Regensburg 2010 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 19: Quantum Chaos

DY 19.11: Vortrag

Mittwoch, 24. März 2010, 17:00–17:15, H38

Coupling fidelity in a microwave billiard — •Bernd Köber¹, Ulrich Kuhl¹, Hans-Jürgen Stöckmann¹, Dmitry Savin², Thomas Gorin³, and Thomas Seligman⁴ — ¹Fachbereich Physik, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg, Germany — ²Department of Mathematical Sciences, Brunel University, Uxbridge UB8 3PH, UK — ³Departamento de Fisica, Universidad de Guadalajara, Guadalajara C.P. 44840, Jalisco, Mexico — ⁴Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Cuernavaca, Mexico

In former microwave fidelity 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. The scattering fidelity is the parametric cross-correlation function, normalized by the auto-correlation function f^(λ)(t)=⟨ Ŝ^(λ)(t)Ŝ(t)⟩/ ⟨ |Ŝ(t)|²⟩, where Ŝ(t) is a scattering matrix element in the time domain, the brackets denote an ensemble average, and λ is the perturbation parameter. The cross-correlation can be rewritten as an auto-correlation with an effective parameter, allowing a direct application of the VWZ approach [3]. The experimentally found fidelity decay is algebraic and in perfect agreement with theory.

[1] R. Schäfer et al., Phys. Rev. Lett. 95184102 (2005).

[2] R. Höhmann et al., Phys. Rev. Lett. 100, 124101 (2008).

[3] J. J. M. Verbaarschot et al., Phys. Rep. 129, 367 (1985).