CN108306676A - The method and apparatus of safety test - Google Patents
The method and apparatus of safety test Download PDFInfo
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- CN108306676A CN108306676A CN201711479689.0A CN201711479689A CN108306676A CN 108306676 A CN108306676 A CN 108306676A CN 201711479689 A CN201711479689 A CN 201711479689A CN 108306676 A CN108306676 A CN 108306676A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/70—Photonic quantum communication
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
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Abstract
The embodiment of the present invention provides a kind of method and apparatus of safety test.The method includes intercepting and capturing the crossed polarized light sent by sender in quantum communication system, the crossed polarized light includes horizontal polarization light and orthogonal polarized light；Repeatedly adjust horizontal polarization light and orthogonal polarized light phase difference so that the phase difference changes within a preset range；For each phase difference, determine that corresponding first error rate, first error rate are the error rates according to the recipient of current phase difference estimation；For each phase difference, the second error rate of recipient is obtained, the second error rate is the error rate detected by recipient in quantum communication system；According to the first error rate and the second error rate, determine whether quantum communication system passes through safety test.The method adjusts horizontal polarization light and orthogonal polarized light phase difference so that the phase difference changes in default range, and according to every 1 first error rate and the second error rate, can accurately carry out safety test.
Description
Technical field
The present embodiments relate to field of communication technology, especially a kind of method and apparatus of safety test.
Background technology
Quantum communications refer to a kind of novel communication modes transmitted into row information using entangled quantum effect.Quantum communications
Major advantage and the motive force of development be its Unconditional security.Early in 1984, first ripe quantum communications scheme was (i.e.
BB84 agreements, Bennett Bennett- Brassard Brassard1984) it has just made third party and has monitored and can centainly have been led to
Believe the theory analysis that both sides have found.
The communicating pair of quantum communications is loaded by single photon and transmits information, since single photon can not divide again, and monochromatic light
The physical characteristics such as quantum state is unclonable of son, if there is third party to monitor, separation, the operations such as clone will be inevitable
A large amount of error code is introduced, and is found by communicating pair.
It configures and completes in quantum communication system, before coming into operation, security test need to be carried out, test uses the quantum communications
It is communicated, if having reached safe performance indexes, that is to say, that if there is third party's monitoring, if it can be found that.
The third-party intercepting and capturing of safety detection generally use-repeating transmission listening mode is realized in the prior art.Third-party section
It is to intercept and capture single photon pulses from the channel of quantum communications to obtain-retransmit listening mode, is monitored, then retransmits the list of forgery
For photon pulse to recipient, whether tester detects recipient it can be found that this communication has third party's monitoring.
Key therein is single-photon detector, and single-photon detector is a kind of ultra-low noise device, and strong sensitivity makes it
Photon can be detected, the detection efficient of single-photon detector in the market only has 10% or so, that is to say, that intercept and capture 100%
Single photon, single-photon detector can only detect wherein 10% photon, and the photon for forging 10% is sent to recipient,
It is equivalent to and has lost 90% photon and be not sent to recipient, it is to be understood that this measurement method has lost absolutely mostly
Number photon, recipient are substantially bound to find that this quantum communications is dangerous.
It is understood that the purpose of test is the prison that can find any degree for the quantum communications for ensureing to come into operation
It listens, and third-party intercepting and capturing-repeating transmission listening mode of the prior art is limited to the performance of equipment, can only determine the light of forgery 10%
Son be sent to the case where recipient can be found that it is monitored, that is to say, that accurately quantum communication system can not be tested.
Invention content
In view of the drawbacks of the prior art, the embodiment of the present invention provides a kind of method and apparatus of safety test.
On the one hand, the embodiment of the present invention provides a kind of method of safety test, the method includes：
The crossed polarized light sent by sender in quantum communication system is intercepted and captured, the crossed polarized light includes horizontal polarization
Light and orthogonal polarized light；
Repeatedly adjust horizontal polarization light and orthogonal polarized light phase difference so that the phase difference becomes within a preset range
Change；
For each phase difference, determine that corresponding first error rate, first error rate are according to current phase difference
The error rate of the recipient of estimation；
For each phase difference, the second error rate of recipient is obtained, the second error rate is in quantum communication system by connecing
The error rate of debit's detection；
According to the first error rate and the second error rate, determine whether quantum communication system passes through safety test.
On the other hand, the embodiment of the present invention provides a kind of device of safety test, and described device includes：
Interception module, for intercepting and capturing the crossed polarized light sent by sender in quantum communication system, the cross-polarization
Light includes horizontal polarization light and orthogonal polarized light；
Adjust module, for adjusting horizontal polarization light and orthogonal polarized light phase difference so that the phase difference
Variation in preset range；
Determining module determines corresponding first error rate, first error rate is basis for being directed to each phase difference
The error rate of the recipient of current phase difference estimation；
Acquisition module obtains the second error rate of recipient, the second error rate is that quantum is logical for being directed to each phase difference
The error rate detected by recipient in letter system；
Test module, for according to the first error rate and the second error rate, determining whether quantum communication system passes through safety
Test.
As shown from the above technical solution, the method and apparatus of safety test provided in an embodiment of the present invention, the method are logical
Cross adjustment horizontal polarization light and orthogonal polarized light phase difference so that the phase difference changes within a preset range, and according to
Every 1 first error rate and the second actually detected error rate of recipient accurately can carry out safe survey to quantum communication system
Examination.
Description of the drawings
Fig. 1 is the light channel structure of double unequal arm Mach-Zender interferometers of the embodiment of the present invention；
Fig. 2 is a kind of flow diagram of the method for safety test provided in an embodiment of the present invention；
Fig. 3 is a kind of schematic diagram of the device for safety test that further embodiment of this invention provides；
Fig. 4 is a kind of schematic diagram of the device for safety test that further embodiment of this invention provides；
Fig. 5 is a kind of schematic diagram of the device for safety test that further embodiment of this invention provides；
Fig. 6 is a kind of schematic diagram of the device for safety test that further embodiment of this invention provides；
Fig. 7 is the basic principle schematic for the polarization beam apparatus that further embodiment of this invention provides；
Fig. 8 is a kind of structural schematic diagram of the device for safety test that further embodiment of this invention provides.
Specific implementation mode
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical solution in the embodiment of the present invention is explicitly described, it is clear that described embodiment is the present invention
Embodiment a part of the embodiment, instead of all the embodiments.
Method provided in an embodiment of the present invention is used to carry out safety test to quantum communication system, in the device of safety test
Upper realization.
The device of safety test can monitor quantum communication system, and the reflection of the recipient of incorporating quantum communication system, real
Existing safety test.
Wherein, monitor quantum communication system refer to the incident light of the sender of quantum communication system can be intercepted and captured, then
The information of incident light is monitored, recipient is retransmitted to.
Fig. 1 is the light channel structure of double unequal arm Mach-Zender interferometers of the embodiment of the present invention.
As shown in Figure 1, quantum communication system, which is sender and recipient, carries out quantum communication system, quantum communication system
Sender sends incident light, and incident light includes multiple photon sequences, and each photon sequence includes the photon of multiple sequential transmissions, often
One photon carries quantum information, is based on Quantum Secure Direct Communication agreement (Quantum secure direct
Communication, QSDC) selected phase coding mode, the phase code experimental program of use is based on double unequal arm Mach-
Zehnder interferometer light path structures.
Wherein, the time interval of the pulse of incident light is 1 μ s, when into first unequal arm region (a-quadrant in Fig. 1),
Incident light is divided into the two mutually perpendicular linearly polarized lights in beam polarization direction, referred to as crossed polarized light, and crossed polarized light is walked up and down respectively
The coding of phase-modulator is passed through on two light paths, upper road, and lower road is without coding.
Optionally, the path length of two light paths is different, will pass through upper road, have that phase-modulator is referred to as long-armed,
Lower road in parallel is known as galianconism, and is 20ns by the long-armed and time difference by galianconism, and note currently passes through the linear polarization of galianconism
Light is | H>, remember that currently passing through long-armed linearly polarized light is | V>.
Wherein, | H>With | V>It is that the state of photon is described using the state of polarization, | H>Indicate that the state of photon is vertical
Directly, | V>Indicate that the state of photon is level.
As shown in Figure 1, the embodiment of the present invention accesses the device of safety test in the position of communicating pair circuit B area, into
Row safety test.
Fig. 2 shows a kind of flow diagrams of the method for safety test provided in an embodiment of the present invention.
As shown in Fig. 2, method provided in an embodiment of the present invention specifically includes following steps：
Step 11 intercepts and captures the crossed polarized light sent by sender in quantum communication system, and the crossed polarized light includes
Horizontal polarization light and orthogonal polarized light；
Optionally, the device of safety test intercepts and captures crossed polarized light from the optical fiber to quantum communication system to be tested, blocks
The crossed polarized light cut enters from the device side of safety test, after the completion of the device processing through safety test, the amount of taking back again
The optical fiber of sub- communication system makes to continue to be sent to recipient.
Step 12, repeatedly adjustment horizontal polarization light and orthogonal polarized light phase difference so that the phase difference is default
Variation in range；
Step 13 is directed to each phase difference, determines corresponding first error rate, first error rate is according to current
The error rate of the recipient of phase difference estimation；
Optionally, in quantum communications, recipient is according to the phase difference of horizontal polarization light and orthogonal polarized lightIt determines
Whether this quantum communications is safe, and recipient is provided with corresponding judgment criteria：Error rate, that is, the photon presence received are lost
It loses, the ratio of the quantity for the photon that the quantity of mistake is sent with sender, if the error rate of recipient is more than threshold value, indicates to receive
Side determines that this quantum communications is monitored, and can determine monitoring degree.
For example, threshold value can be arranged according to actual conditions, can be 11%.
Optionally, preset range is 2n π~(2n+1) π, n ∈ Z, before not intercepting and capturing crossed polarized light, horizontal polarization
The phase difference of light and orthogonal polarized lightFor 2n π, after intercepting and capturing crossed polarized light, if the device of safety test is without prison
It listens, then it is not rightIt is adjusted, i.e., the phase difference that recipient receives is 2n π, thenThere is no mistake, it may be determined that do not monitor,
I.e. error rate theoretically should not exceed threshold value.
It is right if the device of safety test is monitored after intercepting and capturingIt is adjusted, what recipient receivedGreatly
In 2n π, then recipient can determine phase difference mistake, there is monitoring, error rate theoretically should be greater than threshold value.
Optionally,It can be adjusted between 2n π~(2n+1) π, n ∈ Z, phase difference is more than the degree of 2n π, with the first mistake
Rate is proportionate, for example, phase difference is (2n+1) π, can the first error rate be determined to be approximately 100%.
It should be noted that it is 25% that maximum error rate introduced in quantum eavesdropping system is retransmitted in practical intercepting and capturing.
Optionally, the device pair of safety testIt is adjusted, and according toThe first of the recipient of predictive estimation is wrong
Accidentally rate.
Step 14 is directed to each phase difference, obtains the second error rate of recipient, the second error rate is quantum communication system
In by recipient detect error rate；
Optionally, recipient detects phase difference, and determine after the crossed polarized light that the device for receiving safety test is retransmitted
Second error rate, the second error rate are the actually detected error rates of recipient.
Optionally, the device of safety test obtains the second error rate that recipient determines.
Step 15, according to the first error rate and the second error rate, determine whether quantum communication system passes through safety test.
Optionally, phase difference is continuously adjusted, comprehensively, accurately quantum communication system is tested.
Optionally, for the adjustment of phase difference each time, the first error rate is compared with the second error rate, if safety
First error rate of the device estimation of test and the difference of the second actually detected error rate of recipient are in default range, table
Show that the first error rate of the device estimation of safety test is close with the second error rate that recipient is actually detected.
For example, the device of safety test is not adjusted the phase difference of horizontal polarization light and orthogonal polarized light, and connect
Debit is by actually detected, and determination does not have mistake to the phase difference of horizontal polarization light and orthogonal polarized light yet, therefore recipient recognizes
Determine error rate and be less than threshold value, the device of not safety test is monitored, and reality is not monitored really, then it represents that quantum communications
System can accurately identify that whether there is or not monitorings.
Due to channel loss, quantized system inherently has certain inevitable error rate, thus since eavesdropping causes
Mistake be not whole, and cannot be distinguished belong to mistake caused by what reason, thus the setting of recipient's error rate actually
It needs to consider in conjunction with actual channel conditions.
Such as：Since channel loss will produce the bit error rate that can not evade, quantum communication system receives quantum communication system
Depending on the secure threshold of side should be according to real system situation, it is normally about taken as 11%.Phase is not introduced in the device of safety test
In the case of potential difference, if recipient's error rate is less than secure threshold, it is judged to passing through safety test
Such as：During phase is gradually adjusted to (2n+1) π by 2n π, if recipient's error rate be more than threshold value and
Direct proportion is presented and rises situation, then judgement passes through safety detection.
That is, determiningThe each phase difference changed within the scope of 2n π~(2n+1) π, n ∈ Z, and safety test
Device estimate the first error rate respectively, recipient detects the second error rate respectively, the device of safety test by each first
Error rate and corresponding second error rate are compared, if current phase difference can the side of being received discover, adjustment phase place again
Difference estimates the first error rate respectively for current phase difference, detects the second error rate respectively, until reaching scheduled number.
The degree of various phase differences, various monitorings is all tested, if the of the device estimation of safety test each time
The difference of one error rate and actually detected the second error rate of recipient indicates that recipient can be accurate all in default range
Determine the degree monitored, then quantum communication system has passed through this safety test.
In the present embodiment, scene is monitored to quantum communication system simulation to be tested, by adjusting horizontal polarization light and
The phase difference of orthogonal polarized light so thatChange within the scope of 2n π~(2n+1) π, n ∈ Z, adjusts the degree of monitoring, and pass through
According to every 1 first error rate and the second actually detected error rate of recipient, can safety accurately be carried out to quantum communication system
Test.
If there are the first error rates and the second actually detected error rate of recipient of the device estimation of once safety test
Difference be more than preset range, indicate quantum communication system do not meet Quantum Secure Direct Communication agreement, then can't put into
It uses, adjustment need to be re-started.
Wherein, Quantum Secure Direct Communication agreement includes：
1. efficient two steps Quantum Secure Direct Communication scheme：G.L.Long and X.S Liu Phys.Rev.A65,
032302(2002)
2. the two step Quantum Secure Direct Communication schemes based on dense coding：Fu-Guo Deng,Gui-Lu Long and
Xiao-Shu Liu,Phys.Rev.A68,042317(2003)
3. notepaper scheme of quantum：F.G.Deng and G.L.Long,Phys.Rev.A 69,052319(2004).
The method of the safety test of the embodiment of the present invention, by adjusting horizontal polarization light and orthogonal polarized light phase
Difference so that the phase difference changes within a preset range, and according to every 1 first error rate and recipient it is actually detected second
Error rate accurately can carry out safety test to quantum communication system.
On the basis of the above embodiments, the method for the safety test that further embodiment of this invention provides adjusts horizontal inclined
Shake light and orthogonal polarized light phase difference the step of specifically include：
By adjusting the driving frequency of acousto-optic frequency shifters, the phase difference is adjusted.
Optionally, driving frequency is the driving frequency of acousto-optic frequency shift device, and acousto-optic frequency shift device is the device of safety test
In an equipment.
Optionally, horizontal polarization light is input to acousto-optic frequency shift device with orthogonal polarized light, passes through acousto-optic frequency shift device
The adjusting to phase difference is realized in adjustment to optical frequency, and optical frequency is light frequency.
Optionally, by adjusting the driving frequency of acousto-optic frequency shifters, the step of adjusting the phase difference, is specially：
The phase difference is obtained by driving frequency according to following formula：
Wherein,For phase difference, fdIt is the driving frequency of acousto-optic frequency shift device, n is the refractive index 1.5 of optical fiber, and L is light
Fine length, c are the light velocity 3.0 × 108m/s。
Optionally, L be safety test device in light path length.
Optionally, driving frequency has following relationship with phase difference；
Optionally, it is fixed in L, as long as reasonably selecting fd, the phase of crossed polarized light can be accurately controlled
Potential difference.
Optionally, using acousto-optic frequency shifters to fdIt is continuously adjusted so thatIn 2n π~(2n+1) π, n ∈ Z ranges
Interior variation, so that it may to reach the adjustable effect of monitoring degree.
For example, it is illustrated for selecting fiber coupling acousto-optic frequency shifters, fiber coupling acousto-optic frequency shift device carries
The centre-drive frequency of confession is 200MHZ, and specific driving frequency can be continuously adjusted in 190MHZ between 210MHZ.
Driving frequency can repeatedly be adjusted, determines the first error rate and the second error rate respectively.
The optical fiber of L=5m, driving frequency 200MHZ is selected to bring intoIt can obtainPeace
First error rate of the device estimation tested entirely is 11%, if the difference of second error rate actually detected with recipient is default
In the range of, then continue to adjust driving frequency.
Driving frequency is 210MHZ, is brought intoIt can obtainThe device of safety test is estimated
The first error rate 100%.
If the difference of second error rate actually detected with recipient in default range, indicates that recipient can identify
The monitoring of 100% degree.
Optionally, in 200MHZ to slowly adjusting driving frequency between 210MHZ, so that it may to provide 20 π for crossed polarized light
Phase difference between~21 π, to realize the monitoring of 0~100% degree, observing recipient at this time, whether accurate discrimination is without monitoring
With the situation for having monitoring monitoring degree, the safety test of the whether approximate embodiment of the present invention of the second error rate are distinguished if any monitoring
Device the first error rate.
Other steps of the present embodiment are similar to previous embodiment step, and this embodiment is not repeated.
The method of safety test provided in this embodiment, by acousto-optic frequency shift device to by adjusting driving frequency, obtaining
Corresponding phase difference, can accurately adjustment phase place it is poor.
On the basis of the above embodiments, the method for the safety test that further embodiment of this invention provides, by adjusting sound
The driving frequency of optical frequency shifter, the step of adjusting the phase difference be specially：
According to the optical frequency of driving frequency and horizontal polarization light, the first phase of horizontal polarization light is obtained；
According to the optical frequency of driving frequency and orthogonal polarized light, the second phase of orthogonal polarized light is obtained：
According to first phase and second phase, the phase difference is obtained.
Optionally, acousto-optic frequency shift device is respectively adjusted the optical frequency of horizontal polarization light and orthogonal polarized light, in level
It is superimposed driving frequency on the basis of the optical frequency of polarised light, obtains the first phase of horizontal polarization light, correspondingly, in orthogonal polarized light
It is superimposed driving frequency on the basis of optical frequency, obtains the first phase of orthogonal polarized light, first phase and second phase is made the difference, can obtain
To the phase difference.
Fig. 3 is a kind of schematic diagram of the device for safety test that further embodiment of this invention provides.
As shown in figure 3, the acousto-optic frequency shift device includes moving up acousto-optic frequency shifters and moving down acousto-optic frequency shifters, correspondingly,
The first phase can be obtained according to following formula：
Wherein,For first phase, f is the original optical frequency of crossed polarized light, taFor from polarization beam apparatus to moving up acousto-optic
Time used in frequency shifter, tbTo move up acousto-optic frequency shifters to the time moved down used in acousto-optic frequency shifters, tcTo move down acousto-optic frequency translation
Time used in device to polarization beam apparatus；
The original optical frequency f of crossed polarized light is the optical frequency of the crossed polarized light before not intercepting and capturing, horizontal polarization light and vertical
The optical frequency of polarised light is identical, is f.
The second phase can be obtained according to following formula：
Wherein,For second phase, f is the original optical frequency of crossed polarized light；
The phase difference can be obtained according to following formula：
Optionally, the device of safety test can be made of polarization beam apparatus and acousto-optic frequency shift device.
Optionally, the function of polarization beam apparatus is to be divided into two bundles crossed polarized light, and crossed polarized light is vertically into polarization
After beam splitter, crossed polarized light is divided into two bundles by polarization beam apparatus, | V>Enter light path along clockwise direction, | H>Along side counterclockwise
To into light path.
Optionally, safety test device be arranged two Faraday rotators, one in annular light path, one in annular
Outside light path, wherein the effect of Faraday rotator in the optical path is so that clockwise in light path | V>Temporarily be converted to | H>,
In light path counterclockwise | H>Temporarily be converted to | V>, that is, realize polarization direction | H>With | V>Between conversion.
After annular light path, the two again is exchanged using another Faraday rotator.
Optionally, acousto-optic frequency shift device includes moving up acousto-optic frequency shifters, moving down acousto-optic frequency shifters and acousto-optic driver.
Optionally, the effect for moving up acousto-optic frequency shifters is that the optical frequency for the light that will pass through rises to f+f by fd, move down acousto-optic shifting
The effect of frequency device is that the optical frequency for the light that will pass through falls to f-f by fd, fdIt is the driving frequency provided by acousto-optic driver.
Optionally, crossed polarized light is divided into two-way by polarization beam apparatus so that horizontal polarization light | V>It sequentially enters and moves up sound
Optical frequency shifter and acousto-optic frequency shifters are moved down, orthogonal polarized light | H>It sequentially enters and moves down acousto-optic frequency shifters and move up acousto-optic frequency shifters.
Optionally, | V>The path passed through in the device of the safety test of the embodiment of the present invention is：Polarization beam apparatus, it is suitable
Hour hands are then return to polarization beam apparatus by moving up acousto-optic frequency shifters, moving down acousto-optic frequency shifters.
Optionally, crossed polarized light is after polarization beam apparatus beam splitting, and polarization direction is | V>Polarised light clockwise about ring
Shape optic path, after moving up acousto-optic frequency shifters raising frequency, moving down acousto-optic frequency shifters frequency reducing the adjustment of optical frequency will cause phase
Variation, the additional phase in entire loopFor：
By move up acousto-optic frequency shifters to horizontal polarization light increase driving frequency carry out raising frequency, by with move down acousto-optic frequency shifters pair
Horizontal polarization light carries out frequency reducing.In taThis period, | V>Optical frequency be f (i.e. former optical frequency), in tbThis period, | V>Optical frequency
It is f+fd, move up acousto-optic frequency shifters and raising frequency carried out to f, that is, increase driving frequency fd, in tcThis period, | V>Optical frequency be (f+
fd)-fd, acousto-optic frequency shifters are moved down to f+fdFrequency reducing is carried out, acousto-optic frequency shifters is moved down and frequency reducing is carried out to f, that is, reduces a driving frequency
Rate fd。
Correspondingly, frequency reducing is carried out to orthogonal polarized light by moving down acousto-optic frequency shifters, by moving up acousto-optic frequency shifters to vertical inclined
The light that shakes carries out raising frequency, and obtains the second phase of orthogonal polarized light
Optionally, | H>The path passed through in the device of the safety test of the embodiment of the present invention and | H>Implement in the present invention
The path passed through in the device of the safety test of example is reversed：Polarization beam apparatus, process moves down acousto-optic frequency shifters, moves up sound counterclockwise
Optical frequency shifter is then return to polarization beam apparatus.
Similarly, polarization direction is | H>Polarised light counterclockwise around belt optic path, by moving down acousto-optic frequency shifters drop
Frequently after, moving up acousto-optic frequency shifters raising frequency, the adjustment of optical frequency will cause the variation of phase, the additional phase in entire loop
For：
Other steps of the present embodiment are similar to previous embodiment step, and this embodiment is not repeated.
The method of safety test provided in this embodiment obtains level according to the optical frequency of driving frequency and horizontal polarization light
The first phase of polarised light obtains the second phase of orthogonal polarized light according to the optical frequency of driving frequency and orthogonal polarized light, by
One phase and second phase, which make the difference, can be obtained the phase difference, can realize that adjustment phase place is poor by adjusting driving frequency.
On the basis of the above embodiments, the method for the safety test that further embodiment of this invention provides adjusts horizontal inclined
Shake light and orthogonal polarized light phase difference the step of before, the method further includes：
The polarization direction of crossed polarized light is adjusted, cross-polarization optical registration polarization beam apparatus internal optical axis is made.
Optionally, it before carrying out adjusting offset, also needs to be corrected the polarization direction of crossed polarized light.
Optionally, crossed polarized light includes | H>With | V>, | H>With | V>Polarization direction be vertical, be transmitted across in optical fiber
The polarization direction of crossed polarized light may deviate in journey, to avoid influencing test result, be adjusted, correct to polarization direction.
Optionally, the function of polarization beam apparatus be crossed polarized light is divided into two bundles, if crossed polarized light vertical through
Polarization beam apparatus, then polarization beam apparatus can completely obtain all crossed polarized lights, if not having vertical polarization beam splitter, partially
Shake beam splitter can not complete crossed polarized light, cause damages, thus be arranged Polarization Controller adjust crossed polarized light polarization
Direction.
Optionally, using Polarization Controller so that the axis of the polarization directions aligned polarization beam apparatus of incident crossed polarized light
To keeping the polarization direction of crossed polarized light vertical, so as to vertically into polarization beam apparatus, to complete to correct.
Other steps of the present embodiment are similar to previous embodiment step, and this embodiment is not repeated.
The method of safety test provided in this embodiment, by using Polarization Controller so that the polarization side of crossed polarized light
To the axial direction of alignment polarization beam apparatus, make crossed polarized light can be vertically into polarization beam apparatus.
Fig. 4 is a kind of schematic diagram of the device for safety test that further embodiment of this invention provides；
As shown in figure 4, on the basis of the above embodiments, the method for the safety test that further embodiment of this invention provides,
Before the step of adjusting horizontal polarization light and orthogonal polarized light phase difference, the method further includes：
The path of crossed polarized light is adjusted to upper road：Lower road=100：0；
According to the first error rate and corresponding second error rate, determine whether quantum communication system is completed to debug.
Optionally, branch is carried out to crossed polarized light, there are two paths, a paths are known as upper road, and upper road is only arranged
Transmission Fibers, the device of no safety test, another paths are known as lower road, the device of lower road setting safety test.
Optionally, the path of crossed polarized light is adjusted to upper road：Lower road=100：0, it is equivalent at this time all orthogonal
The roads polarised light Dou Congshang directly reach recipient, that is, without listening mode.
Optionally, it is realized and is adjusted using variable ratio fiber optic splitter, variable ratio fiber optic splitter is for adjusting in optical fiber
Transmission path, the ratio of the object of transmission are adjusted.
Optionally, the splitting ratio of variable ratio fiber optic splitter can realize 0~100% continuously adjustable fiber optic splitter.
In no listening mode, it is 11% to estimate the first error rate, if being differed in preset model with corresponding second error rate
In enclosing, indicates current quantum communication system normal work, subsequent safety test can be carried out.
Other steps of the present embodiment are similar to previous embodiment step, and this embodiment is not repeated.
The method of safety test provided in this embodiment by first being debugged to quantum communication system, then carries out safety
Test so that test result is more acurrate.
Fig. 6 is a kind of schematic diagram of the device for safety test that further embodiment of this invention provides.
As shown in fig. 6, the method further includes：
Repeatedly the splitting ratio of adjustment crossed polarized light makes the light pulse institute accounting into lower road within the scope of 0%-100%
Increase；
For each splitting ratio, determine that corresponding first error rate, first error rate are according to current splitting ratio
The error rate of the recipient of estimation；
For each splitting ratio, the second error rate of recipient is obtained；
According to the first error rate and the second error rate, determine whether quantum communication system passes through safety test.
Realize that the adjustable of monitoring degree can pass through two ways：The mode for adjusting phase difference, the present invention is described above
Embodiment introduces another way.
Optionally, after completing correction course, the splitting ratio of variable ratio fiber optic splitter is adjusted to upper road again：Lower road=
100：0.
Again so that upper road：Lower road=100：After 0, driving frequency f is keptdIt is fixed so that phase difference is fixed as
(2n+1)π。
At this point, adjusting splitting ratio, every light into lower road is just bound to malfunction, thus the phase that acousto-optic frequency shifters provide
Difference is constant always, but as the light for entering wiretap increases, that is, the light ratio for entering monitoring device is continuously increased, until reaching
To 100%.
Monitored incident light ratio is continuously increased, then corresponding receiving terminal error rate also can constantly rise.I.e. according to prison
The size for the light pulse ratio listened can directly reflect the size of monitoring degree, more intuitively embody different monitoring degree and connect
The case where thus error rate of debit can be simulated under various monitoring degree, recipient.
The difference of the length on Shang Lu and lower road is in pre-determined threshold.
Explanation：Using this scheme, we need to ensure that two light paths of two variable ratio fiber optic splitters of connection are (i.e. normal
Two light paths of pattern and listening mode) same length, with ensure up and down two-way light pulse collect again after will not produce
Entanglement in raw main system sequential.In fact the requirement of this point is not high, since the light velocity is in 10^8M/s magnitudes, therefore cm grades
Error in length caused by time order error in 0.1ns magnitudes, this can't cause the influence in actual detection.
Crossed polarized light is transmitted to second unequal arm region, the path of crossed polarized light and first unequal arm region phase
Instead, by | H>By the long-armed of phase-modulator, | V>It is orthogonal inclined by galianconism, therefore from sender to recipient on the whole
The path that the light that shakes passes through is identical, therefore finally reaches simultaneously.
The pulse frequency of laser is 1 microsecond, and recipient's detection cycle is also theoretically 1 microsecond.
The present invention avoids common equal brachiums problem in phase code with annular light path, and due to | H>With | V>It is walked
Path is same, the problem of also just changing influence optical fiber state there is no external environment and introduce additional phase error.This and mesh
Sagnac rings used in preceding Single-photon interference experiment and the sub- phase code communication system of plug and play (plug-play) formula weight
Possess same advantage, which is introduced into the device of safety test by the embodiment of the present invention.
In order to more fully understand the technology contents of the present invention, on the basis of the above embodiments, the present embodiment is described in detail
The method of the safety test of offer.
For problem of the prior art, it is desirable that a large amount of losses of photon will not be caused by monitoring, and the side of monitoring is as independent
Third party the clock signal of communicating pair and result of detection cannot be used to feed back, this just represents and arrives can not grasp pulse
To realize that this, which allows for the automatically controlled device based on pulse sequence, to use to the precise manipulation of light pulse under the premise of the moment,
And the selection of passive device and light path design become most important.
As shown in Figure 1, in embodiments of the present invention, in conjunction with the basic principle of phase code, we can will monitor effect
Be equivalent to be by safety instrumentation | V>With | H>Two polarized optical pulses introduce additional phase difference, when the phase that monitoring side introduces
When potential difference is 2n π, n ∈ Z, it is equivalent to no monitoring；When the phase difference that monitoring side introduces is (2n+1) π, n ∈ Z, theoretically can
100% causes recipient to malfunction.
The present invention is devised by above-mentioned basic ideas, the present invention can be with the bipartite communication line of access communications (in Fig. 1
B area) in realize the function of equivalent monitoring, and not by the shadow of the concrete numerical values such as above-mentioned pulse laser frequency and long galianconism time difference
It rings, scheme is described in detail below：
Fig. 5 is a kind of schematic diagram of the device for safety test that further embodiment of this invention provides.
As shown in figure 5, the device of safety test is by two variable ratio fiber optic splitters, a circulator, a polarization control
Device processed, a polarization beam apparatus, a pair respectively can into line frequency up and down move acousto-optic frequency shifters (and matching used acousto-optic driving
Device) and two transmission-type Faraday rotators compositions.
Incident light pulse is provided by main communication system sender, these intercepted light pulses are left by the device of safety test
Side enters, and main communication system recipient is transmitted to by the device rightmost side after the device of safety test.The basic purposes of each device
As described below：
Variable ratio fiber optic splitter：Splitting ratio can realize 0~100% (one of branch accounts for the ratio of total incident light) even
Continue adjustable fiber optic splitter.
Circulator：Three ports 1,2,3 are as shown in figure 5, wherein 1 port incident light is exported by 2 ports, and 2 port incident lights are by 3
Port exports, and 3 port incident lights are exported by 1 port.
Polarization Controller：For adjusting the polarization variations generated in optical fiber transmission process, ensure former and later two at a distance of 20ns
The polarization direction of crossed polarized light can be axially aligned with polarization beam apparatus.
Polarization beam apparatus：Two mutually perpendicular linearly polarized lights are divided into two bundles, wherein | V>Enter ring along clockwise direction
Shape light path, | H>Enter annular light path in the counterclockwise direction.
Acousto-optic frequency shifters and driving：Acousto-optic frequency shifters part is the core of the program, the sound with upshift effect
Optical frequency shifter can make incident light optical frequency rise to f+f by fd, wherein fdFor the frequency of acousto-optic frequency shifters driving；Similarly, by tool
There is the frequency shifter of downshift effect that incident light optical frequency can be made to fall to f-f by fd.It as a result, can after two acousto-optic frequency shifters combinations
The effect of realization is as follows：
After polarization beam apparatus beam splitting, polarization direction is two crossed polarized lights | V>Emergent light clockwise about ring light
Road is transmitted, and additional phase is in entire loop after two acousto-optic frequency shifters distinguish raising frequency, frequency reducing：
Wherein ta, tb, tcRespectively incident light moves up acousto-optic frequency shifters and arrives from polarization beam apparatus to acousto-optic frequency shifters are moved up
Acousto-optic frequency shifters are moved down, and move down the time used in acousto-optic frequency shifters to polarization beam apparatus.
Similarly, polarization direction is | H>Incident light counterclockwise around belt optic path, risen respectively through two acousto-optic frequency shifters
Frequently, additional phase is in entire loop after frequency reducing：
The phase difference then introduced is
L is to move up acousto-optic frequency shifters and move down the fiber lengths between acousto-optic frequency shifters, and n is optical fibre refractivity.As it can be seen that only
Us are wanted to reasonably select L and acousto-optic driver driving frequency fd, can be accurately controlled former and later two at a distance of 20ns polarization hang down
The phase difference of straight veins punching.
After loop | H>With | V>Light converges again at polarization beam apparatus, since walked practical light path is identical thus
It is not in brachium not equal problem.It carried out simulation and monitors that treated that pulse enters circulator by 2 ports, and is defeated by 3 ends
Go out to import main communication system light path.
Fig. 7 is the basic principle schematic for the polarization beam apparatus that further embodiment of this invention provides.
As shown in fig. 7, port3 is input terminal, port1,2 be two output ends, and input light (crossed polarized light) is passed through
Calcite prism be divided into two mutually perpendicular line polarisations in polarization direction (| V>With | H>), input optical fibre is to protect with output optical fibre
Polarisation is fine.
If a branch of polarised light being aligned with slow axis (grey vertical arrows) is inputted in port 3, light beam will be deviated by prism,
Then it is exported from port 1 with polarization direction identical with slow axis.
, whereas if the input light of port 3 is aligned with optical fiber fast axle, as shown in the black level arrow in right figure,
It will be exported from port 2 with polarization direction identical with fast axle after prism.
Light beam bundling device (PBC) can be reversed application, the crossed polarized light that two beams are inputted from polarization maintaining optical fibre branch
Beam is coupled in a single-mode output optical fiber.It is incident on the light beam of port 1 and 2, polarization direction should be aligned with slow axis.From end
The incident light beams of mouth 1 and 2, if its polarization direction is aligned with optical fiber fast axle, prism will be such that it reflects from different directions, finally
It will not be emitted from input terminal 3.
Assuming that | V>It is exported from port 1, will input port be imported by port 2 after annular light path, at this time | V>It is corresponding to be
The fast axle of port 2.
Similarly | H>Input port is imported by port1 fast axles after loop, prism can make light not from output end 3 at this time
Outgoing.So FR must be added in the loop to exchange H and V, so that being incident on the light beam polarization direction of port 1 and 2
It is aligned with optical fiber fast axle.Again H and V is exchanged with FR after port 3 completes normally to export.
Faraday rotator (FR, Faraday Rotator)：The transmission-type Faraday rotation that the device of safety test uses
The rotation angle of device is 90 °, you can to realize polarization direction | H>With | V>Between conversion.
Under the premise of based on aforementioned thinking, to ensure to enter the linearly polarized light of annular light path by polarization beam apparatus | H>With |
V>, beam can be being closed again through polarization beam apparatus to original optical path, need to use Faraday rotation in annular light path after loop
Device will be former | H>With | V>The polarization direction of light is temporarily exchanged mutually, after the outlet of circulator 3 output, is revolved using another faraday
Turn device to exchange again by the two.
It is to be appreciated that whole devices used in above-mentioned experimental program have all had ripe manufacturing process, it can be by each
Apparatus manufacture purchase obtains.And in addition to the QSDC schemes used in the present apparatus, above-mentioned testing program is equally applicable to differ based on double
In OKD (QuantumKeyDistribution, quantum-key distribution) system of arm phase code.
The present invention can be ideal compared to for the technology being currently known simulation quantum communication protocol safety analysis
In monitoring effect.The light utilization ratio of main part (i.e. acousto-optic frequency shifters) in entire experimental provision can theoretically reach
100%, practical commercial product significantly larger than directly intercept and capture-retransmit single when experiment also all 80% even 90% or more
The detection efficient of photon detector 10% because of a large amount of losses of the light pulse without caused by, while can accurately simulate intercepting and capturing-weight
Monitoring side's operation described in hair theory leads to the effect of the rising of recipient's error rate.
Normal communication/containing the switching monitored between communicating both of which may be implemented in the present invention, and it is adjustable to monitor degree, after
Introduce specific regulative mode in face.The size of monitoring degree can be reflected by receiving terminal error rate size, this phenomenon also with theory
On monitoring effect be consistent.
The device of this safety test, which belongs to, is completely independent third party, not the pulse clock of acceptor's communication system communication both sides
The limitation of synchronizing signal and pulse frequency.Acousto-optic frequency shifters required driving frequency signal stabilization when working, thus include it
All devices including remaining passive device are without considering time resolution characteristics so that it is logical that package unit may be equally applicable for high speed
Letter system.
Accurate additive phase control may be implemented in the present invention.Acousto-optic frequency shifters may be implemented in 1ppm (10HZ) magnitude
FREQUENCY CONTROL, so that phase difference degree of regulation is 10-7π magnitudes can meet experimental precision demand completely, and compared to coming
It says, the modulation accuracy of traditional lithium niobate phase modulator is in 1% magnitude.In addition to this, acousto-optic frequency shifters are to polarization insensitive,
Because without generating different modulation to different polarization.
As shown in fig. 6, normal mode (no listening mode)：The splitting ratio of two variable ratio fiber optic splitters is adjusted to
Road：Lower road=100：0, such as dotted portion, be equivalent to the almost all of roads Guang Doucongshang at this time directly by the present apparatus, this just into
Enter without listening mode.
Listening mode：Process is corrected after into listening mode first, enters adjustable listening mode later.
Realize that the adjustable of monitoring degree can pass through two ways：
Method one：
Step 1：The splitting ratio of variable ratio fiber optic splitter is adjusted to upper road first：Lower road=0：100, own at this time
Incident light nearly all enter lower road, adjust Polarization Controller and make incident cross-polarization optical registration polarization beam apparatus axial,
Correction finishes.
Step 2：By the analytic process in technical solution, according toSelect suitable fiber lengths L and
Driving frequency fd.Work as additive phaseWhen, it is equivalent to and the pulse is not monitored；When addition Item isWhen, it is equivalent to and is monitored the light pulse and caused receiving terminal and report an error to this position.
Realize the adjustable pass-through mode of monitoring degree：
Continuously adjust driving frequency fdSo thatChange within the scope of 2n π~(2n+1) π, n ∈ Z, so that it may be monitored with reaching
The adjustable effect of degree.
It is illustrated by taking a kind of common fiber coupling acousto-optic frequency shifters in the market as an example, during which provides
Heart driving frequency is 200MHZ, and driving frequency can be continuously adjusted in 190MHZ between 210MHZ.The optical fiber of L=5m is selected,
It brings intoCan obtain, if we in 200MHZ to slowly adjusting driving frequency between 210MHZ, so that it may with for two
A mutually orthogonal polarised light provides the phase difference between the π of 20 π~21, to realize the monitoring of 0~100% degree and receive
It is reflected on device.
Explanation：
During described in method one, for unidirectional QKD Transmission systems, i.e. photon signal is only transmitted from Alice to Bob
In system, two variable ratio fiber optic splitters and whole upper road can directly remove (as shown in Fig. 6 dotted line frames), because when two
Driving frequency added by acousto-optic frequency shifters just to be equivalent to no eavesdropping state when additional phase error is 2n π.But in view of based on QSDC
Quantum communications main system and two-way QKD transmission plan be required to two-way light and transmit, if above-mentioned light path is removed, due to farad
Circulator and Polarization Controller effect can cause light pulse by it is right to it is left when experience mistake phase code process, thus cannot
The normal encoding communication of entire light path when ensuring without eavesdropping state.
Method two：After completing correction course, the splitting ratio of variable ratio fiber optic splitter is adjusted to upper road again：Lower road=
100：0, it adjusts acousto-optic modulator driving frequency and makes
Keep driving frequency fixed, the splitting ratio for adjusting variable ratio fiber optic splitter makes the light pulse for entering lower road
Institute's accounting gradually increases, that is, the light pulse ratio for entering monitoring system is continuously increased.Monitored light pulse ratio is continuously increased,
Then corresponding receiving terminal error rate also can constantly rise.This scheme more intuitively embodies the effect of monitoring, that is, monitors degree
Size show monitor light path interception light pulse ratio size on.
Explanation：Using this scheme, we need to ensure that two light paths of two variable ratio fiber optic splitters of connection are (i.e. normal
Two light paths of pattern and listening mode) same length, with ensure up and down two-way light pulse collect again after will not produce
Entanglement in raw main system sequential.In fact the requirement of this point is not high, since the light velocity is 108M/s magnitudes, therefore cm grades
For time order error caused by error in length in 0.1ns magnitudes, this can't cause the influence in actual detection.
Fig. 8 is a kind of structural schematic diagram of the device for safety test that further embodiment of this invention provides.
With reference to Fig. 8, on the basis of the above embodiments, the device of safety test provided in this embodiment, described device packet
Interception module 71, adjustment module 72, determining module 73, acquisition module 74 and test module 75 are included, wherein：
Interception module 71 is for intercepting and capturing the crossed polarized light sent by sender in quantum communication system, the cross-polarization
Light includes horizontal polarization light and orthogonal polarized light；Adjustment module 72 is for adjusting horizontal polarization light and orthogonal polarized light phase
Difference so that the phase difference changes within a preset range；Determining module 73 is used to be directed to each phase difference, determines corresponding the
One error rate, first error rate are the error rates according to the recipient of current phase difference estimation；Acquisition module 74 is used for
For each phase difference, the second error rate of recipient is obtained, the second error rate is detected by recipient in quantum communication system
Error rate；Test module 75 is used to, according to the first error rate and the second error rate, determine whether quantum communication system passes through peace
Full test.
Optionally, interception module 71 intercepts and captures crossed polarized light from the optical fiber to quantum communication system to be tested.
Optionally, preset range is 2n π~(2n+1) π, n ∈ Z, before not intercepting and capturing crossed polarized light, horizontal polarization
The phase difference of light and orthogonal polarized lightFor 2n π, after intercepting and capturing crossed polarized light, if the device of safety test is without prison
It listens, then it is not right to adjust module 72It is adjusted, i.e., the phase difference that recipient receives is 2n π, thenThere is no mistake, it may be determined that
It does not monitor, i.e., error rate theoretically should not exceed threshold value.
It is right if the device of safety test is monitored after intercepting and capturingIt is adjusted, what recipient receivedGreatly
In 2n π, then recipient can determine phase difference mistake, there is monitoring, error rate theoretically should be greater than threshold value.
Optionally,It can be adjusted between 2n π~(2n+1) π, n ∈ Z, phase difference is more than the degree of 2n π, with the first mistake
Rate is proportionate, for example, phase difference is (2n+1) π, can the first error rate be determined to be approximately 100%.
Optionally, therefore adjustment module 72 is rightIt is adjusted, and according toThe reception of 73 predictive estimation of determining module
First error rate of side.
Recipient detects phase difference after the crossed polarized light that the device for receiving safety test is retransmitted, and determines that second is wrong
Accidentally rate, the second error rate is the actually detected error rate of recipient.
Acquisition module 74 obtains the second error rate that recipient determines.
Phase difference is continuously adjusted, comprehensively, accurately quantum communication system is tested.
Optionally, for the adjustment of phase difference each time, the first error rate is compared with the second error rate, if safety
First error rate of the device estimation of test in default range, is surveyed with the difference of the second actually detected error rate of recipient
Die trial block 75 determines that the first error rate of the device estimation of safety test is close with the second error rate that recipient is actually detected.
That is, determiningThe each phase difference changed within the scope of 2n π~(2n+1) π, n ∈ Z, and safety test
Device estimate the first error rate respectively, recipient detects the second error rate respectively, the device of safety test by each first
Error rate and corresponding second error rate are compared, if current phase difference can the side of being received discover, adjustment phase place again
Difference estimates the first error rate respectively for current phase difference, detects the second error rate respectively, until reaching scheduled number.
The degree of various phase differences, various monitorings is all tested, if the of the device estimation of safety test each time
The difference of one error rate and actually detected the second error rate of recipient indicates that recipient can be accurate all in default range
Determine the degree monitored, then quantum communication system has passed through this safety test.
In the present embodiment, scene is monitored to quantum communication system simulation to be tested, by adjusting horizontal polarization light and
The phase difference of orthogonal polarized light so thatChange within the scope of 2n π~(2n+1) π, n ∈ Z, adjusts the degree of monitoring, and pass through
According to every 1 first error rate and the second actually detected error rate of recipient, can safety accurately be carried out to quantum communication system
Test.
If there are the first error rates and the second actually detected error rate of recipient of the device estimation of once safety test
Difference be more than preset range, indicate quantum communication system do not meet DL04 agreements, then can't come into operation, need again into
Row adjustment.
The adjustment module is additionally operable to：By adjusting the driving frequency of acousto-optic frequency shifters, the phase difference is adjusted.
The adjustment module is additionally operable to：The phase difference is obtained by driving frequency according to following formula：
Wherein,For phase difference, fdIt is the driving frequency of acousto-optic frequency shift device, n is the refractive index 1.5 of optical fiber, and L is light
Fine length, c are the light velocity 3.0 × 108m/s。
The device of safety test provided in this embodiment, the method that can be used for executing above method embodiment, this implementation is not
It repeats again.
The device of safety test provided in this embodiment, by adjusting module adjust horizontal polarization light and orthogonal polarized light
Phase difference so that the phase difference changes in default range, and test module is according to every 1 first error rate and recipient
The second actually detected error rate accurately can carry out safety test to quantum communication system.
It will be appreciated by those of skill in the art that although some embodiments described herein include being wrapped in other embodiments
Certain features for including rather than other feature, but the combination of the feature of different embodiments mean in the scope of the present invention it
It is interior and form different embodiments.
It will be understood by those skilled in the art that each step in embodiment can with hardware realization, or at one or
The software module run on the multiple processors of person is realized, or is realized with combination thereof.Those skilled in the art should manage
Solution, can realize according to the ... of the embodiment of the present invention one using microprocessor or digital signal processor (DSP) in practice
The some or all functions of a little or whole components.The present invention is also implemented as executing method as described herein
Some or all equipment or program of device (for example, computer program and computer program product).
Although the embodiments of the invention are described in conjunction with the attached drawings, but those skilled in the art can not depart from this hair
Various modifications and variations are made in the case of bright spirit and scope, such modifications and variations are each fallen within by appended claims
Within limited range.
Claims (10)
1. a kind of method of safety test, which is characterized in that the method includes：
Intercept and capture quantum communication system in by sender send crossed polarized light, the crossed polarized light include horizontal polarization light and
Orthogonal polarized light；
Repeatedly adjust horizontal polarization light and orthogonal polarized light phase difference so that the phase difference changes within a preset range；
For each phase difference, determine that corresponding first error rate, first error rate are according to current phase difference estimation
Recipient error rate；
For each phase difference, the second error rate of recipient is obtained, the second error rate is in quantum communication system by recipient
The error rate of detection；
According to the first error rate and the second error rate, determine whether quantum communication system passes through safety test.
2. according to the method described in claim 1, it is characterized in that：Adjust horizontal polarization light and orthogonal polarized light phase difference
The step of specifically include：
By adjusting the driving frequency of acousto-optic frequency shifters, the phase difference is adjusted.
3. according to the method described in claim 2, it is characterized in that：By adjusting the driving frequency of acousto-optic frequency shifters, institute is adjusted
The step of stating phase difference be specially：
The phase difference is obtained by driving frequency according to following formula：
Wherein,For phase difference, fdIt is the driving frequency of acousto-optic frequency shift device, n is the refractive index 1.5 of optical fiber, and L is that optical fiber is long
Degree, c are the light velocity 3.0 × 108m/s。
4. according to the method described in claim 3, it is characterized in that：By adjusting the driving frequency of acousto-optic frequency shifters, institute is adjusted
The step of stating phase difference be specially：
According to the optical frequency of driving frequency and horizontal polarization light, the first phase of horizontal polarization light is obtained；
According to the optical frequency of driving frequency and orthogonal polarized light, the second phase of orthogonal polarized light is obtained：
According to first phase and second phase, the phase difference is obtained.
5. according to the method described in claim 4, it is characterized in that:The acousto-optic frequency shift device include move up acousto-optic frequency shifters and
Acousto-optic frequency shifters are moved down, correspondingly, the first phase can be obtained according to following formula：
Wherein,For first phase, f is the original optical frequency of crossed polarized light, taFor from polarization beam apparatus to moving up acousto-optic frequency translation
Time used in device, tbTo move up acousto-optic frequency shifters to the time moved down used in acousto-optic frequency shifters, tcIt is arrived to move down acousto-optic frequency shifters
Time used in polarization beam apparatus；
The second phase can be obtained according to following formula：
Wherein,For second phase, f is the original optical frequency of crossed polarized light；
The phase difference can be obtained according to following formula：
6. according to the method described in claim 1, it is characterized in that:Adjust horizontal polarization light and orthogonal polarized light phase difference
The step of before, the method further includes：
The polarization direction of crossed polarized light is adjusted, cross-polarization optical registration polarization beam apparatus internal optical axis is made.
7. according to the method described in claim 1, it is characterized in that：Adjust horizontal polarization light and orthogonal polarized light phase difference
The step of before, the method further includes：
The path of crossed polarized light is adjusted to upper road：Lower road=100：0；
According to the first error rate and corresponding second error rate, determine whether quantum communication system is completed to debug.
8. according to the method described in claim 1, it is characterized in that：The method further includes：
Repeatedly the splitting ratio of adjustment crossed polarized light so that the light pulse institute accounting into lower road increases within the scope of 0%-100%
Add；
For each splitting ratio, determine that corresponding first error rate, first error rate are according to current light splitting compared estimate
Recipient error rate；
For each splitting ratio, the second error rate of recipient is obtained；
According to the first error rate and the second error rate, determine whether quantum communication system passes through safety test.
9. according to the method described in claim 8, it is characterized in that：The difference of the length on Shang Lu and lower road is in pre-determined threshold.
10. a kind of device of safety test, which is characterized in that described device includes：
Interception module, for intercepting and capturing the crossed polarized light sent by sender in quantum communication system, the crossed polarized light packet
Include horizontal polarization light and orthogonal polarized light；
Module is adjusted, for adjusting horizontal polarization light and orthogonal polarized light phase difference so that the phase difference is default
Variation in range；
Determining module determines that corresponding first error rate, first error rate are according to current for being directed to each phase difference
Phase difference estimation recipient error rate；
Acquisition module obtains the second error rate of recipient, the second error rate is quantum communications system for being directed to each phase difference
The error rate detected by recipient in system；
Test module, for according to the first error rate and the second error rate, determining whether quantum communication system passes through safety test.
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