Deterministic Photon Pairs via Coherent Optical Control of a Single Quantum Dot

TL;DR

This paper demonstrates a highly pure, coherently controlled single-photon source from a quantum dot, enabling advanced quantum communication and entanglement experiments with minimal laser scattering interference.

Contribution

It introduces a two-photon resonant excitation method for quantum dots that achieves complete laser suppression and coherent control of photon pairs, advancing quantum photonics technology.

Findings

Complete suppression of excitation laser and multi-photon emissions.

Extended coherence time of the ground-biexciton state qubit.

Successful coherent control and deterministic photon pair creation.

Abstract

The strong confinement of semiconductor excitons in a quantum dot gives rise to atom-like behavior. The full benefit of such a structure is best observed in resonant excitation where the excited state can be deterministically populated and coherently manipulated. Due to large refractive index and device geometry it remains challenging to observe resonantly excited emission that is free from laser scattering in III/V self-assembled quantum dots. Here we exploit the biexciton binding energy to create an extremely clean single photon source via two-photon resonant excitation of an InAs/GaAs quantum dot. We observe complete suppression of the excitation laser and multi-photon emissions. Additionally, we perform full coherent control of the ground-biexciton state qubit and observe an extended coherence time using an all-optical echo technique. The deterministic coherent photon pair creation makes this system suitable for the generation of time-bin entanglement and experiments on the interaction of photons from dissimilar sources.