Scalable Sources of Entangled Photons with Wavelength on Demand

TL;DR

This paper presents a scalable method to produce entangled photons with controllable wavelength using quantum dots, enabling improved quantum communication and hybrid network applications.

Contribution

The authors introduce a dynamic strain-engineering technique to control photon energy from quantum dots without losing entanglement quality.

Findings

Controlled photon energy via strain-engineering demonstrated

Entanglement preserved during wavelength tuning

Successful interfacing with atomic vapours for slow entangled photons

Abstract

The prospect of using the quantum nature of light for secure communication keeps spurring the search and investigation of suitable sources of entangled-photons. Semiconductor quantum dots are arguably the most attractive. They can generate indistinguishable entangled-photons deterministically, and are compatible with current photonic-integration technologies, a set of properties not shared by any other entanglement resource. However, as no two quantum dots are identical, they emit entangled-photons with random energies. This hinders their exploitation in communication protocols requiring entangled-states with well-defined energies. Here, we introduce scalable quantum-dot-based sources of polarization-entangled-photons whose energy can be controlled via dynamic strain-engineering without degrading the degree of entanglement of the source. As a test-bench, we interface quantum dots with clouds of atomic vapours, and we demonstrate slow-entangled-photons from a single quantum emitter. These results pave the way towards the implementation of hybrid quantum networks where entanglement is distributed among distant parties using scalable optoelectronic devices.