  For almost two decades, it has been believed that the quantum statistical
properties of bosons are preserved in plasmonic systems. This idea has been
stimulated by experimental work reporting the possibility of preserving
nonclassical correlations in light-matter interactions mediated by scattering
among photons and plasmons. Furthermore, it has been assumed that similar
dynamics underlies the conservation of the quantum fluctuations that define the
nature of light sources. Here, we demonstrate that quantum statistics are not
always preserved in plasmonic systems and report the first observation of their
modification. Moreover, we show that multiparticle scattering effects induced
by confined optical near fields can lead to the modification of the excitation
mode of plasmonic systems. These observations are validated through the quantum
theory of optical coherence for single- and multi-mode plasmonic systems. Our
findings constitute a new paradigm in the understanding of the quantum
properties of plasmonic systems and unveil new paths to perform exquisite
control of quantum multiparticle systems.
