Hybrid entanglement for quantum communication
Date
2017
Authors
Nape, Isaac Mphele
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Abstract
The generation and detection of entangled photons is a topic of interest in quantum
communication. With current state-of-the-art methods it is possible to manipulate
any degree of freedom (DoF) of photons, e.g, polarisation, transverse momentum,
orbital angular momentum and energy. Furthermore, it is possible to combine these
DoF to realise hybrid entanglement { entanglement between the DoF of photons. In
this dissertation we focus on hybrid entanglement between photon states of coupled
orbital angular momentum and polarisation.
We engineer hybrid-entanglement using geometric phase control between spatially
separated photons produced from spontaneous parametric down conversion.
We present a new type of quantum eraser that does not rely on physical path interference.
We show that in principle any other degree of freedom can be used and
demonstrate this e ectively through polarisation control.
The use of high dimensional hybrid photon states in quantum communication,
particularly in quantum cryptography, is still in its infancy. Here we tailor photon
states that are coupled in their polarisation and spatial DoF (orbital angular momentum)
to realise high dimensional encoding alphabets. We show how photons entangled
in their internal DoF can be generated and deterministically detected. We exploit
them in a demonstration of a high dimensional quantum key distribution protocol
and show that our scheme generates secure keys at high rates.
Description
A dissertation submitted to the Faculty of Science
in partial fulfillment of the requirements for the Degree of
Master of Science
School of Physics
University of Witwatersrand
November 1, 2017
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Citation
Nape, Isaac Mphele (2017) Hybrid entanglement for quantum communication, University of the Witwatersrand, Johannesburg, <http://hdl.handle.net/10539/24025>