Constrained quantum mechanics: chaos in non-planar billiards
  We illustrate some of the techniques to identify chaos signatures at the quantum level using as a guiding examples some systems where a particle is constrained to move on a radial symmetric, but non planar, surface. In particular, two systems are studied: the case of a cone with an arbitrary contour or dunce hat billiard and the rectangular billiard with an inner Gaussian surface. 
Robert Paul Salazar and Gabriel Tellez (Universidad de los Andes,   Bogota, Colombia)
quant-ph nlin.CD physics.pop-ph