Fig. 4: Modification of the quantum statistics of a multiphoton system comprising two sources.

The modification of the quantum statistics of a multimode plasmonic system composed of two independent multiphoton sources is shown in panel (a). Here, we plot experimental data together with our theoretical prediction for the degree of second-order coherence. The theoretical model is based on the photon-number distribution predicted by Eq. (2) for two independent multiphoton systems with thermal statistics and same mean photon numbers satisfying \({\bar{n}}_{{{\mbox{s}}}}={\bar{n}}_{{{\mbox{Pl}}}}\). As demonstrated in (b), the photon-number distribution is thermal for the scattered multiphoton system in the absence of near fields (θ = 0^∘). However, an anti-thermalization effect takes place as the strength of the plasmonic near fields is increased (θ = 45^∘), this is indicated by the probability distribution in (c). Remarkably, as reported in (d), the degree of second-order coherence of the hybrid photonic–plasmonic system is 1.5 when plasmonic near fields are strongly confined (θ = 90^∘). These results unveil the possibility of using plasmonic near fields to manipulate coherence and the quantum statistics of multiparticle systems. The error bars represent the standard deviation of ten realizations of the experiment. Each experiment consists of ~100,000 photon-number-resolving measurements.