Quantum mushroom billiards
  We report the first large-scale statistical study of very high-lying eigenmodes (quantum states) of the mushroom billiard proposed by L. Bunimovich in this journal, vol. 11, 802 (2001). The phase space of this mixed system is unusual in that it has a single regular region and a single chaotic region, and no KAM hierarchy. We verify Percival's conjecture to high accuracy (1.7%). We propose a model for dynamical tunneling and show that it predicts well the chaotic components of predominantly-regular modes. Our model explains our observed density of such superpositions dying as E^{-1/3} (E is the eigenvalue). We compare eigenvalue spacing distributions against Random Matrix Theory expectations, using 16000 odd modes (an order of magnitude more than any existing study). We outline new variants of mesh-free boundary collocation methods which enable us to achieve high accuracy and such high mode numbers orders of magnitude faster than with competing methods. 
A. H. Barnett and T. Betcke