Entropic g Theorem in General Spacetime Dimensions

CASINI, HORACIO; LANDEA, IGNACIO SALAZAR; TORROBA, GONZALO

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Año: 2023 vol. 130

0031-9007

We establish the irreversibility of renormalization group flows on a pointlike defect inserted in a d-dimensional Lorentzian conformal field theory. We identify the impurity entropy g with the quantum relative entropy in two equivalent ways. One involves a null deformation of the Cauchy surface, and the other is given in terms of a local quench protocol. Positivity and monotonicity of the relative entropy imply that g decreases monotonically along renormalization group flows, and provides a clear information-theoretic meaning for this irreversibility.