Electric-field control of photon indistinguishability in cascaded decays in quantum dots

TL;DR

This paper demonstrates that applying an electric field to quantum dots can significantly enhance photon indistinguishability in cascaded emissions, improving quantum photonic applications.

Contribution

It introduces a method to tune the lifetime ratio in quantum dot cascades using electric fields, thereby increasing photon indistinguishability.

Findings

Indistinguishability increases with electric field strength.

Emission linewidth remains near the transform limit.

Electric field tuning aligns with theoretical predictions.

Abstract

Photon indistinguishability, entanglement, and antibunching are key ingredients in quantum optics and photonics. Decay cascades in quantum emitters offer a simple method to create entangled photon-pairs with negligible multi-pair generation probability. However, the degree of indistinguishability of the photons emitted in a cascade is intrinsically limited by the lifetime ratio of the involved transitions. Here we show that, for the biexciton-exciton cascade in a quantum dot, this ratio can be widely tuned by an applied electric field. Hong-Ou-Mandel interference measurements of two subsequently emitted biexciton photons show that their indistinguishability increases with increasing field, following the theoretically predicted behavior. At the same time, the emission linewidth stays close to the transform-limit, favoring applications relying on the interference among photons emitted by different sources.