题目：On the original Ulam's problem and its quantization
摘要：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.
时间：2026年2月3日15:00
地点：中国科学院大学中关村校区教学楼 N106
主持人：王东教授
报告人简介：周晶博士多年从事动力系统与数学物理领域的研究，尤其是费米加速模型与无穷测度遍历理论。2023 年 9 月加入大湾区大学理学院，任职助理教授。2020 年博士毕业于美国马里兰大学，2020 年-2023 年于美国宾夕法尼亚州立大学从事博士后研究。研究成果发表于 Communications in Mathematical Physics, Archive for Rational Mechanics and Analysis 等著名数学物理期刊。
