CN205986907U - High one -tenth point -to -point QKD system of code check and transmitting terminal, receiving terminal - Google Patents
High one -tenth point -to -point QKD system of code check and transmitting terminal, receiving terminal Download PDFInfo
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- CN205986907U CN205986907U CN201620910438.8U CN201620910438U CN205986907U CN 205986907 U CN205986907 U CN 205986907U CN 201620910438 U CN201620910438 U CN 201620910438U CN 205986907 U CN205986907 U CN 205986907U
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Abstract
The utility model discloses a high one -tenth point -to -point QKD system of code check and transmitting terminal, receiving terminal, wherein the transmitting terminal is followed light signal transmission direction and is included light source module, encoder, wavelength division multiplexer and optical fiber interface in proper order, still is equipped with the master control logic modules who is used for sending control signal to the encoder, light source module includes that a plurality of light sources just have different emission wavelength respectively, and the output correspondence of every light source is connected with a beam splitter, and the output that the beam splitter will correspond the light source falls into multichannel optical signal output to encoder difference encode, the optical fiber interface is the multicore optical fiber interface for the core fibre is transferred at the most in order to launch to the receiving terminal to the light signal that will come from wavelength division multiplexer. The utility model discloses when QKD system configuration has light source, the m core multicore optic fibre of n different wavelength, can hold nm strip quantum key distribution circuit, the nm who becomes the code check and be original single set QKD system doubly.
Description
Technical field
This utility model be related to point-to-point QKD technology and in particular to a kind of high become code check point-to-point QKD system and
Transmitting terminal, receiving terminal and QKD method.
Background technology
Quantum communications are combined with quantum mechanics and a cryptanalytic new technique, and its safety is by quantum mechanics base
Present principles Heisenberg uncertainty principle and quantum non-clone principle ensure it can be ensured that the safety of encryption key distribution and transmission
Property, therefore suffer from the great attention of national governments and military service, many research institutions carry out the research of a lot of quantum communications.
Quantum communications research contains quantum key distribution (QKD), quantum storage and relaying, Quantum Digital Signature Research, quantum coding, quantum
Privacy sharing, quantum calculate the directions such as agreement safely, and wherein QKD is core research contents, are also that quantum secret communication obtains in fact
The earliest research field of border application.
QKD be capable of communicating pair generate identical key, its key generating rate code check be weigh systematicness
The good and bad important indicator of energy, high one-tenth code check can encrypt more data, forms more complicated encryption system, from birth in 1991
Give birth in the world after first QKD system, improved into code check and be always QKD system and improve and perfect direction.But current report
The QKD system in road becomes code check not high, 2014《APPLIED PHYSICS LETTERS》Literature " Room
temperature single-photon detectors for high bit rate quantum key
Distribution " reports QKD best at present and becomes code check, reaches 1.2Mbps in 50km optical fiber, but has arrived 100km one-tenth
Code check is 1.2kbps, and relatively low one-tenth code check limits that QKD system is commercial on a large scale, such as distributed storage network, interbank big
The demands such as the access of data catastrophic failure-tolerant backup transfer and more users are required for carrying out one-time pad to the data of a large amount of transmission
Unconditional security is encrypted, and is therefore badly in need of the QKD system of higher one-tenth code check.
Existing multiple methods improving into code check at present, 2014《APPLIED PHYSICS LETTERS》Literature
“Room temperature single-photon detectors for high bit rate quantum key
Distribution " employs the method improving single-photon detector performance, so that single-photon detector is operated under room temperature state
Also higher one-tenth code check can be obtained；The Chinese patent application of application number 200610170557.5 discloses a kind of phase code polarization
The QKD system of detection, in QKD system before overcoming, the path of single photon randomly chooses the low shortcoming of the one-tenth code check leading to, and carries
The high utilization ratio of the capacity of resisting disturbance of system and single photon；The Chinese patent application of application number 201020112228.7 is open
A kind of two-way key produces receiving terminal, increases light path selector by light path on QKD, realizes key two-way distribution, real
Show to become higher, the safer QKD system of code check；The Chinese patent application of application number 201310434795.2 discloses one kind
The synchronizer of QKD system, when the frequency of sending signal is much larger than synchronous signal frequency, can reduce synchronizable optical to letter
The impact of number light, is conducive to the operating frequency of raising system, effectively improves QKD system and become code check.In sum, improve QKD system
Uniting into code check main method is to improve the performance of single-photon detector, improve QKD light path system, improve QKD system operating frequency
Deng, these methods are both for the improvement of single QKD system, and the device such as laser instrument, single-photon detector in single QKD system
Operating frequency, work efficiency be all conditional, therefore become code check improve limited.
The report of existing at present many QKD system with regard to being used for multiple access using wavelength division multiplexer, such as patent Shen
Numbers 201410337054.7 Chinese patent application please disclose a kind of multi-user's wavelength-division multiplex quantum key distribution network system
And its key distribution and shared method, realize the key distribution between 1 Alice and multiple Bob.Application number
200680022303.7 Chinese patent application disclose one kind wavelength-division multiplex link and realize between the transmitter and receiver
The system and method for quantum-key distribution, realize the key distribution of multiple quantum transmitting unit and multiple quantum receiving unit.On
The quantum key distribution circuit stating two patents all employs plug and play QKD system scheme based on phase code, due to by sending out
Penetrate end and the modulation accuracy of receiving terminal two phase place manipulator limits, on decoder module, signal interference of light contrast is not high enough, this shadow
Ring the measurement result of detector, the one-tenth code check reducing system is low.
The problem that prior art exists：
In single QKD system, the operating frequency of the device such as laser instrument, single-photon detector, work efficiency are all restricted, because
It is limited that this becomes code check to improve.
The plug and play system scheme based on phase code that existing one-to-many, multi-to-multi QKD multiplexed network use, its
Code check is become to be limited to send out the modulation accuracy receiving two ends phase-modulator.
Utility model content
This utility model provides a kind of QKD system, includes the transmitting terminal being mutually matched and receiving terminal, this utility model
QKD system merges beamsplitter technologies, wavelength-division multiplex technique and multi-core fiber technology, by expanding quantum key distribution number of, lines
Lift the one-tenth code check of point-to-point QKD system, when employed during m- phase place non-equilibrium basic vector coding, the insertion reducing circuit is damaged
Consume and result of detection is not limited it is achieved that high-contrast encodes by device modulation accuracy, light path can also be utilized as needed
Selector builds the QKD system of two-way communication, improves into code check further.A kind of high become the point-to-point QKD system of code check send out
Penetrate end, include light source module, encoder, wavelength division multiplexer and optical fiber interface successively along optical signal transmission direction, be additionally provided with for
Send the master control logic module of control signal to encoder, described light source module includes multiple light sources and is respectively provided with different transmittings
Wavelength, the outfan correspondence of each light source is connected with a beam splitter, and the output of corresponding light source is divided into multi-path light letter by beam splitter
Number export and to be encoded respectively to encoder；Described optical fiber interface is multi-core fiber interface, for by from wavelength division multiplexer
Optical signal is forwarded to multi-core fiber to launch to receiving terminal.
The transmitting terminal of this utility model QKD system can be greatly improved quantum key distribution number of, lines, example using beam splitter
As being provided with the light source (laser instrument) of n different wave length, all light sources can be integrated on one piece of Laser Slabs, corresponding to each light source
Beam splitter emergent light is divided into m bar quantum key distribution circuit, now system can accommodate n*m bar quantum key distribution circuit,
Become n*m times that code check is that original list covers QKD system.When system two-way communication, become code check can improve about 2n*m times.
Because the optical band selected by quantum communications has certain limitations, it is also existing for therefore how making full use of optional wave band
One of problem that technology exists, in limited wavelength band, the quantity of light source of different emission is also accordingly limited, this practicality
New the output of same light source is divided into by a plurality of quantum key distribution circuit by beam splitter, it is possible to resolve optical band makes full use of
Problem, also decreases the quantity of light source, reduces cost and energy consumption on hardware as far as possible.
In this utility model, the quantum key distribution number of, lines due to building is more, in order to improve the integrated level of equipment,
Make full use of hardware resource, preferably, having the one-to-one coding module with each road optical signal in described encoder, described
It is configured with corresponding signal modulator for every road coding module, all signal modulators share master control and patrol in master control logic module
Collect the same randomizer in module.
Although the optical signal of every quantum key distribution circuit needs to be separately encoded, each coding module is required for signal and adjusts
Device processed, but the random number that each signal modulator is utilized can be using the unified group of randomizer existing in master control logic module
Send out (distributing different randoms number respectively), randomizer need not be respectively configured for each signal modulator, reduce hardware
Expense.
In coded system, existing protocol can be adopted, in this utility model preferably, described encoder be based on when
The signal pumped FIR laser module of m- phase code, that is, preferably employ based on when m- phase encoding scheme.
Described signal pumped FIR laser module has coding module corresponding with each road flashlight.For example when tool in light source module
There is n light source, each beam splitter is divided into m road, then a total n*m road flashlight, is provided with n*m in corresponding signal pumped FIR laser module
Individual coding module.
Using when m- phase code when, each coding module be time phase coding module, specifically include time encoding son
Module and phase code submodule.
Time encoding submodule carries out time encoding process and passes through intensity modulator to circuit (i.e. quantum key distribution line
Road) in the intensity of former and later two light pulses be modulated, at random the intensity modulation of one of light pulse is close to zero
Vacuum state, produces and only has the two pulse sequence of first light pulse or only second light pulse to realize encoding.
Described phase code submodule is X basic vector phase code submodule or Y basic vector phase code submodule.Carry out phase
During the coding of position, by phase-modulator PM, one of two light pulses on circuit are modulated forming the effective of two light pulses
Phase contrast to be realized for 0 or π encoding (i.e. X basic vector phase code), or form the effective phase difference of two light pulses by modulation
For pi/2 or 3 pi/2s (i.e. Y basic vector phase code).Phase decoding process does not need phase-modulator, therefore reduces inserting of circuit
Enter loss, and result of detection is not limited by modulation device precision, achievable high-contrast coding, this two aspect improves system
Become code check.Control time, the selection percentage of two groups of basic vectors of phase place, carry out encoding and decoding using non-equilibrium basic vector to flashlight and can enter one
The one-tenth code check of step lift system.
QKD is become the discussion of code check impact refer to 2005 with regard to non-equilibrium basic vector scheme《Journal of
Cryptology》Document " Efficient quantum key distribution scheme and a proof of
its unconditional security”.
Preferably, described beam splitter is multiple, and each light source corresponds, and described wavelength division multiplexer is multiple, each
The input of wavelength division multiplexer terminates wherein one tunnel output of each beam splitter, and the outfan of each wavelength division multiplexer accesses multi-core fiber
Interface corresponding one of fibre core.
Because the input requirements of wavelength division multiplexer are wavelength difference optical signal, therefore only receive wherein one tunnel of each beam splitter
Output, one of emphasis of the present utility model is to adopt multi-core fiber, and the different fibre cores of multi-core fiber are being spatially separating, if can achieve
The parallel transmission of the identical optical signal in main line, has expanded the quantity of Common transport channel between transmitting terminal and receiving terminal, has improve system
The quantity of quantum key distribution circuit can be accommodated it is achieved that system becomes the lifting of code check, the output of each wavelength division multiplexer is by many
Core fibre interface improves integrated level further, and described multi-core fiber interface can be thus permissible using optical fiber sector follower
Between the receiving terminal and transmitting terminal of QKD system, signal transmission is carried out by multi-core fiber.
Preferably, the beam splitting quantity of each beam splitter is identical, and it is equal to the number of wavelength division multiplexer.Device so can be improved
The standardization of part.
It is additionally provided with synchronous radiant and corresponding synchronizable optical transmitting circuit, wherein synchronizable optical in this utility model transmitting terminal
Light source accesses the input of arbitrary wavelength division multiplexer.
In order to improve into code check further, transmitting terminal of the present utility model can also be real by increasing light path selector
Existing two-way communication, preferably, on each optical signaling paths between described encoder and wavelength division multiplexer, respectively
It is provided with light path selector, described transmitting terminal is additionally provided with signal receiving module, and this signal receiving module is selected by each light path
Select device and be coupled into corresponding optical signaling paths.
Light path selector can adopt optical fiber circulator.
The composition of receiver module and emitting portion match, including receiving each road optical signal and carry out the decoding of respective handling
Device and detector.
This utility model also provide a kind of high become the point-to-point QKD system of code check receiving terminal, along optical signal transmission direction according to
Secondary inclusion optical fiber interface, wavelength division multiplexer, decoder and detector, described optical fiber interface is for receiving the many of transmitting end signal
Core fibre interface, a road input of the corresponding wavelength division multiplexer of each fibre core of multi-core fiber.
With transmitting terminal in the same manner, the demultiplexing to wavelength-division multiplex signals by wavelength division multiplexer, it is possible to obtain n*m bar quantum is close
Circuit distributed by key, becomes n*m times that code check is that original list covers QKD system.When system two-way communication, become code check can improve about
2n*m times.
Receiving terminal on decoding process with transmitting terminal be adapted, preferably, described decoder be based on when m- phase place solution
The flashlight decoding module of code.
In order to realize two-way communication, preferably, each optical signal transmission between wavelength division multiplexer and decoder
On path, it is respectively equipped with light path selector, described receiving terminal is additionally provided with signal emission module, and this signal emission module is passed through
Each light path selector is coupled into corresponding optical signaling paths.
Light path selector can adopt optical fiber circulator.
The composition of transmitter module and receiving portion match, and can adopt corresponding part in this utility model transmitting terminal,
Will not be described here.
This utility model also provides a kind of high one-tenth point-to-point QKD system of code check, including the transmitting terminal being mutually matched and reception
End, described transmitting terminal is the transmitting terminal of the high one-tenth point-to-point QKD system of code check of the present utility model, logical between transmitting terminal and receiving terminal
Cross the multi-core fiber communication being connected between optical fiber interface.
Preferably, described receiving terminal is the receiving terminal of the high one-tenth point-to-point QKD system of code check described in the utility model.
The beneficial effects of the utility model are as follows：
1st, when system is provided with the light source of n different wave length, m core multi-core fiber, n*m bar quantum key distribution line can be accommodated
Road, becomes n*m times that code check is that original list covers QKD system.
2nd, based on when m- phase place non-equilibrium basic vector coding QKD system scheme, reduce insertion loss and the detection of circuit
Result is not limited the one-tenth code check therefore improving system it is achieved that high-contrast encodes by modulation device precision；Control two groups of bases
The selection percentage of arrow, using non-equilibrium basic vector flashlight is carried out encoding and decoding can lift system further one-tenth code check.
3rd, by the use of optical fiber circulator as light path selector improved two-way communication QKD system, Alice and Bob can
To launch and to receive quantum information simultaneously, system becomes code check to be promoted to about 2n*m times.
Brief description
Fig. 1 is the schematic diagram of this utility model high one-tenth point-to-point QKD system of code check；
Fig. 2 be on single quantum key distribution circuit based on when m- phase place encoding and decoding fundamental diagram；
Fig. 3 be Fig. 1 in QKD system carry out, for each light source, the schematic diagram that four road work(divide multiplexing；
Fig. 4 is the schematic diagram of this utility model high one-tenth code check point-to-point QKD system two-way communication.
Fig. 5 be Fig. 4 in QKD system carry out, for each light source, the schematic diagram that four road work(divide multiplexing.
Specific embodiment
Embodiment 1 one-way communication
As shown in figure 1, a kind of high one-tenth point-to-point QKD system of code check of the present utility model includes the transmitting terminal being mutually matched
(Alice) and receiving terminal (Bob), communicated by multi-core fiber 104 between transmitting terminal and receiving terminal.
Transmitting terminal includes light source module (specifically adopting Laser Slabs), multiple beam splitter (such as beam splitter 101), encoder
(signal pumped FIR laser module), multiple wavelength division multiplexer (such as wavelength division multiplexer 102), the optical fiber sector as multi-core fiber interface
Follower 103.
Be additionally provided with master control logic module, that is, in Fig. 1 Alice electronic equipment, in order to control Laser Slabs and synchronization
Radiant lights and produces modulated signal to signal pumped FIR laser module etc..
Logic control element in the electronic equipment of Alice controls randomizer generation stochastic signal to send to signal
Generator and signal modulator, signal generator controls Laser Slabs to send flashlight corresponding with stochastic signal, controls same simultaneously
Step radiant sends synchronizable optical corresponding with flashlight, and signal modulator produces corresponding modulated signal after receiving stochastic signal, control
Signal pumped FIR laser module processed encodes to optical signal.
Receiving terminal include as multi-core fiber interface optical fiber sector follower 105, multiple wavelength division multiplexer (such as ripple
Division multiplexer 106), decoder (flashlight decoding module), detector (signal optical detection module).
Be additionally provided with data record unit and auxiliary circuit, that is, in Fig. 1 Bob electronic equipment, connect in order to gather
The measurement result of receiving end.The synchronized photo-detector of synchronizable optical receives and is changed into after processing synchronous optical signal, and synchronous optical signal is through prolonging
When control unit delay process, the detection to flashlight, data records list are opened using the trigger as detector module
Unit's record detector module response, flashlight time of advent, synchronizable optical time of advent, according to the time difference of flashlight and synchronizable optical
Obtain the positional information of flashlight, detector module responds the measurement result with flashlight positional information as receiving terminal.
As quantum key distribution circuits all in Fig. 1 are carried out the synchronization of circuit two ends SRU sending-receiving unit by a synchronous optical signal
Control, wherein synchronous radiant is located at transmitting terminal, and synchronous photo-detector is located at receiving terminal.In Fig. 1 the electronic equipment of Alice and
The electronic equipment of Bob all can adopt prior art, and in the present embodiment, each bar quantum key distribution circuit is operation principle and knot
Structure identical circuit, all circuits work asynchronously simultaneously, and all circuits are by a common road electronic equipment drive control.
Laser Slabs are provided with the light source of n different wave length, light source 1～light source n, and the wavelength of each light source corresponds to λ 1～λ respectively
N, each light source corresponds to a beam splitter, can be multiplexed light source, 1*m beam splitter can be by the emergent light work(of each light source
Divide to m bar quantum key distribution circuit, if system has the light source of n different wave length, n*m bar quantum key can be expanded out
Distribution circuit, this improves the one-tenth code check of system while the utilization rate of lift system light source.
Wavelength division multiplexer (such as wavelength division multiplexer 102 or wavelength division multiplexer 106) can be defeated by encoder Different lightwave length
Go out end or the input of decoder different wave length is integrated into an optical fiber, as shown in figure 1, this optical fiber is as optical fiber sector follower
103 a certain input or the optical fiber sector a certain output of follower 105.The application of wavelength division multiplexer can be same in reduction system dimension
When, reduce multiplex system to optical fiber sector follower numbers of branches demand (existing fiber sector follower numbers of branches limited,
It is usually 4 branches and 7 branches).The numbers of branches of wavelength division multiplexer is identical with the quantity of light source of system Different lightwave length, works as system
Have n different wave length light source when, wavelength division multiplexer has n branch, and each branch connects to different light sources.Wavelength-division is multiple
Determined through the quantum key distribution number of, lines that beam splitter separates by each light source with the quantity of device, when using beam splitter to each
Light source carry out m road multiplexing when, then transmitting terminal need m wavelength division multiplexer with will m group Different lightwave length mixed light input answer
With to an optical fiber, the equally receiving terminal in system needs m identical wavelength division multiplexer to carry out the demultiplexing of mixed light, as above
State, now system needs the wavelength division multiplexer of 2m 1*n branch altogether.
Optical fiber sector follower 103 and optical fiber sector follower 105 are in wavelength division multiplexer (such as wavelength division multiplexer 102
With wavelength division multiplexer 106) on the basis of, in system optical fiber sector follower 103 and Optical fibre fan integrated further to system light path
Shape follower 105 is symmetrically the same device.Optical fiber sector follower is the composition of many single-mode fibers and a multi-core fiber
Device, the fibre core of each single-mode fiber is directed at the light of transmission in the different fibre cores of multi-core fiber, each single-mode fiber along multi-core fiber
Corresponding fibre core continues to transmit independent parallelly it is achieved that the spatial reuse of light or demultiplexing.When using m core multi-core optical, optical fiber
There is in fan-shaped follower the independent parallel light path of m bar, accordingly there is the input of m root single-mode fiber or export.Alice end, each
The input of n integrated wavelength of wavelength division multiplexer constitutes a mixed light group (λ1、λ2、...λn) output, and mixed light group is passed
It is input into an input of optical fiber sector follower 103.M wavelength division multiplexer constitutes m group identical mixed light group (λ1、
λ2、...λn), in order to avoid the crosstalk between co-wavelength optical signal, m mixed light group (λ1、λ2、...λn) independent parallelly in optical fiber
Transmission in the different light paths of fan-shaped follower 103.The symmetrical wavelength division multiplexer in system two ends (such as wavelength division multiplexer 102 and ripple
Division multiplexer 106), symmetrical optical fiber sector follower (optical fiber sector follower 103 and optical fiber sector follower 105) and multicore
Optical fiber 104 has collectively constituted the light path of intensive style, carries out the optical transmission of information between encoder.
Synchronous radiant is using the light wavelength lambda different from flashlightn+1, its optical fiber transmission line is through system left end wavelength-division again
With device 107, optical fiber sector follower 103 integrated with the quantum key distribution circuit at Alice end, after through the symmetrical ripple in Bob end
Separate with flashlight after division multiplexer 108 demultiplexing, and input synchronous photo-detector and generate synchronizing signal.
In sum, in point-to-point QKD system, n different light source is carried out m road work(respectively through beam splitter and divide multiplexing
When, the intensive light path forming by wavelength division multiplexer, optical fiber sector follower, m core multi-core fiber, you can realize n*m bar amount
The expansion of quantum key distribution circuit, the one-tenth code check of point-to-point QKD system is improved n*m times.
Fig. 2 props up the fundamental diagram of quantum key distribution circuit for the present embodiment list, and it is tied in double unequal arm MZ interferometers
On structure, flashlight is carried out based on when m- phase place encoding-decoding process.Single quantum key distribution circuit mainly includes transmitting terminal
(Alice), single-mode fiber transmission channel 206, receiving terminal (Bob) three part.Transmitting terminal (Alice) is by light source 1, coding module
(being equivalent to a part for signal pumped FIR laser module) and master control logic module (electronic equipment of Alice) are constituted, and wherein protect and partially divide
Bundle device 201, phase-modulator PM, optical fiber delay coil 202, the inclined polarization beam apparatus 203 of guarantor, intensity modulator 204, strength retrogression
Device 205 constitutes coding module.Receiving terminal (Bob) is by decoder module (being equivalent to the part that flashlight decodes module), detection
Module (being equivalent to the part detecting module) data recording unit is constituted, wherein 207,90 ° of polarization rotators of beam splitter
208th, the inclined polarization beam apparatus 209 of guarantor, optical fiber delay coil 210, polarization-maintaining beam splitter 211 constitute decoder module.Detector module
It is made up of three single-photon detectors, detector D1, detector D2 are used for measuring the single photon pulses of phase decoding output, detect
Device D3 is used for the single photon pulses of time of measuring decoding output.The response value of each detector is gathered and located by data record unit
Reason.
In coding module, decoder module, polarization-maintaining beam splitter 201 and protect between inclined polarization beam apparatus 203 and protect and wilfully shake point
Two light paths up and down between bundle device 209 and polarization-maintaining beam splitter 211 constitute unequal arm MZ interferometer structure, and upper light path is MZ interferometer
Long-armed, the galianconism of lower light path MZ interferometer, light between the long galianconism of quantum key distribution circuit two ends two unequal arm MZ interferometer
Path difference is equal.Transmitting terminal (Alice) and all of device of receiving terminal (Bob) and optical fiber are all that guarantor is inclined.Quantum key distribution line
In road, each device is ripe prior art, can be replaced using other devices of function identical in a particular embodiment.
Light source 1 launches the pulsed light of strong linear polarization.Phase-modulator PM is the phase code unit of flashlight, and it is to warp
The light pulse crossed randomly carries out 0 or π phase-modulation.Intensity modulator 204 is the time encoding unit of flashlight, and it is to circuit
Two light pulses of left end MZ interferometer long galianconism output carry out intensity modulated, randomly one of optical pulse intensity are decayed
It is the vacuum state close to 0.
In the electronic equipment of Alice in Fig. 2, each device plays and identical effect in Fig. 1, wherein signal modulator according to
The stochastic signal that randomizer produces, is randomly chosen phase-modulator PM or intensity modulator 204, and controls phase place to adjust
The device PM processed or intensity modulator 204 random coded process to flashlight.
In FIG in the electronic equipment of Alice, each coding module for signal pumped FIR laser module has individually
Signal modulator is attached thereto, and realizes and Fig. 2 identical function, and all signal modulators are subject to common randomizer control
System.
Optical fiber delay coil 202 and optical fiber delay coil 210 are used for increasing the long-armed light path of MZ interferometer, with MZ interferometer
Form optical path difference between long galianconism.
Polarization-maintaining beam splitter 201, on the premise of keeping the original polarization state of input light, realizes the beam splitting of light wave power.
Polarization-maintaining beam splitter 211, on the premise of keeping the original polarization state of input light, realizes conjunction bundle and the beam splitting of light wave power.
Protect inclined polarization beam apparatus 203 and the inclined polarization beam apparatus 209 of guarantor realize polarization combiner and polarization in the line respectively
The function of light beam splitting, and realize carrying out 90 ° of changes to fixing branch road light polarization direction.
Intensity attenuators 205 are used for for input light decaying to the other light pulse of single-photon-level.
Beam splitter 207 is common 1*2 luminous power beam splitter, and in the output of its two-way, a road connects flashlight phase decoding unit
(the unequal arm MZ interferometer structure of 90 ° of polarization rotators 208 and circuit right-hand member), another road connects the spy of flashlight time decoder
Survey device cells D 3.Beam splitter 207 splitting ratio as needed depending on, it is not modulated by the active of electronic equipment in the line, as
Passive modulation device (compared with the active modulation device controlling with electronic equipment, passive modulation device cost is relatively low), works as splitting ratio
For 50：During value beyond 50, define based on when the non-equilibrium basic vector of m- phase place coding and decoding scheme.System here is with different
Ratio selected phase basic vector or time basic vector carry out decoding and the detection process of flashlight.90 ° of polarization rotators 208 are used for entering
The polarization direction penetrating light rotates 90 °, and such as orthogonal polarized light (V) is changed into horizontal polarization light (H) or inverse process.
In phase place encoding-decoding process, as shown in Figure 2, in Alice transmitting terminal, light source 1 sends strong linearly polarized photon arteries and veins
Punching (H), in circuit left end MZ interferometer galianconism and long-armed middle formation two bundle identical horizontal lines after polarization-maintaining beam splitter 201 beam splitting
Polarisation (Ha、Hb), a, b represent two outfans of polarization-maintaining beam splitter 201 respectively, also represent circuit left end MZ respectively and interfere
The galianconism of instrument and long-armed.
Light pulse (H in galianconisma) directly input the inclined polarization beam apparatus 203 of guarantor, long-armed middle light pulse through polarization maintaining optical fibre transmission
(Hb) it is phase-modulated the phase-modulation that device PM carries out 0 or π at random, input after the delay transport through optical fiber delay coil 202 is protected
Polarization beam apparatus 203 partially.Through protecting inclined polarization beam apparatus 203 before and after above-mentioned two light pulses, guarantor's inclined polarization beam apparatus 203 are according to defeated
The different choice ground of inbound port changes light pulse (Hb) polarization direction, be changed into light pulse (V after being rotated 90 °b)；Light arteries and veins
Punching (Ha) polarization direction do not change.Protect the orthogonal light pulse (H in two polarization directions before and after inclined polarization beam apparatus 203 final outputa、
Vb), and two light pulse (Ha、Vb) be attenuated after intensity attenuators as single photon rank.
Two light pulses reach Bob receiving terminal through single-mode fiber transmission channel 206.In Bob receiving terminal, after beam splitter 207
Enter two light pulse (H before and after 208,90 ° of polarization rotators 208 of 90 ° of polarization rotators changea、Vb) polarization direction be two smooth arteries and veins
Punching (Va、Hb), protect inclined polarization beam apparatus 209 by light pulse (Va) 90 ° of change of polarized direction incoming line right-hand member MZ interferometer
In long-armed, by light pulse (Hb) be sent directly in interferometer galianconism.So far, before respectively in the galianconism of circuit left end MZ interferometer
Light pulse (H with long-armed middle transmissiona、Hb) after same single-mode fiber transmission channel 206, in circuit right-hand member MZ interferometer
Galianconism and long-armed in carried out Cross transfer, that is, the galianconism of circuit right-hand member MZ interferometer and long-armed respectively transmit light pulse (Hb、
Ha).
Because the optical path difference between the long galianconism of two ends MZ interferometer is identical, two light pulses are through same fiber-optic transfer channel
206, the light path of therefore two light pulses is identical, i.e. two light pulses reach polarization-maintaining beam splitter 211 simultaneously.Because two light pulse (Ha、Hb)
For same frequency light, light polarization direction is identical, have stable phase potential difference 0 or the π of phase-modulator PM modulation, that is, meet interference of light bar
Part, therefore two light pulse (Ha、Hb) interfere on polarization-maintaining beam splitter 211.When phase-modulator PM has randomly choosed 0 phase-modulation
When, detector D1 responds；When phase-modulator PM has randomly choosed π phase-modulation, detector D2 responds.
In the encoding-decoding process of time, as shown in Figure 2, identical with phase place encoding-decoding process, the strong line that light source 1 sends
Property polarized optical pulse (H) after the MZ interferometer of circuit left end, with former and later two light pulses (Ha、Vb) form output.This phase
One of light pulse is modulated to vacuum state by position manipulator 204 at random, and intensity attenuators 205 are by two light pulse (Ha、Vb) decline
It is kept to single photon rank, and transmit arrival Bob receiving terminal through single-mode fiber transmission channel 206.Two light pulse (Ha、Vb) warp
Cross and enter detector cells D3 after beam splitter 207, detector D3 by with the working asynchronously of Alice transmitting terminal, to two light pulses
Carry out time resolution seizure, and measure the light intensity value of before and after two pulse, finally draw the quantum state of time decoder.
The quantum state of phase place encoding and decoding acquisition quantum state and time encoding and decoding acquisition together constitutes the quantum of Bob receiving terminal
State sequence.After being compared by Alice and Bob basic vector, both sides have obtained primary key, then after the corrected, data such as privacy is amplified
Process operation, both sides finally give identical safe key.Refer to than reciprocity Data Post process with regard to basic vector
Christian Kollmitzer etc. writes《Appliced Quantum Cryptography》In one book, chapter 3 is with regard to amount
The associated description of quantum key distribution.
When Fig. 3 is to carry out 4 road work(to system source to divide multiplexing, structure schematic diagram of the present utility model.In figure only draws
The quantum key distribution circuit of point-to-point QKD system, it is identical with Fig. 1 that synchronizable optical sends out take-up road, i.e. all quantum key distribution
Circuit is used in conjunction with a synchronous optical signal, and synchronizable optical light path is incorporated in corresponding light group by a certain wavelength division multiplexer in transmitting terminal and passes
Defeated, and with the transmission of this light group in the same fibre core of optical fiber sector follower, the symmetrical wavelength division multiplexer solution in final receiving end
Multiplexing, is detected by synchronous photo-detector and processes and generate synchronous optical signal, act on the detecting module of receiving terminal.
In the present embodiment, Laser Slabs are integrated with the light-pulse generator of 5 different wave lengths, and external electronic device controls 5 pulsed lights
Source works asynchronously.4 road work(are carried out to the emergent light of each light-pulse generator using 1*4 beam splitter and divides multiplexing, draw 4 quantum respectively
Key distributes circuit.Now system is by using 8 1*5 wavelength division multiplexers, the optical fiber sector follower of 2 1*4 ports and four cores
The intensive light path of optical fiber composition, carries out signal pumped FIR laser module and flashlight decodes the optical transmission of information between module.This enforcement
The light source of 5 different wave lengths is carried out 4 road work(through beam splitter and divides multiplexing by example respectively, by above-mentioned intensive style light path, achievable 5*4
The expansion of bar quantum key distribution circuit, the one-tenth code check of point-to-point QKD system is improved 5*4 times.
In figure 3, the system of explanation carries out 5*4 bar quantum taking 4 quantum key distribution circuits that light source 1 is drawn as a example
Key is distributed circuit and is expanded encoding and decoding and detection process with flashlight.It is close that light source 1 introduces 4 quantum by 1*4 beam splitter 301
Circuit distributed by key.On the 1st article of quantum key distribution circuit, polarization-maintaining beam splitter 302, phase-modulator PM, optical fiber delay coil
303rd, the inclined polarization beam apparatus 304 of guarantor, intensity modulator 305, intensity attenuators 306 constitute coding module, and other 3 quantum are close
The coding module composition that circuit distributed by key is same.Article 4, the encoded module coding of flashlight on quantum key distribution circuit
After respectively enter 4 identical 1*5 wavelength division multiplexers (such as wavelength division multiplexer 307), the letter of the 1st article of quantum key distribution circuit
Number light enters an input of wavelength division multiplexer 307.Carry out quantum when system enables other 4 light sources (light source 2 is to light source 5)
When key distributes the expansion of circuit, other 4 light sources (light source 2 is to light source 5) are each introduced into 4 new quantum in the same way
Key distributes circuit, and 4 quantum key distribution circuits that same light source introduces respectively enter above-mentioned 4 after encoded module
Individual 1*5 wavelength division multiplexer (such as wavelength division multiplexer 307).External electronic device controls all quantum key distribution circuits simultaneously
Phase code unit (phase-modulator PM) or time encoding unit (intensity modulator), respectively believe in the electronic equipment of Alice
Number manipulator controls the Stochastic Modulation process to flashlight for each phase-modulator PM or each intensity modulator simultaneously.In 1*5 wavelength-division
After the interior five kinds of input optical wavelength ECDC bundles of multiplexer (such as wavelength division multiplexer 307) in the form of mixed light group in an optical fiber
Continue transmission, 4 1*5 wavelength division multiplexers (such as wavelength division multiplexer 307) of Alice export 4 light groups.Defeated through optical fiber sector
Go out the coupling of device 308,4 light group individual transmission in the different fibre cores of four-core fiber 309 respectively, and by a symmetric fiber
Enter 4 different single-mode fibers after the coupling output of fan-shaped follower 310 and continue transmission.4 light component supplementary biographies are input into Bob's
4 1*5 wavelength division multiplexers (such as wavelength division multiplexer 311), here will carry out the beam splitting process of five kinds of optical wavelength.Draw in light source 1
On the 1st article of quantum key distribution circuit entering, 312,90 ° of polarization rotators 313 of beam splitter, the inclined polarization beam apparatus 314 of guarantor, optical fiber
Delay winding 315, polarization-maintaining beam splitter 316 constitute decoder module, and detector D1, detector D2, detector D3 constitute detection
Module, in system, other quantum key distribution circuit correlation modules composition is same.4 1*5 wavelength division multiplexer (examples of Bob
As wavelength division multiplexer 311) each outfan be connected to decoder module and the detecting module of flashlight, quantum key distribution line
Here is completed decoding and the detection process of flashlight by road.
Embodiment 2 two-way communication
Fig. 4 be can two-way communication high become the point-to-point QKD system of code check.It is the improvement project of embodiment 1, using optical fiber
Circulator (such as optical fiber circulator 401 and optical fiber circulator 407) is distinguished in the Alice transmitting terminal of embodiment 1 and Bob receiving terminal
Add the device symmetrical with former multiplex system：Flashlight decoding module 2, signal optical detection module 2 and Laser Slabs 2, flashlight are compiled
Code module 2, makes the quantum communications of forward and reverse direction share wavelength division multiplexer (such as wavelength division multiplexer 402 and wavelength division multiplexer
406), optical fiber sector follower (optical fiber sector follower 403 and optical fiber sector follower 405) and multi-core fiber 404 form
Intensive light path, increase in systems simultaneously a Bob end to Alice end synchronizable optical send out take-up road (synchronous radiant 2 to
Synchronous photo-detector 2).Optical fiber circulator (such as optical fiber circulator 401 and optical fiber circulator 407) selects as the path of light output
Select that device optical signal 1 is incident from port 1, through circulator Path selection by port 2 outgoing, optical signal 2 is incident from port 2,
Through circulator Path selection by port 3 outgoing.
Can be same by adding the master control logic module data recording unit symmetrical with former multiplex system and auxiliary circuit
When drive control Alice end and the quantum information at Bob end send out receipts process, synchronous radiant 1 and synchronous photo-detector 1 constitute synchronization
Light sends out take-up road 1, for the synchronization of transmitting terminal Alice and receiving terminal Bob when controlling positive communication；Synchronous radiant 2 and synchronization
Photo-detector 2 constitutes synchronizable optical and sends out take-up road 2, for controlling the synchronization of transmitting terminal Bob and receiving terminal Alice during reverse link communication.
As above-mentioned, Alice and Bob can send simultaneously and accept quantum information, and therefore system becomes code check to improve to about 2n*m times.
The list of intercommunication system prop up quantum key distribution circuit still using embodiment 1 (in Fig. 2) based on when m- phase place
The QKD structure of encoding scheme, no longer repeats herein.The communication in two kinds of directions of system has each independent encoding and decoding and detection etc.
Device, both are only multiplexed above-mentioned integrated optical circuit.
When Fig. 5 is to carry out 4 road work(to system source to divide multiplexing, structure schematic diagram of the present utility model.Two ends light source is sent out
The flashlight going out encodes through two ends coding module, and the flashlight of coding is in each end optical fiber circulator (such as optical fiber circulator
501) there is Path selection in place, and for transmitting terminal, flashlight is inputted and exported by port 2 by port 1, all light sources (light source 1 to
Light source 5) flashlight that sends sentences same light group in wavelength division multiplexer (such as wavelength division multiplexer 502 and wavelength division multiplexer 503)
(λ 1, λ 2 ... λ 5) form to enter wavelength division multiplexer (such as wavelength division multiplexer 502 and wavelength division multiplexer 507), optical fiber fan-shaped
Follower (optical fiber sector follower 504 and optical fiber sector follower 506), the light path of the intensive style of multi-core fiber 505 composition, and
In the other end demultiplexing of intensive light path, each detached flashlight is in optical fiber circulator (the such as fiber optic loop of the system other end
Shape device 508) there is Path selection in place again, and for receiving terminal, flashlight is inputted and exported by port 3 by port 2, the signal of output
Light is detected by corresponding detector after each decoder module decodes.Alice and Bob can quantum information simultaneously, through simultaneously
Encoding and decoding, receive at two ends simultaneously, and now the one-tenth code check of system is 2*4*5 times.Fiber optic splitter, coding module, solution in system
In code module, detecting module and embodiment one Fig. 3, composition and function phase are same, no longer describe one by one herein.
Claims (12)
1. a kind of transmitting terminal of the high one-tenth point-to-point QKD system of code check, includes light source module, coding successively along optical signal transmission direction
Device, wavelength division multiplexer and optical fiber interface, are additionally provided with the master control logic module for sending control signal to encoder, and its feature exists
In described light source module includes multiple light sources and is respectively provided with different emission, and the outfan correspondence of each light source is connected with
One beam splitter, the output of corresponding light source is divided into multipath light signal and exports and encoded respectively to encoder by beam splitter；Described
Optical fiber interface is multi-core fiber interface, for the optical signal from wavelength division multiplexer is forwarded to multi-core fiber to send out to receiving terminal
Penetrate.
2. as claimed in claim 1 high become the point-to-point QKD system of code check transmitting terminal it is characterised in that in described encoder
There is the one-to-one coding module with each road optical signal, in described master control logic module, be configured with phase for every road coding module
The signal modulator answered, all signal modulators share the same randomizer in master control logic module.
3. as claimed in claim 1 high become the point-to-point QKD system of code check transmitting terminal it is characterised in that described encoder is
Based on when m- phase code signal pumped FIR laser module.
4. the transmitting terminal of the high one-tenth point-to-point QKD system of code check as claimed in claim 1 is it is characterised in that described beam splitter is
Multiple, and each light source one-to-one corresponding, described wavelength division multiplexer is multiple, and the input of each wavelength division multiplexer terminates each beam splitter
Wherein one tunnel output, the outfan of each wavelength division multiplexer accesses multi-core fiber interface corresponding one of fibre core.
5. as claimed in claim 4 high become the point-to-point QKD system of code check transmitting terminal it is characterised in that each beam splitter point
Bundle quantity is identical, and is equal to the number of wavelength division multiplexer.
6. the transmitting terminal of the high one-tenth point-to-point QKD system of code check as claimed in claim 1 is it is characterised in that be additionally provided with synchronizable optical
Light source and corresponding synchronizable optical transmitting circuit, wherein synchronous radiant accesses the input of arbitrary wavelength division multiplexer.
7. as described in any one of claim 1～6 high become the point-to-point QKD system of code check transmitting terminal it is characterised in that in institute
State on each optical signaling paths between encoder and wavelength division multiplexer, be respectively equipped with light path selector, described
Transmitting terminal is additionally provided with signal receiving module, and this signal receiving module is coupled into corresponding optical signal by each light path selector
Transmission path.
8. a kind of receiving terminal of the high one-tenth point-to-point QKD system of code check, includes optical fiber interface, wavelength-division successively along optical signal transmission direction
Multiplexer, decoder and detector are it is characterised in that described optical fiber interface is to connect for receiving the multi-core fiber of transmitting end signal
Mouthful, a road input of the corresponding wavelength division multiplexer of each fibre core of multi-core fiber.
9. the receiving terminal of the high one-tenth point-to-point QKD system of code check as claimed in claim 8 is it is characterised in that described decoder is
Based on when m- phase decoding flashlight decoding module.
10. the receiving terminal of the high one-tenth point-to-point QKD system of code check as claimed in claim 8 or 9 is it is characterised in that answer in wavelength-division
With, on each optical signaling paths between device and decoder, being respectively equipped with light path selector, described receiving terminal is also
It is provided with signal emission module, this signal emission module is coupled into corresponding optical signal transmission road by each light path selector
Footpath.
11. a kind of high become the point-to-point QKD system of code check, including the transmitting terminal being mutually matched and receiving terminal it is characterised in that described
Transmitting terminal is transmitting terminal, transmitting terminal and the receiving terminal of the high one-tenth point-to-point QKD system of code check described in any one of claim 1～7
Between by the communication of the multi-core fiber that is connected between optical fiber interface.
12. the high one-tenth point-to-point QKD system of code check is it is characterised in that described receiving terminal will for right as claimed in claim 11
Seek the receiving terminal of the high one-tenth point-to-point QKD system of code check described in 8～10 any one.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108880808A (en) * | 2018-08-06 | 2018-11-23 | 广东石油化工学院 | A kind of quantum-key distribution equipment is at code rate test method and system |
| CN110620655A (en) * | 2019-05-06 | 2019-12-27 | 科大国盾量子技术股份有限公司 | Polarization multiplexing bidirectional quantum key distribution method and system |
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2016
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108880808A (en) * | 2018-08-06 | 2018-11-23 | 广东石油化工学院 | A kind of quantum-key distribution equipment is at code rate test method and system |
| CN110620655A (en) * | 2019-05-06 | 2019-12-27 | 科大国盾量子技术股份有限公司 | Polarization multiplexing bidirectional quantum key distribution method and system |
| CN110620655B (en) * | 2019-05-06 | 2023-01-31 | 科大国盾量子技术股份有限公司 | Polarization multiplexing bidirectional quantum key distribution method and system |
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