Experimental demonstration of bosonic quantum interference of single surface plasmon polaritons

We have demonstrated the Hong-Ou-Mandel (HOM) type interference experiment with single surface plasmon polaritons (SSPPs) excited via single-photons. When two SSPPs were simultaneously incident at each input port of a 50/50 directional coupler, photons emerged together in one output or the other, which is the evidence that the quantum interference of SSPPs is bosonic.