Highly-reduced Fine-structure splitting in InAs/InP quantum dots offering efficient on-demand 1.55 $\mu$m entangled photon emitter

TL;DR

This paper predicts that InAs/InP quantum dots have significantly reduced fine structure splitting and emit at 1.55 μm, making them highly suitable for efficient on-demand entangled photon sources in quantum communication.

Contribution

The study provides theoretical evidence that InAs/InP quantum dots have much smaller FSS and match telecom wavelengths, advancing quantum dot-based entangled photon emitters.

Findings

InAs/InP QDs have an order of magnitude smaller FSS than InAs/GaAs QDs.

InAs/InP QDs emit at 1.55 μm, suitable for fiber optic communication.

Theoretical modeling explains the reduced FSS in InAs/InP QDs.

Abstract

To generate entangled photon pairs via quantum dots (QDs), the exciton fine structure splitting (FSS) must be comparable to the exciton homogeneous line width. Yet in the (In,Ga)As/GaAs QD, the intrinsic FSS is about a few tens $\mu$eV. To achieve photon entanglement, it is necessary to Cherry-pick a sample with extremely small FSS from a large number of samples, or to apply strong in-plane magnetic field. Using theoretical modeling of the fundamental causes of FSS in QDs, we predict that the intrinsic FSS of InAs/InP QDs is an order of magnitude smaller than that of InAs/GaAs dots, and better yet, their excitonic gap matches the 1.55 $\mu$m fiber optic wavelength, therefore offer efficient on-demand entangled photon emitters for long distance quantum communication.