Plasmonic Superradiance of Two Emitters Near Metal Nanorod
  Quantum emitters, such as q-dots and dye molecules, in the immediate vicinity of plasmonic nanostructures, resonantly excite surface plasmon-polaritons (SPPs) under incoherent pump. The efficiency in the excitation of SPPs increases as the number of the emitters, because the SPP field synchronizes emission of the coupled emitters, in analogy with the superadiance (SR) of coupled emitters in free space. Using fully quantum mechanical model for two emitters coupled to a single gold nanorod, we predict up to 15% increase in the emission yield of single emitter compared to only one emitter coupled to the nanorod due to plasmonic SR. (XW: I use emission yield because the quantum efficiency is one for emitters in free space and there is no room for enhancement). Such emission enhancement is stationary and should be observable even with strong dissipation and dephasing under incoherent pump. Solid-state quantum emitters with blinking behaviors may be utilized to demonstrate such plasmonic SR emission enhancement. Plasmonic SR may find implications in the excitation of non-radiative modes in plasmonic waveguides; and lowing threshold of plasmonic nanolasers. 
Igor Protsenko, Shunping Zhang, Alexander Uskov, Xuewen Chen and   Hongxing Xu
quant-ph