2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/15600The structure of the semiclassical trace formula can be used to construct a quasi-classical evolution operator whose spectrum has a one-to-one correspondence with the semiclassical quantum spectrum. We illustrate this for marginally unstable integrable and non-integrable billiards and demonstrate its utility by quantizing them using arbitrary non-periodic trajectories.revtex, epsf, ps figures; to appear in the proceedings of the Int. Conf. on Nonlinear Dynamics and Computational Physics (Physical Research Laboratory, Ahmedabad, INDIA)Chaotic Dynamicstext