled to superconducting microwave cavities are promising candidates for robust experiments in cavity quantum electrodynamics (QED) and for future technologies employing quantum mechanical effects. In particular the electron spins hosted by nitrogen-vacancy centers in diamond. We used this system to study a broad variety of effects, such as cavity protection effect and hole burning which can extend the coherence time and reduce dephasing. Furthermore, this platform allows to study superradiance and the coupling of spins over macroscopic distances.
We use a dispersive detection scheme based on cQED to observe the spin relaxation of the negatively charged nitrogen vacancy center in diamond. We observe exceptionally long longitudinal relaxation times T1 of up to 8h. To understand the fundamental mechanism of spin-phonon coupling in this system we develop a theoretical model and calculate the relaxation time ab-initio. The calculations confirm that the low phononic density of states at the NV− transition frequency enables the spin polarization to survive over macroscopic timescales.
Johannes worked as a postdoctoral fellow in the Robert Schoelkopf group of Yale University in 2003 until 2007, focusing on circuit quantum electrodynamics and transmon qubits. From 2007 until 2019, he served as an assistant professor at TU Wien, during which he pioneered experimental research on hybrid quantum systems combining superconducting resonators and diamond nitrogen vacancy color centers spin ensembles. Since 2020 he is a full professor at the Shanghai branch of the CAS center for Quantum Information and Quantum Physics at the University of Science and Technology of China. His main publications include 5 paper in Nature, 2 in Nature Physics, 1 paper in Nature Materials and Nature Photonics and 7 paper is PRL.
Tencent meeting link: https://meeting.tencent.com/dm/p9H2R1ItzfNv Meeting ID: 372 845 255 no password