PhD Thesis Defenses

PhD thesis defense: Photonic Multipartite Communication Complexity, measurements and Bell inequalities

The interdisciplinary field of quantum communication and quantum information processing merges quantum mechanics,
optics, photonics, information processing, and electronics to solve information and communication tasks that are impossible
to solve efficiently with classical resources. Here in this thesis experimental demonstrations of some of such tasks are
presented. In particular, using a single qubit system and quantum Zeno effect we investigated a class of communication
complexity problems (CCP) for multi-parties. As solutions, three different quantum strategies are evaluated by proof of
concept experimental demonstrations. Our results go beyond the classical limits. Furthermore, the same single qubit system
is used to show that preparation contextuality can be shared among multiple observers through a quantum state ensemble
while implementing sequential unsharp measurement. We showed that this is possible for any amount of white noise and
presented experimental demonstration for three parties. In addition, characterization of unsharp measurements based on
quantum random access code and quantifying the degree of incompatibility of sequential measurements in a wide range
of sharpness parameters are also presented.
Finally, I present the experimental generation of multi-photon entanglement to meet the basic requirement of modern
quantum information processing.Using this source we produced a state with high fidelity that can violate a tight Bell
inequality maximally with maximally incompatible local measurements.
Stockholm 2021
ISBN 978-91-7911-418-3
ISBN 978-91-7911-419-0