a compact surface plasmonics polariton quantum entanglement device

Large-scale quantum integrated circuit requires its basic component at nanoscale beyond the diffraction limit. to obtain nanodimensional quantum operation, we introduce two surface plasmonic polariton (spp) mode interference couplers as a fundamental component. the handel-ou-mandel (hom) interference of the coupler of 50:50 splitting ratio provides high-fidelity quantum entanglement. it also enhances the visibility in quantum regime in comparison to that in classical regime. the degradation of fidelity due to small deviation of waveguide width is lower than that of a spp mode directional coupler. our results promise to achieve the complexity of quantum plasmonic circuit with high fabrication tolerances.