A Source of Indistinguishable Time-Bin Entangled Photons from a Waveguide-Embedded Quantum Dot

Abstract

Deterministic sources of multi-photon entanglement are highly attractive for quantum information processing but are challenging to realize experimentally. In this paper, we demonstrate a route towards a scaleable source of time-bin encoded Greenberger-Horne-Zeilinger and linear cluster states from a solid-state quantum dot embedded in a nanophotonic crystal waveguide. By utilizing a selfstabilizing double-pass interferometer, we measure a spin-photon Bell state with (67.8±0.4)% fidelity and devise steps for significant further improvements. By employing strict resonant excitation, we demonstrate a photon indistinguishability of (95.7 ± 0.8)%, which is conducive to fusion of multiple cluster states for scaling up the technology and producing more general graph states.