2024年研究生学风建设主题教育暨学术月活动
STU-GTIIT光学论坛（No.23）
报告地点：at Conference Room 426 in the Administrative Center Building of STU（汕大行政中心426）
报告时间：2024年6月4日 17:00
报告题目: QED unveiled in slow atomic collisions（全英报告）
报 告 人：Dmitry A. Telnov（St. Petersburg State University）
报告摘要:
When quantum electrodynamics was established in 1930s, it was realized almost immediately that the theory predicts spontaneous creation of electron-positron pairs from vacuum by static uniform electric fields. This effect was later named after J. Schwinger. The Schwinger effect was never observed experimentally because extremely strong electric fields are required to produce positrons with noticeable probabilities. About 50 years ago, it was predicted that spontaneous electron-positron pair creation may take place in close collisions of heavy nuclei. However, the spontaneous pair creation in this scenario is masked by the contributions due to dynamic mechanism where the pair creation results from quantum transitions caused by time-dependent external fields. We perform a theoretical and computational study of the electron-positron pair creation in slow collisions of bare atomic nuclei, solving the time-dependent Dirac equation with the help of the generalized pseudospectral method in modified prolate spheroidal coordinates. Our results show that signatures of the spontaneous electron-positron pair creation mechanism can be found in both total probabilities of pair creation and energy–angle distributions of outgoing positrons if some coincidence schemes are implemented in the experiments and only the data from close collisions with small impact parameters and large scattering angles are collected and analyzed.
报告人简介：
Professor Dmitry received his doctor degree from St. Petersburg State University in 1988. Afterwards he worked as a Research Associate at the University of Kansas and as a senior visiting scientist at Taiwan University. The most important results obtained by D. A. Telnov include calculations of electron energy and angular distributions after multiphoton above-threshold ionization, high-order harmonic generation spectra in atoms and diatomic molecules, Floquet formulation of the density-functional theory and calculations performed within the framework of this theory. The time-dependent density functional theory methods have been used to calculate orientation-dependent ionization probabilities and harmonic spectra of multielectron diatomic molecules, including the contributions from inner electronic shells. Numerical algorithms based on the generalized pseudospectral method in various coordinate systems and sets of collocation points have been implemented to solve the time-dependent Schrödinger and Kohn-Sham equations.
欢迎全校师生参加！
理学院
2024年5月21日
