k1十年体育品牌

报告人：Prof. Yuan Zhang (张元), Zhengzhou University (郑州大学)

时 间：2026年8月18日（周二）下午15:30-16:30

地 点：良乡校区，物理实验中心229-230会议室

摘要: In 1950, Hahn introduced spin echoes: dephasing from frequency inhomogeneity after a first π/2 pulse is canceled by reversed precession after a second π/2 pulse. This refocusing underpins dynamical decoupling, widely used in magnetic resonance spectroscopy, imaging, quantum computation, and qubit noise spectroscopy. Hahn also introduced the stimulated echo, where a third π/2 pulse converts the population grating into a coherence grating that refocuses. Weak coupling to a microwave resonator enhances the echo signal without altering Hahn's mechanism. Strong coupling, however, intertwines coherent energy exchange with spin excitation and precession. In phosphorus, neodymium, and erbium ensembles strongly coupled to superconducting resonators, self-stimulated echoes appear as echo trains. However, the mechanism behind this novel effect remains under debate. Inspired by the population-grating picture, we developed a theory of self-stimulated echoes, emphasizing frequency-grating formation and multiple rephasing of spin sub-ensembles.

简历：Prof. Yuan Zhang received his Ph.D. from Humboldt University of Berlin, Germany in 2015. He then conducted four years of postdoctoral research in the group of Prof. Klaus Mølmer at Aarhus University, Denmark, and in the group of Javier Aizpurua at the Center for Materials Physics, Spain. In 2019, he joined the School of Physics at Zhengzhou University. His research focuses on theoretical cavity quantum electrodynamics (QED) and quantum sensing with nitrogen-vacancy (NV) centers in diamond. He has published more than 30 papers as first or corresponding author in journals including Physical Review X, Physical Review Letters, Nature Communications, npj Quantum Information, and Advanced Materials. He leads projects funded by the Ministry of Education (Scientific Research Innovation Capability Support Program for Young University Teachers), the NSFC Excellent Young Scientists Fund, and the NSFC General Program, and so on.

联系方式：hao.wu@bit.edu.cn

邀请人： 吴昊 助理教授

网 址：http://physics.bit.edu.cn/

承办单位：k1十年体育品牌、先进光电量子结构设计与测量教育部重点实验室