# Fractionalized Excitations Revealed by Entanglement Entropy

## TL;DR

This paper introduces a method to detect and characterize fractionalized excitations in quantum spin liquids using real-space entanglement entropy, providing a new way to explore exotic quantum phases.

## Contribution

The authors develop a general procedure to reveal fractionalized excitations and construct spinon Fermi surfaces from entanglement entropy in critical spin liquids.

## Key findings

- Entanglement entropy can identify fractionalized excitations.
- Method applies to critical spin liquids relevant to experiments.
- Constructs spinon Fermi surfaces from entanglement data.

## Abstract

Fractionalized excitations develop in many unusual many-body states such as quantum spin liquids, disordered phases that cannot be described using any local order parameter. Because these exotic excitations correspond to emergent degrees of freedom, how to probe them and establish their existence is a long-standing challenge. We present a general procedure to reveal the fractionalized excitations using real-space entanglement entropy in critical spin liquids that are particularly relevant to experiments. Moreover, we show how to use the entanglement entropy to construct the corresponding spinon Fermi surface. Our work defines a new pathway to establish and characterize exotic excitations in novel quantum phases of matter.