Dissertation > Mathematical sciences and chemical > Physics > Optics > The light nature of the theory > Quantum optics

Study on Quantum Key Distribution Protocols in Free Space

Author YuanZuo
Tutor ZhaoShengMei
School Nanjing University of Posts and Telecommunications
Course Signal and Information Processing
Keywords Quantum cryptography Quantum key distribution Orbital angular momentum Tangle Phase modulation Atmospheric turbulence
CLC O431.2
Type Master's thesis
Year 2011
Downloads 32
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Quantum cryptography is based on the Heisenberg uncertainty principle in quantum mechanics and quantum no-cloning principle to develop a new type of confidential communication technology in theory has been proven to be absolutely safe , unbreakable . Has broad application prospects in the fields of military, diplomatic , communications , e-commerce due to its absolute security . Recent studies show that : In addition to the spin angular momentum ( spin angular momentum , SAM ) , the beam also has the orbital angular momentum ( orbital angular momentum OAM ) generated by a spiral phase structure and polarization quantum states ( spin angular momentum ) , the the OAM state can contain any number of state . BB84 quantum key distribution protocol (quantum key distribution , QKD) based on the OAM application to QKD process to obtain a multi-dimensional space QKD scheme , and numerical simulation . Simulation results show that the OAM - based QKD protocol greatly improve the efficiency of key generation , and there is no need to adjust the reference system , suitable for free-space communication ; Subsequently, cross partial base concept OAM entanglement concept combined to obtain two suitable free-space communication QKD protocols , are based on the entanglement properties of random phase QKD protocols and the feasibility of OAM state entanglement - based QKD protocol , given their specific experimental realization of the process by numerical simulation and experimental validation protocol ; OAM is space wave function , when the the OAM as quantum information carrier transmission in free space inevitably influenced by atmospheric turbulence Finally the statistical properties of the atmospheric turbulence random channel atmospheric turbulence mathematical model , numerical tool to Labview OAM state analysis of the atmospheric turbulence , the quantum bit error rate performance of the proposed agreement . Papers on the ground point-to-point atmospheric free-space optical link QKD experiment , as well as the satellite - terrestrial quantum communication with some reference .

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