Two-photon interference from remote deterministic quantum dot microlenses

TL;DR

This paper demonstrates two-photon interference between remote quantum dot microlenses, highlighting their potential for quantum communication and entanglement swapping due to efficient photon extraction and tunability.

Contribution

It introduces a fabrication method for remote quantum dot sources with microlenses enabling two-photon interference, advancing quantum photonic integration.

Findings

Achieved TPI visibilities of 49% and 22% for individual sources.

Observed 29% mutual TPI visibility between remote sources.

Demonstrated broad spectral range photon extraction (>20 nm).

Abstract

We report on two-photon interference (TPI) experiments using remote deterministic single-photon sources. Employing 3D in-situ electron-beam lithography, we fabricate quantum-light sources at specific target wavelengths by integrating pre-selected semiconductor quantum dots within monolithic microlenses. The individual single-photon sources show TPI visibilities of 49% and 22%, respectively, under pulsed p-shell excitation at 80 MHz. For the mutual TPI of the remote sources, we observe an uncorrected visibility of 29%, in quantitative agreement with the pure dephasing of the individual sources. Due to its efficient photon extraction within a broad spectral range (> 20 nm), our microlens-based approach is predestinated for future entanglement swapping experiments utilizing entangled photon pairs emitted by distant biexciton-exciton radiative cascades.