Universal entanglement spectra in critical spin chains

TL;DR

This paper demonstrates that in critical 1D spin chains, a momentum-space entanglement gap isolates universal spectral features dictated by conformal field theory, distinguishing them from non-universal model-specific parts.

Contribution

It introduces the concept of a universal entanglement spectrum gap in critical spin chains, supported by evidence from multicritical models with specific Wess-Zumino-Witten descriptions.

Findings

Identification of a universal entanglement gap in critical spin chains

Evidence from multicritical models with SU(2)$_2$ and SU(3)$_1$ Wess-Zumino-Witten theories

Separation of universal and non-universal spectral parts

Abstract

We advocate that in critical spin chains, and possibly in a larger class of 1D critical models, a gap in the momentum-space entanglement spectrum separates the universal part of the spectrum, which is determined by the associated conformal field theory, from the non-universal part, which is specific to the model. To this end, we provide affirmative evidence from multicritical spin chains with low energy sectors described by the SU(2)$_2$ or the SU(3)$_1$ Wess-Zumino-Witten model.