The aim of the treatise was the implementation of QKD (Quantum Key Distribution), i.e., of the protocol of quantum cryptography unconditionally secure scheme, employing, in a quantum channel, the nonentangled and entangled photons. These implementations have been demonstrated on two systems, on the first one, on nonentangled photons, Clavis II (the product of Swiss spinoff University in Geneva, idQuantique) and on the second one, on entangled photons, EPR S405 Quelle (of Austrian Institute of Technology, spin-off University in Vienna). Both the hardware and software of these systems have been recognized, in details analyzed and effectively installed. The appropriate descriptions were included to the treatise, which would serve as the manual for related QKD demonstrations. The analysis of possibility of practical usage of both systems in commercial telecom network has been done. Simultaneously the comparison of both systems has been done, including the recognition of technical advantages and the level of resistance against hacker attacks and security protection. An assessment of practical usage of both analyzed quantum cryptographic systems in real commercial telecom networks is also presented from point of view of non-ideal technical solutions and dissipative network conditions. The treatise comprises the wide theoretical introductory part addressed to the quantum mechanics background and to the quantum information processing preliminaries. The similar description of cryptography and QKD protocols is also developed. The detailed description of QCD protocols is presented, including the standard quantum protocols, BB84 and E91 and some new modifications applied in the analyzed systems. The practical implementation of the quantum cryptographic schemes on Clavis II and EPR S405 Quelle is presented and described in details including the technical description of the systems and the relevant software. The manuals for both implementations are prepared, which would serve for quantum cryptography laboratory (upon National Laboratory of Quantum Technology at Wroclaw University of Technology), in particular, for students of Computer Science Faculty.