Non-Hermitian tearing by dissipation

In the paper, we study the non-Hermitian system under dissipation and give the effective \(2\times 2\) Hamiltonian in the k-space by reducing the \(N\times N\) Hamiltonian in the real space for them. It is discovered that the energy band shows an imaginary line gap. To describe these phenomena, we propose the theory of “non-Hermitian tearing” , in which the tearability we define reveals a continuous phase transition at the exceptional point. The non-Hermitian tearing manifests in two forms — separation of bulk state and decoupling of boundary state. In addition, we also explore the one-dimensional Su–Schrieffer–Heeger model and the Qi–Wu–Zhang model under dissipation using the theory of non-Hermitian tearing. Our results provide a theoretical approach for exploring the controlling of non-Hermitian physics on topological quantum states.