Abstract
This topical review article reports rapid progress on the generalization and application of entanglement in non-Hermitian free-fermion quantum systems.We begin by examining the realization of non-Hermitian quantum systems through the Lindblad master equation,alongside a review of typical non-Hermitian free-fermion systems that exhibit unique features.A pedagogical discussion is provided on the relationship between entanglement quantities and the correlation matrix in Hermitian systems.Building on this foundation,we focus on how entan-glement concepts are extended to non-Hermitian systems from their Hermitian free-fermion counterparts,with a review of the general properties that emerge.Finally,we highlight various concrete studies,demonstrating that entanglement entropy remains a powerful diagnostic tool for characterizing non-Hermitian physics.The entan-glement spectrum also reflects the topological characteristics of non-Hermitian topological systems,while unique non-Hermitian entanglement behaviors are also discussed.The review is concluded with several future directions.Through this review,we hope to provide a useful guide for researchers who are interested in entanglement in non-Hermitian quantum systems.