Entanglement entropy and negativity of disjoint intervals in CFT: Some numerical extrapolations

TL;DR

This paper develops a numerical extrapolation method to compute entanglement entropy and negativity for disjoint intervals in conformal field theories, addressing challenges in analytic continuation.

Contribution

It introduces a rational interpolation-based numerical approach to evaluate entanglement measures in CFTs, including cases with multiple disjoint intervals.

Findings

Numerical results match existing lattice model data.

Extended analysis to three disjoint intervals in Ising and free boson models.

Computed negativity for non-compact free boson.

Abstract

The entanglement entropy and the logarithmic negativity can be computed in quantum field theory through a method based on the replica limit. Performing these analytic continuations in some cases is beyond our current knowledge, even for simple models. We employ a numerical method based on rational interpolations to extrapolate the entanglement entropy of two disjoint intervals for the conformal field theories given by the free compact boson and the Ising model. The case of three disjoint intervals is studied for the Ising model and the non compact free massless boson. For the latter model, the logarithmic negativity of two disjoint intervals has been also considered. Some of our findings have been checked against existing numerical results obtained from the corresponding lattice models.