Entanglement Hamiltonian and effective temperature of non-Hermitian quantum spin ladders

Pei-Yun Yang¹, Yu-Chin Tzeng^2*

¹Department of Physics, National Taiwan University, Taipei, Taiwan
²Department of ElectroPhysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan

* Presenter:Yu-Chin Tzeng, email:yctzeng@nycu.edu.tw

Quantum entanglement plays a crucial role not only in understanding Hermitian many-body systems but also in offering valuable insights into non-Hermitian quantum systems. In this paper, we analytically investigate the entanglement Hamiltonian and entanglement energy spectrum of a non-Hermitian spin ladder using perturbation theory in the biorthogonal basis. Specifically, we examine the entanglement properties between coupled non-Hermitian quantum spin chains. In the strong coupling limit (J_rung≫1), first-order perturbation theory reveals that the entanglement Hamiltonian closely resembles the single-chain Hamiltonian with renormalized coupling strengths, allowing for the definition of an ad hoc temperature. Our findings provide new insights into quantum entanglement in non-Hermitian systems and offer a foundation for developing novel approaches for studying finite temperature properties in non-Hermitian quantum many-body systems.


Reference: Pei-Yun Yang and Yu-Chin Tzeng, arXiv:2409.17062 (to be published in SciPost Physics Core)

Keywords: non-Hermitian, entanglement Hamiltonian, entanglement spectrum, spin ladder