CN101799586B - Light quantum coding device and coding method thereof - Google Patents
Light quantum coding device and coding method thereof Download PDFInfo
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- CN101799586B CN101799586B CN 201010108866 CN201010108866A CN101799586B CN 101799586 B CN101799586 B CN 101799586B CN 201010108866 CN201010108866 CN 201010108866 CN 201010108866 A CN201010108866 A CN 201010108866A CN 101799586 B CN101799586 B CN 101799586B
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Abstract
The invention relates to a light quantum coding device and a coding method thereof. Optical pulse transmitted by a light source is connected with input ends of at least one of optical elements which divide one bundle of light into a plurality of light paths to transmit; the pulse signal output end of each optical element is connected with signal input ends of at least two of optical parts for controlling a light path to be communicated with or cut off and controlling the amplitude of the light intensity under the communicating state; signal output ends of the two optical parts are connected with signal input ends of at least one of optical polarizing beam splitters; and the signal output ends of at least one of the optical polarizing beam splitters is connected with an transmitting port through a coupler. The light quantum coding device and the coding method thereof can realize interconnection with the other nodes in a network by means of higher secret key generation efficiency, thereby really realizing the dilatation of the network.
Description
Technical field
The present invention relates to quantum communications device and communication means, particularly for the coding method and the implement device that make up the required quantum cryptography machine of quantum secret communication network.
Background technology
Quantum secret communication is the secret communication mode that is different from classical communication, and it has in theory can certified being perfectly safe property.Quantum key distribution can be set up the identical random number of a string random length by handling and transmit the method for quantum bit between two places; Use this random number to encrypt classical information by the mode of " one-time pad " (One-Time Pad), the security of can guarantee information transmitting.
First quantum key distribution agreement proposed in 1984, was referred to as BB84.After this, a series of related protocol is suggested, and comprises that mainly photon state prepares/measures and tangles and distribute two macrospecies.But wherein based on the entangled light source of the quantum key scheme of tangling distribution owing to present shortage high brightness practicability, also only rest on the laboratory study stage, can't be used for making up actual quantum communication system.The present invention i.e. the light quantum polarization state coding method efficiently by providing a kind of maturation, practicality, and the quantum cryptography machine of realizing according to the method can be used to make up the quantum secret communication network of commercialization.
Preparation/the measurement of photon state mainly comprises two kinds of methods: a kind of is the distribution that realizes quantum key by the phase information of coding photon state; Another kind is to realize the key distribution by the polarization information of coding photon state.
The mode that phase encoding usually adopts, as generally adopting the phase encoding scheme of Mach-Ze De interferometer, a pair of unequal arm that needs to realize light pulse in the sending and receiving device of communicating pair is interfered mutually length and is disappeared mutually, plays the purpose of quantum state Code And Decode.This has relation one to one with regard to the encoding/decoding device that requires communicating pair.Such as, if A communicates by letter with B, if the difference of its unequal arm interferometer length of phase encoding device that the A point adopts is L, then the difference of its unequal arm interferometer length of phase decoding device of B point employing also is necessary for L; If this moment, C point required to add A-B, form the loop network of 3 of A-B-C-A, A-B wherein, A-C, but the equal intercommunication of B-C, then the C phase encoding of ordering and the difference of its unequal arm interferometer length of decoding device also are necessary for L.On the other hand, because the effect of expanding with heat and contract with cold that external interference such as temperature causes makes accurate length coupling be difficult to realize, when node users increases in the mode of network, the mismatch of length will influence the password production rate of phase encoding scheme greatly.
Obviously, consider the network interconnection pattern between the multi-user, this scheme is difficult to realize interfering between different user the requirement of length coupling, is unfavorable for forming the quantum key distribution network that does not land on a large scale.
Summary of the invention
The present invention is directed to the deficiencies in the prior art, provide a kind of and can overcome existing encoding scheme weak point, and can with network in other nodes realize with higher key production rate interconnected, thereby really realize light quantum code device and the coding method thereof of the dilatancy of network.
This method utilizes one tunnel light pulse to be beamed into four tunnel method, produces four kinds of polarization states.These four kinds of polarization states only have the difference on the polarization encoder, therefore satisfy the preparation of the desired quantum state of quantum key distribution agreement fully.The quantum state coding that uses this device to produce is realized simply, and take over party's decoding device be there is no corresponding dependence requirement, therefore can with whole network in any certain node communication as the take over party, thereby guaranteed network extensibility.
The present invention is achieved by the following technical solutions:
A kind of light quantum code device, the light pulse of light source outgoing is connected with the input end of the optical device of one road both-end output; Each output terminal of this optical device connects the input end of the optical device of one road both-end output; Each output terminal of these two optical device (totally four tunnel: I, II, III, IV) connects the input end of the optics of the single-ended output of one tunnel single-ended input; Each output terminal of optics I and II is connected the input end of the optical polarization beam splitter of a both-end input; An output terminal of this polarising beam splitter connects the input end of the coupling mechanism V of one road both-end input; Each output terminal of optics III and IV is connected the input end of the optical polarization beam splitter of a both-end input; The output terminal of this polarising beam splitter connects the input end of the Polarization Controller of the single-ended output of one tunnel single-ended input; The input end of Polarization Controller connects another input end of the coupling mechanism V of the both-end input of stating on the way; The light quantum polarization state that the output terminal output of this coupling mechanism prepares.
A kind of light quantum code device, described optical device is to the equal basically identical of the path of telling between the coupling mechanism.
A kind of light quantum code device, described optical device is beamed into the two-way light pulse for road light pulse with incident and propagates along two light paths.
A kind of light quantum code device, described light intensity modulator is used for the gating of the intensity of modulating light pulse and control light path or blocks.
A kind of light quantum code device, described optical polarization beam splitter is used for modulating light pulse to corresponding two orthogonal polarisation state.
A kind of light quantum code device, described Polarization Controller is for the polarization state direction that will change and control light pulse.
A kind of coding method of light quantum code device, the light pulse of light source outgoing is divided into the two-way light pulse through beam splitter, at least one beam splitter is passed through on every road of this two-way light pulse more respectively, be divided into two-way light pulse at least, light intensity modulator is passed through on this every road of at least four tunnel light pulses respectively, light path is carried out intensity modulation, the every two ways of optical signals of at least four tunnel light pulses after the modulation is outputed to optical polarization beam splitter, optical polarization beam splitter is prepared the polarization of input optical signal, light pulse after wherein one or more of at least two optical polarization beam splitter will prepare is controlled by Polarization Controller and is changed light polarization direction, with the light pulse polarization state after the preparation by the coupling mechanism outgoing that is coupled.
In order to overcome the difficulty described in the background technology, the method that the present invention adopts is the polarization encoder scheme.The solution of the present invention does not also require that the both sides of communication realize a pair of unequal arm interferometer, does not just have the strict requirement that equates of arm length difference naturally yet.This scheme does not also require that there are one-to-one relationship in emission side and take over party, therefore subsequent node can add existing network at an easy rate, after assurance self strictness has realized our desired coding method, can with network in other nodes realize with higher password production rate interconnected, thereby really realize the dilatancy of network.
Realize quantum key distribution with the polarization state of light quantum coding, way commonly used is to adopt four road laser instruments to produce four tunnel light pulses, and Polarization Modulation is carried out in the light pulse of every road, and the polarization of light pulse is prepared on the corresponding polarization state.Namely be to adopt the mode of four road laser pulse Polarization Modulation such as the polarization encoder solution that provides in the paper " Practical Aspects ofQuantum Cryptographic Key Distribution " (J.Cryptology (2000) 13:207-220).It is pointed out that the light pulse that this scheme requires four road laser to produce can have the difference except polarization characteristic, its complementary characteristic all need be consistent, otherwise this scheme has the leak in the security.This realizes that to the control of laser instrument and having relatively high expectations of stable aspect difficulty is bigger.And the scheme that we adopt only needs one road laser instrument, thereby does not have this type of difficulty.In addition, for some key distribution protocol, may require to prepare the laser pulse of varying strength, this scheme requires the laser instrument respective extension to the number (such as inveigling the attitude cipher protocol to need eight road laser instruments) of protocol requirement, realizes that difficulty further improves.And our scheme can adopt the adjustable light intensity modulator of intensity to realize, realizes that difficulty is lower.
Description of drawings
Fig. 1 is that this polarization encoder implement device is formed structural representation.
Fig. 2 is that embodiment 2 devices are formed the partial structurtes synoptic diagram.
Embodiment
Embodiment 1
Shown in accompanying drawing 1.
The light pulse of light source outgoing of the present invention connects one road beam splitter 2 through port one; These one road beam splitter, 2 output terminals are divided into two-way and connect 3,4, two beam splitters 3 of two beam splitters respectively, each beam splitter in 4 is told two-way again, and the pulse signal output end on every road connects a light intensity modulator 5,6 respectively, 7,8 signal input part; Four road signal input parts of four road light intensity modulator signals, 5,6,7,8 output terminals and two-way optical polarization beam splitter 9,10 connect; Wherein the signal output part of one tunnel optical polarization beam splitter 9 links to each other with the input end of No. one coupling mechanism 12, the signal output part of another road optical polarization beam splitter 10 links to each other with one road Polarization Controller, 11 input ends, and the output terminal of this Polarization Controller 11 reconnects another input end of the coupling mechanism of stating 12.Beam splitter 2 to the length of telling between the coupling mechanism 12 should be consistent substantially. Wherein beam splitter 2,3, and 4 are beamed into the two-way light pulse for road light pulse with incident propagates along two light paths.Wherein light intensity modulator 5,6,7,8, and the break-make or the modulation light intensity that are used for the control light path are taken office the meaning ratio.Optical polarization beam splitter 9,10 is used for two-way is imported on the polarization state that polarisation of light is prepared into pair of orthogonal.Polarization Controller 11 is used for certain angle is arrived in control and the change polarization direction of light pulse.
To light intensity modulator 5,6,7,8 requirement be, can realize arbitrary proportion light intensity modulation or control passing through and blocking of this road light.Be that the two-way input of optical polarization beam splitter forces input light to be positioned on a pair of mutually orthogonal polarization state respectively to optical polarization beam splitter 9,10 requirement.The requirement of Polarization Controller 11 is that Polarization Controller increases by 45 degree with the polarization direction rotation of input pulse.
The light pulse of light source outgoing is divided into the two-way light pulse through beam splitter, at least one beam splitter is passed through on every road of this two-way light pulse more respectively, be divided into two-way light pulse at least, light intensity modulator is passed through on this every road of at least four tunnel light pulses respectively, light path is carried out intensity modulation, the every two ways of optical signals of at least four tunnel light pulses after the modulation is outputed to optical polarization beam splitter, optical polarization beam splitter is prepared the polarization of input optical signal, light pulse after wherein one or more of at least two optical polarization beam splitter will prepare is controlled by Polarization Controller and is changed light polarization direction, with the light pulse polarization state after the preparation by the coupling mechanism outgoing that is coupled.
The present invention can realize multichannels by a plurality of beam splitters with this scheme, is not limited among the embodiment four the tunnel.
Shown in accompanying drawing 2.Polarization Controller 11 and coupling mechanism 12 can be merged into a coupling mechanism 14, and the two-way input of this coupling mechanism 14 forces the light pulse polarization to be positioned at a pair of differing on 45 polarization states of spending.All the other are with embodiment 1.
Claims (5)
1. light quantum code device, the light pulse of light source outgoing connects a beam splitter input end that is used for a branch of light is divided into many light path outgoing through port; The signal output part of described beam splitter is told two-way, and every road is connected with a described beam splitter respectively and tells two-way; The pulse signal output end of the every road beam splitter after telling connects one respectively and is used for controlling conducting light paths or blocking, and can control the light intensity modulator signal input part of light intensity amplitude under conducting state; The signal output part of the described light intensity modulator that is connected with same described beam splitter output terminal connects the signal input part of same optical polarization beam splitter; The signal output part of each optical polarization beam splitter all is connected with exit ports by coupling mechanism; Be provided with the Polarization Controller that at least one is used for changing and controlling light polarization direction between described coupling mechanism and the optical polarization beam splitter.
2. a kind of light quantum code device according to claim 1 is characterized in that described beam splitter is all consistent to a plurality of paths of telling between the coupling mechanism.
3. a kind of light quantum code device according to claim 1 and 2 is characterized in that described beam splitter is the light Port Multiplier.
4. a kind of light quantum code device according to claim 1 is characterized in that described light intensity modulator is photoswitch.
5. the coding method of a kind of light quantum code device according to claim 1, the light pulse that it is characterized in that the light source outgoing is divided into the two-way light pulse through beam splitter, every road of this two-way light pulse is more respectively through a beam splitter, be divided into the two-way light pulse, light intensity modulator is passed through on this every road of four tunnel light pulses respectively, light path is carried out intensity modulation, the every two ways of optical signals of four tunnel light pulses after the modulation is outputed to optical polarization beam splitter, optical polarization beam splitter is prepared the polarization of input optical signal, light pulse after wherein one or more of two optical polarization beam splitter will prepare is controlled by Polarization Controller and is changed light polarization direction, with the light pulse polarization state after the preparation by the coupling mechanism outgoing that is coupled.
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| CN102739394B (en) * | 2012-06-07 | 2013-11-06 | 中国科学技术大学 | Light quantum phase modulating system |
| CN102820968B (en) * | 2012-07-10 | 2016-04-20 | 中国电力科学研究院 | Based on quantum key distribution transformer station between measurement and control signal one-time pad transmission system |
| KR101729663B1 (en) * | 2015-12-31 | 2017-04-24 | 에스케이텔레콤 주식회사 | Apparatus and method for managing performance of random number generator based on quantum shot noise |
| CN110620619B (en) * | 2018-09-18 | 2022-12-16 | 科大国盾量子技术股份有限公司 | Quantum communication system, transmitting end thereof and quantum communication method |
| CN109039619B (en) * | 2018-10-29 | 2023-05-26 | 中国电子科技集团公司电子科学研究院 | Quantum key distribution time bit-phase decoding method and device and corresponding system |
| CN111740823B (en) * | 2020-07-09 | 2021-02-19 | 国开启科量子技术(北京)有限公司 | Time-phase quantum key coding device, system and method |
| CN116781264B (en) * | 2023-08-25 | 2023-10-27 | 北京中科国光量子科技有限公司 | Quantum key distribution transmitting terminal based on endogenous quantum random numbers |
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| US5768378A (en) * | 1993-09-09 | 1998-06-16 | British Telecommunications Public Limited Company | Key distribution in a multiple access network using quantum cryptography |
| US6748083B2 (en) * | 2000-04-28 | 2004-06-08 | The Regents Of The University Of California | Method and apparatus for free-space quantum key distribution in daylight |
| CN201689217U (en) * | 2010-02-04 | 2010-12-29 | 安徽量子通信技术有限公司 | Light quantum coding device |
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| US5768378A (en) * | 1993-09-09 | 1998-06-16 | British Telecommunications Public Limited Company | Key distribution in a multiple access network using quantum cryptography |
| US6748083B2 (en) * | 2000-04-28 | 2004-06-08 | The Regents Of The University Of California | Method and apparatus for free-space quantum key distribution in daylight |
| CN201689217U (en) * | 2010-02-04 | 2010-12-29 | 安徽量子通信技术有限公司 | Light quantum coding device |
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Address after: 230088, D3, building 1, 4, 5, 6, 7, 800, Wangjiang Industrial Park, Wangjiang West Road, hi tech Zone, Anhui, Hefei Patentee after: QUANTUM COMMUNICATION TECHNOLOGY CO., LTD. Address before: 230088 No. 3, Tianyuan Road, Hefei hi tech Zone, Anhui 2, Building 102 Patentee before: Anhui Liangzi Communication Technology Co., Ltd. |