The control, manipulation and detection of surface plasmons and cold atoms.
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Date
2017
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Abstract
Cold atoms and surface plasmons are now widely recognised as having a vast potential
as sources for future quantum information technologies, including in quantum simulations,
quantum computing and quantum-enhanced metrology. In the first part of
this Thesis an experimental investigation of the decoherence of single surface plasmon
polaritons in plasmonic waveguides is carried out. In the study, a Mach-Zehnder configuration
previously considered for measuring decoherence in atomic, electronic and
photonic systems, is used. By placing waveguides of di erent lengths in one arm measurements
of the amplitude damping time, pure phase damping time and total phase
damping time were achieved. Decoherence was found to be mainly due to amplitude
damping and thus losses arising from inelastic electron and photon scattering play
the most important role in the decoherence of plasmonic waveguides in the quantum
regime. However, pure phase damping is not completely negligible. In the second
part of the Thesis the properties of light in the fundamental mode of a subwavelengthdiameter
plasmonic nanowire are also investigated. One of the applications of the light
is the trapping of atoms by the optical force of the evanescent field and the subsequent
guiding of the emitted light from the atoms. The quantum correlation functions of
the emitted light from di erent numbers of atoms into the wave guided mode of the
nanowire are investigated analytically. It is found that the nanowire provides an efficient
method of generating quantum states of light - it gives a faster time scale for
the dynamics and improved coupling e ciency compared to an equivalent dielectric
nanofiber. The results of this Thesis will be useful for the design of plasmonic waveguide
systems for carrying out phase-sensitive quantum applications, such as quantum
sensing, and for the generation of novel quantum states of light for quantum computing
and quantum communication. The probing techniques developed for the plasmonic
waveguides may also be applied to other types of plasmonic nanostructures, such as
those used as nanoantennas, as unit cells in metamaterials and as nanotraps for cold
atoms.
Description
Doctoral Degree. School of Chemistry and Physics, University of KwaZulu-Natal, Durban, 2017.