Quantum-entangled light from localized emitters

TL;DR

This paper explores how localized quantum emitters produce light that exhibits both nonclassicality and entanglement, providing a link between these quantum properties and offering methods to detect multipartite entanglement.

Contribution

It establishes a direct relation between nonclassicality and entanglement in localized emission sources and introduces entanglement witnesses based on observed nonclassical effects.

Findings

Nonclassicality in one direction implies entanglement across directions.

The approach extends to multipartite entanglement and multi-time correlations.

Examples include fluorescence from two-level atoms and semiconductor quantum wells.

Abstract

Localized radiation sources are analyzed with respect to the relation of nonclassicality and quantum entanglement of the emitted light. The source field parts of the radiation emitted in different directions are closely related to each other. As a consequence, nonclassicality of the light fields in one direction directly implies entanglement of the field modes in different directions. This implication can be extended to multipartite-entanglement and multi-time quantum correlations. Given that a nonclassical effect is observed, our approach explicitly yields the multipartite entanglement witnesses. Two examples are considered, the fluorescence radiation of a system of two-level atoms and of excitons in a semiconductor quantum well.