Finite-size corrections in critical symmetry-resolved entanglement

In the presence of a conserved quantity, symmetry-resolved entanglement entropies are a refinement of the usual notion of entanglement entropy of a subsystem. For critical 1d quantum systems, it was recently shown in various contexts that these quantities generally obey entropy equipartition in the scaling limit, i.e. they become independent of the symmetry sector. In this paper, we examine the finite-size corrections to the entropy equipartition phenomenon, and show that the nature of the symmetry group plays a crucial role. In the case of a discrete symmetry group, the corrections decay algebraically with system size, with exponents related to the operators' scaling dimensions. In contrast, in the case of a U(1) symmetry group, the corrections only decay logarithmically with system size, with model-dependent prefactors. We show that the determination of these prefactors boils down to the computation of twisted overlaps.

Automated summary

Symmetry-resolved entanglement entropies are a refinement of the usual notion of entanglement entropy of a subsystem in the presence of a conserved quantity. It was shown that for critical 1d quantum systems, these quantities generally obey entropy equipartition in the scaling limit, independent of the symmetry sector. Finite-size corrections to this phenomenon were examined, with the nature of the symmetry group playing a crucial role in the decay rate of the corrections.