Cooper-pair based photon entanglement without isolated emitters

TL;DR

This paper introduces a new method for generating entangled photons using Cooper-pair luminescence in semiconductors, avoiding the need for isolated emitters like quantum dots, and highlights the role of quantum well structures and temperature in optimizing entanglement.

Contribution

It demonstrates that semiconductor quantum wells enable efficient, pure photon entanglement via Cooper-pair luminescence without isolated emitters, leveraging superconducting coherence.

Findings

Entanglement purity increases with larger light-hole heavy-hole splitting.

Quantum wells remove degeneracy, enabling efficient entanglement.

Lower temperatures improve entanglement quality.

Abstract

We propose a novel approach for efficient generation of entangled photons, based on Cooper-pair luminescence in semiconductors, which does not require isolated emitters such as single atoms or quantum dots. We show that in bulk materials, electron-spin entanglement in Cooper pairs should not be expected to be translated into pure entangled photons despite the selection rules, due to mixing introduced by light-hole heavy-hole degeneracy. Semiconductor quantum wells, however, remove this degeneracy, allowing efficient photon entanglement generation in simple electrically-driven structures, taking advantage of the superconducting macroscopic coherence. The second-order decay of two-electron states in Cooper-pair luminescence leaves no which-path information, resulting in perfect coherence between two pathways and hence in principle, perfect entanglement. We calculate the purity of the entangled-photon state and find that it increases for larger light-hole heavy-hole energy splitting and for lower temperatures. These results provide new insights into light-matter interaction in solids and enable realization of novel quantum photonics based on matter condensates.