Moving Mirrors, Page Curves, and Bulk Entropies in AdS2

Abstract

Understanding the entanglement of radiation in quantum field theory has been a long-standing challenge, with implications ranging from black hole thermodynamics to quantum information. We demonstrate how the case of the free fermion in 1+1 dimensions reveals the details of the density matrix of the radiation produced by a moving mirror. Using the resolvent method rather than standard conformal field theory techniques we derive the Rényi entropies, modular Hamiltonian, and flow of the radiation and determine when mirrors generate unitary transformations.