Timelike entanglement in the quantum vacuum

Abstract

For quantum fields with m=0, it is pointed out that timelike separated
fields are quantized as independent subsystems. This allows us to ask the question of whether the field in the future region is entangled with the field in the past region of Minkowski space, in the Minkowski vacuum state. I will show that the answer is "yes," and then explore some consequences, including a thermal effect and a procedure for extracting
the timelike entanglement with two inertial Unruh-DeWitt detectors.