  Confining light to scales beyond the diffraction limit, quantum plasmonics
supplies an ideal platform to explore strong light-matter couplings. The
light-induced localized surface plasmons (LSPs) on the metal-dielectric
interface acting as a quantum bus have wide potential in quantum information
processing; however, the loss nature of light in the metal hinders their
application. Here we propose a mechanism to make the reversible energy exchange
and the multipartite quantum correlation of a collective of quantum emitters
(QEs) mediated by the LSPs persistent. Via investigating the quantized
interaction between the QEs and the LSPs supported by a spherical metal
nanoparticle, we find that the diverse signatures of the quantized QE-LSP
coupling in the steady state, including the complete decay, population
trapping, and persistent oscillation, are essentially determined by the
different number of bound states formed in the energy spectrum of the QE-LSP
system. Enriching our understanding on the light-matter interactions in a lossy
medium, our result is instructive in the design of quantum devices using
plasmonic nanostructures.
