Energy-time entanglement preservation in plasmon-assisted light   transmission
  We report on experimental evidences of the preservation of energy-time entanglement for extraordinary plasmonic light transmission through sub-wavelength metallic hole arrays, and for long range surface plasmon polaritons. Plasmons are shown to coherently exist at two different times separated by much more than the plasmons lifetime. This kind of entanglement involving light and matter is expected to be useful for future processing and storing of quantum information. 
Sylvain Fasel, Nicolas Gisin, Hugo Zbinden, Daniel Erni, Esteban   Moreno, Frank Robin