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Enhanced and Coherent Light-Matter Interactions Based on Epsilon-Near-Zero Plasmonic Waveguides
Photonic coherent emission effects, such as superradiance and subradiance, can be achieved only when the neighboring quantum emitters are placed very close to each other at highly subwavelength distances, which limits their practical applications. In this thesis, several new areas of investigation into coherent light-matter interactions are presented, focusing on collective spontaneous emission, coherent perfection absorption (CPA), and entanglement mediated by narrow plasmonic waveguides with epsilon-near-zero (ENZ) response. We first consider a scheme to realize nonlinear CPA at the nanoscale using the ENZ plasmonic waveguide nanochannels. The strong and uniform field enhancement inside the nanochannels of the waveguides at the ENZ resonance can efficiently boost Kerr nonlinearities, resulting in a new all-optical switching intensity-dependent CPA phenomenon, which can be tunable with ultrafast speed. Then, we consider the Photonic exceptional points (EPs) and spectral singularities inside a nanoscale active plasmonic waveguide system leading to several novel functionalities. The proposed active system exhibits an effective ENZ response combined with reflectionless transmission and perfect loss-compensation. When we further increase the gain coefficient of the dielectric material loaded in the slits, a spectral singularity occurs leading to super scattering (lasing) response at both forward and backward directions. In this thesis, we demonstrate a new plasmonic route to control the collective spontaneous emission when the plasmonic waveguides are loaded with two-level quantum emitters and exhibit an effective ENZ response at their cut-off frequency. The related plasmonic resonant modes are found to efficiently enhance the constructive (superradiance) or destructive (subradiance) interference between different quantum emitters located inside the waveguides. Finally, we thoroughly investigate the efficient inter-emitter entanglement and large enhancement of resonance energy transfer between two optical qubits placed inside the proposed ENZ plasmonic periodic waveguide system. The strong and uniform field enhancement inside the nanochannels of the waveguides at the ENZ resonance can efficiently improve and extend the entanglement, and make it independent of the emitters’ position. The presented results are expected to be useful for the future quantum communication and information plasmonic-based nanodevices.
Li, Ying, "Enhanced and Coherent Light-Matter Interactions Based on Epsilon-Near-Zero Plasmonic Waveguides" (2020). ETD collection for University of Nebraska - Lincoln. AAI28031452.