Deterministic Quantum Key Distribution Using Two Non-orthogonal Entangled States

A deterministic quantum key distribution scheme using two non-orthogonal entangled states is proposed.In the proposed scheme,communicators share key information by exchanging one travelling photon with two random and secret polarization angles.The security of the distributed key is guaranteed by three checking phases in three-way channel and the communicators' secret polarization angles.     

Quantum Key Distribution Based on Coherent States

Ｏｎｅｏｆｔｈｅｍｏｓｔｉｎｔｒｉｇｕｉｎｇａｎｄｅｘｃｉｔｉｎｇｒｅｃｅｎｔｄｅｖｅｌｏｐｍｅｎｔｓｉｎｑｕａｎｔｕｍｍｅｃｈａｎｉｃｓｉｓｔｈｅｐｒｅｄｉｃｔｉｏｎａｎｄｄｅｍｏｎｓｔｒａｔｉｏｎｏｆａｃｒｙｐｔｏｇｒａｐｈｉｃｋｅｙｄｉｓｔｒｉ...     

Deterministic Quantum Key Distribution with Pulsed Homodyne Detection

In this paper, we propose a deterministic quantum communication protocol using weak coherent states and pulsed homodyne detection. In this protocol, the communication parties exchange their secret information deterministicaJly in two rounds. The devices and efficiency of the protocol are discussed respectively. We also show the security of the protocol against intercept-resend and Trojan-Horse eavesdropping attacks.     

Deterministic Quantum Key Distribution Using Gaussian-Modulated Squeezed States

A continuous variable ping-pong scheme, which is utilized to generate deterministic private key, is proposed. The proposed scheme is implemented physically by using Gaussian-modulated squeezed states. The deterministic characteristic, i.e., no basis reconciliation between two parties, leads a nearly two-time efficiency comparing to the standard quantum key distribution schemes. Especially, the separate control mode does not need in the
proposed scheme so that it is simpler and more available than previous ping-pong schemes. The attacker may be detected easily through the fidelity of the transmitted signal, and may not be successful in the beam splitter attack strategy.     

A Review of Security Evaluation of Practical Quantum Key Distribution System

Although the unconditional security of quantum key distribution (QKD) has been widely studied, the imperfections of the practical devices leave potential loopholes for Eve to spy the final key. Thus, how to evaluate the security of QKD with realistic devices is always an interesting and opening question. In this paper, we briefly review the development of quantum hacking and security evaluation technology for a practical decoy state BB84 QKD system. The security requirement and parameters in each module (source, encoder, decoder and detector) are discussed, and the relationship between quantum hacking and security parameter are also shown.     

空间量子密码通信

量子密码术是一门崛起的新兴技术，其传输的安全性基于量子力学的Heisenberg不确定原理。而其中空间量子密码通信以其近期迅猛的发展和广阔的前景备受瞩目。本文从量子密码术的基本原理出发，综合叙述了空间量子密码通信的发展和最新成果。     

Quantum Key Distribution Protocol Optimization

Quantum key distribution is a practically implementable cryptographic communication methodology from the hardware and software point of view. It is an information‐theoretic secure method for transmitting keys to remote partners practicing quantum communication. After examining various protocols from the most basic on, BBM92, DPSK, SARG04 and MDI (Measurement Device Independent) protocols are described in view of targeting the longest possible communication distance with the highest secret key bitrate. How any protocol can be optimized with respect to distance is discussed by analyzing the various steps impacting hardware and software that are developed, starting from the underlying assumptions proper to every protocol and ending with the corresponding performance in each case.     

Tomographic Approach in Three-Orthogonal-Basis Quantum Key Distribution

At present, there is an increasing awareness of some three-orthogonal-basis quantum key distribution protocols, such as, the reference-frame-independent (RFI) protocol and the six-state protocol. For secure key rate estimations of these protocols, there are two methods: one is the conventional approach, and another is the tomographic approach. However, a comparison between these two methods has not been given yet. In this work, with the general model of rotation channel, we estimate the key rate using conventional and tomographic methods respectively. Results show that conventional estimation approach in RFI protocol is equivalent to tomographic approach only in the case of that one of three orthogonal bases is always aligned. In other cases, tomographic approach performs much better than the respective conventional approaches of the RFI protocol and the six-state protocol. Furthermore, based on the experimental data, we illustrate the deep connections between tomography and conventional RFI approach representations.     

1550 nm单模光纤中的量子密钥分配

从实验中实现了红外波段的远程量子密钥分配。系统采用双不等臂M-Z干涉仪相位编码方式，工作波长为1550nm。通过分析量子密钥分配系统传输距离与误码率之间相互关系，给出了理论上理想不等臂M-Z系统与实际系统的最低误码率与传输距离间的关系，以及系统实测传输距离与误码率的关系。实验结果显示，本密钥分配系统已非常接近理想实验系统的性能。     

The Performance of Satellite-Based Links for Measurement-Device-Independent Quantum Key Distribution

Measurement-device-independent quantum key distribution (MDI-QKD) protocol has high practical value. Satellite-based links are useful to build long-distance quantum communication network. The model of satellite-based links for MDI-QKD was proposed but it lacks practicality. This work further analyzes the performance of it. First, MDI-QKD and satellite-based links model are introduced. Then considering the operation of the satellite the performance of their combination is studied under different weather conditions. The results may provide important references for combination of optical-fiber-based links on the ground and satellite-based links in space, which is helpful for large-scale quantum communication network.     

Mediated Semi‐Quantum Key Distribution Without Invoking Quantum Measurement

This paper proposes a new semi‐quantum key distribution protocol, allowing two “classical” participants without sophisticated quantum capability to establish a shared secret key under an untrusted third party (a quantum server). The proposed protocol is free from several well‐known attacks. Furthermore, the efficiency is better than the existing three‐party SQKD protocol in which the classical participants must have the quantum measurement capability.     

Deterministic Secure Quantum Communication on the BB84 System

In this paper, we propose a deterministic secure quantum communication (DSQC) protocol based on the BB84 system. We developed this protocol to include quantum entity authentication in the DSQC procedure. By first performing quantum entity authentication, it was possible to prevent third-party intervention. We demonstrate the security of the proposed protocol against the intercept-and-re-send attack and the entanglement-and-measure attack. Implementation of this protocol was demonstrated for quantum channels of various lengths. Especially, we propose the use of the multiple generation and shuffling method to prevent a loss of message in the experiment.     

基于六光子量子避错码的量子密钥分发方案

量子信道中不可避免存在的噪声将扭曲被传输的信息,对通信造成危害。目前克服量子信道噪声的较好方案是量子避错码（QEAC）。将量子避错码思想用于量子密钥分发,能有效克服信道中的噪声,且无需复杂的系统。用六光子构造了量子避错码,提出了一种丛于六光子避错码的量子密钥分发（QDK）方案。以提高量子密钥分发的量子比特效率和安全性为前提,对六光子避错码的所有可能态进行组合,得到一种六光子避错码的最优组合方法,可将两比特信息编码在一个态中,根据测肇结果和分组信息进行解码,得到正确信息的平均概率为7／16。与最近的基于四光子避错码的克服量子信道噪声的量子密钥分发方案相比,该方案的量子比特效率提高了16．67％,密钥分发安全性足它的3．5倍。     

连续变量量子密钥分发系统同步方案及实现

同步技术是连续变量量子密钥分发系统的核心技术之一,能实现通信双方的实时通信,确保量子信息的有效提取。本文提出了一种新型的同步方案,能有效克服量子信道噪声及误码的影响,实现发送端和接收端的准确同步。文章从理论上介绍了方案的同步机制,并对其性能进行了仿真分析。     

基于随机相位编码的确定性量子密钥分配

提出一种新的随机相位编码的确定性量子密钥分配(QKD)方案.在该方案中，通信双方不需要公布测量基，就可以共享秘密信息，提高了密钥生成效率.因为传输的量子比特是随机编码的，即便光源非严格为单光子，该方案仍旧是安全的.理论分析显示出，对于光子数分裂攻击，中间人攻击和特洛伊木马等攻击手段，本方案比之前的QKD方案具有更强的安全性.     

Advances in Chip-Based Quantum Key Distribution

Quantum key distribution (QKD), guaranteed by the principles of quantum mechanics, is one of the most promising solutions for the future of secure communication. Integrated quantum photonics provides a stable, compact, and robust platform for the implementation of complex photonic circuits amenable to mass manufacture, and also allows for the generation, detection, and processing of quantum states of light at a growing system’s scale, functionality, and complexity. Integrated quantum photonics provides a compelling technology for the integration of QKD systems. In this review, we summarize the advances in integrated QKD systems, including integrated photon sources, detectors, and encoding and decoding components for QKD implements. Complete demonstrations of various QKD schemes based on integrated photonic chips are also discussed.     

湍流大气对量子密钥分布系统性能的影响

自由空间量子密钥分布系统是全球性量子保密通信的关键组成部分之一。因此研究湍流大气信道对量子密钥分布系统性能的影响就非常重要。使用光束近场传播和统计分析的方法定量分析了湍流大气信道对基于BB84协议的自由空间量子密钥分布系统的误码率的影响。数值计算结果表明,大气衰减系数超过-3dB/km时,大气衰减对量子密钥分布系统的误码率影响很大;在大气传输因子小于0.5的区域,系统误码率比无湍流影响时的系统误码率高出一个数量级。     

Unsymmetrical Quantum Key Distribution Using Tripartite Entanglement

An unsymmetrical quantum key distribution protocol is proposed, in which Greenherger-Horne-Zeilinger （GHZ） triplet states are used to obtain the secret key. Except the lost qubits due to the unperfectness of the physical devices, the unsymmetrical characteristic makes all transmitted qubits useful. This leads to：an excellent efficiency, which reaches 100% in an ideal case. The ＇security is studied from the aspect of information theory. By using the correlation of the GHZ tripartite entanglement state, eavesdropping can be easily checked out, which indicates that the presented protocol is more secure.