ABCD formulation of propagator of a time-dependent quantum system
含时量子系统传播子的ABCD形式

The evolution of states of a time dependent quantum system can be supposed to be the propagation of a matter wave beam along the time coordinate. The beam width, divergence, curvature radius, quality factor and entropy were introduced to represent the matter wave beam. For a quantum system with a conservative beam quality factor, the evolutions of position operator and momentum operator are linear, the propagator is of the ABCD formulation, and the formulation of the minimum wave packet, of which the quality factor is unity, is time independent. The applications of these to quantum systems of constant potential and oscillators were also discussed.