الفهرس 
Cover EnglishOnly 14 pages are availabe for public view
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Abstract
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 “qubits” (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. To obtain high-fidelity entangled state without restricting the detection to narrow spatial-spectral windows, the relative-phase map needs to be carefully flattened over the position-frequency space. We introduce a method to optimally achieve tunable spatial-spectral relative-phase compensation using birefringent elements. The results of our model are verified of excellent match with measurements of some recent experiments. On the other hand, the photon pairs originated in the first crystal needs to be indistinguishable in any degree of freedom from those originated in the second crystal. Among these degrees of freedom is the time delay which needs to be compensated to a value less than the coherence time of the pump beam. For a compensated two-photon emission, we determine the optimal characterization of the spatial window (iris width) and the spectral window (full width half maximum of the spectral filter) that reduces the relative-phase variations while maintaining a required two-photon flux. We carry out an experiment, in which time- and phase-compensated hyperentangled photons are collected on multimode detectors over ultra-wide emission angles. We use computer-programmable spatial light modulator (SLM) to compensate the emerging photon pairs for spatial phase variations over wide extent. The time-delay compensation is accomplished using birefringent elements. The experimental measurements are then compared with the results of our theoretical and numerical analysis. In part II, we introduce novel entanglement-based applications of optical communications. While the common approach in QI and QC is to establish entirely quantum schemes, we adopt a different paradigm by introducing hybrid quantum-classical schemes. As a first application, we present a hybrid (completely classical) modulation system that features high receiver sensitivity. The performance of the proposed differential phase shift keying-multipulse pulse position modulation (DPSK-MPPM) is evaluated taking into account the effect of the optical amplifier noise and the nonlinearity of long-haul optical fiber channel. Inspired from the DPSK-MPPM, we then present a hybrid quantum-classical coding scheme capable of encoding additional (time-bin) bits into the already dense-coded photons. The classical timebin in this case represents a new high-dimensional space that paves the way to implement hyper-dense encoding of photons beyond the experimental limits found to date. As a second application, we propose a novel dual-channel optical chaos system with the time-delay (TD) feature simultaneously suppressed in all observables, i.e., in both intensity and phase. Using this optical chaos generator, we numerically demonstrate the generation of ultra-fast physically random sequence of bits. The randomness quality of the generated random bits is evaluated by the 15 statistical tests of NIST Special Publication 800-22. We then present an entanglement-based optical chaos system which integrates together the privacy and the eavesdropping-detection of quantum key distribution and the high encryption rate of optical chaos systems.