报告题目:Quantum Dynamics of Inflation

报  告  人:Cheng Chin,James Franck institute, Enrico Fermi institute, and Department of Physics, University of Chicago

报告时间:2017年3月24日10:00

报告地点:物理系C302报告厅

报告摘要:Phase transitions are both ubiquitous and fascinating.  Snow from the sky, a result of a phase transition, is run-of-the-mill in Chicago; however, we remain intrigued when realizing that the beautiful crystals of a snow flake, millimeter in size, grows from the molecular structure at the nano-meter scale. Beyond classical systems, an exponential growth of new symmetry across a phase transition, called inflation, reaches frontier of research on quantum many-body dynamics, as well as in the evolution of early universe.  

Based on a cesium Bose-Einstein condensate driven across a quantum phase transition, we have observed in the past years a series of interesting phenomena: emergence of topological defects (domain walls), exotic excitations (rotons), as well as the scaling symmetry of temporospatial correlations (Kibble-Zurek mechanism). A fundamental question I will address in this talk is: Is inflation a symmetry-breaking process that follows the second law of thermodynamics, or a quantum coherent process that is unitary and reversible?