Entanglement in nonequilibrium steady states and many-body localization breakdown in a current-driven system

We model a one-dimensional current-driven interacting disordered system through a non-Hermitian Hamiltonian with asymmetric hopping and study the entanglement properties of its eigenstates. In particular, we investigate whether a many-body localizable system undergoes a transition to a current-carrying nonequilibrium steady state under the drive and how the entanglement properties of the quantum states change across the transition. We also discuss the dynamics, entanglement growth, and long-time fate of a generic initial state under an appropriate time evolution of the system governed by the non-Hermitian Hamiltonian. Our study reveals rich entanglement structures of the eigenstates of the non-Hermitian Hamiltonian. We find transition between current-carrying states with volume-law to area-law entanglement entropy, as a function of disorder and the strength of the non-Hermitian term.