Spatio-temporal second-order quantum correlations of surface plasmon polaritons.

We present an experimental methodology to observe spatio-temporal second-order quantum coherence of surface plasmon polaritons which are emitted by nitrogen vacancy color centers attached at the apex of an optical tip. The approach relies on leakage radiation microscopy in the Fourier space, and we use this approach to test wave-particle duality for surface plasmon polaritons.