CN207135114U - The CV QKD system unrelated from the measuring apparatus of steady phase - Google Patents
The CV QKD system unrelated from the measuring apparatus of steady phase Download PDFInfo
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- CN207135114U CN207135114U CN201720641276.7U CN201720641276U CN207135114U CN 207135114 U CN207135114 U CN 207135114U CN 201720641276 U CN201720641276 U CN 201720641276U CN 207135114 U CN207135114 U CN 207135114U
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Abstract
The utility model provides a kind of measuring apparatus from steady phase unrelated CV QKD systems, the CV QKD system unrelated from the measuring apparatus of steady phase, including source ends, first client, second client and relay, first client and the second client arrangement are in annular light path, the optical signal that source ends are sent is divided into two-way and enters the annular light path with opposite transmission direction, wherein modulated all the way in the first client, another way is modulated in the second client, two ways of optical signals is passed through measured into relay after whole annular light path respectively, client consults generation safe key according to the measurement result of relay.The two ways of optical signals from source ends and carries out coded modulation accordingly with identical path respectively by the first client and the second client in the utility model, can realize the stabilization of two ways of optical signals relative phase.
Description
Technical field
It the utility model is related to quantum communications field, more particularly to a kind of MDI CV-QKD systems
Background technology
The correlative study of quantum key distribution (QKD) is always the emphasis in quantum information field, and is most connect in the field
It is bordering on the achievement of practical application.Information technology developed rapidly in the last few years, but information security also has become people's concern simultaneously
Hot issue, QKD fast development has benefited from it will be to the dramatic change that information security field is brought.QKD is based on most base
This principle of quantum mechanics, make communicating pair (commonly referred to as Alice and Bob) or (can be commonly referred to as in listener-in in many ways
Eve the key of generation safety is consulted in environment existing for).First based on QKD mechanism generation key before each communication, then using should
Cipher key pair communication content is encrypted, and the security of communication will can be completely secured in the communication mode of such one-time pad.Therefore QKD
The correlative study and popularization of mechanism can solve existing various information security issues substantially.
Existing main flow QKD schemes are divided into two kinds：(1) the quantum key distribution mechanism (DV-QKD) based on discrete variable；
(2) the quantum key distribution mechanism (CV-QKD) based on continuous variable.And CV-QKD due to use existing general optics,
Compared with DV-QKD and possess that technology maturation, cost be relatively low and the more high series of advantages of code check.
Earliest QKD correlative studys all concentrate on the system that communication party is directly connected by optical fiber, and such system is general
Referred to as point-to-point QKD system.But this mode has the defects of obvious, the mode that communicating pair is joined directly together can not be to structure
Build the multiterminal relaying quantum network of more practical terminal-to-terminal service.It is between communication party and non-straight in the current communication technology
Connect connected, but pass through relay station or server and carry out transfer.Accordingly, in current QKD researchs, a kind of measuring apparatus is unrelated
(MDI) QKD mechanism is suggested.In MDI QKD systems, it is connected between Alice and Bob by relaying, and the measurement of signal
Through row in relaying.The measuring apparatus of relaying can be manipulated (measuring apparatus is unrelated to hence obtain one's name) by Eve, but Alice and Bob are still
Safe key can be generated according to measurement result.It is credible that MDI QKD are not required for measuring apparatus, therefore solves original various
In QKD mechanism, measuring apparatus easily by various attacks the problem of.Also it is the quantum key distribution net by terminal-to-terminal service simultaneously
The structure of network specifies developing direction.
For MDI CV-QKD schemes are than corresponding MDI DV-QKD, there is higher code in tens kilometers of fiber distance
Rate and cost is more economical.Therefore, it is to build a kind of feasible program of following quantum communication network based on MDI CV-QKD schemes.
Referring to Fig. 1, existing MDI CV-QKD systems (such as Nature Photonics 10,83 (2015), PRA 89,
052301 (2014), PRA 89,042335 (2014)) carry out key distribution process it is as follows：
1. pulse laser sends laser pulse.
2. laser pulse is through balancing beam splitter (BS11) beam splitting, transmitted pulse and reflected impulse are respectively through optical fiber 11 and optical fiber
12 are transferred to Alice ends and Bob ends.
3. subsequent Alice and Bob ends carry out identical Gaussian modulation to laser pulse (being described with coherent state).
Signal after the completion of modulation is sent to relaying by 4.Alice and Bob via optical fiber 13 and optical fiber 14 respectively.
5. in relaying, the pulse received from Alice and Bob is interfered via the second balance beam splitter (BS12).
6. the two-way outgoing pulse after coupling is measured by two balanced homodyne measurement apparatus BHD1 and BHD2 through row respectively, point
The corresponding x-component and p-component of other measurement signal (this is the Bell state measurement of continuous variable).By the measurement knot of two detectors
Fruit is added and subtracts each other and finally give numerical value q_And p+。
7. the two results are integrated and generated by relayingAnd each Υ concrete outcome is passed through into classics
Communication port (being not drawn into figure) informs Alice and Bob.
8. according to Υ result, Alice and Bob can each extrapolate the quantum state that other side accordingly modulates pulse.Both sides
Using a side as reference, the Gaussian random variable of one group of association is obtained.
9. both sides are held consultation by classical passage, the amplification of error correction and privacy ultimately generates safe key.
Local oscillator pulse has also been needed during homodyne detection as auxiliary.Alice and Bob is respectively necessary for a local oscillator pulse, local oscillator
Pulse can be sent to BHD1 and BHD2 (not drawn in figure) by individual fibers.It is also contemplated that the mode of sideband coding,
Object using the sideband of laser as coding, and master tape is as local oscillator.Now the balanced homodyne measurement apparatus in such scheme can
To replace with simple photodetector, but it is consistent in overall principle, therefore is no longer described in detail (referring to Nature Photonics
10,83(2015))。
MDI CV-QKD maximum difficult point be encoded signal light that Alice and Bob each send respectively through it is long away from
From optical fiber be transferred to up to how setting up reliable phase reference after relay.Only when phase with reference to it is reliable when, relaying
End carries out the obtained result of continuous variable Bell state measurement just can be to Alice or Bob with reference to value, and otherwise key can not give birth to
Into.Influenceed by optical fiber or environment, after being transmitted through long-distance (using optical fiber or free space) between two paths of signals light
There is random offset in relative phase, establish reliable phase and influence to eliminate the random phase to measurement is implied that with reference to it.
In the scheme of prior art, do not solve to establish reliable phase with reference to this significant problem, technical scheme and it is imperfect, it is necessary to
New actively or passively phase stabilization technique is introduced to realize the stabilization of phase.
Utility model content
The utility model provides a kind of measuring apparatus from steady phase unrelated CV-QKD systems, the two-way light from source ends
Signal passes through identical light path, so as to realize the stabilization of two ways of optical signals relative phase, and accordingly in the first client
Coded modulation is carried out with the second client.
A kind of unrelated CV-QKD systems of measuring apparatus from steady phase, including source ends, the first client, the second client
And relay, in annular light path, the optical signal that source ends are sent is divided into for first client and the second client arrangement
Two-way simultaneously enters the annular light path with opposite transmission direction, wherein being modulated all the way in the first client, another way is second
Client is modulated, and two ways of optical signals is passed through measured into relay after whole annular light path respectively, and client is according to relaying
The measurement result at end consults generation safe key.
In the utility model, for prior art, annular light path is built, from source ends and is sent to the first client, second
The two ways of optical signals of client all measures via the annular light path into relay, overcomes two-way light letter in the prior art
The problem of number transmission path each can not establish accurate phase reference caused by independence.
The optical signal that source ends are sent all is in public ring light to returning to during beam splitter is interfered through beam splitter beam splitting
Transmitted in road, the light path that two-way beam splitting flashlight passes through is identical therefore relative phase can keep stable；Two ways of optical signals exists
It is also all right through the first client and the second client in transmittance process, wherein opposite transmission direction be relative to annular light path and
Speech.
Preferably, the relay is provided with the beam splitter in the annular light path, the light that the source ends are sent
Signal is divided into two ways of optical signals via the beam splitter and enters annular light path with opposite transmission direction.
Preferably, in the two ways of optical signals, wherein pass through the first client and the second client successively all the way, and
Second client is modulated；Another way passes through the second client and the first client successively, and is adjusted in the first client
System, two ways of optical signals is modulated and whole annular light path of passing through after return to the beam splitter and interfered and interference signal light is entered
Row measurement.
According to transmission path, if first passing through the second client, after by the first client in modulate, can avoid adjusting
The premature loss of intensity after system, if similarly first passing through the first client, after by the second client in modulate.
Preferably, setting the first measurement apparatus and the second measurement apparatus in the relay, it is respectively used to measurement and comes from
The interference signal light of described two output ends of beam splitter；
The measurement result of reception first measurement apparatus and the second measurement apparatus is additionally provided with the relay and to it
The data processing equipment post-processed.
Preferably, the beam splitter and the first measurement apparatus and the second measurement apparatus pass through tie point and second respectively
Branch road is connected, and a branch road is provided with fiber optical circulator wherein, and the optical signal that the source ends are sent is via the fiber optical circulator
Wherein Single port input to the beam splitter.
Transmitting-receiving separation is realized by circulator, the signal of transmission is given to beam splitter, reception signal will be sent to survey all the way
Measure device.
Preferably, the first polarized controller is provided with the source ends, to adjust the optical signal of source ends transmission
Polarization direction, be additionally provided with the annular light path：
Second polarization beam apparatus, the optical signal for polarization direction control the first client of disengaging according to optical signal are walked
To；
3rd polarization beam apparatus, the optical signal for polarization direction control the second client of disengaging according to optical signal are walked
To；
Modulation module and the change for modulated optical signal are equipped with first client and the second client
The adjusting means of optical signal polarization direction.
By the first polarized controller in source ends, can be adjusted before optical signal branch expected from polarization direction,
Such as selection horizontal direction (vertical direction is similarly), when optical signal transmits in annular light path, pass through the second polarization beam apparatus, the
Adjusting means in three polarization beam apparatus and the first client and the second client can change light by adjusting polarization
Transmission direction, to realize that two ways of optical signals is passed through whole annular light path in opposite direction.
First polarized controller can use polarization beam apparatus, Polarization Controller (PC) or half-wave plate (HWP), can be real
Now to the Polarization Modulation of emergent light.
The adjusting means is faraday rotation mirror, and optical signal passes through this in the inside of the first client or the second client
Faraday rotation mirror is turned back.
The adjusting means is polarization-maintaining beam splitter, and optical signal passes in and out the first client or the second visitor by the polarization-maintaining beam splitter
Family end.
Revolving mirror and polarization-maintaining beam splitter is drawn all to make the change for realizing polarization direction, in order to which optical signal is by
When two polarization beam apparatus or three polarization beam apparatus, its transmission path is controlled according to polarization direction.
Optionally, in the two ways of optical signals obtained from source ends and by the beam splitter beam splitting：
The first client is wherein entered by the second polarization beam apparatus with the first polarization direction all the way, via the tune of transmitting terminal
The second visitor is entered by the second polarization beam apparatus, the 3rd polarization beam apparatus with the second polarization direction behind section device change polarization direction
Family end；The 3rd polarization beam apparatus is still passed through with the first polarization direction after changing polarization direction via the adjusting means of the second client
Return to the beam splitter；
Another way enters the second client with the first polarization direction by the 3rd polarization beam apparatus, via the second client
Enter first by the 3rd polarization beam apparatus, the second polarization beam apparatus behind adjusting means change polarization direction with the second polarization direction
Client；The second polarization beam splitting is still passed through with the first polarization direction after changing polarization direction via the adjusting means of the first client
Device returns to the beam splitter.
First polarized controller, the second polarization beam apparatus and the 3rd polarization beam apparatus, it is preferred to use polarization beam apparatus.
First polarization direction and the second polarization direction are orthogonal, and generally, one is horizontal polarization direction, and another one is
Vertical polarization.
Analyzed more than, the second client or the first client are entered with different polarization direction per road；Even with
First polarization direction enters the first client, then enters the second client with the second polarization direction；If conversely, with the second polarization side
To the first client is entered, then the second client is entered with the first polarization direction.
Moreover, two ways of optical signals exports after changing polarization direction in the second client or the first client.
As modulation module in itself, prior art, such as the phase including being handled successively optical signal can be used to adjust
Device and amplitude modulaor processed.
With regard to the measurement of the optical signal generation of source ends and relay to optical signal in itself, all of prior art can be used
Multi-form, certain the utility model also provides preferable mode.
Metering system, measured value and the step of be subsequently generated key it is identical with prior art, will not be described in further detail.
The utility model also provides a kind of MDI CV-QKD methods from steady phase, and the optical signal that source ends are sent is divided into two-way
And annular light path is entered with opposite transmission direction, wherein pass through the first client and the second client successively all the way, and
Two clients are modulated；Another way passes through the second client and the first client, and is modulated in the first client, two-way
Optical signal is modulated and whole annular light path of passing through after interfered and measured.
Preferably, after the optical signal that source ends are sent is divided into two-way, the second client is entered with different polarization direction per road
End and the first client；Exported after changing polarization direction in the second client and the first client.
The light path that optical signal of the two-way from source ends passes through in the utility model is identical, so as to as caused by optical fiber
Phase offset is also identical.Therefore the steady of two paths of signals light relative phase is realized without complicated phase stabilization device can
It is fixed.
Brief description of the drawings
Fig. 1 is the schematic diagram of MDI CV-QKD systems in the prior art；
Fig. 2 is the schematic diagram of MDI CV-QKD systems in the utility model embodiment 1；
Fig. 3 is the schematic diagram of MDI CV-QKD systems in the utility model embodiment 2；
Fig. 4 a are the schematic diagram of the utility model measurement apparatus；
Fig. 4 b are the schematic diagram of the utility model another kind measurement apparatus；
Fig. 5 is the schematic diagram of MDI CV-QKD systems in the utility model embodiment 3；
Fig. 6 is the schematic diagram of MDI CV-QKD systems in the utility model embodiment 4；
Fig. 7 is the schematic diagram of MDI CV-QKD systems in the utility model embodiment 5；
Fig. 8 is the schematic diagram of the utility model balanced homodyne measurement apparatus.
Embodiment
Embodiment 1：
Referring to Fig. 2, MDI CV-QKD systems include in the present embodiment：
Source ends, specifically include the laser that can generate continuous laser and as the first inclined of the first polarized controller
Shake beam splitter (PBS1), and PBS1 can will receive continuous laser and the laser of horizontal polarization (H) is emitted from transmission end.
Wherein, the first polarized controller can also use Polarization Controller (PC) or half-wave plate (HWP), can realize pair
The Polarization Modulation of emergent light.
Relay, provided with the beam splitter (BS) in annular light path, the horizontal polarization light that source ends are sent is via optical fiber
The wherein Single port of circulator, which inputs, to be divided into two ways of optical signals to beam splitter (BS) and enters annular light path in a reverse direction；Two-way
Optical signal is passed through and returns and interfere, two kinds of result of interference (i.e. beam splitting from beam splitter (BS) again after whole annular light path respectively
Two output ends of device) via tie point and the second branch road the first measurement apparatus and the second measurement apparatus are respectively enterd, respectively
For measuring the result of interference from two output ends of beam splitter；It is additionally provided with relay and receives the first measurement apparatus and second
The measurement result of measurement apparatus and the data processing equipment post-processed.Fiber optical circulator is set on the first leg cutting
Change the transmission direction of optical signal.
First client and the second client, the second polarization beam apparatus (PBS2) and the 3rd polarization are additionally provided with annular light path
Beam splitter (PBS3).The modulation module and change light for modulated optical signal are equipped with first client and the second client
The adjusting means in signal polarization direction.
In two ways of optical signals wherein from source ends and by beam splitter (BS)：
The second polarization beam apparatus is wherein transmitted through all the way and enters the first client, is changed via the adjusting means of transmitting terminal
Polarization direction back reflection enters the second client by the second polarization beam apparatus, the 3rd polarization beam apparatus；Via the second client
Adjusting means change polarization direction after be transmitted through the 3rd polarization beam apparatus and enter beam splitter；
Another way is transmitted through the 3rd polarization beam apparatus and enters the second client, and the adjusting means via the second client changes
Become polarization direction back reflection and enter the first client by the 3rd polarization beam apparatus, the second polarization beam apparatus；Via the first client
The second polarization beam apparatus, which is transmitted through, behind the adjusting means change polarization direction at end enters beam splitter.
If the first polarization beam apparatus of source ends is from the laser of reflection end outgoing vertical polarization (H), by identical reason
Transmitted in annular light path.The inside of the first client and the second client also serves as one of annular light path in the present embodiment
Point.
MDI CV-QKD methods include in the present embodiment：
1. in source ends, laser generation continuous laser.Continuous laser is brought out after polarization beam apparatus (PBS1) from transmission
Penetrate horizontal polarization (H) laser.
2. the transmission through optical fiber 1, laser enters relay.
3. continuous laser enters beam splitter (specific using balance beam splitter, BS) through fiber optical circulator, it is divided into intensity through BS
Identical two-way.Following narration is by taking (left) optical signal wherein all the way as an example, and another way is similarly.
4. left laser enters the second polarization beam apparatus (PBS2), because its polarization is H therefore directly transmissions.
5. left transmission laser is transferred into Alice ends i.e. the first client through optical fiber 2.
6. incident laser first passes through Polarization Controller (PC1) through the corresponding polarization compensation of row, correct in a fiber over long distances
Polarization deflection caused by transmission.
7. laser passes through phase-modulator (PM1) and amplitude modulaor (AM1), but now two instruments and without any
Modulation.
8. laser deflects after faraday rotation mirror (FM) reflection and is changed into vertical polarization (V) by horizontal polarization (H).
9. the laser of reflection again passes by AM1 and PM1, now still without any modulation.
10. laser again passes by optical fiber 2 and returns to PBS2, but because the polarization of now laser has been changed to V, therefore laser passes through
It will be reflected after PBS2 hence into right side.
11. laser enters the 3rd polarization beam apparatus (PBS3), because the polarization of laser is V, therefore now laser still by
PBS3 reflects.
12. the laser reflected enters Bob ends i.e. the second client after optical fiber 3 transmits.
13. incident laser carries out corresponding polarization compensation through the second Polarization Controller (PC2).
14. laser enters second phase modulator (PM2) and the second amplitude modulaor (AM2), base now is carried out to laser
It is specific as follows in the Gauss coded modulation of sideband：
A. Gaussian modulation signal is produced by quantum random number generator (QRNG).In laser and follow-up detector
In, obvious low-frequency noise be present.In order to avoid interference of the low-frequency noise to sideband, introducing a 50MHz, (this frequency has no tool
Body limits) cosine wave be used as carrier wave, so as to be translated to the frequency of sideband.
B. Gaussian modulation signal and carrier wave are mixed, modulation control signal of the signal after mixing as PM2, so as to
Complete the frequency translation of sideband and the Gaussian modulation of sideband phase simultaneously.Similarly, AM2 also has a set of modulation of corresponding identical
Device, complete the Gaussian modulation of sideband amplitude.
15. completing the laser after modulation to reflect through faraday rotation mirror (FM), polarize and H is changed into by V.
16. the laser of reflection returns to PBS3 through optical fiber 3, because polarization is H, now laser directly transmits and enters relaying
End.
17. the above-mentioned flow for left laser, similarly, and right wing laser is into first for the flow of corresponding right wing laser
Coded modulation is just carried out during client.Simultaneously before left and right two-way enters BS, wherein all the way through third phase modulator (PM3)
The phase-modulation for the pi/2 being fixed, PM3 do not modulate when optical signals BS is emitted to it.By this phase-modulation so that
Two paths of signals light differs pi/2 phase, ensures that the two-way interference signal intensity of the BS outputs in interference is more or less the same.
It is the 3rd branch road, beam splitter (BS) and the 3rd polarization point between beam splitter (BS) and the second polarization beam apparatus (PBS2)
Beam device (PBS3) is the 4th branch road, and the 3rd branch road or the 4th branch road are provided with third phase modulator (PM3), complete coded modulation
The phase-modulation for the pi/2 being fixed when optical signal afterwards is via PM3.Such as PM3 is located on the 4th branch road, then via the second visitor
The phase-modulation of pi/2 that the optical signal after coded modulation is fixed at PM3 is completed at family end, then enters back into BS, and via
First client completes the optical signal after coded modulation and is no longer pass through PM3, but enters BS by the 3rd branch road.
Interfere 18. encoded left and right two-way laser is come back at BS.
19. interference coupling formed two-way laser respectively enter measurement apparatus, first respectively by photodetector (D1 and
D2) measure.
20. the demodulation that obtained signal first passes through 50MHz cosine carriers is measured, so as to which the frequency of sideband be moved back to again.
21. filter out side-band signal with low pass filter (LPF).
22. two paths of signals is sent into data processing equipment, digital sample is carried out to it.
23. the numerical value that two-way is sampled is added and subtracted each other respectively, new value x is obtained_And x+.Then both are carried out
Combination, is obtainedΥ value is announced by classical passage to Alice or the sides of Bob mono-.
24.Alice or Bob can calculate the opposing party's coherent state according to the value and Υ of the coherent state of oneself modulation
Value；So as to have the gaussian variable of one group of association between Alice and Bob.
25.Alice and Bob compares a part of data by classical communication passage between the two, estimates safe code check；If
Safe code check is more than 0, then both sides can be put by the CV-QKD (continuous variable quantum key distribution) of standard error correction and privacy
Big step generates the safe key of corresponding code check；If the safe code check of theoretical calculation is less than 0, abandon this time communicating.
Embodiment 2：
Referring to Fig. 3, MDI CV-QKD methods include in the present embodiment：
1. using phase-modulation light source in source ends (pulse generation device i.e. in figure), it includes phase and prepares laser
Device and pulse prepare laser；
2. phase prepares laser generation long pulse, and the driving voltage of long pulse does not make any modulation to ensure follow-up life
Into short pulse pair between phase difference be 0.
3. by optical fiber circulator 1, long pulse injected pulse prepares laser, generates short pulse pair.The length each injected
Pulse generates a pair of short pulses, and this is 0 to the phase difference between short pulse.Phase difference between pulse pair is random.
4. the pulse counterweight of generation newly enters the first polarization beam apparatus (PBS1) by optical fiber circulator 1, corresponding
PBS1 transmission ends receive pulse, and what is received is pulse of the polarization for H (horizontal polarization).
5. after the preparation for completing polarized pulses, pulse enters relay by optical fiber 1.Through balancing beam splitter (BS) beam splitting,
Pulse is divided into the row subpulse of identical two and enters the left and right sides.Explained below by taking left pulses as an example.
6. pulse enters the second polarization beam apparatus (PBS2).Because the polarization of pulse is H, therefore directly transmit.
7. pulse enters Alice ends by optical fiber 2, first through the first Polarization Controller (PC1) through row polarization compensation.
8. then, successively by variable optical attenuator (VATT1), first phase modulation (PM1) and the first amplitude modulaor
(AM1), but not pulse is modulated.Faraday rotation mirror (FM) reflection is entered in pulse, and polarization is changed into V (vertical polarization) and original
Road returns.
9. returning to pulse due to the deflection of polarization, reflected through PBS2, into right side.
10. pulse enters the 3rd polarization beam apparatus (PBS3), continue to be reflected.
11. reflected impulse enters Bob ends after optical fiber 3.
12. pulse is through the second Polarization Controller (PC2) through row polarization compensation.
13.Bob ends carry out Gauss coding to pulse, and concrete operations mode is as follows：
A. pulse makes it into after the second variable optical attenuator (VATT2), carrying out significantly decay to its signal pulse
(Yu Xianxuanding previous or the latter per group pulse pair is signal pulse, and another is local oscillator arteries and veins in AM2 modulation range
Punching), local oscillator pulse is not weaker than to signal pulse of the local oscillator pulse after row is decayed and is decayed far；
B. by second phase modulator (PM2) and the second amplitude modulaor (AM2) to signal pulse through row Gaussian modulation.
Quantum state after modulation is designated as：|αA>=| xA+ipA>。
14. the pulse after coding is reflected through faraday rotation mirror (FM), polarization is changed into H and backtracking again.
15. returning to pulse to transmit after PBS3, relay is reentered to complete to measure.
16. similar with said process, in step 4 pulse on the right also pass through similar operation, it is only unlike pass through
After VATT1, while two pulses of the pulse centering that significantly decays.After completing to encode at Alice ends relaying is transmitted into through PBS2
End measures through row.(the local oscillator pulse of right side pulse can also be retained and the local oscillator pulse of left side pulse is done and decayed.)
17. because the path of two-way pulse experience is identical, therefore two-way pulse will enter hop simultaneously.Through
BS is coupled, and the two pulses after coupling, which respectively enter, measures that (measurement apparatus is shown in Fig. 4 a in measurement apparatus 1 and measurement apparatus 2
With Fig. 4 b).
Signal pulse into measurement apparatus 1 is to be coupled to form by the signal pulse of Alice and Bob modulation through beam splitter,
Its quantum state is：After the pi/2 phase modulation of phase-modulator, obtained through BHD measurements
18. the signal pulse for entering measurement apparatus 2 also undergoes similar step, only the difference is that without phase-modulation.
Quantum state into the coupled signal of measurement apparatus 2 is：Due to not phase modulated, surveyed through BHD
Measure
19. measurement result enters data processing equipment (generally computer), according to every group of measurement knot in data set
Fruit (q-, p+) be calculatedRelaying informs the Υ numerical value that measurement obtains by classical communication passage
Alice or Bob.
20. according to equation(δ represents the noise in detection process), Alice or Bob can roots
The value of the opposing party's coherent state is calculated according to the value and Υ of the coherent state of oneself modulation；So as to Alice
Have the gaussian variable of one group of association between Bob.
21.Alice and Bob compares a part of data (α by classical communication passage between the twoA, αB, Υ), pass through meter
Calculate distribution p (αA, αB, Υ) and estimate safe code check；If safe code check is more than 0, both sides (can be connected by the CV-QKD of standard
Continuous variable quantum key distribution) error correction and privacy amplification procedure generate the safe key of corresponding code check；If theoretical calculation
Safe code check is less than 0, then abandons this time communicating.
Measurement apparatus 1 and measurement apparatus 2 are referring to Fig. 4 a and Fig. 4 b.
Illustrate below by taking measurement apparatus 1 as an example：
1. incident pulse includes signal pulse and local oscillator pulse, beam splitter (BS) beam splitting is first passed through.
2. reflected impulse by what faraday's speculum (FM), fiber delay line and polarization beam apparatus (PBS) were formed by being prolonged
When device be delayed；The length of twice of delay line meets delay time for local oscillator pulse and the time difference of signal pulse.Due to farad
The effect of speculum, the polarization of pulse are changed into V from H；Pass through half-wave plate (HWP) with afterpulse, polarization is changed into H again.
3. reflected impulse passes through phase-modulator (PM), the phase-modulation for the pi/2 that PM fixes to pulse is follow-up to ensure
The p-component of measurement signal pulse.
4. two-way pulse measures into balanced homodyne measurement apparatus.
Compared with measurement apparatus 1, measurement apparatus 2 carries out phase-modulation without PM, therefore it measures the x of respective pulses points
Amount.
Embodiment 3
Referring to Fig. 5, the present embodiment MDI CV-QKD methods include：
1. the continuous impulse that laser is sent forms laser pulse after acousto-optic modulator (AOM) modulation.Also can directly select
Use pulse laser.
2. pulse is through beam splitter (BS1) beam splitting, it is transmitted and reflectivity is 1：99；The weak pulse punching of transmission is signal pulse,
The flash of reflection is local oscillator pulse.
3. the delay that signal pulse is formed via fiber delay line, polarization beam apparatus (PBS0) and faraday rotation mirror (FM)
Device is delayed, and it is separated with corresponding local oscillator pulse in sequential；Line delay can also be entered to local oscillator pulse.
4. local oscillator pulse and signal pulse couple through beam splitter (BS2)；BS2 can be balance beam splitter (transmission and reflection
Than for 50：50)；Also non-equilibrium beam splitter can be selected, now require that transmissivity is less than reflectivity, so as to further increase signal arteries and veins
Punching and the strong and weak contrast of local oscillator pulse.
The remaining step and embodiment 2 of the present embodiment are identical, will not be described in further detail.It should be noted that in this embodiment, survey
Measure device 1 and the fiber delay time line length in measurement apparatus 2 is identical with the fiber delay time line length in pulse generation device.
Embodiment 4
Referring to Fig. 6, preceding step and embodiment 2 are identical in MDI CV-QKD methods in the present embodiment, and difference is
In step 6：After laser pulse enters Alice ends, the H ends for first passing through polarization-maintaining beam splitter enter；Filled with afterpulse by each modulation
Put, same each modulating device is not modulated now；Pulse returns to polarization-maintaining beam splitter through polarization maintaining optical fibre and enters its V port,
Pulse polarization is set to be changed into V from H.Faraday rotation mirror is replaced with polarization-maintaining beam splitter to complete the transformation of polarization, corresponding Bob
End also using the instrument the same with Alice ends and carries out similar operation.
Optical fiber after polarization-maintaining beam splitter is polarization maintaining optical fibre, and device remainder is single-mode fiber.
Remaining step of the present embodiment and embodiment 2 are identical, are just no longer described in detail.
Embodiment 5
Referring to Fig. 7, MDI CV-QKD systems are compared with embodiment 3 in the present embodiment, by the way of in embodiment 4, are used
Polarization-maintaining beam splitter substitutes original faraday rotation mirror to reach the effect of polarization rotation.
Specific steps are no longer described in detail herein referring to embodiment 3 and the appropriate section of embodiment 4.
Balanced homodyne measurement apparatus
The balanced homodyne measurement apparatus BHD structures that the utility model uses are shown in Fig. 8.
Mainly by balance beam splitter (BS, a splitting ratio 50：And two identical high-performance optical electric explorer (D1 50)
Formed with D2).And what is exported is then that two-way detects difference between obtained photoelectric current.By the phase-modulation to local oscillator light,
X or p value in flashlight quantum state can be determined by difference current.
Disclosed above is only embodiment of the present utility model, but the utility model is not limited to this, this area
Technical staff can carry out various changes and modification without departing from spirit and scope of the present utility model to the utility model.Obviously
These changes and modification all should belong in the protection domain protection of the requires of the utility model.In addition, although used in this specification
Some specific terms, but these terms are merely for convenience of description, the utility model do not formed any specifically limited.
Claims (9)
1. a kind of unrelated CV-QKD systems of measuring apparatus from steady phase, including source ends, the first client, the second client with
And relay, it is characterised in that first client and the second client arrangement are in annular light path, the light of source ends transmission
Signal is divided into two-way and enters the annular light path with opposite transmission direction, wherein modulated all the way in the first client, it is another
Road is modulated in the second client, and two ways of optical signals is passed through measured into relay after whole annular light path respectively, client
Generation safe key is consulted according to the measurement result of relay.
2. as claimed in claim 1 from the unrelated CV-QKD systems of the measuring apparatus of steady phase, it is characterised in that the relay
Provided with the beam splitter in the annular light path, the optical signal that the source ends are sent is divided into two-way light letter via the beam splitter
Number and annular light path is entered with opposite transmission direction.
3. as claimed in claim 2 from the unrelated CV-QKD systems of the measuring apparatus of steady phase, it is characterised in that the two-way light
In signal, wherein passing through the first client and the second client successively all the way, and it is modulated in the second client；Another way according to
It is secondary to pass through the second client and the first client, and be modulated in the first client, two ways of optical signals is modulated and passes through whole
The beam splitter is returned to after individual annular light path to interfere and measure interference signal.
4. as claimed in claim 3 from the unrelated CV-QKD systems of the measuring apparatus of steady phase, it is characterised in that the relay
The first measurement apparatus of interior setting and the second measurement apparatus, it is respectively used to measure the interference letter from described two output ends of beam splitter
Number light；
The measurement result for receiving first measurement apparatus and the second measurement apparatus is additionally provided with the relay and it is carried out
The data processing equipment of post processing.
5. as claimed in claim 4 from the unrelated CV-QKD systems of the measuring apparatus of steady phase, it is characterised in that the beam splitter
It is connected respectively by tie point and the second branch road with the first measurement apparatus and the second measurement apparatus, a branch road is provided with wherein
Fiber optical circulator, the optical signal that the source ends are sent are inputted to the beam splitting via the wherein Single port of the fiber optical circulator
Device.
6. as claimed in claim 5 from the unrelated CV-QKD systems of the measuring apparatus of steady phase, it is characterised in that the source ends
The first polarized controller is inside provided with, to adjust the polarization direction of the optical signal of source ends transmission, in the annular light path
It is additionally provided with：
Second polarization beam apparatus, the optical signal trend for polarization direction control the first client of disengaging according to optical signal；
3rd polarization beam apparatus, the optical signal trend for polarization direction control the second client of disengaging according to optical signal；
The modulation module and change light letter for modulated optical signal are equipped with first client and the second client
The adjusting means of number polarization direction.
7. as claimed in claim 6 from the unrelated CV-QKD systems of the measuring apparatus of steady phase, it is characterised in that from source ends
And pass through in the two ways of optical signals that the beam splitter beam splitting obtains：
The first client is wherein entered by the second polarization beam apparatus with the first polarization direction all the way, via the adjuster of transmitting terminal
The second client is entered by the second polarization beam apparatus, the 3rd polarization beam apparatus with the second polarization direction behind part change polarization direction
End；Still returned after changing polarization direction via the adjusting means of the second client with the first polarization direction by the 3rd polarization beam apparatus
To the beam splitter；
Another way enters the second client with the first polarization direction by the 3rd polarization beam apparatus, via the regulation of the second client
The first client is entered by the 3rd polarization beam apparatus, the second polarization beam apparatus with the second polarization direction behind device change polarization direction
End；Still returned after changing polarization direction via the adjusting means of the first client with the first polarization direction by the second polarization beam apparatus
To the beam splitter.
8. as claimed in claim 7 from the unrelated CV-QKD systems of the measuring apparatus of steady phase, it is characterised in that the adjuster
Part is faraday rotation mirror, and optical signal is turned back in the inside of the first client or the second client by the faraday rotation mirror.
9. as claimed in claim 7 from the unrelated CV-QKD systems of the measuring apparatus of steady phase, it is characterised in that the adjuster
Part is polarization-maintaining beam splitter, and optical signal passes in and out the first client or the second client by the polarization-maintaining beam splitter.
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| CN201720641276.7U CN207135114U (en) | 2017-06-05 | 2017-06-05 | The CV QKD system unrelated from the measuring apparatus of steady phase |
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| CN201720641276.7U CN207135114U (en) | 2017-06-05 | 2017-06-05 | The CV QKD system unrelated from the measuring apparatus of steady phase |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107171793A (en) * | 2017-06-05 | 2017-09-15 | 浙江神州量子网络科技有限公司 | From the unrelated CV QKD systems of the measuring apparatus of steady phase and method |
| CN108574577A (en) * | 2018-06-12 | 2018-09-25 | 清华大学 | A kind of quantum key distribution system and method |
| CN110896329A (en) * | 2018-09-12 | 2020-03-20 | 中国科学技术大学 | Continuous variable quantum key distribution coherent detection system based on local oscillator light scheme |
| CN112929163A (en) * | 2021-01-25 | 2021-06-08 | 中南大学 | Measuring device-independent continuous variable quantum key distribution method and system |
-
2017
- 2017-06-05 CN CN201720641276.7U patent/CN207135114U/en active Active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107171793A (en) * | 2017-06-05 | 2017-09-15 | 浙江神州量子网络科技有限公司 | From the unrelated CV QKD systems of the measuring apparatus of steady phase and method |
| CN108574577A (en) * | 2018-06-12 | 2018-09-25 | 清华大学 | A kind of quantum key distribution system and method |
| CN110896329A (en) * | 2018-09-12 | 2020-03-20 | 中国科学技术大学 | Continuous variable quantum key distribution coherent detection system based on local oscillator light scheme |
| CN112929163A (en) * | 2021-01-25 | 2021-06-08 | 中南大学 | Measuring device-independent continuous variable quantum key distribution method and system |
| CN112929163B (en) * | 2021-01-25 | 2022-01-07 | 中南大学 | Measuring device-independent continuous variable quantum key distribution method and system |
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