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Hybrid Quantum Systems: Coupling Diamond Color Centers to Superconducting Cavities

Johannes Majer (University of Science and Technology of China)


Mardi 15 Juin à 14h

Zoom link : https://univ-grenoble-alpes-fr.zoom.us/j/91808901596?pwd=UWZ2cml2N1VBOEZBenk0d3RJek9rdz09

Abstract: 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 (1) 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 (2). 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.

(1) Andreas Angerer, Kirill Streltsov, Thomas Astner, Stefan Putz, Hitoshi Sumiya, Shinobu Onoda, Junichi Isoya, William J. Munro, Kae Nemoto, Jörg Schmiedmayer, and Johannes Majer, Superradiant emission from colour centres in diamond, Nature Physics 14, 1168-1172 (2018) (2) T. Astner, J. Gugler, A. Angerer, S. Wald, S. Putz, N. J. Mauser, M. Trupke, H. Sumiya, S. Onoda, J. Isoya, J. Schmiedmayer, P. Mohn, and J. Majer, Solid-state electron spin lifetime limited by phononic vacuum modes, Nature Materials 17, 313-317 (2018)