Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 36: TR: Poster Session

TT 36.27: Poster

Thursday, March 25, 2010, 14:00–18:00, Poster A

Galvanic coupling of two superconducting microwave resonators — Thomas Weissl¹, •Elisabeth Hoffmann¹, Frank Deppe¹, Edwin P. Menzel¹, Achim Marx¹, Rudolf Gross¹, David Zueco², Georg M. Reuther², Juan J. Garcia-Ripoll³, and Enrique Solano⁴ — ¹Walther-Meissner-Institut and TU München, Garching, Germany — ²Universität Augsburg, Augsburg, Germany — ³Instituto de Fisica Fundamental, CSIC, Madrid, Spain — ⁴Universidad del País Vasco-Eurskal Herriko Unibertsitatea, Spain

Thermal entanglement, e.g. in a system of two degenerate coupled superconducting microwave resonators, is achieved just by lowering the temperature below a critical temperature T_c and can be detected via suitable correlation measurements. T_c depends on the coupling strength of the two resonators. To obtain a critical temperature of about 100 mK in an actual experiment, a coupling strength of the order of 1 GHz is required. For superconducting flux quantum circuits, such a large coupling can be realized by making use of the kinetic inductance: the circuits have to be galvanically connected and form a single entity. Nevertheless, the physics can often be described by two separate modes with an enhanced coupling constant. Our experiments show that the mode structure of two coupled superconducting microwave resonators changes discontinuously when connecting them galvanically instead of just placing them very close to each other. This is explained within a simple toy model. This work is supported by the DFG within SFB 631 and NIM.