Entanglement between dependent degrees of freedom: Quasiparticle correlations

TL;DR

This paper investigates quantum entanglement in systems with dependent degrees of freedom, especially in quasiparticle excitations of light-matter systems, revealing nuanced differences from traditional entanglement notions.

Contribution

It introduces a framework for understanding entanglement in dependent degrees of freedom and compares it with independent cases in light-matter quasiparticle systems.

Findings

Certain states are nonentangled in dependent degrees but entangled in independent descriptions.

Quantum correlations differ significantly when considering dependent versus independent degrees of freedom.

Insights into quantum resourcefulness in light-matter systems with dependent degrees of freedom.

Abstract

Common notions of entanglement are based on well-separated subsystems. However, obtaining such independent degrees of freedom is not always possible because of physical constraints. In this work, we explore the notion of entanglement in the context of dependent degrees of freedom. As a physically relevant application, we specifically study quantum correlation features for quasiparticle descriptions. Those are paramount for interacting light-matter systems, utilizing excitations of fermion-boson hybrid modes. By comparing independent and dependent degrees of freedom, we uncover that certain states are nonentangled although they would be entangled when only focusing on the common, independent description, and vice versa. Therefore, insight is provided into the resourcefulness of quantum correlations within the rarely discussed context of dependent degrees of freedom for light-matter links in quantum information applications.