Relation between timelike and spacelike entanglement entropy

Abstract: In this study, we establish a connection between timelike and spacelike entanglement entropy. Specifically, for a diverse range of states, the timelike entanglement entropy is uniquely determined by a linear combination of the spacelike entanglement entropy and its first-order temporal derivative. This framework reveals that the imaginary component of the timelike entanglement entropy primarily originates from the non-commutativity between the twist operator and its first-order temporal derivative. Furthermore, we analyze the constraints of this relation and highlight the possible extension to accommodate more complex state configurations.