On-demand source of dual-rail photon pairs based on chiral interaction in a nanophotonic waveguide

TL;DR

This paper presents an on-demand, deterministic source of dual-rail photon pairs using a quantum dot in a nanophotonic waveguide, enabling scalable quantum photonic applications with high entanglement control.

Contribution

It introduces and experimentally demonstrates a novel dual-rail photon pair source leveraging chiral light-matter interaction in nanophotonics, compatible with integrated quantum photonic circuits.

Findings

Deterministic generation of dual-rail Bell pairs achieved

Chirality controls the amount of entanglement

Source can be extended to multi-photon entanglement

Abstract

Entanglement is the fuel of advanced quantum technology. It is for instance consumed in measurement-based quantum computing and allows loss-tolerant encoding of quantum information. In photonics, entanglement has traditionally been generated probabilistically, requiring massive multiplexing for scaling up to many photons. An alternative approach utilizes quantum emitters in nanophotonic devices for deterministic generation of single photons, which an be extended to two- and multi-photon generation on demand. The proposed polarization-entanglement sources are, however, incompatible with spatial dual-rail qubit encoding, which is preferred in photonic quantum computing realized in scalable integrated photonic circuits. Here we propose and experimentally realize an on-demand source of dual-rail photon pairs using a quantum dot in a planar nanophotonic waveguide. The source exploits the cascaded decay of a biexciton state and chiral light-matter coupling to achieve deterministic generation of spatial dual-rail Bell pairs with the amount of entanglement determined by the chirality. The operational principle can readily be extended to multi-photon entanglement generation, and such sources may be interfaced with advanced photonic-integrated circuits, e.g., for efficient preparation of entanglement resource states for photonic quantum computing.