  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 self-stabilizing double-pass interferometer, we measure a
spin-photon Bell state with $(67.8\pm0.4)\%$ fidelity and devise steps for
significant further improvements. By employing strict resonant excitation, we
demonstrate a photon indistinguishability of $(95.7\pm0.8)\%$, which is
conducive to fusion of multiple cluster states for scaling up the technology
and producing more general graph states.

Quantum Physics