Quantum Mechanics of a Rotating Billiard
  Integrability of a square billiard is spontaneously broken as it rotates about one of its corners. The system becomes quasi-integrable where the invariant tori are broken with respect to a certain parameter, $\lambda = 2E/\omega^{2}$ where E is the energy of the particle inside the billiard and $\omega$ is the angular frequency of rotation of billiard. We study the system classically and quantum mechanically in view of obtaining a correspondence in the two descriptions. Classical phase space in Poincar\'{e} surface of section shows transition from regular to chaotic motion as the parameter $\lambda$ is decreased. In the Quantum counterpart, the spectral statistics shows a transition from Poisson to Wigner distribution as the system turns chaotic with decrease in $\lambda$. The wavefunction statistics however show breakdown of time-reversal symmetry as $\lambda$ decreases. 
Nandan Jha and Sudhir R. Jain
nlin.CD quant-ph