量子密钥分配的原理性实验及技术研究

发布时间：2018-09-18 18:34

【摘要】：信息安全关乎人们生活的方方面面。随着金融、军事等重要领域的信息化,它甚至关系到国家的安全。信息安全的基石是现代密码体系。但基于数学计算复杂度的密码受到能力与日俱增的计算机的持续威胁,尤其是被寄予厚望的量子计算机。“一次一密”作为唯一被严格证明是安全的密码,可以在量子时代为信息保驾护航。“一次一密”的密钥分配困难可以由量子密钥分配解决,两者的结合能提供无条件安全的通信。从1984年开始,量子密钥分配历经三十余年的发展,在理论以及实验方面取得了很大的成就,累积了非常多的经验和成熟技术,被认为是第一个可实用化并且实际上已经接近实用化的量子信息技术。本文总结了本人攻读博士学位期间在量子密钥分配实用化以及原理验证性实验方面做的主要工作：1.光纤信道的偏振变化是影响量子密钥分配性能的重要因素,但目前缺乏相应的测量以及统计分析。为此,我们对一个广域的埋地电信光纤网络以及一段架空光缆的偏振变化进行了长时间测量,对测量结果进行了详细的统计分析以及频率分析,可为量子通信的偏振补偿提供重要参考。其中一根埋地光纤跨过了长江。被测架空光缆与超高压直流输电线并行架设,这是首次针对该类特殊环境的偏振测量。2.搭建了基于光纤挤压器的偏振快速恢复以及自动补偿系统。光纤挤压器以其较低的插入损耗而被广泛应用于量子密钥分配系统。但它存在延迟范围有限可调的缺陷,为此提出了一个新颖的约束方案。相比于重置等传统方案,它具备简单,易实现且无需校准的优点。结合该方案以及梯度算法,通过控制光纤挤压器实现了10rad/s量级的连续偏振跟踪,处于同类偏振补偿系统的最好水平。统计得到的偏振恢复时间可为量子密钥分配的中断式偏振补偿提供重要参考。3.首次演示了基于纠缠的能容忍信道损耗和噪声的确定性量子密钥分配实验。该实验也是第一个在电信光纤上传输的基于纠缠的往返式(two-way)量子密钥分配实验。4.研究了相位独立的弱相干态脉冲之间的干涉,该类干涉的可见度关系到测量设备无关量子密钥分配协议的性能。基于量子光学对该类干涉进行了详细的理论分析,并做了实验验证。根据该类干涉对环境的相位噪声不敏感,讨论了基于该干涉的测距方案。
[Abstract]:Information security concerns all aspects of people's lives. With the financial, military and other important areas of information, it even relates to national security. The cornerstone of information security is the modern cryptographic system. However, the cryptography based on the computational complexity of mathematics is constantly threatened by the computer with increasing ability, especially the quantum computer with high expectations. "one at a time" as the only strictly proven secure password, can be used to protect information in the quantum age. The key distribution problem of "one secret at a time" can be solved by quantum key distribution, and the combination of the two can provide unconditional secure communication. Since 1984, quantum key distribution has been developed for more than 30 years. It has made great achievements in theory and experiment, and accumulated a lot of experience and mature technology. It is considered to be the first practical quantum information technology, which is in fact close to practicality. This paper summarizes the main work done by me in the practical and principle verification experiments of quantum key distribution during my doctoral degree. The polarization change of optical fiber channel is an important factor affecting the performance of quantum key distribution, but there is a lack of corresponding measurement and statistical analysis. Therefore, the polarization changes of a wide-area buried telecommunication fiber network and an aerial optical cable are measured for a long time, and the results are analyzed and analyzed in detail. It can provide important reference for polarization compensation of quantum communication. One of the buried fibers crossed the Yangtze River. The measured aerial optical cable is set up in parallel with the UHV DC transmission line. This is the first polarization measurement of this kind of special environment. A fast polarization recovery and automatic compensation system based on fiber extruder is built. Fiber extruder is widely used in quantum key distribution system due to its low insertion loss. However, the delay range is limited and adjustable, so a novel constraint scheme is proposed. Compared with traditional schemes such as reset, it has the advantages of simple, easy to implement and no calibration. Combined with this scheme and gradient algorithm, continuous polarization tracking in 10rad/s order is realized by controlling fiber extruder, which is at the best level of the similar polarization compensation system. The obtained polarization recovery time can provide an important reference for the interrupt polarization compensation of quantum key distribution. A deterministic quantum key distribution experiment based on entanglement, which can tolerate channel loss and noise, is demonstrated for the first time. This experiment is also the first entanglement based round trip (two-way) quantum key distribution experiment. The interference between the phase independent weak coherent state pulses is studied. The visibility of the interference is related to the performance of the measurement device independent quantum key distribution protocol. The theoretical analysis of this kind of interference is carried out based on quantum optics, and the experimental results are verified. According to the fact that the interference is insensitive to the phase noise of the environment, the ranging scheme based on the interference is discussed.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O413;TN918.4

【相似文献】