活动类型：

学术活动
活动名称：

On the original Ulam's problem and its quantization
地点：

教学楼N106

主讲人：

王东
联系人：

王东
联系方式：

15910781583
开始时间：

2026-02-03 15:00
结束时间：

2026-02-03 17:00
说明:

We show that under general resonance the classical piecewise linear Fermi-Ulam accelerator behaves substantially different from its quantization, in the sense that the classical accelerator exhibits typical recurrence and non-escaping while the quantum version enjoys quadratic energy growth in general. We also describe a procedure to locate the escaping orbits, though exceptionally rare in the infinite-volume phase space, for the classical accelerators, which in particular include Ulam's very original proposal and the linearly escaping orbits therein in the existing literature, and hence provide a complete (modulo a null set) answer to Ulam's original question. For the quantum accelerators, we reveal under resonance the direct and explicit connection between the energy growth and the shape of the quasi-energy spectrum.