Controlled Cavity-Free, Single-Photon Emission and Bipartite Entanglement of Near-Field-Excited Quantum Emitters

We report theoretical statistics of 1- and 2-qubit (bipartite) systems, namely, photon antibunching and entanglement, of near-field excited quantum emitters. The sub-diffraction focusing of a plasmonic waveguide is shown to generate enough power over a sufficiently small region (<50 × 50 nm²) to strongly drive quantum emitters. This enables ultrafast (10^-14 s) single-photon emission as well as creates entangled states between two emitters when performing a controlled-NOT operation. A comparative analysis of silicon and near-zero index materials demonstrates advantages and uncovers challenges of embedding quantum emitters for single-photon emission and for bipartite entanglement. The use of a movable plasmonic waveguide, in lieu of stationary nanostructures, allows high-speed rasterization between sets of qubits and enables spatially flexible data storage and quantum information processing. Furthermore, the sub-diffraction focusing of the waveguide is shown to achieve cavity-free dynamic entanglement. This greatly reduces fabrication constraints and increases the speed and scalability of nanophotonic quantum devices.