While the zeros of complex partition functions, such as Lee-Yang zeros and Fisher zeros, have been instrumental in characterizing temperature-driven phase transitions, the extension of this concept to zero temperature remains an open and active topic. In this talk, we will discuss on a new type of zeros ——Imaginary-Temperature Zeros (ITZs), which is defined as the roots of the imaginary-temperature partition function. We study the properties of ITZs in the transverse-field Ising chain, and find that the ITZs are distributed in sectorial structures, accompanied by universal singular behaviors for such quantities as the edge density of ITZs and the magnetization. The singularities remarkably differ from those in the Lee-Yang theory, and are demonstrated to be intimately related to quantum criticality and the Ising critical exponents. We additionally illuminate the correspondence between ITZs and the zeros of the spectral form factor, which offers a practical way for detecting ITZs through quantum dynamics.

陈立, 博士, 山西大学理论物理研究所副教授。2014-2018年于山西大学理论物理研究所攻读博士学位; 2016-2018年赴美国莱斯大学联合培养; 2019-2021于清华大学高等研究院做博士后。主要从事冷原子、机器学习的量子应用等方面的理论研究。在Physical Review Letters/A/B/E/Research等期刊上发表SCI论文十余篇。