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Coupling fidelity in a microwave billiard Bernd Köber(1), Ulrich Kuhl(1), Hans-Jürgen Stöckmann(1), Dmitry Savin(2), Thomas Gorin(3) and Thomas Seligman(4) (1) Fachbereich Physik, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg, Germany (2) Department of Mathematical Sciences, Brunel University, Uxbridge UB8 3PH, UK (3) Departamento de Fisica, Universidad de Guadalajara, Guadalajara C.P. 44840, Jalisco, Mexico (4) Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Cuernavaca, Mexico We investigate the scattering fidelity in a microwave billiard. In former studies we found for global perturbation an agreement with prediction from random matrix theory [1], whereas in case of a local perturbation an algebraic decay was found [2]. In this presentation we use the coupling to an external channel as a perturbation parameter, which is inherent to systems to be used for quantum computing. We derive an exact formula using an supersymmetrical ansatz and compare it with experiments in an chaotic billiard, where the coupling of a channel was changed. Again an algebraic decay is predicted theoretically for large times, which is confirmed in the experiment. [1] R. Schäfer, H.-J. Stöckmann, T. Gorin, and T. H. Seligman, Phys. Rev. Lett. 95184102 (2005). [2] R. Höhmann, U. Kuhl, and H.-J. Stöckmann, Phys. Rev. Lett. 100, 124101 (2008) |
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