Type-I entanglement source : Novelty, optimization and applications in optical Communications / Salem Farag Salem Hegazy ; Supervisied Yehia Abdelhamid Badr , Salah Sabry Obayya ,Jala Mahmoud Elazab

Thesis (Ph.D.) - Cairo University - National Institute of Laser Enhanced Sciences - Department of Lasers Applications Engineering

Quantum information (QI) and quantum computation (QC) are arising sciences that establish links between quantum-mechanical description of nature and information and communication technology (ICT). One of the founding principles of QI and QC is the 2qubits3 (quantum bits) which, compared to the two-level classical bits, can take superposition values of 0 and 1. Manipulation of qubits in the space structured by the firm theories of quantum mechanics moves us to a new arena of applications and capabilities of ICT. One of the key quantum-mechanical features that QI and QC exploit is quantum entanglement; a phenomenon that has no counterpart in the classical world. It describes the very special behavior of a multiple-qubit system in coherent superposition state. Initially, each qubit of the entangled set does not have its own value away from the ensemble, until one qubit of the set is measured. This wavefunction collapse gives immediate and instantaneous value for the other qubits of the set, even when the set is space-like separated. Quantum entanglement is of great importance for QI and QC ranging from its fundamental role as a basic (pure) multi-qubit state to several operations and applications such as quantum teleportation, quantum dense coding, and quantum cryptography. Our study comes in two main parts. In part I, we investigate the theory and operation of a bright hyperentangled photons source based on a cascade of two orthogonal type-I crystals. We develop a theoretical model to describe the maps of the relative phase, the time delay, and the coincidence all over the emission cone of entangled photons

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