Time-bin entangled photons from a quantum dot

TL;DR

This paper demonstrates a robust source of time-bin entangled photon pairs using a quantum dot, advancing long-distance quantum communication by providing a more reliable and phase-stable entangled photon source.

Contribution

It introduces a novel quantum dot-based source of time-bin entangled photons with high fidelity and stability, improving upon previous parametric down-conversion methods.

Findings

Achieved a fidelity of 0.69 in entanglement verification.

Measured a concurrence of 0.41 indicating significant entanglement.

Utilized phase-stable interferometry for long-term measurements.

Abstract

Long distance quantum communication is one of the prime goals in the field of quantum information science. With information encoded in the quantum state of photons, existing telecommunication fiber networks can be effectively used as a transport medium. To achieve this goal, a source of robust entangled single photon pairs is required. While time-bin entanglement offers the required robustness, currently used parametric down-conversion sources have limited performance due to multi-pair contributions. We report the realization of a source of single time-bin entangled photon pairs utilizing the biexciton-exciton cascade in a III/V self-assembled quantum dot. We analyzed the generated photon pairs by an inherently phase-stable interferometry technique, facilitating uninterrupted long integration times. We confirmed the entanglement by performing a quantum state tomography of the emitted photons, which yielded a fidelity of 0.69(3) and a concurrence of 0.41(6).