Dynamical tunneling in mushroom billiards
  We study the fundamental question of dynamical tunneling in generic two-dimensional Hamiltonian systems by considering regular-to-chaotic tunneling rates. Experimentally, we use microwave spectra to investigate a mushroom billiard with adjustable foot height. Numerically, we obtain tunneling rates from high precision eigenvalues using the improved method of particular solutions. Analytically, a prediction is given by extending an approach using a fictitious integrable system to billiards. In contrast to previous approaches for billiards, we find agreement with experimental and numerical data without any free parameter. 
A. B\"acker, R. Ketzmerick, S. L\"ock, M. Robnik, G. Vidmar, R.   H\"ohmann, U. Kuhl, H.-J. St\"ockmann