Reduced density matrix and entanglement of interacting quantum field theories with Hamiltonian truncation

Entanglement is the fundamental difference between classical and quantum systems has become one of guiding principles in exploration high- low-energy physics. The calculation entanglement entropies interacting field theories, however, remains challenging. Here, we present first method for explicit computation reduced density matrices theories using truncated Hamiltonian methods. based on constructing an isomorphism Hilbert space full system tensor product spaces subintervals. This naturally enables von Neumann arbitrary Rényi as well mutual information, logarithmic negativity, other measures entanglement. Our applicable to equilibrium states nonequilibrium evolution real time. It model independent can be applied any truncation that uses a free basis expansion. We benchmark Klein-Gordon theory finding excellent agreement with analytic results. further demonstrate its potential sine-Gordon model, studying scaling entropy ground real-time dynamics following quenches model.5 MoreReceived 17 March 2022Accepted June 2022DOI:https://doi.org/10.1103/PhysRevResearch.4.033039Published by American Physical Society under terms Creative Commons Attribution 4.0 International license. Further distribution this work must maintain attribution author(s) published article's title, journal citation, DOI. Open access publication funded Max Planck Society.Published SocietyPhysics Subject Headings (PhySH)Research AreasEntanglement entropyQuantum entanglementQuantum theoryParticles & FieldsQuantum Information