The multimode nature of entanglement in QFT

Quantifying entanglement between two regions is particularly elusive in the context of quantum field theory (QFT), mainly because the Hilbert space of a QFT does not factor as a tensor product of Hilbert spaces associated with different regions of spacetime. In this talk, I will adapt tools from Gaussian quantum information theory to analyze entanglement in subsystems made of finitely many field degrees of freedom, in a free scalar theory in D + 1-dimensional Minkowski spacetime. Applying these techniques, I will argue that while entanglement between localized individual modes is limited, bipartite multimode entanglement in quantum field theory is ubiquitous.