物理学院学术报告（第33期）

报告题目:Fidelity zeros and Lee-Yang theory of quantum phase transitions

报告专家:孙高永 副研究员 南京航空航天大学

报告时间:2026年06月04日（周四）10:30

报告地点:理6栋302    邀请人:贺亮

报告内容：

Lee-Yang theory is central to the analysis of thermal phase transitions. However, the underlying mechanism of the theory and the nature of Lee-Yang zeros in quantum many-body systems remain elusive. In this talk, I will present a unified framework for understanding quantum phase transitions from fidelity zeros induced by non-Hermitian symmetry breaking. These zeros, arising from transitions between symmetry sectors, obey the Lee-Yang theorem and give rise to fidelity edges near critical points. Quantum criticality is further characterized through the finite-size scaling of fidelity zeros. As concrete examples, we investigate fidelity zeros analytically in one-dimensional and numerically in two-dimensional quantum Ising models under a complex magnetic field, showing excellent agreement with analytical theory and with quantum Monte Carlo and tensor-network simulations. Our results provide insights into the mechanism of Lee-Yang theory and open avenues for exploring unexplored landscapes of phase transitions in quantum many-body systems.

专家简介：

孙高永，副研究员。2015年于德国汉诺威大学获得博士学位，2015-2017年在德国马克斯普朗克复杂系统物理研究所从事博士后研究，2017年在南京航空航天大学工作。迄今为止，在Phys. Rev. Lett., Phys. Rev. A/B/Research 等期刊上发表学术论文30余篇。