High-Visibility On-Chip Quantum Interference of Single Surface Plasmons

In this work, the on-chip quantum interference of two single surface plasmons is achieved using dielectric-loaded surface-plasmon-polariton waveguides. The high visibility (greater than 90%) proves the bosonic nature of single plasmons and emphasizes the feasibility of achieving basic quantum logic gates for linear optical quantum computation. The effect of intrinsic losses in plasmonic waveguides with regard to quantum-information processing is also discussed. Although the influence of this effect is negligible in the current experiment, our studies reveal that such losses can dramatically reduce quantum-interference visibility in certain cases; thus, quantum coherence must be carefully considered when designing quantum photonic integrated circuit devices.