The Fermionic Entanglement Entropy of Causal Diamonds in Two-Dimensional Minkowski Space
Felix Finster, Magdalena Lottner, Albert Much, Simone Murro
TL;DR
The paper analyzes the fermionic Renyi entanglement entropy of a causal diamond in two-dimensional Minkowski space for a quasi-free Dirac field with ultraviolet regularization. It extends matrix-valued symbol techniques to truncated pseudo-differential operators to derive a logarithmically enhanced area law: the entropy scales as the logarithm of the inverse regularization parameter with a universal coefficient that depends only on the Renyi index. The analysis decomposes into physical preliminaries, operator-norm bounds, and a detailed spectral study of truncated operators, ultimately showing that off-diagonal matrix effects are negligible in the limit. This work provides a rigorous relativistic analogue of area-law behavior for entanglement in a simple spacetime geometry and yields explicit universal constants for the entropy growth.
Abstract
The fermionic Rényi entanglement entropy is studied for causal diamonds in two-dimensional Minkowski spacetime. Choosing the quasi-free state describing the Minkowski vacuum with an ultraviolet regularization, a logarithmically enhanced area law is derived.
