Modular Flow of Excited States
Abstract
We develop new techniques for studying the modular and the relative modular flows of general excited states. We show that the class of states obtained by acting on the vacuum (or any cyclic and separating state) with invertible operators from the algebra of a region is dense in the Hilbert space. This enables us to express the modular and the relative modular operators, as well as the relative entropies of generic excited states in terms of the vacuum modular operator and the operator that creates the state. In particular, the modular and the relative modular flows of any state can be expanded in terms of the modular flow of operators in vacuum. We illustrate the formalism with simple examples including states close to the vacuum, and coherent and squeezed states in generalized free field theory.
 Publication:

arXiv eprints
 Pub Date:
 November 2018
 arXiv:
 arXiv:1811.05052
 Bibcode:
 2018arXiv181105052L
 Keywords:

 High Energy Physics  Theory;
 Mathematical Physics;
 Quantum Physics
 EPrint:
 40 pages, 5 figures. v2: Fixed typos and added new domain arguments for real time perturbation theory in Appendix H