dc.description.abstract |
The study of light-matter interactions is the most exciting and powerful technique
for expanding our understanding of atomic and light physics. The past many years
have further motivated this as applications for coherent control of matter were envisioned.
These include applications as single-photon sources, efficient photon collection,
single-photon transistor, and optical coupling of quantum bits over long
distances for quantum communications. However, generating and controlling strong
coherence can be difficult between otherwise weakly interacting quantum emitters
(QEs) and light. Moreover, light and single emitters have vast size differences; hence,
their light-matter interaction is weak. Nowadays, a wide range of solutions, including
cavities, photonic bandgap structures, and optical lattices, have been improved
and studied, but none has achieved superiority. However, the use of cavities and
other methods limits the bandwidth and size of the devices.
There has been another proposal to exploit the light-emitter interaction in the
vicinity of plasmonic structures to develop future quantum technology. Plasmonic
modes can be squeezed into regions significantly smaller than the diffraction limit,
providing strong interaction between light and emitters. Surface plasmon Polaritons
(SPPs), which are hybrid modes of light and electronic oscillations that propagate
on the metal-dielectric interface, have been helpful in coupling to QEs such as single
atoms or ions, quantum dots (QDs), color centers in diamonds, and fluorescent
molecules. Earlier studies have already achieved the strong coupling between SPPs
and various emitter types: J-aggregates, dye molecules, and quantum dots. QEs near
metallic structures interact strongly with the SPP modes, modifying the radiation
rates and the radiation profile. In addition, providing enhanced interaction between
the emitters and light, SPPs due to highly confined fields offers new possibilities for the quantum control of light, enabling devices such as efficient single-photon sources,
transistors, and ultra-compact circuitry at the nanoscale. This thesis aims to further
explore the interaction between QEs and SPP modes present on metal-dielectric
interface. We demonstrate that by employing two-level QEs near a metal-dielectric
interface, one can prepare photons emitted from the QEs in path-entangled state.
These photons display coalescence when detected by two detectors. In addition,
the photons exhibits non-classical behaviour. We emphasize that in our model,
long-range coupling between distant QEs is achievable by their common coupling to
the SPPs. Our suggested architecture thereby opens up the possibility of on-chip
quantum communication between several QEs. We propose that these photons can
be further used for long-distance communication using free space or optical fiber.
We also describe that our model can be implemented through already available
technologies. Furthermore, such a system could also be used as an element in a
distributed quantum network.
Next, we present a method for enhancing the transmission of the SPP field using
multiple interacting two-level QEs in a plasmonic environment. This is accomplished
by arranging an array of two-level QEs along a plasmonic waveguide that interacts
through guided SPP and non-waveguide photon modes. Our system depends on the
quantum interference effect; it may be regarded as a plasmonic analog of electromagnetic
induced transparency (EIT), usually associated with driven atomic systems.
The fabrication of our proposed architecture is highly feasible, as several studies
have indicated. Furthermore, similar to the Ising spin chain, our model with many
interacting QEs may be employed for broadband transmission of the SPP field. In
addition to transmission management, our work also paves the way for plasmonic
devices such as slow light devices, and by using suitable waveguides tailored to the
appropriate frequency, one can exploit different transmissions.
Finally, we discuss nonlinear optical interactions that can be significantly enhanced
at the nanoscale level using metallic structures. We describe non-linear
surface plasmon polaritons, known as plasmon solitons confined to an interface between
a nonlinear dielectric and a metal. Then, we express our current work and
future ideas in the field of Non-linear plasmonics. |
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