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Laboratory task - Polarization-based quantum key distribution
Poláková, Sylva ; Münster, Petr (referee) ; Klíčník, Ondřej (advisor)
This bachelor thesis focuses on a detailed analysis of quantum key distribution (QKD) with a focus on one-way prepare-and-measure protocols with discrete variable (DV-QKD) and polarization coding. The thesis is divided into a theoretical and practical part. The introductory theoretical part of the thesis provides a comprehensive overview of polarization as a fundamental physical phenomenon that is essential for understanding the operation of QKD protocols. Various aspects of polarization are discussed, including Jones vectors, Stokes parameters, and the Poincaré sphere. The next section covers the basics of quantum mechanics with a focus on qubit and the representation of quantum states. The work then moves on to quantum key distribution itself, where the basic principles of QKD are explained, and the most important protocols are also analysed. In the practical part, a laboratory task is designed to demonstrate the importance of polarization in the context of QKD protocols.
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Quantum key distribution over optical fibre infrastructure
Klíčník, Ondřej ; Horváth, Tomáš (referee) ; Münster, Petr (advisor)
The aim of this bachelor thesis is to create a comprehensive view of the current technology of quantum key distribution (QKD) over optical fiber, in theoretical terms, a completely secure key exchange. The thesis can be divided into theoretical and practical parts. The theoretical part illuminates the reasons for the use of these systems and the fundamentals of quantum mechanics needed to understand the function of individual QKD protocols. Furthermore, the principles of operation of both the protocols and related services such as post-quantum cryptography (PQC) and quantum number generation (QRNG) are described. The last chapter is devoted to the architecture of QKD networks and describes current standards for QKD communications. In the practical part, a detailed analysis of commercially available devices is performed. Subsequently, simulation results of selected QKD protocols are presented and a custom QKD polygon is designed, built and tested.
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Quantum cryptography
Turčanová, Klára ; Dejdar, Petr (referee) ; Münster, Petr (advisor)
The bachelor thesis focuses on quantum cryptography. In the theoretical part, there is an analysis of secure key distribution in the fiber-optic infrastructure. Methods such as quantum key distribution (QKD) or physical layer secret key generation for fiber-optic networks are analyzed, including a description of the security and technical limitations of the methods. The thesis also attempts to interpret some basic principles of the optic infrastructure used in QKD. In addition to the distribution of keys, the thesis also tries to approximate the basic principles of the optic infrastructure used in QKD and, last but not least, post-quantum cryptography (including a comparison with quantum cryptography and current protocols). In the practical part, the effect of the macrobending of the fiber and the reflectivity of the connectors on the operation of the quantum system was demonstrated. It was also demonstrated that temperature and light acting on the QKD optic infrastructure do not have a fundamental effect.
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Quantum key distribution
Klíčník, Ondřej ; Burda, Karel (referee) ; Münster, Petr (advisor)
This thesis is indirectly related to the bachelor thesis Quantum key distribution over optical fiber infrastructure. Unlike the previous paper, the focus will be mainly on the practical application of the QKD (Quantum key distribution) system Clavis3. For this reason, physical phenomena related to practically used QKD protocols are briefly explained in the theoretical part. These are mostly based on phase coding. In particular, special attention is paid to the Coherent one-way protocol (COW) implemented in Clavis3 devices. This protocol is also compared with practical implementations of the BB84 protocol. Furthermore, the principles of other advanced QKD techniques are outlined and the phenomena in the optical fiber that may affect the quantum channel are discussed. A separate chapter is also devoted to standardization and topologies of QKD networks. Last but not least, the thesis addresses the topic of attacks against practical implementations of QKD protocols. In the practical part, measurements aimed at practical deployment of Clavis3 devices in a common communication network are performed. These include the possibility of combining a quantum channel into a single fiber together with classical channels using Wavelength-division multiplexing (WDM) and the analysis of the effect of Raman noise on the maximum communication distance. At the same time, the robustness of the system against polarization changes and fiber manipulation is verified. Finally, the performance of the system using three-state and four-state versions of the COW protocol is compared and the eavesdropping simulation module is tested.
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Quantum Key Distribution Polygon
Klíčník, Ondřej
This article presents basics of quantum key distribution BB84-like protocols. Brieflyexplains principles of their operations and impact of QBER on intrusion detection. Afterwards resultsof QKD simulations are presented as well as own QKD polygon draft (on multiplexed optical fibre).
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Quantum key distribution over optical fibre infrastructure
Klíčník, Ondřej ; Horváth, Tomáš (referee) ; Münster, Petr (advisor)
The aim of this bachelor thesis is to create a comprehensive view of the current technology of quantum key distribution (QKD) over optical fiber, in theoretical terms, a completely secure key exchange. The thesis can be divided into theoretical and practical parts. The theoretical part illuminates the reasons for the use of these systems and the fundamentals of quantum mechanics needed to understand the function of individual QKD protocols. Furthermore, the principles of operation of both the protocols and related services such as post-quantum cryptography (PQC) and quantum number generation (QRNG) are described. The last chapter is devoted to the architecture of QKD networks and describes current standards for QKD communications. In the practical part, a detailed analysis of commercially available devices is performed. Subsequently, simulation results of selected QKD protocols are presented and a custom QKD polygon is designed, built and tested.
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