The fidelity decay in a microwave billiard is considered, where the coupling to an attached antenna is varied. The resulting quantity, coupling fidelity, is experimentally studied for three different terminators of the varied antenna: a hard wall reflection, an open wall reflection, and a 50 Ohm load, corresponding to a totally open channel. The model description in terms of an effective Hamiltonian with a complex coupling constant is given. Quantitative agreement is found with the theory obtained from a modified VWZ approach [Verbaarschot et al, Phys. Rep. 129, 367 (1985)].
@article{arxiv.1006.3478,
title = {Microwave fidelity studies by varying antenna coupling},
author = {B. Köber and U. Kuhl and H. -J. Stöckmann and T. Gorin and D. V. Savin and T. H. Seligman},
journal= {arXiv preprint arXiv:1006.3478},
year = {2010}
}