CN106209361B - A kind of star-like quantum key distribution network still can guarantee safety without credible relaying - Google Patents
A kind of star-like quantum key distribution network still can guarantee safety without credible relaying Download PDFInfo
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- CN106209361B CN106209361B CN201610585336.8A CN201610585336A CN106209361B CN 106209361 B CN106209361 B CN 106209361B CN 201610585336 A CN201610585336 A CN 201610585336A CN 106209361 B CN106209361 B CN 106209361B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0819—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s)
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0852—Quantum cryptography
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Abstract
The invention discloses a kind of star-like quantum key distribution network without credible relaying based on MDIQKD agreement.The present invention is extended to Star Network structure in point-to-point MDIQKD system-based, not only saves network resource consumption, but also solves network extension bring difficulty.Equipment used in light-source structure proposed by the present invention, time feedbacking scheme, phase feedback scheme and polarization feedback scheme is simple and reusable, keeps quantum key distribution network simpler, it is easier to integrated and can reduce cost.But also it can further realize that safety, high speed and large-scale engineering, functionization are laid a good foundation by further optimizing reduction feedback requirements for quantum secret communication.
Description
Technical field
The present invention relates to optical fiber transmission of quantum private communication technology field, in particular to a kind of credible relaying still can guarantee peace
Complete and stable high speed star-like quantum key distribution network.
Background technique
Quantum secret communication is new branch of science of the quantum mechanics in conjunction with contemporary cryptology, the quantum secret communication amount of including
The research directions such as quantum key distribution, quantum secret sharing, Quantum Secure Direct Communication, quanta identity authentication, and most common of them
Also gradually one kind of functionization is quantum key distribution.Due to quantum key distribution be using quantum-mechanical basic principle as
Basis, along with the communication mode of " one-time pad " to ensure that communication is at being perfectly safe for physics level, for
It is undoubtedly very important for the very important national defence unit of confidentiality, financial industry, government department etc..
From 1984 first quantum key distribution agreement (BB84 agreement) propose to today had nearly 30 years when
Between, various forms of quantum key distribution agreements constantly propose, but the quantum key distribution based on BB84 agreement is to mesh
Before until use most widely agreement.Due to the importance of quantum secret communication, point-to-point quantum key distribution and networking
Quantum secret communication cause national governments and the highest attention of scholar.
However, with the continuous development of quantum key distribution system and network, it is some existing for real system not to be inconsistent rationally
Also gradually it is exposed by the defect of hypothesis, is easy by quantum hacker attack.The foremost attack in light source part is number of photons point
From attack, it is using there are the loopholes of multi-photon ingredient to be attacked in non-ideal single-photon source.It proposes later and inveigles state reason
By having effectively turned off the attack loophole.Compared to the attack of light source, the problem of end of probe of QKD system, then becomes apparent from more intractable.
It is currently suggested a variety of attacks for detecting devices, such as wavelength attack, time shift attack, dead time attack, strong photic blind attacks
It hits, and the actual attack system based on these schemes has also carried out attack demonstration.In addition to these it has been found that system leakage
Hole, however it remains many potential threats, this makes QKD real system impossible to guard against.
Current most of QKD networks are all based on the structure of credible relaying, and the section of the network center based on hub-and-spoke configuration
Point reduces network construction expense frequently as receiving end, to save detector resource.However, once credible relaying is by for measurement
The attack of equipment, then collapsing the safety of entire QKD network.
Luo Kaiguang group, Canada in 2012 proposes the unrelated quantum key distribution agreement (MDIQKD) of measuring device, the association
It is easily hidden by the safety of hacker attack successfully to solve measuring system in actual environment independent of measuring device for the safety of view
Suffer from, substantially increases the safety of real quantum key distribution system.However the real system having been carried out at present is point-to-point
MDIQKD system many difficulties will be present and need to solve when Point-to-Point system expands to network system.Firstly, multiple use
Family point is in different places, and they need work just to can guarantee that whole network system efficiently generates under the same clock
Key.Secondly, the benchmark of the space encoder of all users needs unanimously, if it is coding on polarized spatial, then require each
The polarization benchmark that user reaches at central node is consistent；If it is coding on phase space, then require each user's
The phase reference of interferometer is consistent.Finally, Bell's state measurement is the core technology of MDIQKD agreement, and switch different user
When, need to guarantee the Stability and veracity of Bell's state measurement, this mode for depending on the interference of discrete laser is consistent, and is wrapped
Include wavelength mode, time mode etc..This will become extremely difficult in the multi-user case.
Summary of the invention
The present invention is easy under attack and leads to unsafe problem for the existing QKD network based on credible relaying,
A kind of safety for not needing credible relaying, high speed and stable quantum key distribution network are proposed, which is based on MDIQKD
Agreement sets up star-like MDIQKD network, do not require wherein heart node be credible relaying, greatly improve the peace of whole network
Quan Xing.The present invention is extended in point-to-point MDIQKD system-based by series of new techniques achievable at a high speed and stable
Star Network structure, saves network resource consumption, and it is difficult also to solve network extension bring.
Still guarantee in safe QKD network in the credible relaying that do not need of the invention, all transmissions as legitimate user
Side is placed at the outer end node in Star Network, and Bell's state measuring device is placed at the central node of Star Network, can
To be shared by all users, reduce the construction cost of network.Outer end node passes through the light exchange connection Bell at central node
State measuring device.By the switching of optical switch, any 2 users may be coupled to Bell's state measuring device progress MDIQKD and mention
Take security key.
One aspect of the present invention disclose it is a kind of without it is credible relaying still guarantee safe star-like quantum key distribution
Network comprising a central node and a plurality of clients being attached thereto through respective quantum channel, and only there are two use simultaneously
Family end (its role is respectively A or B) is switched access central node.Each user terminal exports encoded and intensity and meets trick state
The pulse light that scheme requires.Bell's state measuring device in central node is according to the measurement result of the signal light to user terminal
Judge whether to constitute legal Bell's state；When thinking to constitute legal Bell's state, legal Bell's state information is sent to user
Hold A, B.User terminal A, B carry out basic vector to the legal Bell's state received according to the Data Post process of MDIQKD protocol contents
Comparison, error correction and privacy amplification, finally generate security key.
It in one aspect of the invention, can also include phase feedback module, time feedbacking in quantum key distribution network
One or more of module, polarization feedback module, to guarantee the Stability and veracity of Bell's state measurement.Wherein, phase is anti-
Feedback module can be used for eliminating undesirable phase reference drift in Star Network.Time feedbacking module may be used to obtain user
The time mode that the pulse light of end output reaches central node is consistent.Polarization feedback module can be used for compensating quantum channel
On polarization scrambling.
In one aspect of the invention, quantum key distribution network can also by a key light source and be respectively placed in it is each
Multiple light sources 8 constituted from source ends in user terminal.Slave source ends in each user terminal have identical structure, and as letter
Number light source uses.Key light source may include main laser 8-1 and beam splitter 8-2.The continuous light that main laser 8-1 is issued is through dividing
Beam device 8-2 is divided into after the continuous light of multichannel the slave source ends through respective optic path into each user terminal respectively.From source ends
It may include intensity modulator 8-3, from laser 8-4 and phase-modulator 8-5.Intensity modulator is for continuous light to be chopped into
Light pulse, to excite as seed light source from the better pulse light of laser 8-4 output spectrum performance.Phase-modulator 8-
5 for carrying out randomization modulation to the phase of pulse light, to evade the loophole of phase leaking.Based on this light-source structure,
The consistency of the signal light of each user terminal spectrally can be realized automatically.
Further, user terminal can also include unequal arm the Mach once special interferometer 12,13,14, intensity modulated of polarization-maintaining
Device 9,10,15,16 and phase-modulator 17.Wherein, the unequal arm Mach pulse that once special interferometer is used to export from source ends
Signal light is divided into two pulse components；Intensity modulator is configured to carry out intensity modulated to the two pulse components, so that in Z
Only retain one of them under basic vector, or allow two pulse components to pass through under X basic vector, to form time encoding；Phase tune
Device processed is configured to add random phase between two pulse components under X basic vector, to form phase code.Further
Ground, user terminal can also include adjustable attenuator, for making the number of photons by time bit-phase code pulse light
Level decays to light intensity value required for inveigling state scheme.
In another aspect of the invention, from the intensity modulator 8-3 in source ends may be configured to continuous light into
2 copped wave of row, so that generating 2 light pulses under X basic vector or only retaining a light pulse under Z basic vector, using as seed
Light source activation is from the better pulse light of laser 8-4 output spectrum performance.Phase-modulator 8-5 is used for pulse light
Phase carry out randomization modulation.By this set, it is possible to reduce user terminal is for carrying out time bit-phase code light
Device is learned, the complexity and construction cost of system are reduced, and is made without carrying out phase feedback in a network.
In another aspect of the invention, time feedbacking module may include the multiple users being divided into a plurality of clients
End part and a measurement end part in central node, and a plurality of clients part structure having the same.When work,
It measures end part and exports two different wave length λ based on same clockA、λBSynchronizable optical.Synchronizable optical λABy central node and use
Additional optical path between the B of family end is transferred into user's end part in user terminal B.User's end part in user terminal B will synchronize
Light λACentral node is returned to through the quantum channel between user terminal B and central node.Central node is by synchronizable optical λAThrough centromere
Additional optical path between point and user terminal A is sent to user's end part in user terminal A.User's end part in user terminal A
In, it is based on synchronizable optical λARelatively high-frequency clock signal of system is generated, to trigger the slave laser 8-4 in user terminal A
It shines, while the clock reference for being used for signal light modulation being provided.
Further, in time feedbacking module of the invention, measurement end part may include a clock source, two
Adjustable delay chip 62, two have different wave length λAAnd λBSynchronous laser 63A, 63B, two the first wavelength division multiplexers
67A, 67B, the first photoswitch 71 and two the second wavelength division multiplexers 701,702.User's end part may include two pole of photoelectricity
Pipe 65, phase-locking frequency multiplication circuit 66, the second photoswitch 72, third wavelength division multiplexer 68A, 68B and the 4th wavelength division multiplexer 69A,
69B.Wherein, first, third wavelength division multiplexer, which may be configured to its reflection end, allows synchronizable optical λBPass through, transmission end allows same
Walk light λAPass through；The second, the 4th wavelength division multiplexer, which may be configured to its reflection end, allows synchronizable optical to pass through, and transmission end allows to use
The signal light of family end output passes through.The low frequency synchronisation trigger signal of clock source output triggers after the processing of adjustable delay chip delays
Synchronous light laser 63A, 63B issue two synchronizable optical λA、λB.The reflection end of first wavelength division multiplexer 67A connects synchronous ray laser
Device λBOutput end, transmission end connect the second wavelength division multiplexer 702 reflection end.The transmission end of first wavelength division multiplexer 67B connects
Meet synchronous light laser λAOutput end, reflection end connect the second wavelength division multiplexer 701 reflection end.Second wavelength division multiplexer
701,702 transmission end is separately connected Bell's state measuring device of central node.When work, the first photoswitch 71 can be configured
At make the common end of the first wavelength division multiplexer 67A through additional optical path connection third wavelength division multiplexer 68A common end, first wave
Common end of the common end of division multiplexer 67B through additional optical path connection third wavelength division multiplexer 68B.In user terminal B, second is opened
Closing 72B may be configured so that the transmission end of third wavelength division multiplexer 68B connects the reflection end of the 4th wavelength division multiplexer 69B,
Reflection end connects photodiode 65B.Photodiode 65B may be configured to for synchronizable optical to be converted into synchronous electric signal with
High frequency system clock signal is generated in phase-locking frequency multiplication circuit, generates signal light in user terminal B for triggering.The letter of user terminal B
Number light is sent to the transmission end of the 4th wavelength division multiplexer 69B.In user terminal A, second switch 72A is configured so that third
The reflection end of wavelength division multiplexer 68A connects the reflection end of the 4th wavelength division multiplexer 69A, and transmission end connects photodiode 65A.Light
Electric diode 65A may be configured to for synchronizable optical to be converted into synchronous electric signal to be used for phase-locking frequency multiplication circuit 66A generation high frequency
Clock signal of system generates signal light in user terminal A for triggering.It is multiple that the signal light of user terminal A is sent to the 4th wavelength-division
With the transmission end of device 69B.The common end of 4th wavelength division multiplexer 69A, 69B is respectively through user terminal A, user terminal B and central node
Between quantum channel connect the second wavelength division multiplexer 701,702 common end.Consider from total time, for user terminal A's
The signal light of synchronizable optical and user terminal A and the signal light of synchronizable optical and user terminal B for user terminal B are reaching central node
It experienced identical optical path when Bell's state measuring device, thus be cancelled all possible time change in optical path will, two
Without carrying out time feedbacking when the signal light that user finally generates reaches central node, it is only necessary to be carried out by time delay chip
The calibration of regular time difference.In the time feedbacking module that this aspect of the invention is related to, synchronizable optical can also be avoided
Transmission direction and signal light reverse transfer, the influence of noise so as to avoid reversed Raman scattering to signal light.
Further, the class for being switched two user terminals of access central node can be distributed and informed by central node
Type is A or B.
In the present invention, Bell's state measuring device in central node may include a polarization-maintaining beam splitter and be placed on guarantor
2 single-photon detectors of 2 output ports of inclined beam splitter.
In the present invention, the signal light of user terminal output can exchange the guarantor for being exported to Bell's state measuring device by light
The input terminal of inclined beam splitter.
In the present invention, selection may is that Bell's state is surveyed after Bell's state of time bit-phase code MDIQKD scheme
2 detectors in amount equipment respectively judge the time location of detection, if 2 detectors have response, and same
One time cycle, and a detection is in time location 0, a detection is in (the time of position 0 and position 1 of time location 1
The arm length difference of the corresponding unequal arm Mach of difference once special interferometer), then it is assumed that it is at this time legal Bell's state.
In the present invention, phase feedback module can use following working method: the unequal arm Mach in all user terminals
Once special interferometer was all referring to the once special interferometer of another unequal arm Mach at central node, the input terminal of another interferometer
Connect wavelength phase feedback laser identical with the signal light laser in user terminal, and the feedback light of output end output
It is divided at least n subport (user's number that n is Star Network) by beam splitting, then is connected to each user terminal through optical path respectively.
The feedback light is monitored device after the unequal arm Mach in user terminal once special interferometer and receives and monitor, and one way in which can
To monitor counting rate using single-photon detector, another way can monitor performance number using power meter.It is dry in user terminal
The phase drift of interferometer can be reflected in the monitoring results such as counting rate or performance number, inside the interferometer by adjusting user terminal
The voltage of phase shifter compensates this phase drift.
In the present invention, polarization feedback module can use following working method: photoswitch and guarantor in central node
Polarization Controller and polarization-maintaining PBS are inserted between inclined beam splitter.Wherein, the reflector port of polarization-maintaining PBS places a single photon detection
Device adjusts the voltage loaded on Polarization Controller by recording the counting rate of single-photon detector, to form a polarization
Feedback closed loop.Advantageous effects of the invention:
1) all measuring devices are attacked due to MDIQKD agreement all immune, previous all utilizes receiving end so as to eliminate
It is existing when as credible relaying to be easy by the hidden danger of quantum hacker attack.
2) since measuring system is higher compared to light-source system cost, system is more complicated huge, it is unfavorable for integrating, it is of the invention
Using central node as receiving end, the measuring device for being included can be total to star-like MDIQKD network by all legal user terminals
It enjoys, so network construction cost can be greatly reduced.
3) all user terminals are all signal light senders, and sender mainly includes laser and modulation device, compared to reception
The measuring device at end is cheap, simply and readily integrated, therefore, when number of network node increases, it is only necessary to increase sender
And the photoswitch port number at central node, it advantageously reduces network construction cost and facilitates the extension of the network user.
4) the automatic full of each user terminal signal light wavelength coherence request may be implemented in light-source structure used in the present invention
Foot, without additional wavelength feedback, the realization difficulty of wavelength feedback technology needed for thus greatly reducing previous system.
5) the another preferred embodiment of light-source structure proposed by the present invention can meet phase stabilization requirement automatically, without additional
Phase feedback, thus phase feedback technical difficulty needed for reducing previous system.
6) a kind of time feedbacking module with time automatic compensation function proposed by the present invention, which can allow, is switched in access
When the signal light of two user terminals of heart node reaches Bell's state measuring device, the variation of time mode is cancelled to protect automatically
It holds relatively stable, not will receive the influence of time drift in optical path.Moreover, the design structure for using optimization in the program can be with
Synchronous optical transmission direction and signal light reverse transfer are avoided, influence of noise of the reversed Raman scattering to signal light is avoided.It should be certainly
Device used in dynamic compensation scheme is simple, further such that the quantum key distribution network be easy to extend and cost substantially under
Drop, the network further realize large-scale engineering and functionization is laid a good foundation.
Detailed description of the invention
Fig. 1 (a) is of the invention without the structural framing figure of the star-like quantum key distribution network reliably relayed.
Fig. 1 (b) is the structural framing figure of the quantum key distribution network of the shared measuring system of the prior art.
Fig. 2 schematically shows the system according to the present invention based on the star-like MDIQKD network of time bit-phase code
Index path.
Fig. 3 diagrammatically illustrates the phase feedback module of star-like MDIQKD network according to the present invention.
Fig. 4 diagrammatically illustrates the time feedbacking module of star-like MDIQKD network according to the present invention.
Fig. 5 diagrammatically illustrates another embodiment of the time feedbacking module of star-like MDIQKD network according to the present invention.
Fig. 6 diagrammatically illustrates the alternative embodiment of the light source for star-like MDIQKD network of the invention.
Specific embodiment
With reference to the accompanying drawings and examples, specific embodiments of the present invention will be described in further detail.Implement below
Example is not intended to limit the scope of the invention for illustrating the present invention.
Fig. 1 (a) shows the structural framing figure of the quantum key distribution Star Network without credible relaying of the invention, should
Quantum key distribution network uses MDIQKD agreement, and including 3 users (but number of users of distribution network of the invention and unlimited
It in 3, and can be any number of).As shown in Fig. 1 (a), which includes 3 user 1-3 and central node.
Central node as receiving end (measurement end) use, may include photoswitch 4, be used to form the polarization-maintaining beam splitter 5 of interference with
And two detectors 6,7.Each of user terminal 1-3 can be connected to the respective input of photoswitch 4 by quantum channel
Mouthful, 2 output ports of photoswitch 4 are connected respectively to 2 input ports of polarization-maintaining beam splitter 5,2 output ends of beam splitter 5
Mouth is separately connected detector 6 and detector 7.By the switching of photoswitch 4, there will be the quantum channel of 2 users to be switched entrance
2 input ports of polarization-maintaining beam splitter 5, the signal light for being switched two users of access central node are assisted thus according to MDIQKD
View generates security key.
Fig. 1 (b) shows the quantum key distribution network of the shared measuring system of the prior art, and the relaying used is can
Letter relaying, thus it is different from network shown in Fig. 1 (a) in the setting of central node.Specifically, in the amount using credible relaying
In quantum key distribution network, central node includes photoswitch 4 and a detector 6.In use, photoswitch is only by a user
Quantum channel switching access receiving end, then the user and receiving end generate security key according to the BB84 agreement of standard.Such as
Shared key is needed between two users of fruit, then the two users is needed successively separately to generate security key with receiving end
And then realize that the key between two users is shared by the credible trunking scheme of the receiving end.It is this to be based on credible relaying
Distribution network safety depend on for relaying receiving end confidence level, once the equipment such as detector of receiving end exist
Security breaches, then all users in entire distribution network will face security risk.
Fig. 2 shows according to the present invention based on the star-like MDIQKD network of time bit-phase code.The Star Network
Including a plurality of clients, multiple quantum channels 19 corresponding with a plurality of clients, photoswitch 20 and central node.
As shown in Fig. 2, user terminal can successively include: light source 8, intensity modulator 9,10, circulator 11, by polarization-maintaining beam splitting
The unbalanced Mech-Zehnder interferometer (AMZI) that device 12, phase shifter 13 and polarization-maintaining beam splitter 14 form, intensity modulator 15,
16, phase-modulator 17 and adjustable attenuator 18.
In each user terminal, first had to carry out intensity modulated by intensity modulator 9 by the laser pulse that light source 8 exports.
Intensity modulator 9 goes out the light pulse of at least two kinds of same intensity for Stochastic Modulation, to meet the modulation requirement for inveigling state scheme.
Intensity modulator 10 is used for so that user terminal exports 2 non-orthogonal volumes in time bit-phase encoding scheme
The light intensity of code basic vector (i.e. Z basic vector with X basic vector) is consistent, that is, the intensity for encoding basic vector normalizes.
Through the modulated light pulse of intensity modulator 10 via circulator 11 enter by polarization-maintaining beam splitter 12, phase shifter 13,
The light pulse of entrance is divided into two, obtains by the unbalanced Mech-Zehnder interferometer that polarization-maintaining beam splitter 14 forms, the interferometer
To 2 separated in time pulse components, and the time interval of the two pulse components is by the brachium of 2 optical paths in interferometer
Difference determines that phase shifter 13 is for the phase drift in compensating interferometer instrument.
Intensity modulator 15 and 16 is used for time bits of encoded, and 2 light pulse components of interferometer output are via intensity tune
Device 15 and intensity modulator 16 processed are encoded, which is configured such that under Z basic vector, according to random
Bit information 0 or 1 is corresponding to eliminate previous or the latter pulse component, i.e., only retains a pulse component, and allows under X basic vector
Two pulse components pass through.In the present invention, two are preferably used for the intensity modulator of time bits of encoded, thus
Advantageously enhance the extinction ratio of time bit.
Phase-modulator 17 is encoded for phase bits, is configured such that under X basic vector, according to bit information 0 or 1
0 or 90 ° of phase is loaded on former and later two separated in time pulse components.
It is noted that if the Z basic vector of input intensity modulator 15,16,17 is identical with the intensity of X basic vector,
Under the modulating action of intensity modulator 15-17, will finally be occurred not by the average intensity of the Z basic vector of user terminal output and X basic vector
Unanimously, this will will cause follow-up signal processing and complicate.It is therefore preferred that the present invention is provided with intensity modulator 10, the intensity
Modulator 10 is configured to compensation intensity modulator 15-17 to the modulation difference of different basic vectors, so that X basic vector and Z basic vector
Light intensity after modulator 10,15-17, it is consistent with the light intensity of Z basic vector by the X basic vector of user terminal final output.Preferably, exist
In the present invention, intensity modulator 10 is arranged before unbalanced Mech-Zehnder interferometer, rather than is arranged after AMZI.
Since this position is arranged, so that intensity modulator 10 needs the quantity of light pulse modulated compared to be set to can after AMZI
To reduce half, thus largely reduce to system electronics requirement, because with the increase of modulating light pulse quantity,
Can all there be higher requirement to the flatness of electrical signal, electronics bandwidth etc..
Adjustable attenuator 18 is used to decaying to the number of photons level of light pulse into light intensity value required for inveigling state scheme.Through
When m- phase bits coding light pulse signal exported after adjustable attenuator 18 from user terminal, and transmitted through quantum channel 19
To photoswitch 20.Then, the user needed can be made by access measurement end by the switching of photoswitch 20.Quantum channel 19 can be with
For fiber reel or outfield optical cable 19.
With continued reference to Fig. 2, central node of the invention can successively include: filter part 21/25, automatically controlled Polarization Controller
22/26, polarization-maintaining polarization beam apparatus 23/27, polarization-maintaining beam splitter 29 and single-photon detector 30/31.Wherein, filter part 21
It is used to filter the stray light in the signal light for the user being switched in via photoswitch 20 with 25, such as intensive wave can be used
Division multiplexer or grating.Subscriber signal light through filtering reaches polarization-maintaining polarization beam apparatus 23/ through automatically controlled Polarization Controller 22/26
27.In the present invention, quantum channel uses single mode optical fiber, and photoswitch and automatically controlled Polarization Controller are usually single mode device, and are protected
Inclined beam splitter 29 is polarization-maintaining device, it is therefore preferred that the subscriber signal light through filtering is transferred to polarization beam splitting in the form of single mode
In device 23/27, while polarization beam apparatus 23/27 uses single mode to the type of polarization-maintaining, so that the complexity of system light path be effectively reduced
Property.
The transmission port of two polarization-maintaining polarization beam apparatus 23/27 is all connected to polarization-maintaining beam splitter 29, and reflector port is then distinguished
Connect single-photon detector 24/28.Single-photon detector 24/28 is used to monitor the polarization variations of subscriber signal light.Single-photon detecting
It surveys device 24/28 and connects polarization control unit, the prison which is exported based on single-photon detector 24/28
Feedback voltage is calculated in measured value, and by feedback voltage load on automatically controlled Polarization Controller 22/26, with compensation and the use
Polarization scrambling on the quantum channel (such as optical fiber) of family connection, so that at the reflector port of polarization beam apparatus 23/27
Light intensity minimizes, and the light intensity at transmission port maximizes.Specifically, in the control of polarization control unit of the invention
Journey is as follows: if the monitor value that single-photon detector 24/28 exports is smaller than last monitor value, then it is assumed that the calibration of voltage value
It is in the right direction, it can continue to adjust voltage along this direction to keep monitor value next time smaller；If monitor value is than last
Monitor value it is big, then change the calibrating direction of voltage value and become smaller to monitor value next time, reach the monitor value most
It is small and in this state keep stablize.
On polarization-maintaining beam splitter 29, is interfered via the signal light of two users of photoswitch access, interfere output end
Order photon detector 30 and single-photon detector 31 respectively.Finally, passing through the number between analysis single-photon detector 30 and 31
According to judging respectively the time location of detection.If 2 detectors 30 and 31 have response in the period at the same time,
And a detector is responded on time location 0, another detector is that generation response is (so-called on time location 1
The time difference of time location 0 and 1 corresponds to the arm length difference of unequal arm Mach once special interferometer), then it is assumed that it is legal for one at this time
Bell's state.Then, legal Bell's state information is sent to currently accessed two users by disclosed classic network,
User carries out basic vector comparison, error correction and privacy to these Bell's states according to the Data Post process of MDIQKD protocol contents and puts
Greatly, final security key is generated.
Time bit-phase encoding scheme will be believed on X basic vector related with phase code according to random bit
Breath 0 or 1 loads corresponding 0 or 90 ° of phase on two light pulse components, reflects encoded radio by the phase difference.In fact, this
Kind phase difference will receive the influence of the phase reference (the long-armed phase difference between galianconism of as AMZI itself) inside AMZI, and
The phase reference can generate drift with factors such as temperature, vibrations, if the benchmark does not keep stable, can to encode
Value is also no longer accurate, leads to system error code.Therefore, optionally, star-like MDIQKD network of the invention can also include that phase is anti-
Module is presented, so that the inside phase reference of AMZI keeps stablizing.
Fig. 3 shows the structural schematic diagram of phase feedback module according to the present invention.As shown in figure 3, the phase feedback mould
Block includes user's end part and measurement end part, and wherein each user terminal in MDIQKD network can be set in user's end part
User's end part structure having the same at place and each user terminal, measurement end part can be set at central node, and two
It can be connected for example, by fiber reel or outfield optical cable 41 between person.Measuring end part may include phase feedback laser
46, unbalanced Mech-Zehnder interferometer, circulator 43 and the beam splitter being made of polarization-maintaining beam splitter 45, polarization-maintaining beam splitter 44
42.User's end part may include the unequal arm Mach- being made of polarization-maintaining beam splitter 12, phase shifter 13, polarization-maintaining beam splitter 14
Zehnder interferometer, circulator 11 and detector 34,35.Phase feedback laser 46 can use pulse laser.Laser
46 wavelength is preferably identical as the wavelength of user terminal light source 8, so that the signal light for more easily reflecting that user terminal light source 8 exports exists
Phase drift on AMZI.The light pulse that laser 46 exports polarization-maintaining beam splitter 45, polarization-maintaining beam splitter 44 by being made of
It is divided into two after AMZI, enters one to more beam splitters 42 (for single beam splitter or by multiple beam splitting using circulator 43
Device cascades) after be divided into multiple light pulses, each of these light pulses are respectively along corresponding optical channel (such as light
It is fine) enter corresponding user's end part.
After entering user's end part, light pulse enters the (port of the AMZI AMZI by the idle port 40 of AMZI first
39 output ports of the signal light through AMZI exported for user terminal light source 8, connection can be for example the intensity modulated in Fig. 2
Device 15).Measure end part the AMZI being made of polarization-maintaining beam splitter 44 and polarization-maintaining beam splitter 45 arm length difference preferably have with
Family end part by the arm length difference identical with the AMZI that polarization-maintaining beam splitter 14 forms of polarization-maintaining beam splitter 12 so that dry by two
Long-armed and another (such as the AMZI's in user's end part) of one (such as AMZI in measurement end part) in interferometer
The light pulse of galianconism and galianconism by one (such as AMZI in measurement end part) in described two interferometers and described
The long-armed light pulse of another (such as AMZI in user's end part) is when interfering with good interference contrast.It surveys
The a port for measuring the polarization-maintaining beam splitter 12 of the AMZI of end part connects monitor 35, another port passes through the one of circulator 11
A port connects monitor 34.Here, the setting of circulator 11 effectively ensure that the signal light and phase that user terminal light source 8 issues
Differentiation of the feedback light pulse issued in feedback module by measurement end part in optical transmission direction.
Be located at measurement end part and the two AMZI of user's end part between phase drift will reflect in this two
On the monitor value of a monitor 34 and 35, then according to these monitor values, the phase shifter inside the AMZI of user's end part is controlled
13 voltage carries out phase compensation, eliminates phase drift.The monitor 34,35 can be single-photon detector or classics
Detector.In phase feedback module, after the voltage for controlling phase shifter 13 carries out phase compensation, if two monitors
34,35 monitor value ratio becomes smaller, then shows that the calibrating direction of voltage value is correct, can continue to adjust along this direction, so that under
The monitor value ratio of primary two monitors 34,35 continues to become smaller；Conversely, then changing the calibrating direction of voltage value, in reverse direction
Voltage is adjusted, so that monitor value ratio next time becomes smaller；Until monitor value reaches minimum and keeps stablizing in this state.
Optionally, in phase feedback module of the invention, it can only be arranged one in monitor 34,35, i.e., only adopt
With single single-photon detector or single classical detector.At this point, after the voltage for controlling phase shifter 13 carries out phase compensation,
If monitor value is smaller than last, then it is assumed that the calibrating direction of voltage value is correct, can continue to adjust along this direction, so that next
Secondary monitor value is smaller；Conversely, then changing the calibrating direction of voltage value, voltage is adjusted in reverse direction, so that monitor value next time
Become smaller；Until monitor value reaches minimum and keeps stablizing in this state.
Core in MDIQKD agreement about the measurement of Bell's state is the interference of separate laser pulse, and the performance interfered by
Consistency to the various modes of interference influences, such as time mode.If time mode is inconsistent, interference performance will lead to
Variation error rate of system increases.Therefore, optionally, star-like MDIQKD network of the invention can also include time feedbacking module
(as shown in Figure 4) sends out so that all working on the basis of same clock frequency in all-network user from different user terminals
The time mode that laser pulse out reaches at the polarization-maintaining beam splitter 29 of central node is consistent.
As shown in figure 4, time feedbacking module according to the present invention may include user's end part and measure end part, wherein
User's end part at each user terminal of MDIQKD network and at each user terminal can be set with phase in user's end part
Same structure, measurement end part can be set at central node, between the two can be for example, by fiber reel or live light
Cable 54 connects.
Measurement end part may include 51, two adjustable delay chips 52 of a clock source, company corresponding with two chips 52
The synchronous light laser 53 of two connect and photoswitch.User's end part may include photodiode 55 and phase locking frequency multiplying electricity
Road 56.
When carrying out time feedbacking, as shown in Fig. 2, the signal light of two user terminals in MDIQKD distribution network reaches list
Photon detector 30 and 31, the output signal by statisticalling analyze single-photon detector 30 and 31 determine the arrival of signal pulse
Time, based on obtained signal pulse arrival time, by time feedbacking module to the signal light arrival time of the two users
It is compared and implements feedback control.In time feedbacking module, accused first by the measurement end of distribution network by classic network
Tell 2 user types for needing to match in time feedbacking module current network, such as respectively user A and user B, time feedbacking
The photoswitch of the measurement end part of module will be set in user A and user B for example, by fiber reel or live optical cable 54
User's end part of time feedbacking module is respectively connected to one in two synchronous light lasers 53 of measurement end part.By when
Clock source 51 generates two synchronous triggering signals of low frequency, and synchronous triggering signal is defeated after adjustable delay chip 52 carries out delay disposal
Electric signal triggers synchronous light laser 53 and shines out, and the photodiode 55 of user's end part detects the synchronization optical signal, then
Optical path is sent by the signal light that the system clock that phase-locking frequency multiplication circuit 56 generates high frequency triggers MDIQKD distribution network user terminal
Each electronics device (such as light source 8 in Fig. 2 and each modulator 9-17 etc.) in 57, to realize the user A in use
With consistency of the user B on time mode.
But according to the working method of the time feedbacking module, before the start-up operation of MDIQKD distribution network, on the one hand
Start the time feedbacking module deadline calibration so that between each user time mode it is consistent, distribution network work one section
Due to time possible drift in optical path after time, it is still desirable to interruption of work and be again introduced into time feedbacking calibration mode；Separately
On the one hand, in each time feedbacking calibration process, the output of the single-photon detector 30 and 31 of distribution network measurement end is obtained
The statistical data analysis of value is also required to take a certain time to run up to enough data.In terms of the two, Fig. 4
Shown in time feedbacking module will cause entire MDIQKD distribution network it is effective at the code time reduce.
Therefore, another embodiment that Fig. 5 shows time feedbacking module according to the present invention in this embodiment can
To realize the automatic compensation to optical fiber time drift, switch the process of feedback without stopping normal flow, so as to effective
Improve the effective at the code time and at code rate of MDIQKD distribution network.
As shown in figure 5, another time feedbacking module according to the present invention may include user's end part and measurement end part,
Wherein the tool of user's end part at each user terminal of MDIQKD network and at each user terminal can be set in user's end part
There is identical structure, measurement end part can be set at central node, for example, by fiber reel or can show between the two
Field optical cable 64 connects.
Measuring end part may include a clock source, two adjustable delay chips 62, two synchronizable opticals being attached thereto
Laser 63, photoswitch 71, wavelength division multiplexer 67 and photoswitch 20 and filter that MDIQKD distribution network central node is set
Wavelength division multiplexer 701/702 between light component 21/25.User's end part may include: photodiode 65；Phase locking frequency multiplying electricity
Road 66；Wavelength division multiplexer 68；Wavelength division multiplexer 69 after the adjustable attenuator 18 of MDIQKD distribution network user terminal is set；
And photoswitch 72.
In another time feedbacking module according to the present invention, firstly, being passed through by the measurement end of MDIQKD distribution network
Classic network tells that 2 users for needing to match in time feedbacking module current network are, for example, user A and user B.By clock
Source generates two synchronous triggering signals of low frequency, and synchronous triggering signal exports electricity after adjustable delay chip 62 carries out delay disposal
Signal triggers synchronous light laser 63 and shines, and two synchronous light lasers 63 have different output wavelengths, for example, laser
The wavelength X of 63BBThe output end that can be configured to laser 63B is connected to the reflection end of wavelength division multiplexer 67A (end r), laser
The wavelength X of device 63AAThe output end that can be configured to laser 63A is connected to the transmission end of wavelength division multiplexer 67B (end p), wave
Division multiplexer 67A can be by the synchronous optically coupling to common end (end c) of respective wavelength with 67B.Photoswitch 71 makes wavelength division multiplexer
The corresponding optical path in the end c of 67A and 67B is connected to the user's end part being located in user A and user B respectively.Wavelength is λAIt is same
Step light is sent to user's end part of user B, in user's end part, synchronizable optical λAIt is transferred to wavelength division multiplexer 68B
The end c；The end p and the end r of wavelength division multiplexer 68B is separately connected the port p1 and p2 of photoswitch 72B.User B is according to oneself use
Family type B sets the state of photoswitch 72B to be connected directly (the i.e. port connectivity port the p1 p3 of photoswitch 72B, port p2 company
Meet port p4).At this point, synchronizable optical λBThe end r that will enter into wavelength division multiplexer 69B, then enters user B and centromere from the end c
The quantum channel 19B of point returns to central node.The quantum channel of user B is connected to wavelength-division by the photoswitch 20 at central node
The end c of multiplexer 702.At this point, wavelength XASynchronizable optical will from the end r of wavelength division multiplexer 702 export, be transferred to wavelength division multiplexer
The end p of 67A, then the end c through wavelength division multiplexer 67A and photoswitch 71 are sent to the user terminal of user A by quantum channel 64
Part.In user's end part of user A, wavelength XASynchronizable optical be input to the end c of wavelength division multiplexer 68A；Wavelength division multiplexer
The end p and the end r of 68A is separately connected the port p1 and p2 of photoswitch 72A.User A is according to oneself user type A by photoswitch
The state of 72A, which is set as intersecting, is connected (i.e. the port connectivity port the p1 p4 of photoswitch 72A, port p2 connectivity port p3).At this point,
Synchronizable optical λAIt will enter into two pole 65A of photoelectricity to be detected and screened, obtain synchronous electric signal.
To wavelength XASynchronizable optical detected to obtain synchronous electric signal after, which passes through phase-locking frequency multiplication circuit
The signal light that 66A generates the system clock triggering MDIQKD distribution network user terminal A of high frequency sends each electronics device in optical path
Part (i.e. light source 8 described in Fig. 2 and each modulator 9-17 etc.).It is sent by the signal light of MDIQKD distribution network user terminal A
Then the end p of the signal light connects wavelength division multiplexer 69A of optical output is exported from the end c, and through between user A and central node
Quantum channel 19A be transferred to the photoswitch 20 at central node.Then wavelength-division is input under the switching of photoswitch 20
Then the end c of multiplexer 701 is exported from its end p, reach the Bell's state measurement being made of device 21-31 shown in Figure 2 and set
It is standby.
It should be noted that wavelength XASynchronizable optical and by its triggering the signal light from user terminal A reach center
It has passed through all optical fiber between user A, B and central node when the detector 30/31 of node in total.
Similarly, wavelength XBSynchronizable optical and by its triggering the signal light from user terminal B reach central node spy
It also will be by all optical fiber between user A, B and central node when surveying device 30/31.
It can be seen that since synchronizable optical, being used in addition to the fixation route difference inside user A, user B and central node
When the signal light that family A, B are generated eventually arrives at Bell's state measuring device, the optical fiber of the user A, user B and central node that are passed through
Time drift on route will be not necessarily to time feedbacking by automotive resistance.
Fig. 6 schematically shows the alternative embodiment of the light source 8 for star-like MDIQKD network of the invention.In the reality
It applies in example, light source 8 can be by constituting from source ends and key light source, wherein key light source quantity is 1, and each user terminal is all provided with
It is equipped with a light source from source ends as the user terminal, key light source and respectively connects from passing through optical fiber between source ends.Such as Fig. 6
Shown, key light source may include main laser 8-1 and beam splitter 8-2.Main laser 8-1 can be continuous light laser, point
Beam device 8-2 can be single beam splitter or be cascaded by multiple beam splitters.The continuous light that main laser 8-1 is issued is by beam splitting
Device 8-2 is divided into multichannel light, which is transferred to the slave source ends at user terminal by corresponding optical fiber respectively.From light
Source may include intensity modulator 8-3, from laser 8-4 and phase-modulator 8-5.At source ends, it is passed to by optical fiber
Continuous light generation pulse laser is chopped by intensity modulator 8-3；The pulse laser as seed light source be injected into from
In laser 8-4, the better laser pulse of spectrum property is generated from laser 8-4 by stimulated radiation；By defeated from laser 8-4
Laser pulse out using phase-modulator 8-5 carry out phase-modulation, so that its phase is had the characteristics that randomization, thus evade and
Phase reveals related loophole, prevents the possible USD to light source from attacking, guarantees the final safety of theoretical calculation at code rate.
By the alternative embodiment of the light source 8, can be effectively ensured that all user terminal light sources in Star Network issue swashs
Optical wavelength is automatically coherent, it is not necessary that complicated phase feedback structure is additionally arranged, so that greatly reduction system complexity and network are built
It is set as this, is conducive to the popularization and practice of quantum communication network.
In still another aspect of the invention, the improvement embodiment of light source 8 shown in fig. 6 is disclosed.Wherein, from source ends,
Intensity modulator is being set before laser, is being used to carry out 2 copped wave to the continuous light sent from key light source, so that
2 pulse lasers are generated under X basic vector, or only retain first pulse or second pulse under Z basic vector.It is generated by copped wave
One or two pulse laser inject as seed light source from laser, generated from laser by stimulated radiation corresponding
One or two signal pulse.By the improvement embodiment, it is convenient to omit be located at the device of user terminal as shown in Figure 2
12-16, to further decrease system complexity and network construction cost.The above is only embodiments of the present invention, is answered
This is pointed out for those of ordinary skill in the art, without departing from the technical principles of the invention, can also be made
Several improvements and modifications, these improvements and modifications also should be regarded as protection scope of the present invention.
Claims (6)
1. a kind of still guarantee safe star-like quantum key distribution network without credible relaying comprising a plurality of clients and one
A central node, each of the multiple user terminal connect the central node through corresponding quantum channel, wherein
The user terminal is used to form encoded and intensity and meets the pulse light for inveigling state scheme to require；
The central node includes Bell's state measuring device；
The pulse light of two user terminals A, B output in the multiple user terminal is switched the access centromere
Point；Two pulse lights from the user terminal A and B interfere effect in the central node, based on warp
Whether the measurement result judgement of the signal light of interference effect output currently constitutes legal Bell's state；When thinking to constitute legal Bell
When state, legal Bell's state information is sent to described user terminal A, B, described user terminal A, B are according to unrelated with measuring device
The Data Post process of quantum key distribution protocol content carries out basic vector comparison, error correction and hidden to legal Bell's state for receiving
Private amplification, finally generates security key, it is characterised in that:
The quantum key distribution network further includes phase feedback module, time feedbacking module, one in polarization feedback module
Or it is multiple, to guarantee the Stability and veracity of Bell's state measurement；Wherein, the phase feedback module is described star-like for eliminating
Undesirable phase reference drift in network；The time feedbacking module is used for the pulse light so that user terminal output
The time mode for reaching the central node is consistent；The polarization that the polarization feedback module is used to compensate on the quantum channel is disturbed
It is dynamic；
The quantum key distribution network further includes light source (8), and the light source (8) includes a key light source and multiple from light source
End, each user terminal, which is provided with, described to be used from one of source ends as signal optical source；
The key light source includes main laser (8-1) and beam splitter (8-2), the continuous light that the main laser (8-1) issues
The continuous light of multichannel is divided by the beam splitter (8-2), the continuous light of multichannel is respectively by respective optic path to described more
It is a from source ends；
Described from source ends includes intensity modulator (8-3), from laser (8-4) and phase-modulator (8-5), is input to described
Generation light pulse is chopped by the intensity modulator (8-3) from the continuous light of source ends, the light pulse is as kind
Sub-light source be injected into it is described from laser (8-4), it is described more preferable by stimulated radiation output spectrum performance from laser (8-4)
Pulse light, pulse light phase after the phase-modulation of the phase-modulator (8-5) is randomized, described
The pulse light of phase randomization is encoded again and intensity modulated forms the pulse light for meeting and state scheme being inveigled to require.
2. still guaranteeing safe star-like quantum key distribution network, feature without credible relaying as described in claim 1
Be, the user terminal further include polarization-maintaining unequal arm Mach once special interferometer (12,13,14), intensity modulator (9,10,15,
16) and phase-modulator (17), for compiling to carrying out time bit-phase by the pulse light exported from source ends
Code；Wherein, the intensity modulator (9) goes out the light pulse of at least two varying strengths for Stochastic Modulation, to meet trick state
The modulation requirement of scheme；The unequal arm Mach once special interferometer (12,13,14) by the pulse signal exported from source ends
Light is divided into two pulse components；The intensity modulator (10,15,16) is configured to adjust described two pulse components
System so that only retaining one of them under Z basic vector, or allows described two pulse components to pass through, when being formed under X basic vector
Between encode；The phase-modulator (17) is configured to add random phase between two pulse components under X basic vector, with shape
At phase code；
The user terminal further includes adjustable attenuator, is configured to make by time bit-phase code pulse light
Number of photons level decay to inveigle state scheme required for light intensity value.
3. still guaranteeing safe star-like quantum key distribution network, feature without credible relaying as described in claim 1
It is, in the intensity modulator (8-3) from source ends is configured to that the continuous light of input cut for 2 times
Wave so that generating 2 light pulses under X basic vector, or only retains a light pulse, copped wave smooth arteries and veins generated under Z basic vector
Punching is described from laser (8-4) as seed light source injection, described accordingly to generate one by stimulated radiation from laser (8-4)
Or two pulse lights；Pulse light phase after the phase-modulation of the phase-modulator (8-5) is randomized；
The user terminal further includes for the phase tune for carrying out phase code by the pulse light exported from source ends
Device (17) processed is configured to add random phase between 2 light pulses under X basic vector to form phase code；
The user terminal further includes adjustable attenuator, is configured to make by time bit-phase code pulse light
Number of photons level decay to inveigle state scheme required for light intensity value.
4. still guarantee safe star-like quantum key distribution network without credible relaying as claimed in claim 2 or claim 3, it is special
Sign is,
The time feedbacking module includes a plurality of clients part and a measurement end part, the multiple user's end part difference
It is arranged at the multiple user terminal and structure having the same, the measurement end part is arranged at the central node；
The measurement end part, which is used under same clock form two based on relatively low-frequency synchronous triggering signal, to be had
Different wave length λA、λBSynchronizable optical；
Wherein, the wavelength is λASynchronizable optical transmitted by the additional optical path between the central node and the user terminal B
To user's end part in the user terminal B, the wavelength is λ by user's end part in the user terminal BASynchronizable optical warp
Quantum channel between the user terminal B and the central node returns to the central node, and the central node will be described
Wavelength is λASynchronizable optical be sent in the user terminal A through the additional optical path between the central node and the user terminal A
User's end part；It is λ that user terminal in the user terminal A, which is based partially on the wavelength,ASynchronizable optical generate relatively high frequency
The clock signal of system of rate is shone with triggering the slave laser (8-4) in the user terminal A, while being provided and being used for signal light modulation
Clock reference；
The wavelength is λBSynchronizable optical institute is transmitted to by the additional optical path between the central node and the user terminal A
User's end part in user terminal A is stated, the wavelength is λ by user's end part in the user terminal ABSynchronizable optical warp described in
Quantum channel between user terminal A and the central node returns to the central node, and the central node is by the wavelength
For λBSynchronizable optical the use in the user terminal B is sent to through the additional optical path between the central node and the user terminal B
Family end part；It is λ that user terminal in the user terminal B, which is based partially on the wavelength,BSynchronizable optical generate it is relatively high-frequency
Clock signal of system with trigger the slave laser (8-4) in the user terminal B shine, while provide for signal light modulation when
Clock benchmark.
5. still guaranteeing safe star-like quantum key distribution network, feature without credible relaying as claimed in claim 4
It is, the measurement end part has different wave length λ including a clock source, two adjustable delay chips (62), twoAAnd λB
Synchronous laser (63A, 63B), two the first wavelength division multiplexers (67A, 67B), the first photoswitch (71) and two second
Wavelength division multiplexer (701,702)；
User's end part includes photodiode (65), phase-locking frequency multiplication circuit (66), the second photoswitch (72), third wavelength-division
Multiplexer (68) and the 4th wavelength division multiplexer (69)；
First wavelength division multiplexer (67A, 67B) and the third wavelength division multiplexer (68), which are configured to its reflection end, allows institute
Stating wavelength is λBSynchronizable optical pass through, transmission end allows the wavelength to be λASynchronizable optical pass through, and described synchronize is optically coupled to
Common end；
Second wavelength division multiplexer (701,702) and the 4th wavelength division multiplexer (69), which are configured to its reflection end, to be allowed together
Step light passes through, and transmission end allows the signal light of the user terminal output to pass through, and the synchronizable optical and signal are optically coupled to public affairs
End altogether；
The clock source exports the synchronous triggering signal of described two rather low-frequencies, and described two synchronous triggering signals are respectively through institute
The output electric signal triggering synchronous light laser (63A, 63B) issues wave after stating two adjustable delay chip (62) delay disposals
Long is respectively λAAnd λBTwo synchronizable opticals；
It is λ that the reflection end of one (67A) in first wavelength division multiplexer, which connects the wavelength,BSynchronization light laser it is defeated
Outlet, transmission end connect the reflection end of one (702) in second wavelength division multiplexer；In first wavelength division multiplexer
It is λ that the transmission end of another (67B), which connects the wavelength,ASynchronization light laser output end, reflection end connection described second
The reflection end of another (701) in wavelength division multiplexer；The transmission end of second wavelength division multiplexer (701,702) is separately connected
Bell's state measuring device of the central node；
In use, first photoswitch (71) is configured so that one (67A) in first wavelength division multiplexer
Common end connects the common end of the third wavelength division multiplexer (68A) in the user terminal A through additional optical path, and first wavelength-division is multiple
The third wavelength division multiplexer (68B) in the user terminal B is connected through additional optical path with the common end of another (67B) in device
Common end；
In the user terminal B, the second photoswitch (72B) is configured so that the transmission of the third wavelength division multiplexer (68B)
End connects the reflection end of the 4th wavelength division multiplexer (69B), and the reflection end of the third wavelength division multiplexer (68B) is connected
Meet the photodiode (65B)；The photodiode (65B) is configured to for the synchronizable optical being converted into synchronous telecommunications
Number；The phase-locking frequency multiplication circuit (66B) generates the clock signal of system of high frequency based on the synchronous electric signal, described for triggering
User terminal B generates signal light；The signal light of the user terminal B is sent to the transmission end of the 4th wavelength division multiplexer (69B)；
In the user terminal A, the second photoswitch (72A) is configured so that the reflection of the third wavelength division multiplexer (68A)
End connects the reflection end of the 4th wavelength division multiplexer (69A), and the transmission end of the third wavelength division multiplexer (68A) is connected
Meet the photodiode (65A)；The photodiode (65A) is configured to for the synchronizable optical being converted into synchronous telecommunications
Number；The phase-locking frequency multiplication circuit (66A) generates the clock signal of system of high frequency based on the synchronous electric signal, described for triggering
User terminal A generates signal light；The signal light of the user terminal A is sent to the transmission end of the 4th wavelength division multiplexer (69B)；
The common end of the 4th wavelength division multiplexer (69A) in the user terminal A is through between the user terminal A and the central node
Quantum channel connect the common end of another (701) in second wavelength division multiplexer；The 4th wave in the user terminal B
The common end of division multiplexer (69B) connects second wave through the quantum channel between the user terminal B and the central node
The common end of one (702) in division multiplexer.
6. still guaranteeing safe star-like quantum key distribution network, feature without credible relaying as claimed in claim 5
It is, two user terminals for being switched access central node are the user terminal A or user terminal B by the central node point
Match and informs.
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