Active reset of a radiative cascade for superequilibrium entangled photon generation

TL;DR

This paper introduces an active reset technique for quantum dot cascades that significantly enhances the rate and fidelity of entangled photon pair generation, surpassing previous equilibrium methods.

Contribution

It presents a novel active reset regime for radiative cascades in quantum dots, enabling higher fidelity and intensity of entangled photon pairs.

Findings

Achieved record entangled photon pair fidelity of 79.5%.

Generated entangled photons at a record rate of 1.15 GHz.

Demonstrated theoretical and experimental improvements over equilibrium methods.

Abstract

The generation rate of entangled photons emitted from cascaded few-level systems is intrinsically limited by the lifetime of the radiative transitions. Here, we overcome this limit for entangled photon pairs from quantum dots via a novel driving regime based on an active reset of the radiative cascade. We show theoretically and experimentally the driving regime to enable the generation of entangled photon pairs with higher fidelity and intensity compared to the optimum continuously driven equilibrium state. Finally, we electrically generate entangled photon pairs with a total fidelity of $(79.5 \pm 1.1)\%$ at a record clock rate of 1.15GHz.