CN102916807B - Polarization compensation implementation method of continuous variable quantum key distribution system - Google Patents

Polarization compensation implementation method of continuous variable quantum key distribution system Download PDF

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CN102916807B
CN102916807B CN201210389008.2A CN201210389008A CN102916807B CN 102916807 B CN102916807 B CN 102916807B CN 201210389008 A CN201210389008 A CN 201210389008A CN 102916807 B CN102916807 B CN 102916807B
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polarization
light
step
voltage
dc
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CN102916807A (en
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房坚
黄端
何广强
曾贵华
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上海交通大学
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Abstract

本发明公开一种连续变量量子密钥分发系统的偏振补偿实现方法,具体为:发送端采用偏振复用的方式将信号光与本振光通过一根光纤进行传输,接收端通过偏振分束器将信号光与本振光分离,其中的偏振反馈控制方法分为两个阶段:在分光检测阶段,连续变量量子密钥分发的接收端分出一部分本振光,并通过转换电路将其转换为直流反馈电压信号;在偏振校正阶段,接收端根据直流反馈电压,用反馈算法控制动态偏振控制器,完成偏振校正。 The present invention discloses a continuous variable polarization compensator quantum key distribution system implemented method, specifically as follows: the transmitting side by way of the polarization multiplexed signal light and the local light transmitted through an optical fiber, the receiving end through the polarizing beam splitter the signal light and the local light separator, wherein the polarization feedback control method has two phases: spectroscopic detection phase continuous variable quantum key distribution terminal receiving part of the separated polarized light, and through the switching circuit to convert it to DC feedback voltage signal; polarizing calibration phase, the receiving end according to the DC feedback voltage, a feedback control algorithm for dynamic polarization controller, the polarization correction is completed. 本发明提出了一种全新的连续变量量子密钥分发系统的偏振反馈控制实现方法,有效地抑制了在光纤通信过程中连续变量量子信号的偏振状态受到的环境干扰,提高了系统的稳定性,推进了连续变量量子密码的实用化。 The present invention proposes a new Continuous variable quantum key distribution system of a polarization feedback control implemented method effectively suppress interference in the optical fiber communication environment during continuous variable quantum signals received by the polarization state, to improve the stability of the system, to promote the practical application of continuous variable quantum cryptography.

Description

连续变量量子密钥分发系统的偏振补偿实现方法 Continuous variable quantum key distribution system implemented method polarization compensation

技术领域 FIELD

[0001] 本发明涉及一种量子密码通信领域的技术,具体地说,是一种连续变量量子密钥分发系统的偏振补偿实现方法。 [0001] The present invention relates to a technique in the field of quantum cryptography communications, and more particularly, a polarization compensator is a continuous variable quantum key distribution system implementation.

背景技术 Background technique

[0002] 随着经济的发展和科学的进步,信息化、数字化进程不断加快,信息传递和互换越来越频繁,因此对信息传达过程的安全性和可靠性有越来越高的要求。 [0002] With economic development and scientific progress, information technology, accelerating the process of digitization, information transfer and exchange more frequently, therefore increasing demands for security and reliability of information transmission process. 如何安全地传递信息已经成为现代通信领域的重要问题。 How secure transmission of information has become an important issue in the field of modern communications. 应用密码学由此应运而生,尤其在第二次世界大战中的广泛使用,更加体现出了密码学的重要性。 Applied Cryptography which came into being, in particular, is widely used in World War II, more it reflects the importance of cryptography. 到目前为止,密码学在政治、军事、经济、文化等社会生活的各个方面都起着重要的作用。 So far, cryptography in all aspects of political, military, economic, cultural and social life plays an important role.

[0003] 经典密码通信可以分为两大类:非对称密码系统和对称密码系统。 [0003] classical cryptography communication can be divided into two categories: symmetric and asymmetric cryptographic system cryptography. 非对称密码系统又称为公开密钥系统,如现在广为采用的RSA算法。 Asymmetric cryptography, also known as public key systems, such as the RSA algorithm is now widely used. 接收方先选择一组只有他知道的专用密钥,依次计算出相应的公开密钥,再将公开密钥分给所以人用来加密信息。 Selecting a first set of receiver only he knows the private key, sequentially computing the corresponding public key, then the public key used to encrypt and give information so people. 非对称密码系统的安全性依赖于计算的复杂度。 Security asymmetric cryptosystem relies on the computational complexity. 一旦量子计算机研制出世,计算的速度将会极大提升,破解非对称密码系统的难度将会显著降低;对称密码系统又称为专用密钥系统,如公认绝对安全的一次一密包(One-Time-Pad),发送方与接收方拥有相同的密钥。 Once born quantum computer development, the calculated speed will greatly enhance the difficulty of guessing an asymmetric cryptosystem will be significantly reduced; asymmetric cryptosystem private key system is also known, such as recognized absolute security of one-time pad package (One- Time-Pad), the sender and recipient have the same key. 密钥只用一次,并且密钥长度不小于信息长度。 Key is used only once, and the key length is not less than the information length. 这样安全性就得到了保证,代价是降低了密码的使用效率。 Such security is guaranteed, at the cost of reducing the efficiency of the use of passwords.

[0004] 量子密码通信与经典密码通信不同,其安全性基于量子物理的基本特性而非计算的复杂性。 [0004] The quantum cryptography communication to communicate with different classical cryptography, security is based on the complexity of their basic characteristics of quantum physics, rather than calculated. 它不是单纯利用计算复杂性使窃听者在有限时间内不能破译密码,而是利用量子力学的基本原理和特性来发现是否有窃听者存在,以此确立合法通信者与窃听者之间对比出的信息优势,从而确保通信的安全。 It is not simple to make use of the computational complexity of an eavesdropper can not decipher the code within a limited time, but the use of the basic principles and the characteristics of quantum mechanics to discover whether an eavesdropper is present, in order to establish a comparison between a person with legal communications eavesdropper information superiority, in order to ensure secure communication. 因此,在量子计算不断发展的今天,研宄并实现量子密码技术是非常必要的。 Therefore, in the continuous development of quantum computing today, it is necessary to study traitor and quantum cryptography.

[0005] 经过这二十几年的发展,量子密码通信已从理论研宄逐步走向实际应用。 [0005] After twenty years of development, the theory of quantum cryptographic communication from a Subsidiary gradually moving towards practical application. 根据实现方式的不同,主要分为离散变量量子密钥分发系统和连续变量量子密钥分发系统。 According to different implementations, divided into discrete variable quantum key distribution system and a continuous variable quantum key distribution system. 其中离散变量量子密钥分发通过单光子的方式来实现。 In which discrete variable quantum key distribution is achieved by way of a single photon. 由于现在还无法使用理想的单光子源,因此主要是通过将相干光进行衰减,使得每个脉冲的平均光子数小于IO激光源的光子数服从泊松分布,除了含有单光子脉冲之外还含有多光子脉冲。 Since now can not be used over a single-photon source, primarily attenuated by the coherent light, such that the average number of photons per pulse is less than the number of photons of the laser source IO Poisson distribution, in addition to containing a single photon pulse further comprises multi-photon pulses. 这些多光子脉冲被窃听之后不会被察觉,从而影响密码系统的安全性。 These multi-photon pulses will not be noticed after being tapped, thus affecting the security of the password system. 使用诱骗态(Decoy State)可以很大程度上解决这个问题,但是增加了实际系统的复杂程度。 The use of decoy state (Decoy State) can largely solve this problem, but increases the complexity of the actual system.

[0006] 连续变量量子密码起步比离散变量要晚一些,直到1999年Ralph首先提出利用连续变量进行量子密钥分发的概念。 [0006] continuous variable quantum cryptography start than discrete variables would be late, until 1999 Ralph first proposed the use of the concept of continuous variable quantum key distribution. 与离散变量不同,连续变量将信息编码在连续的正则分量上(如正则位置X和正则动量P),在每个比特上能够比离散变量编码更多的信息。 Discrete variables, continuous variable information is encoded on a continuous regular components (e.g., X and n canonical momenta position P), capable of encoding more information than a discrete variable on each bit. 采用的光源可以是相干态、压缩态或者纠缠态。 The light source may be coherent states, squeezed states or entanglement. 考虑到实验上的方便,一般都采用相干激光作为光源。 For the convenience of the experiment, generally used as a coherent laser source. 连续变量量子密钥分发采用Homodyne检测器作为量子检测器,与离散变量相比,具有成本上的优势。 Continuous variable quantum key distribution using Homodyne detector quantum detector as compared with the discrete variables, with a cost advantage. 因此连续变量量子密钥分发有着很好的实用化发展前景。 Therefore, continuous variable quantum key distribution has a good practical prospect.

[0007]目前,连续变量量子密钥分发系统均采用的双不等臂干涉结构。 [0007] Currently, two unequal arms continuous variable quantum key distribution systems use interferometric structures. 此种结构很容易受到各种因素的影响。 Such a structure is easily affected by various factors. 这些因素包括但不限于: These factors include, but are not limited to:

[0008] 1.温度变化:铌酸锂材质的电光调制器本身对于温度的变化比较敏感,不稳定的环境温度会在调制时产生较大的偏差。 [0008] 1. The temperature: lithium niobate electro-optic modulator itself is made more sensitive to changes in temperature, unstable environment will have a greater temperature variation during modulation.

[0009] 2.系统所受到的机械振动,机械振动会在光纤中产生应力,导致折射率发生改变,使得在光纤中传输的光偏振态产生漂移。 Mechanical vibration [0009] 2. The system suffered the mechanical vibration causes the stress in the optical fiber, the refractive index change, such that the polarization state of light generated in the optical fiber transmission drift.

[0010] 3.空气流动的影响。 [0010] 3. Effect of air flow. 空气流动会对未紧致固定的光纤产生扰动,导致偏振态发生漂移。 Compact fixing air flow will not result in disturbances of the fiber, resulting in the polarization drift.

[0011] 4.电磁辐射场的影响:电磁辐射(诸如手机信号、交流电产生的电磁波)会对系统的电路部分产生比较明显的干扰,收到的干扰最明显就是量子检测器部分。 [0011] 4. Effects of Electromagnetic Field: electromagnetic radiation circuit portion of the system will (phone signal, such as an electromagnetic wave generated by an alternating current) generated obvious interference, interference received the most obvious is the quantum detector portion.

[0012] 为了解决这些问题,让连续变量量子密钥分发系统能够具有较高的稳定性,我们需要对环境的影响进行监测,并通过反馈的方式来校准,使得系统对于环境干扰具有抵抗能力,并能够长时间连续工作。 [0012] In order to solve these problems, so continuous variable quantum key distribution system can have high stability, we need to monitor the impact on the environment, and calibrated by way of feedback, making the system resistant to environmental interference capability, and can work continuously for a long time.

发明内容 SUMMARY

[0013] 针对现有技术中的缺陷,本发明的目的在于针对连续变量量子密钥分发系统偏振反馈控制方案的空白,提出了一种全新的偏振反馈控制方案,推进了连续变量量子密码的实用化,同时有效地抑制了在量子通信过程中连续变量量子信号的偏振受到的环境干扰。 [0013] For the prior art drawbacks, an object of the present invention is for the continuously variable quantum key distribution system of a polarization feedback control scheme blank, put forward a new polarization feedback control scheme to promote continuous variable practical quantum cryptography technology, while effectively suppressing environmental interference in a quantum communication process continuous variable quantum signals subjected to polarization.

[0014] 根据本发明的一个方面,提供一种连续变量量子密钥分发系统的偏振补偿实现方法,具体为: [0014] In accordance with one aspect of the present invention, there is provided a continuously variable polarization compensator quantum key distribution system implementations, in particular:

[0015] 在发送端:将激光器产生的脉冲激光经衰减器衰减后通过保偏分束器分为信号光和本振光两束;令信号光经过幅度调制和相位调制后,通过衰减器衰减到量子水平,然后与本振光一起通过偏振耦合器进入光纤中传输至接收端; [0015] at the transmitting end: After the laser generates pulse laser light attenuated by the attenuator polarizer beam splitter into two signal light and the local light beam to pass through security; light after the command signal amplitude and phase modulation, the attenuation by the attenuator quantum level, and by the LO light with polarization couplers into the transmission fiber to the receiving end;

[0016] 在接收端:令光纤中传输来的信号经动态偏振控制器后,通过偏振分束器分为信号光与本振光两束;令信号光直接进入保偏親合器;令本振光先通过保偏分束器分为两束,其中,偏振反馈控制单兀接收并根据其中的一束向动态偏振控制器输出偏振反馈控制信号,另一束通过相位调制器完成相位补偿,与信号光一起通过偏振耦合器进入量子检测器做相干检测。 [0016] At the receiving end: optical fiber transmission command signal to the controller after dynamic polarization by the polarization beam splitter and an optical signal into two beams of local light; command signal light directly into the polarization-maintaining affinity; a present order polarized light by the first polarization beam splitter into two beams, wherein the polarization and the feedback control unit receiving an output polarizer Wu dynamic polarization controller according to a bundle wherein the feedback control signal, the other beam to complete the phase compensation by a phase modulator, together with the signal light by the polarization coupler into the quantum detector for coherent detection.

[0017] 优选地,在接收端:偏振反馈控制单元包括依次连接的光电二极管、放大器、以及有效值转换电路,其中,通过光电二极管将本振光通过保偏分束器分出的一束由光脉冲转化为电脉冲,然后通过放大器放大电脉冲,再令放大后的电脉冲经有效值转换电路转化为直流反馈电压输出到动态偏振控制器。 [0017] Preferably, at the receiving end: a polarization feedback control unit comprises a photodiode connected in sequence, an amplifier, and the effective value converting circuit, wherein the photodiode by the local light by polarization beam splitter from the bundle of separated light pulses into electrical pulse, electric pulse is then amplified by an amplifier, so that the electric pulse and then amplified by the converted RMS to DC converter circuit outputs a feedback voltage to the dynamic polarization controller.

[0018] 优选地,动态偏振控制器通过改变其内部的四个光纤挤压器上的电压对偏振态进行控制,使直流反馈电压达到最大值,具体包括如下步骤: [0018] Preferably, the dynamic polarization controller by changing the voltage on its internal four fiber squeezer polarization state control, the DC feedback voltage reaches a maximum value, includes the following steps:

[0019] 步骤(I):动态偏振控制器采集直流反馈电压; [0019] Step (I): dynamic polarization controller collects the DC voltage feedback;

[0020] 步骤(2):选择第一个光纤挤压器的控制电压; [0020] Step (2): Select the first fiber squeezer control voltage;

[0021] 步骤(3):适当地增加控制电压,采集此时反馈回来的直流反馈电压; [0021] Step (3): suitably increased control voltage, current collection at this time the feedback voltage fed back;

[0022] 步骤(4):如果直流反馈电压增大,则返回步骤(3),否则进入步骤(5); [0022] Step (4): If the DC feedback voltage is increased, returns to step (3), otherwise go to step (5);

[0023] 步骤(5):适当地减小控制电压,采集此时的直流反馈电压; [0023] Step (5): to appropriately reduce the control voltage, a DC feedback voltage acquired at this time;

[0024] 步骤(6):如果直流反馈电压增大,则返回步骤(5),否则进入步骤(7); [0024] Step (6): If the DC feedback voltage is increased, returns to step (5), otherwise go to step (7);

[0025] 步骤(7):选择下一个光纤挤压器的控制电压,进入步骤(3)。 [0025] Step (7): Selects a fiber squeezer device control voltage, the process proceeds to step (3).

[0026] 优选地,有效值转换电路采用有效值直流转换器(RMS-DC)来计算脉冲信号的真有效值,有效值直流转换器进行实时测量,完成脉冲电压到直流电压的实时转换。 [0026] Preferably, the effective value of true RMS converter circuit RMS to DC converter (RMS-DC) calculates the pulse signal, RMS to DC converter for real-time measurements in real time to complete the conversion pulse voltage a DC voltage.

[0027] 优选地,在发送端,将信号光与本振光通过偏振复用的方式在同一根光纤中传输;在接收端,通过偏振分束器将偏振复用的本振光与信号光分成两路后,对本振光进行分光。 [0027] Preferably, the transmitting side, the signal light and the local light transmission by optical fibers in the same manner as polarization multiplexing; at the receiving end, through the polarizing beam splitter the local light polarization multiplexed signal light after divided into two, of the local oscillator light beam splitter.

[0028] 更为具体地,为实现上述目的,本发明的一个优选的实施例所采用的技术方案如下: [0028] More specifically, to achieve the above object, a preferred embodiment of the present invention employed the following technical solution:

[0029] 本发明所述的具有偏振反馈功能的连续变量量子密钥分发系统,包含发送端和接收端两部分,发送端和接收端均由各自的光路部分和电路部分组成。 [0029] Continuous variable quantum key distribution system having a feedback function of the polarization of the present invention, comprising transmitter and receiver ends of the two portions, the transmitter and receiver of each of the optical path portion and the end portion by the circuit components. 其中所述光路部分主要由激光器、衰减器、保偏分束器、保偏親合器、法拉第镜、可调延时线、偏振親合器、偏振分束器、动态偏振控制器、幅度调制器和相位调制器组成;所述电路部分由真随机密钥产生器、发送端和接收端的控制电路、量子检测器和偏振反馈控制单元组成。 Wherein said main portion by the laser light path, attenuators, polarization beam splitter, polarization affinity, a Faraday mirror, adjustable delay line, the affinity of polarization, a polarization beam splitter, a dynamic polarization controller, amplitude modulation and a phase modulator composition; said circuit portion by a true random key generator, the transmission and receiving ends of the control circuit, and the polarization detector quantum feedback control unit.

[0030] 发送端:激光器产生脉冲激光,经衰减器衰减后被10:90保偏分束器分为两束,10%的一束作为信号光,90%的一束作为本振光。 [0030] transmitting end: a laser generating pulsed laser light, after being attenuated by the attenuator 10:90 by polarization beam splitter into two beams, 10% of the bundle of light as a signal, 90% of the local light as a bundle. 信号光经过幅度调制和相位调制后,通过衰减器衰减到量子水平,然后与本振光一起通过偏振耦合器进入光纤中传输。 After the optical signal amplitude and phase modulation, to the quantum level of attenuation by the attenuator, and by the LO light with the polarization couplers into the transmission fiber.

[0031] 接收端:光纤中的信号通过动态偏振控制器后,被偏振分束器分为信号光与本振光两束。 [0031] the receiving end: the signal fiber in the dynamic polarization controller, a polarization beam splitter is divided into signal light and the local light two beams. 信号光直接进入保偏耦合器,本振光先通过10:90的保偏分束器分为两束,10%的一束用来做为偏振反馈控制信号,其余通过相位调制器完成相位补偿,与信号光一起做相干检测。 Signal light directly into the polarization-maintaining coupler, the first local oscillator light by the partial retention of 10:90 beam splitter into two beams, a bundle of 10% as a polarizer for a feedback control signal, to complete the remaining phase compensation by a phase modulator , do the coherent detection of the signal light together. 通过调节可调延时线使得双不等臂干涉结构达到平衡。 By adjusting the adjustable delay line such that the double-arm interferometer structure ranging equilibrium.

[0032] 本发明提出的偏振反馈控制实现方法分为两个阶段,分光检测阶段和偏振校正阶段。 [0032] The polarizer of the present invention is made to realize the feedback control method is divided into two phases, phase and polarization spectroscopic detection correction phase. 方案如下: Program are as follows:

[0033] 分光检测阶段:连续变量量子密钥分发的接收端将收到的信号用偏振耦合器进行偏振解复用,之后将得到的本振光分出一部分,通过脉冲转换电路将脉冲光信号转换为直流电压信号。 [0033] spectroscopic detection phase: Continuous variable quantum key distribution terminal receiving the received signal is polarization de-multiplexed by polarization couplers, after which the resulting separated part of the local light by pulsed light pulse signal conversion circuit into a DC voltage signal.

[0034] 脉冲转换电路采用光电二极管将光脉冲转化为电脉冲。 [0034] The pulse converter circuit using a photodiode light pulses into electrical pulses. 由于用于分光检测的光强很小,电脉冲信号很微弱,因此需要使用放大器进行放大。 Since for detecting the spectral light intensity is small, the electric pulse signal is very weak, it is necessary to use an amplifier to amplify. 放大后的电脉冲用有效值转换器(RMS-DC)进行处理,将其转化为直流电压。 Amplified electric pulse treatment with an rms converter (RMS-DC), which was converted to a DC voltage.

[0035] 偏振校正阶段:将脉冲转化电路输出的直流电压反馈给接收端的动态偏振控制器,动态偏振控制器对直流反馈电压进行采样,并通过下述的偏振反馈控制算法来持续调节动态偏振控制器,使得直流反馈电压保持最大值。 [0035] The polarization calibration phase: the DC voltage conversion circuit output pulse is fed back to the dynamic polarization controller receiving end, the dynamic polarization controllers DC voltage feedback samples, and a feedback control algorithm to continuously adjust the polarization following the DPC device, such that the maximum holding current feedback voltage.

[0036] 动态偏振控制器通过改变其内部的四个光纤挤压器上的电压对偏振态进行控制。 [0036] The dynamic polarization controller controls the polarization state by changing the voltage on its internal four fiber squeezer. 偏振反馈算法的主要步骤如下: Feedback algorithm polarization main steps as follows:

[0037] 步骤(I):动态偏振控制器采集直流反馈电压; [0037] Step (I): dynamic polarization controller collects the DC voltage feedback;

[0038] 步骤(2):选择第一个光纤挤压器的控制电压; [0038] Step (2): Select the first fiber squeezer control voltage;

[0039] 步骤(3):适当地增加电压,采集此时反馈回来的直流反馈电压; [0039] Step (3): suitably increased voltage, current collection at this time the feedback voltage fed back;

[0040] 步骤(4):如果直流反馈电压增大,则返回步骤(3),否则进入步骤(5); [0040] Step (4): If the DC feedback voltage is increased, returns to step (3), otherwise go to step (5);

[0041] 步骤(5):适当地减小电压,采集此时的直流反馈电压; [0041] Step (5): suitably reduced voltage, a DC feedback voltage acquired at this time;

[0042] 步骤(6):如果直流反馈电压增大,则返回步骤(5),否则进入步骤(7); [0042] Step (6): If the DC feedback voltage is increased, returns to step (5), otherwise go to step (7);

[0043] 步骤(7):选择下一个光纤挤压器的控制电压,进入步骤(3)。 [0043] Step (7): Selects a fiber squeezer device control voltage, the process proceeds to step (3).

[0044] 通过以上过程,可以将直流反馈电压一直保持在最大值状态。 [0044] Through the above process, it may be a DC feedback voltage remains in the maximum state. 此时对应的本振光的强度最强,即实现了偏振反馈控制的功能。 At this time, the intensity of the corresponding local light is strongest, i.e., to achieve a polarization-feedback control.

[0045] 与现有技术相比,本发明的主要优点如下: [0045] Compared with the prior art, the major advantages of the present invention are as follows:

[0046] 1、安全性方面:由于在本发明中,偏振反馈控制采用分出部分本振光的方法,没有对于信号光进行分光和测量,根据量子密钥分发的分析理论,本发明对密钥的安全性不会造成任何影响。 [0046] 1, safety: In the present invention, since the polarization feedback control portion of the LO light is separated using the method, for the signal light without spectroscopic measurement and, according to the theory of quantum key distribution, the adhesion of the present invention security key does not have any impact.

[0047] 2、连续变量量子密钥分发的量子信号由于达到了量子级别,因此在光纤信道的传输过程中特别容易受到环境干扰,造成偏振漂移,进而造成系统的误码率的增加。 [0047] 2, the continuous variable quantum key distribution quantum signal due to reaching the quantum level, so during the transmission fiber channel is particularly susceptible to environmental interference, causing polarization drift, which causes the system error rate increases. 本发明中的接收端通过偏振分束器,将本振光和信号光分开;之后对一部分本振光进行检测,以得知偏振漂移的程度;这部分本振光强度越小,说明漂移的程度越严重;这部分本振光强度达到最大时,即为偏振得到补偿的状态。 The receiving end in the present invention by the polarization beam splitter, the local oscillation light and signal light are separated; After a part of the local light is detected to know the degree of polarization drift; the smaller this part of the local light intensity, indicating drift the severity; this part of the local light intensity reaches the maximum, that is, the state of polarization to obtain compensation. 从而能够有效抑制在量子密钥分发过程中的环境干扰,使得偏振持续处于稳定状态,降低了误码率,增强了系统的稳定性。 Thereby effectively suppressing environmental interference in the quantum key distribution process, so that a stable state of polarization continuously reduced error rate, and enhance the stability of the system.

附图说明 BRIEF DESCRIPTION

[0048] 通过阅读参照以下附图对非限制性实施例所作的详细描述,本发明的其它特征、目的和优点将会变得更明显: [0048] By reading the following detailed description of non-limiting embodiments given with reference to the following figures, other features of the present invention, objects and advantages will become more apparent:

[0049] 图1为根据本发明提供的连续变量量子密钥分发系统的偏振补偿实现方法的框图。 [0049] FIG. 1 is a key distribution system block diagram of a polarization compensation method implemented in accordance with the present invention, the continuous variable quantum provided.

[0050] 图中:100为光纤信道,901为发送端的可调衰减器,902为发送端的法拉第镜,801为接收端的可调衰减器,802为法拉第镜,803为真有效值转换电路,804为放大器,805为光电二极管。 [0050] figure: 100 is a Fiber Channel 901 to the transmitting side variable attenuator 902 is a transmitting side Faraday mirror 801 to receive the end of the variable attenuator 802 to the Faraday mirror 803 rms converter circuit, 804 an amplifier, 805 is a photodiode.

具体实施方式 Detailed ways

[0051] 下面结合具体实施例对本发明进行详细说明。 Specific embodiments of the present invention will be described in detail [0051] below in conjunction. 以下实施例将有助于本领域的技术人员进一步理解本发明,但不以任何形式限制本发明。 The following examples will assist those skilled in the art a further understanding of the invention, but do not limit the present invention in any way. 应当指出的是,对本领域的普通技术人员来说,在不脱离本发明构思的前提下,还可以做出若干变形和改进。 It should be noted that one of ordinary skill in the art, without departing from the spirit of the present invention, further modifications and changes may be made. 这些都属于本发明的保护范围。 All these fall within the scope of the present invention.

[0052] 在本实施例中,所述连续变量量子密钥分发系统偏振补偿实现方法,具体步骤如下: [0052] In the present embodiment, the continuous variable quantum key distribution system to achieve polarization compensation method, the following steps:

[0053] (I)分光检测阶段:连续变量量子密钥分发系统的接收端将量子信号通过偏振分束器,根据光的偏振理论及偏振耦合器的性质,如果偏振无漂移,则本振光将会和信号光完全分开。 [0053] (I) spectroscopic detection phase: Continuous variable quantum key distribution system receiving end quantum signals through the polarization beam splitter, depending on the nature and theoretical polarization of light polarization couplers, if the polarization drift, the LO light and the signal light will be completely separate. 在存在偏振漂移的情况下,本振光会泄露一部分到信号光端,使得本振光自身能量降低。 In the presence of polarization drift, a part of the local oscillation light to leak light signal terminal, so that the local light power itself is reduced. 通过对分出的一部分本振光进行检测,可以得知偏振的漂移程度。 By a portion separated local light is detected, we can know the degree of polarization drift. 在偏振匹配的情况下,本振光的强度达到最大。 In the case of matching the polarization, the intensity of the LO light is maximized. 此时即为最佳的偏振状态。 At this time, the polarization state is the best.

[0054] 用于连续变量量子密钥分发系统所使用的本振光强度很小,每个脉冲约有18个光子,在时钟触发频率为IMHz的情况下,功率只有-48.9dBm。 [0054] for the local light intensity Continuous variable quantum key distribution system used is very small, about 18 photons per pulse, in the case where the clock frequency of IMHz trigger, the power is only -48.9dBm. 分出的光占本振光能量的10%,即每个脉冲有约17光子,在IMHz的时钟频率下功率为-58.9dBm。 10% of the light separated local light energy, i.e., about 17 photons per pulse, at a clock frequency of IMHz power of -58.9dBm. 经过光电二极管转换后,得到的电流非常微弱(约为luA),因此需要放大器对其进行放大。 After conversion photodiode, current is very weak (about LUA), requiring an amplifier amplifies. 放大器将微弱电流放大到峰值为500mV的脉冲电压信号。 Amplifier amplifying a weak current pulse to the peak voltage signal of 500mV.

[0055] 放大后的脉冲电压信号通过脉冲转换电路转换为直流反馈电压。 [0055] The pulse voltage signal amplified by the pulse conversion circuit converts a DC voltage feedback. 本发明采用有效值直流转换器(RMS-DC)来计算脉冲电压的真有效值,输出直流电压。 The present invention employs a RMS to DC converter (RMS-DC) to calculate the true RMS voltage pulse, the output DC voltage. 有效值直流转换器在很宽的输入频率范围内可以进行实时测量,完成脉冲信号到直流信号的转换。 RMS to DC converter may be measured in real time over a wide range of input frequencies, RCO signal into a DC signal.

[0056] (2)偏振校正阶段:脉冲转化电路输出的直流电压反馈给接收方的动态偏振控制器,动态偏振控制器对反馈电压进行采样,并通过下述的偏振反馈控制算法来持续调节动态偏振控制器,使得直流反馈电压保持最大值。 [0056] (2) polarization calibration phase: pulsed DC voltage conversion circuit output is fed back to the dynamic polarization controller of the receiver, the dynamic polarization controller feedback voltage is sampled, and continuously adjusted to dynamically through polarization feedback control algorithm described below The polarization controller, the DC feedback so that the voltage holding maximum value.

[0057] 动态偏振控制器通过改变其内部的四个光纤挤压器上的电压V1、V2、V3、V4对偏振态进行控制,电压调节范围为-12V到+12V之间。 , V2, V3, V4 for controlling the polarization state [0057] By dynamically changing the polarization controller the voltage V1 on the inside of the four fiber squeezer, voltage regulation range between -12V to + 12V. 光的偏振态用邦加球上的点来描述,斯托克斯参量S1、S2、S3对应着邦加球的坐标轴。 To describe the point on the Poincaré sphere by a polarization state of light, the Stokes parameters S1, S2, S3 correspond to the axes of the Poincare sphere. 如果增加电压Vl或V3,则偏振态会绕着SI轴顺时针旋转;相反,如果减少Vl或V3,则偏振态会绕着SI轴逆时针旋转。 If the increase in the voltage Vl or V3, the polarization will be rotated clockwise around the shaft SI; the contrary, if the reduction Vl or V3, the polarization will be rotated counterclockwise around the shaft SI. 另一方面,如果增加电压V2或V4,则偏振态会绕着S2轴顺时针旋转,如果降低V2或V4,偏振态则会绕着S2轴逆时针旋转。 On the other hand, if the increase in the voltage V2 or V4, the polarization will be rotated clockwise around the shaft S2, if reduced or V2 V4, the polarization state S2 will be rotated about the axis counterclockwise. 由此,只要输入光的偏振态与SI和S2的方向都不垂直,那么输入光的偏振态都可以通过操作最少2个电压改变到任意一个偏振态。 Thus, as long as the direction of polarization of the light input SI and S2 are not vertical, then the polarization state of input light can be changed by the operation of a minimum of 2 to a voltage of any one polarization state.

[0058] 由此,一个优选的偏振反馈算法的具体流程如下: [0058] Accordingly, a particularly preferred process polarizing feedback algorithm is as follows:

[0059] 步骤(I):动态偏振控制器的单片机对直流反馈电压采样并记录数据; [0059] Step (I): Dynamic polarization controller MCU DC voltage feedback samples and records transactions;

[0060] 步骤(2):四个光纤挤压器的控制电压都置为0V,选择第一个光纤挤压器控制电压; [0060] Step (2): four fiber squeezer control voltage are set to 0V, the first fiber squeezer select a control voltage;

[0061] 步骤(3):适当地增加控制电压,此时偏振态会在邦加球上绕着对应的矢量轴做顺时针转动,采集此时的直流反馈电压,如果电压已经达到了+12V,则跳至步骤(7); [0061] Step (3): appropriately increasing the control voltage so that the polarization vector will be around the corresponding axis on the Poincare sphere is rotated clockwise, the acquisition at this time the DC feedback voltage, if the voltage has reached a + 12V , skip to step (7);

[0062] 步骤(4):如果直流反馈电压增大,则返回步骤3,否则进入步骤(5); [0062] Step (4): If the DC feedback voltage is increased, returns to step 3, otherwise go to step (5);

[0063] 步骤(5):适当地减小控制电压,此时偏振态会在邦加球上绕着对应的矢量轴做逆时针转动,采集此时的直流反馈电压,如果电压已经达到了-12V,则跳至步骤(7); [0063] Step (5): suitably reduction control voltage so that the polarization vector will be around the corresponding axis in the counter-clockwise rotation of the Poincare sphere, collecting feedback DC voltage at this time, if the voltage has been reached - 12V, skip to step (7);

[0064] 步骤(6):如果直流反馈电压增大,则返回步骤(5),否则进入步骤(7); [0064] Step (6): If the DC feedback voltage is increased, returns to step (5), otherwise go to step (7);

[0065] 步骤(7):选择下一个光纤挤压器的控制电压,进入步骤(3)。 [0065] Step (7): Selects a fiber squeezer device control voltage, the process proceeds to step (3).

[0066] 通过以上过程,可以将直流反馈电压一直保持在最大值状态。 [0066] Through the above process, it may be a DC feedback voltage remains in the maximum state. 根据上面的分析,这时对应的本振光强度最强,即本振光没有发生泄漏,偏振达到最佳状态。 According to the above analysis, then the LO light intensity corresponding to the strongest, i.e., no light leakage occurs LO, polarization best.

[0067] 安全性方面:由于在本发明中,偏振反馈控制采用分出部分本振光的方法,没有对于信号光进行分光和测量,根据量子密钥分发的分析理论,本发明对密钥的安全性不会造成任何影响。 [0067] safety: Since the present invention, feedback control of the polarization of the LO light portion using the separation method, for the signal light without spectroscopic measurement and, according to the theory of quantum key distribution, key to the present invention, security will not have any impact.

[0068] 连续变量量子密钥分发的量子信号由于达到了量子级别,因此在光纤信道的传输过程中特别容易受到环境干扰,造成偏振漂移,进而造成系统的误码率的增加。 [0068] Continuous variable quantum key distribution due to the quantum signal reaches the quantum level, so during the transmission fiber channel is particularly susceptible to environmental interference, causing polarization drift, which causes the system error rate increases. 本发明采用上述技术方案,有效抑制了在量子密钥分发过程中的环境干扰,使得偏振持续处于稳定状态,降低了误码率,增强了系统的稳定性。 The present invention adopts the above technical solution, effectively suppressing environmental interference in the quantum key distribution process, so that the polarization sustained in a stable state, the error rate is reduced, enhancing the stability of the system.

[0069] 以上对本发明的具体实施例进行了描述。 [0069] The foregoing specific embodiments of the invention have been described. 需要理解的是,本发明并不局限于上述特定实施方式,本领域技术人员可以在权利要求的范围内做出各种变形或修改,这并不影响本发明的实质内容。 Is to be understood that the present invention is not limited to the particular embodiments, those skilled in the art can make various changes and modifications within the scope of the appended claims, this does not affect the substance of the present invention.

Claims (3)

1.一种连续变量量子密钥分发系统的偏振补偿实现方法,其特征在于,具体为: 在发送端:将激光器产生的脉冲激光经衰减器衰减后通过保偏分束器分为信号光和本振光两束;令信号光经过幅度调制和相位调制后,通过衰减器衰减到量子水平,然后与本振光一起通过偏振耦合器进入光纤中传输至接收端; 在接收端:令光纤中传输来的信号经动态偏振控制器后,通过偏振分束器分为信号光与本振光两束;令信号光直接进入保偏耦合器;令本振光先通过保偏分束器分为两束,其中,偏振反馈控制单兀接收并根据其中的一束向动态偏振控制器输出偏振反馈控制信号,另一束通过相位调制器完成相位补偿,与信号光一起通过偏振耦合器进入量子检测器做相干检测; 在接收端:偏振反馈控制单元包括依次连接的光电二极管、放大器、以及有效值转换电路,其中, A polarization compensation Continuous variable quantum key distribution system implemented method, comprising, in particular: at the sending end: After the laser generates pulse laser light attenuated by the attenuator polarizer beam into signal light by Paul local light two beams; command signal light after the amplitude and phase modulation, is attenuated to the quantum level through the attenuator, and the LO light together through polarization couplers into the transmission fiber to the receiver; at the receiving end: order fiber signal transmitted after the dynamic polarization controller, the polarization beam splitter into two signal light beam and local light; command signal light directly into the polarization-maintaining coupler; to make the local light into polarization beam splitter by two beams, wherein the polarization and the feedback control unit receiving an output polarizer Wu dynamic polarization controller according to a bundle wherein the feedback control signal, the other beam to complete the phase compensation by a phase modulator, the optical signals through the polarization coupler into the quantum detector coherent detection is made; at the receiving end: a polarization feedback control unit comprises a photodiode connected in sequence, an amplifier, and the effective value converting circuit, wherein 过光电二极管将本振光通过保偏分束器分出的一束由光脉冲转化为电脉冲,然后通过放大器放大电脉冲,再令放大后的电脉冲经有效值转换电路转化为直流反馈电压输出到动态偏振控制器; 动态偏振控制器通过改变其内部的四个光纤挤压器上的电压对偏振态进行控制,使直流反馈电压达到最大值,具体包括如下步骤: 步骤(I):动态偏振控制器采集直流反馈电压; 步骤(2):选择第一个光纤挤压器的控制电压; 步骤(3):适当地增加控制电压,采集此时反馈回来的直流反馈电压; 步骤(4):如果直流反馈电压增大,则返回步骤(3),否则进入步骤(5); 步骤(5):适当地减小控制电压,采集此时的直流反馈电压; 步骤(6):如果直流反馈电压增大,则返回步骤(5),否则进入步骤(7); 步骤(7):选择下一个光纤挤压器的控制电压,进入步骤(3)。 Through the photodiode local oscillation light by polarization beam splitter separated by a bundle of optical pulses are converted electrical pulse, electric pulse is then amplified by an amplifier, so that the effective value conversion circuit and then converted by the amplified electrical pulses to a DC voltage feedback is output to the dynamic polarization controller; dynamic polarization controller controls the polarization state by changing the voltage on its internal four fiber squeezer, the DC feedback voltage reaches a maximum value, includes the following steps: step (the I): dynamic collecting feedback voltage DC polarization controller; step (2): select the control voltage of the first fiber squeezer; step (3): suitably increased control voltage, current collection at this time the feedback voltage fed back; step (4) : If the DC feedback voltage is increased, returns to step (3), otherwise go to step (5); step (5): to appropriately reduce the control voltage, current collection at this time the feedback voltage; step (6): If the DC feedback voltage is increased, it returns to step (5), otherwise go to step (7); step (7): Selects a fiber squeezer device control voltage, the process proceeds to step (3).
2.根据权利要求1所述的连续变量量子密钥分发系统的偏振补偿实现方法,其特征在于,有效值转换电路采用有效值直流转换器来计算脉冲信号的真有效值,有效值直流转换器进行实时测量,完成脉冲电压到直流电压的实时转换。 2. The polarization compensation method implemented continuously variable quantum key distribution system according to claim 1, characterized in that the effective value converting circuit using the RMS to DC converter to calculate the true RMS pulse signal, RMS to DC converter real-time measurement, the pulse voltage to the completion of real-time conversion of the DC voltage.
3.根据权利要求1所述的连续变量量子密钥分发系统的偏振补偿实现方法,其特征在于,在发送端,将信号光与本振光通过偏振复用的方式在同一根光纤中传输;在接收端,通过偏振分束器将偏振复用的本振光与信号光分成两路后,对本振光进行分光。 The continuous variables according to claim 1 quantum key distribution system to achieve polarization compensation method, characterized in that, the signal light transmitted in the same optical fibers by way of the local light polarization multiplexing on the transmitting side; at the receiving end, the light is divided into two, of the local oscillator light beam splitter through the polarization beam splitter and the local light polarization multiplexed signal.
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