Abstract

Plasmons, in the form of Surface Plasmon Polaritons (SPPs) have been shown to preserve photon entanglement in an experiment in which the photons in one path are converted to plasmons and back to photons in the middle of an energy-time entangled Franson-type Bell Test [Fasel, et.al., Phys. Rev. Lett. 94 , 110501 (2005)].  Plasmons have also been shown to exhibit quantum interference in a Hong-Ou-Mandel test using a photonic directional coupler [Fakonas, et.al., Nat. Photonics 8 , 317 (2014)].  Our plan is to extend this work into an entirely plasmonic version of a Bell Test by forming plasmonic Mach-Zehnder interferometer on chip with two directional couplers and fixed length transmission lines.  The experiments planned will determine whether the collective excitation plasmon can be described as a single quantum mechanical particle in terms of entanglement.  Is entanglement a property of the plasmons themselves or are plasmons only capable of preserving entanglement already present in the incoming photons?