Quantum Plasmonics: From Quantum Statistics to Quantum Interferences

Abstract

Plasmons are characterized by losses into the metal, here we want to investigate the effect of these losses on their quantum properties. This is a field not yet fully investigated and the work presented here will give us the possibility to understand the effect of losses on the plasmons quantum properties. This will allow us to see how plasmons can be used in the quantum information technology field, since they keep the quantum information regardless of their lossy character. Another key property yet here investigated is the bosonic character of single surface plasmon polaritons (SPPs). The quasi-particle nature of SPPs, consisting of a photon (boson) coupled to a charge density wave of electrons (fermions), makes them an unusual type of quantum excitation. Here, we will show the bosonic character of plasmons, making use of interference experiments. We describe the first direct observation of quantum interference in the Hong-Ou and Mandel quantum interference effect for single SPPs, demonstrating by this way the bosonic nature of plasmons. This study opens opportunities for controlling quantum states of light in ultra-compact nanophotonic plasmonic circuitry.