Symmetric quantum dots as efficient sources of highly entangled photons

TL;DR

This paper demonstrates a highly symmetric quantum dot source that efficiently produces entangled photon pairs with high fidelity, advancing scalable quantum communication technologies.

Contribution

The authors develop a naturally symmetric GaAs quantum dot cascade that emits highly entangled photon pairs on demand, with high Bell state fidelity without postselection.

Findings

Photon pairs strongly violate Bell's inequality.

Fidelity to Bell state reaches 86% without postselection.

Source is based on strain-free GaAs dots on a (111)A surface.

Abstract

An ideal source of entangled photon pairs combines the perfect symmetry of an atom with the convenient electrical trigger of light sources based on semiconductor quantum dots. We create a naturally symmetric quantum dot cascade that emits highly entangled photon pairs on demand. Our source consists of strain-free GaAs dots self-assembled on a triangular symmetric (111)A surface. The emitted photons strongly violate Bell's inequality and reveal a fidelity to the Bell state as high as 86 (+-2) % without postselection. This result is an important step towards scalable quantum-communication applications with efficient sources.