Key points are not available for this paper at this time.
A semiclassical theory is developed for the appearance of an excitation gap in a ballistic chaotic cavity connected by a point contact to a superconductor. Diffraction at the point contact is a singular perturbation in the limit 0, which opens up a gap E₆₀ in the excitation spectrum. The time scale /E₆₀^-1ln (with the Lyapunov exponent) is the Ehrenfest time, the characteristic time scale of quantum chaos.
Adagideli et al. (Thu,) studied this question.