Chaos Induced by Quantization
  In this paper, we show that two-dimensional billiards with point interactions inside exhibit a chaotic nature in the microscopic world, although their classical counterpart is non-chaotic. After deriving the transition matrix of the system by using the self-adjoint extension theory of functional analysis, we deduce the general condition for the appearance of chaos. The prediction is confirmed by numerically examining the statistical properties of energy spectrum of rectangular billiards with multiple point interactions inside. The dependence of the level statistics on the strength as well as the number of the scatterers is displayed.   KEYWORDS: wave chaos, quantum mechanics, pseudointegrable billiard, point interaction, functional analysis 
Takaomi Shigehara (Saitama U), Hiroshi Mizoguchi (Saitama U),   Taketoshi Mishima (Saitama U), Taksu Cheon (Kochi Tech)