Plasmonic interferences of two-particle N00N states

TL;DR

This paper reports the first observation of two-plasmon N00N state interferences on a plasmonic beamsplitter, analyzing loss effects and demonstrating faster decay of N00N states compared to classical states.

Contribution

It presents the first experimental observation of two-plasmon N00N state interference and provides a detailed analysis of loss effects in plasmonic quantum states.

Findings

N00N states decay N times faster than classical states due to propagation losses.

Intrinsic losses cause quantum nonlinear absorption at the beamsplitter.

First demonstration of two-plasmon N00N state interference in plasmonics.

Abstract

Quantum plasmonics lies at the intersection between nanophotonics and quantum optics. Genuine quantum effects can be observed with non-classical states such as Fock states and with entangled states. A N00N state combines both aspects: it is a quantum superposition state of a Fock state with N excitations in two spatial modes. Here we report the first observation of two-plasmon (N=2) N00N state interferences using a plasmonic beamsplitter etched on a planar interface between gold and air. We analyze in detail the role of losses at the beamsplitter and during the propagation along the metal/air interface. While the intrinsic losses of the beamsplitter are responsible for the emergence of quantum nonlinear absorption, we note that N00N states decay N times faster than classical states due to propagation losses.