Nonlinear Atom-Plasmon Interactions Enabled by Nanostructured Graphene

Abstract

Electrically tunable graphene plasmons are anticipated to enable strong light-matter interactions with resonant quantum emitters. However, plasmon resonances in graphene are typically limited to infrared frequencies, below those of optical excitations in robust quantum light sources and many biologically interesting molecules. Here we propose to utilize near fields generated by the plasmonassisted nonlinear optical response of nanostructured graphene to resonantly couple with proximal quantum emitters operating in the near-infrared. We show that the nonlinear near-field produced by a graphene nanodisk can strongly excite and coherently control quantum states in two-and threelevel atomic systems when the third harmonic of its plasmon resonance is tuned to a particular electronic transition. In the present scheme, emitter and plasmon resonances are nondegenerate, circumventing strong enhancement of spontaneous emission. We envision potential applications for the proposed nonlinear plasmonic coupling scheme in sensing and temporal quantum control.

Nonlinear plasmon-exciton coupling enhances sum-frequency generation from a hybrid metal/semiconductor nanostructure

“…We demonstrate how fundamental plasmonic fields couple to higher-energy excitons via SF mixing, enhancing coherent excitonic emission. The much prolonged excitonic fields may provide a valuable tool for coherent control via nonlinear plasmon-emitter coupling 20 . Our results not only allow us to unravel the different microscopic contributions to the nonlinear signal enhancement, but may also prove helpful for the design of a new class of hybrid nanostructures with coupled, phased arrays of plasmonic antennas 15 , and quantum emitters with strong optical nonlinearities.…”

“…We show that the coupling between plasmonic hot spot fields and excitonic quantum emitters, via SF quantum channels, boosts nonlinear excitonic emission from ZnO. The results are valuable for improving and controlling optical nonlinearity via nonlinear plasmon-quantum emitter coupling 20 .…”

Strong Light–Matter Interactions Enabled by Polaritons in Atomically Thin Materials

“…The strong intrinsic field enhancement provided by the long‐lived and electrically tunable plasmons of monolayer graphene (cf. Section ) has naturally launched explorations of its ability to enhance nonlinear optical phenomena, stimulating fertile research efforts in nonlinear graphene plasmonics . Fortuitously, the unique linear electronic dispersion relation of graphene, giving rise to its universal 2.3% broadband light absorption and facile electrical tunability, also endows this 2D material with an intrinsically anharmonic response to external electromagnetic fields: low‐energy charge carriers within a single Dirac cone have energies ε k = ℏ v F | k |, where k is the electron wavevector and v F ≈ c /300 is the Fermi velocity, endowing them with a velocity of fixed magnitude that instantaneously changes sign when crossing the Dirac point; an applied ac electric field E ( t ) = E 0 cos( ωt ) thus leads to a square‐wave surface current density J ( t ) = − env F sign{sin ( ωt )} in the E 0 → ∞ limit that is weighted by the charge carrier density n and contains significant contributions from all odd harmonics in its Fourier decomposition (see Figure a) .…”

Second-Harmonic Generation from a Quantum Emitter Coupled to a Metallic Nanoantenna

“…[33][34][35][36][37][38][39][40][41] Moreover, the capability of the MNP-QE interaction to modify the second-harmonic emis-sion has been demonstrated for plasmonic nanostructures, 42,43 and also the strong nonlinear response of graphene nanostructures has been proposed as a way to excite the electronic transitions in atomic or molecular species. 44 Here we study the SHG resulting from a hybrid system consisting of a QE placed in the vicinity of a spherical MNP, as scketched in Figure 1a. The small individual centrosymmetric nanoparticle does not allow for second-harmonic emission, but the presence of the QE lifts this symmetry constraint.…”