It is a pleasure to announce this exceptional PQM seminar by former PQM member Yu-Chin Tzeng, now at National Center for Theoretical Sciences Taiwan.
Time: Friday 14 June, 11am-12pm.
Location: Howard Rogers Room, Rm 234, Ingram Building, University of Kent
Talk abstract:
In the Hermitian quantum many-body systems, the fidelity susceptibility and the entanglement entropies are tools borrowed from quantum information science to study quantum phases and transitions. The fidelity susceptibility detects the quantum critical point by looking for its divergence behavior in the parameter space, and the entanglement entropies present a logarithmic scaling with the central charge when a one-dimensional many-body system is at the critical point. The central charge is an important character of the universality class for the phase transition in 1D. Recently, non-Hermitian systems, where the Hamiltonian is non-Hermitian, have attracted the attention of condensed matter physicists.
In addition to the quantum critical points, the non-Hermitian systems also have the Exceptional Pints (EP) in the parameter space, where two or more eigenvectors coalesce into one. Moreover, in some of the 1D non-Hermitian critical systems, the central charge can be a negative number. In this talk, I will introduce new definitions of fidelity and entanglement entropies for the generalization into non-Hermitian systems. We show that the fidelity susceptibility detects both the quantum critical point and the exceptional point, and the negative central charge can be extracted by the logarithmic scaling of the entanglement entropies.
References:
[1] YCT, Chia-Yi Ju, Guang-Yin Chen, Wen-Min Huang, Phys. Rev. Research 3, 013015 (2021)
[2] Yi-Ting Tu, Iksu Jang, Po-Yao Chang, YCT, Quantum 7, 960 (2023)
[3] Yi-Ting Tu, YCT, Po-Yao Chang, SciPost Phys. 12, 194 (2022)