Plasmon

Optics

Quantum entanglement

Physics

Quantum dot

Coupling (piping)

Excited state

Atomic physics

Metallurgy

Materials science

Optoelectronics

Quantum mechanics

Quantum optics

Quantum

ACS Photonics

Establishing strong coupling between spatially separated and thus selectively addressable quantum emitters is a key ingredient to complex quantum optical schemes in future technologies. Insofar as many plasmonic nanostructures are concerned, however, the energy transfer and mutual interaction strength between distant quantum emitters can fail to provide strong coupling. Here, based on mode hybridization, the longevity and waveguide character of an elliptical plasmon cavity are combined with intense and highly localized field modes of suitably designed nanoantennas. Based on FDTD simulations a quantum emitter–plasmon coupling strength ℏg = 16.7 meV is reached while simultaneously keeping a small plasmon resonance line width ℏγs = 33 meV. This facilitates strong coupling, and quantum dynamical simulations reveal an oscillatory exchange of excited state population and a notable degree of entanglement between the quantum emitters spatially separated by 1.8 μm, i.e., about twice the operating wavelength.

Strong Coupling and Entanglement of Quantum Emitters Embedded in a Nanoantenna-Enhanced Plasmonic Cavity