Biography
Kai Zhang is an Assistant Professor in the School of Physics at Zhejiang University. His current research focuses on non-equilibrium phases of matter in open quantum systems, non-Hermitian many-body physics, and mixed-state quantum phases.
He received his Ph.D. from the Institute of Physics, Chinese Academy of Sciences, in 2022, where he worked in Chen Fang’s group. From 2022 to 2026, he was a Research Fellow in Kai Sun’s group at the University of Michigan. In May 2026, he joined Zhejiang University.
Research Interests
Open quantum systems; Non-Hermitian physics; topological phases of matter; non-equilibrium many-body quantum dynamics.
Highlighted Works
1. Correspondence between winding numbers and skin modes in non-Hermitian systems
We establish a correspondence between nonzero Bloch-spectrum winding under periodic boundary conditions and the emergence of the non-Hermitian skin effect under open boundary conditions in one dimension. This work reveals the topological origin of the non-Hermitian skin effect and provides a simple criterion for its occurrence.
2. Universal non-Hermitian skin effect in two and higher dimensions
We establish a universal spectral theorem showing that non-Hermitian Hamiltonians without the non-Hermitian skin effect occupy a measure-zero subset of parameter space. We further uncover a new phenomenon, termed the geometry-dependent skin effect, in which wave functions generically accumulate at the boundaries of open polygons but become extended under special geometries selected by symmetry.
3. Dynamical degeneracy splitting and directional invisibility in non-Hermitian systems
We establish dynamical degeneracy splitting as a framework linking the frequency-resolved non-Hermitian skin effect to anomalous Green's-function behavior, spectral broadening, scattering, and wave-packet directional invisibility in higher-dimensional non-Hermitian systems.
4. Algebraic non-Hermitian skin effect and generalized Fermi surface formula in arbitrary dimensions
We uncover the quasi-long-range algebraic localization of the higher-dimensional skin effect and establish the generalized Fermi surface framework.
5. Non-Hermitian bulk-boundary correspondence and auxiliary generalized Brillouin zone theory
We develop a systematic analytic method for calculating the generalized Brillouin zone and open-boundary continuum spectrum of generic one-dimensional non-Hermitian band systems, rendering a broad class of non-Hermitian lattice Hamiltonians analytically tractable.
# Equal contribution. * Corresponding author.