报告题目（Title）：Watching ultracold two-body collisions one at a time
报 告 人（Speaker）：Doerte Blume 教授, PRA编辑(Department of Physics and Astronomy, The University of Oklahama)
报告时间（Time）：2018年11月5 日 （周一） 10：30
报告地点（Place）：校本部G309
邀请人（inviter）：张永平
报告摘要（Abstract）：
The one-dimensional harmonic oscillator is discussed in many physics text books, ranging from introductory classical mechanics to quantum mechanics to quantum optics and field theory. The physics of the one-dimensional harmonic oscillator is simple: Its classical orbits are sinusoidal and periodic and the quantum propagator has a compact analytical expression. The harmonic oscillator also allows one to gain intuition for the dynamics of multi-dimensional systems. The classical paths of two one-dimensional harmonic oscillators with rational frequencies trace out so-called Lissajous figures, while irrational frequencies lead to open paths in position space. This work studies the dynamics of an anisotropic three-dimensional harmonic oscillator in which the three degrees of freedom are coupled by a point scatterer of varying strength that is located at the origin. Since the point scatterer has a measure of zero, the classical trajectories are not influenced by the point scatterer. However, the situation changes drastically when one enters the quantum regime since the point scatterer can simultaneously partially reflect and partially transmit the wave packet, or even reflect the wave packet in its entirety. Parameter-free theoretical quantum predictions for this setup are shown to be in excellent agreement with the experimental results from the Jochim group in Heidelberg. Experimentally, the three-dimensional anisotropic harmonic oscillator with point scatterer is realized by trapping two ultracold atoms, which interact via a short-range van der Waals potential, optically. The combined theory-experiment study provides a novel means to observe, one collision at a time, the wave packet dynamics.
