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测量设备无关量子密钥分发协议可以免疫所有测量端的漏洞,极大地推进量子保密通信的实用化进程。美中不足的是,该协议依然对源端有极强的安全性假设。源端设备的非完美性同样会留下多种侧信道,从而威胁系统的实际安全性。针对此问题,提出无特征源测量设备无关量子密钥分发协议。该协议在量子态制备不完美的情况下依然可以提取出安全的密钥,是理论无条件安全性与实际安全性的完美结合。通过三强度诱骗态方法以及自行研制的Sagnac-Asymmetric-Mach-Zehnder编码结构,成功搭建无特征源的测量设备无关量子密钥分发系统,并在长为50.4 km的光纤信道和25 MHz的系统重复频率下达到1.91×10-6的安全密钥分发速率。 相似文献
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Temperature characterizations of silica asymmetric Mach-Zehnder interferometer chip for quantum key distribution 下载免费PDF全文
Quantum key distribution (QKD) system based on passive silica planar lightwave circuit (PLC) asymmetric Mach-Zehnder interferometers (AMZI) is characterized with thermal stability, low loss and sufficient integration scalability. However, waveguide stresses, both intrinsic and temperature-induced stresses, have significant impacts on the stable operation of the system. We have designed silica AMZI chips of 400 ps delay, with bend waveguides length equalized for both long and short arms to balance the stresses thereof. The temperature characteristics of the silica PLC AMZI chip are studied. The interference visibility at the single photon level is kept higher than 95% over a wide temperature range of 12 ℃. The delay time change is 0.321 ps within a temperature change of 40 ℃. The spectral shift is 0.0011 nm/0.1 ℃. Temperature-induced delay time and peak wavelength variations do not affect the interference visibility. The experiment results demonstrate the advantage of being tolerant to chip temperature fluctuations. 相似文献
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The estimation of key rate is an important aspect of the quantum key distribution process,especially in the use of dead time.In this paper,we demonstrate a numerical simulation to estimate the average detection probability and the key rate.Using our method,the estimated average detection probability is better than the previous result.Besides,we can easily find the best dead time,especially when considering the impact of after pulse. 相似文献
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Recently,the Hong-Ou-Mandel(HOM) interference between two independent weak coherent pulses(WCPs) has been paid much attention due to the measurement-device-independent(MDI) quantum key distribution(QKD).Using classical wave theory,articles reported before show that the visibility of this kind of HOM-type interference is ≤ 50%.In this work,we analyze this kind of interference using quantum optics,which reveals more details compared to the wave theory.Analyses confirm the maximum visibility of 50%.And we conclude that the maximum visibility of 50%comes from the two single-photon states in WCPs,without considering the noise.In the experiment,we successfully approach the visibility of 50%by using WCPs splitting from the single pico-second laser source and phase scanning.Since this kind of HOM interference is immune to slow phase fluctuations,both the realized and proposed experiment designs can provide stable ways of high-resolution optical distance detection. 相似文献
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以浙江省瑞安市为研究案例,从居民出行特征、交通环境状况等方面对我国发达地区中小城市的交通特征进行了分析,认为其具有出行时间和出行距离短、出行方式依赖私家车、绿色交通弱和交通环境差等特征.城市发展的多元化和交通应对措施的相对落后是形成目前城市交通局面的主要因素.为优化中小城市的交通环境,应提倡慢行交通为主导的城市交通建设,强化慢行交通在城市交通中的地位. 相似文献
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马氏体具有四方的结构,其四方性随含碳量的增加而增大,点阵发生扭曲,当含碳量比较高时,原来α-铁晶体的晶面如(110)、(200)、(211)、(220)等的衍射线条分解成为双重线(101-110、002-200、112-211、202-220)。当含碳量降低时,双重线非常靠近,形成了一条宽的线带,使得马氏体晶格参量的测量十分困难。本文利用每对双重线中的多重性因素的变化特点(如101为8,110为4,002为2,200为4,112为8,211为16等)提出了低碳马氏体晶格参量的测量方法。 相似文献
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In the original BB84 quantum key distribution protocol, the states are prepared and measured randomly, which lose the unmatched detection results. To improve the sifting efficiency, biased bases selection BB84 protocol is proposed. Meanwhile, a practical quantum key distribution protocol can only transmit a finite number of signals, resulting in keys of finite length. The previous techniques for finite-key analysis focus mainly on the statistical fluctuations of the error rates and yields of the qubits. However, the prior choice probabilities of the two bases also have fluctuations by taking into account the finite-size effect. In this paper, we discuss the security of biased decoy state BB84 protocol with finite resources by considering all of the statistical fluctuations. The results can be directly used in the experimental realizations. 相似文献
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