Boundary effects on symmetry resolved entanglement

We study the symmetry resolved entanglement entropies in one-dimensional systems with boundaries. We provide some general results for conformal invariant theories and then move to a semi-infinite chain of free fermions. We consider both an interval starting from the boundary and away from it. We derive exact formulas for the charged and symmetry resolved entropies based on theorems and conjectures about the spectra of Toeplitz+Hankel matrices. En route to characterise the interval away from the boundary, we prove a general relation between the eigenvalues of Toeplitz+Hankel matrices and block Toeplitz ones. An important aspect is that the saddle-point approximation from charged to symmetry resolved entropies introduces algebraic corrections to the scaling that are much more severe than in systems without boundaries.

Automated summary

The study focuses on the symmetry resolved entanglement entropies in one-dimensional systems with boundaries, providing general results for conformal invariant theories. Exact formulas for charged and symmetry resolved entropies are derived based on spectra of Toeplitz+Hankel matrices. The saddle-point approximation introduces algebraic corrections to the scaling particularly severe in systems with boundaries.