Nonlinear atom-plasmon interactions enabled by nanostructured graphene

The extreme spatial light confinement associated with electrically-tunable plasmons in doped graphene is anticipated to yield strong light-matter coupling with resonant quantum emitters. However, plasmon resonance frequencies... [ view full abstract ]

The extreme spatial light confinement associated with electrically-tunable plasmons in doped graphene is anticipated to yield strong light-matter coupling with resonant quantum emitters. However, plasmon resonance frequencies in graphene typically lie in the infrared and terahertz regimes, away from optically-active electronic transitions in many robust quantum light sources and biologically-interesting molecules. Here we propose to utilize the near-field generated by the plasmon-enhanced nonlinear optical response of nanostructured graphene to resonantly couple the 2D layer with proximal quantum emitters operating in the near-infrared. As a proof-of-concept, we predict that the nonlinear plasmonic third-harmonic near-field produced by a moderately-doped graphene nanodisk can strongly excite a two-level emitter and drive electromagnetically-induced transparency or coherent population control in three-level atoms, and that these processes can be actively controlled when the third-harmonic of a graphene plasmon resonance is tuned to the relevant atomic transition. In the present scheme, emitter and plasmon resonances are non-degenerated, circumventing strong plasmonic enhancement of spontaneous decay in the emitter. We envision potential applications for the proposed nonlinear plasmonic coupling scheme in nonlinear sensing and in actively-controllable elements for quantum information networks.