Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 5: Transport: Quantum Coherence and Quantum Information Systems 1 (jointly with MA and HL)

TT 5.6: Talk

Monday, March 26, 2012, 10:45–11:00, BH 243

High cooperativity in a microwave resonator coupled to YIG — Hans Huebl¹, •Johannes Lotze¹, Christoph Zollitsch^1,2, Fredrik Hocke¹, Sebastian T. B. Goennenwein¹, and Rudolf Gross^1,2 — ¹Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching, Germany — ²Physik-Department, Technische Universität München, Garching, Germany

Understanding the coupling of magnetic moments (spins) to light fields (photons) on a quantum level is of fundamental interest. Recent work [1,2] on paramagnetic samples coupled to superconducting resonators has shown coherent coupling between microwave photons and electron spins. This coupling is enhanced compared to a single spin by a factor of √N, where N is the number of spins in the ensemble. Here, we study a bulk ferrimagnetic Ga-doped yttrium iron garnet (YIG) crystal coupled to a superconducting niobium resonator operating at 6 GHz. Measuring the transmission through the resonator in a magnetic field, we observe an anticrossing of the spin and photon dispersions with a splitting of 450 MHz. Analyzing the magnetic field dependence of the resonance linewidths in this system in the interaction regime, we find that the coupling clearly dominates the intrinsic loss rates of the spin system and the resonator, an important requirement for studying the magnon-photon interaction in the strong coupling regime. The impact of microwave power and system temperature will be critically discussed.
D. I. Schuster et al., Phys. Rev. Lett. 105, 140501 (2010)
Y. Kubo et al., Phys. Rev. Lett. 105, 140502 (2010)