A source of entangled photons based on a cavity-enhanced and strain-tuned GaAs quantum dot

TL;DR

This paper presents a novel hybrid device combining a cavity-enhanced quantum dot and strain tuning to produce highly entangled, bright photon sources suitable for quantum communication, overcoming previous technological limitations.

Contribution

It introduces a new integrated device that simultaneously enhances brightness and entanglement fidelity of quantum dot photon sources using a circular Bragg resonator and piezoelectric strain tuning.

Findings

Achieved extraction efficiencies up to 0.69(4).

Generated entangled photons with fidelity up to 0.96(1).

Potential for scalable quantum communication applications.

Abstract

A quantum-light source that delivers photons with a high brightness and a high degree of entanglement is fundamental for the development of efficient entanglement-based quantum-key distribution systems. Among all possible candidates, epitaxial quantum dots are currently emerging as one of the brightest sources of highly entangled photons. However, the optimization of both brightness and entanglement currently requires different technologies that are difficult to combine in a scalable manner. In this work, we overcome this challenge by developing a novel device consisting of a quantum dot embedded in a circular Bragg resonator, in turn, integrated onto a micromachined piezoelectric actuator. The resonator engineers the light-matter interaction to empower extraction efficiencies up to 0.69(4). Simultaneously, the actuator manipulates strain fields that tune the quantum dot for the generation of entangled photons with corrected fidelities to a maximally entangled state up to 0.96(1). This hybrid technology has the potential to overcome the limitations of the key rates that plague QD-based entangled sources for entanglement-based quantum key distribution and entanglement-based quantum networks.