报告题目：The power of non-Hermitian quantum sensing

报告人：杨文（北京计算科学研究中心）

报告时间：2021年6月10日（周四）15：30

报告地点：线上报告（腾讯会议ID：334 175 351 ）

报告摘要：

Hermiticity of a Hamiltonian is one of the key postulates in quantum mechanics. It leads to two key consequences: (i) The energy eigenvalues must be real, which ensures the conservation of the  probability. (ii) The eigenstates form an ortho-normal complete basis, so that the response of the eigen-energy and the eigenstates to external perturbations are bounded. In recent years, there has  been widespread interest in open quantum systems described by a non-Hermitian Hamiltonian, which breaks both (i) and (ii). In particular, at the exceptional points where multiple eigenvalues and eigenstates coalesce, the energy eigenvalues show divergent response to external perturbations. This causes recent debates about whether unlimited sensitivity is possible by operating the  non-Hermitian quantum sensors near the exceptional point. In this talk, I will try to convey my understanding about  these issues, including how to calculate the non-Hermitian evolution, how to simulate a non-Hermitian Hamiltonian through the use of ancilla qubits, and why the eigenvalues and eigenstates of non-Hermitian Hamiltonian are much more sensitive to small perturbations than their Hermitian counterparts.

报告人简介：

杨文，男，北京计算科学研究中心研究员。2002年7月获北京师范大学物理学学士学位，2007年7月获中国科学院半导体研究所物理学博士学位，随后在香港中文大学和美国加州大学圣地亚哥分校任博士后，2011年底加入北京计算科学研究中心，2012年获教育部高等学校科学研究优秀成果奖（第二署名人），2013年获国家自然科学基金优秀青年基金项目资助。杨文博士长期致力于半导体中的自旋输运和量子信息中自旋退相干的理论研究，近年来聚焦量子传感。主持面上项目两项，培养博士生5名，博士后3名。