Coherent Interaction of Light with a Metallic Structure Coupled to a Single Quantum Emitter: From Superabsorption to Cloaking

We provide a general theoretical platform based on quantized radiation in absorptive and inhomogeneous media for investigating the coherent interaction of light with material structures in the immediate vicinity of quantum emitters. In the case of a very small metallic cluster, we demonstrate extreme regimes where a single emitter can either counteract or enhance particle absorption by 3 orders of magnitude. For larger structures, we show that an emitter can eliminate both scattering and absorption and cloak a plasmonic antenna. We provide physical interpretations of our results and discuss their applications in active metamaterials and quantum plasmonics.

Figure 1

(a) Poynting flux lines flow from left to right for a TLS in a homogenous medium. (b) Absorption and scattering cross sections of a composite system on a logarithmic scale. Dashed lines refer to the case of an isolated nanoparticle. The inset shows the arrangement of a gold nanosphere (diameter 5 nm) at a distance of 18 nm from an emitter oriented radially. (c), (d) Same as (a) but for the composite system at ${\omega }_A$ (zero detuning) and at ${\omega }_d$.

Figure 2

(a) Schematics of the arrangement. The length, base diameter, and separation of the gold nanocones are 100, 100, and 10 nm, respectively. The TLS lies in the mid gap with its dipole moment along the symmetry axis. (b) Spectra of the absorption and scattering cross sections of the composite. (c) The $z$-component electric field distribution of a FRPB propagating along $z$ in the presence of the TLS and antenna. (d) Same as (c) but without the TLS or antenna. (e) Same as (c) but without a TLS. (f) Frequency dependence of the magnitudes of the induced dipole moments ${\mathbf{d}}_E$, ${\mathbf{d}}_L$, their sum (${\mathbf{d}}_m$) and their phase difference. Notation: dipole induced in TLS in homogenous medium (${\mathbf{d}}_0$), in the particle by the laser (${\mathbf{d}}_L$), in the particle by the TLS (${\mathbf{d}}_E$), in the particle in total (${\mathbf{d}}_m$).

Figure 3

(a) Enhancement of the spontaneous emission rate as a function of the emitter transition wavelength. The TLS was placed in the 20 nm gap between two gold prolate spheroids with long and short axes of 200 nm and 100 nm, respectively. Inset plots the field distribution of a dipole radiating at octupolar resonance 642 nm. (b) Spectra of the absorption and scattering cross sections of a TLS coupled to the antenna.