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Doctorate thesis defense of Amor GUEDDANA

Doctorate thesis defense on Tuesday, December 2nd, 2014, at 14h00, in Sup'Com, Amphi 1

Entitled : Modeling and Optimization of Quantum Logic Gates: Application to Quantum Cryptography and Information Encoding

Presented by : Amor GUEDDANA 



Houria REZIG

Professor, École Nationale d'Ingénieurs de Tunis, Tunisia.






Professor, School of Optometry and Vision Science, University of Waterloo, Canada



Professor, Ecole Polytechnique de Tunisie, Tunisia.



Mourad ZGHAL

Professor, Sup'Com, Tunisia.


Thesis director

Mourad MENIF

Associate Professor, Sup'Com, Tunisia.


This thesis describes several results dealing with optical quantum Controlled NOT gate and its application to the fields of quantum information encoding and quantum cryptography. Three major research areas are studied.

The first area concerns the modeling of generalized behavior of the non-deterministic CNOT gate based on physical realizations. We define an abstract probabilistic model of the CNOT gate and detail realizability assessment based on experimental features. Theoretical results are directly compared with experimental results. Two CNOT models based on linear optical components are proposed for this purpose. Further studies on the origin of the errors related to the experimental aspects of these two models allow us to better understand the quantum behavior of the probabilistic CNOTs. This investigation pared the way for us to optimize the success probability of the CNOT by designing our own model. Our concept is based on different encoding techniques for the target and control qubit.

The second thrust of this thesis on quantum CNOT based circuits permitted the design and querying of Quantum Relational Databases (QRDB). First, we propose a complete set of transformation rules to design any multi-table QRDB and then we illustrate how to perform basic and advanced queries to insert, update, delete and select records from single or joined digitized tables. A Quantum Query Language (QQL) is formulated and we illustrate for a simple QRDB how QQL performs. We highlight the scheme allowing us to traduce the QQL semantics to the corresponding CNOT based implementation and we underline the evolution of the probability amplitude of the superposed states contained in the tables.

The third thrust is a fiber-based Quantum Key Distribution Protocol (QKDP) in which a CNOT gate could be used. To this end, we study the QKDP BB84 working at the telecom wavelength 1550nm, taking into consideration an optimized attack strategy. First, we show the advantages of using quantum dots embedded in a micro-cavity in comparison to the heralded single photon sources and attenuated laser. Second, we propose an optimized version of the QKDP BB84 based on Quantum Dense Coding that could be implemented by quantum CNOT gates.