CN110460433A - Time phase decoding apparatus and quantum key distribution system including it - Google Patents
Time phase decoding apparatus and quantum key distribution system including it Download PDFInfo
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- CN110460433A CN110460433A CN201910528190.7A CN201910528190A CN110460433A CN 110460433 A CN110460433 A CN 110460433A CN 201910528190 A CN201910528190 A CN 201910528190A CN 110460433 A CN110460433 A CN 110460433A
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- 238000009826 distribution Methods 0.000 title claims abstract description 32
- 230000003287 optical effect Effects 0.000 claims abstract description 74
- 230000010287 polarization Effects 0.000 claims abstract description 60
- 230000008878 coupling Effects 0.000 claims abstract description 7
- 238000010168 coupling process Methods 0.000 claims abstract description 7
- 238000005859 coupling reaction Methods 0.000 claims abstract description 7
- 239000013307 optical fiber Substances 0.000 claims description 37
- 210000001367 artery Anatomy 0.000 claims description 5
- 210000003462 vein Anatomy 0.000 claims description 5
- 238000004080 punching Methods 0.000 claims description 4
- 238000002347 injection Methods 0.000 claims 3
- 239000007924 injection Substances 0.000 claims 3
- 230000006698 induction Effects 0.000 abstract description 5
- 230000007423 decrease Effects 0.000 abstract description 4
- 238000001514 detection method Methods 0.000 description 21
- 230000005540 biological transmission Effects 0.000 description 20
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- 238000012805 post-processing Methods 0.000 description 7
- 238000004891 communication Methods 0.000 description 4
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- 239000000835 fiber Substances 0.000 description 3
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- 230000004927 fusion Effects 0.000 description 2
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical group [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 235000013399 edible fruits Nutrition 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 230000005610 quantum mechanics Effects 0.000 description 1
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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
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/67—Optical arrangements in the receiver
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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
- H04B10/60—Receivers
- H04B10/66—Non-coherent receivers, e.g. using direct detection
- H04B10/67—Optical arrangements in the receiver
- H04B10/671—Optical arrangements in the receiver for controlling the input optical signal
-
- 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
- H04B10/80—Optical aspects relating to the use of optical transmission for specific applications, not provided for in groups H04B10/03 - H04B10/70, e.g. optical power feeding or optical transmission through water
- H04B10/85—Protection from unauthorised access, e.g. eavesdrop protection
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0819—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s)
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0852—Quantum cryptography
- H04L9/0858—Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding
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- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
The present invention proposes a kind of time phase decoding apparatus and the quantum key distribution system including it.The time phase decoding apparatus include: beam splitter, respectively two reflection units through two arms and beam splitter optical coupling, at least one of be set to beam splitter front end or be set to two arms on phase-modulator, single single-photon detector.Each reflection unit is polarized orthogonal rotary reflection device, and each reflection unit is quarter-wave plate reflecting mirror, and quarter-wave plate reflecting mirror with mirror integral is formed by quarter-wave plate.Single-photon detector is coupled to a port in the port for not being coupled to described two arms of beam splitter, for detecting within a pulse period to the signal of continuous first time slot, the second time slot and third time slot.Time phase coding quantum key distribution decoding scheme of the invention is resistant to polarization induction decline, and helps to eliminate or reduce the safety issue that multi-detector generates.
Description
Technical field
The present invention relates to optical transport private communication technology field more particularly to a kind of time phase decoding apparatus and quantum are close
Key dissemination system.
Background technique
Quantum Secure Communication is the forward position focus field that quantum physics are combined with information science.Based on quantum key
Distribution technology and one time cryptosystem principle, quantum secret communication can be in the safe transmissions of overt channel realization information.Quantum is close
Key distribution can be realized based on physical principles such as quantum mechanics Heisenberg uncertainty relationship, quantum non-clone principles in user
Between safely shared key, and can detecte potential eavesdropping behavior, it is contour to can be applied to national defence, government affairs, finance, electric power
The field of security information transmission demand.
Ground quantum key distribution is based primarily upon fibre channel transmission, because phase code uses the phase of front and back light pulse
Difference carrys out encoded information, can stablize holding during long-distance optical fiber transmission, so being carried out using unequal arm interferometer
Phase code or time phase encoding scheme comprising one group of phase code are the primary coding schemes of quantum key distribution application.
However, there are non-circular symmetrical, the fiber core refractive index radially non-idealities such as uneven distribution, and optical fiber in section for optical fiber fabrication
It is influenced in the actual environment by temperature, strain, bending etc., random birefringence effect can be generated.Therefore, light pulse is through long range light
Fibre transmits and after the transmission of unequal arm interferometer two-arm optical fiber, exists when carrying out phase decoding interference by unequal arm interferometer
The problem of polarization induction decline, causes decoding interference unstable, the bit error rate is caused to increase.If will increase using correcting device and be
Complexity of uniting and cost, and stable application is difficult to realize for strong jammings situations such as aerial optical cable, road and bridge optical cables.In addition, the time
The decoding of phase code quantum key distribution system generally comprises time base decoding optical path and phase base decoding optical path with right respectively
Time base and phase base carry out selecting base decoding detection, this needs four detectors, and system cost is high, and due to four detectors
Can exist inconsistent to there is potential attack loophole.
For time phase encoding scheme, how to carry out to stability and high efficiency interference decoding is based on existing optical cable infrastructure
Carry out the hot spot and problem of quantum secret communication application.
Summary of the invention
It is a primary object of the present invention to propose a kind of time phase decoding apparatus and quantum based on the decoding apparatus is close
Key dissemination system, to solve phase decoding interference caused by polarization induction declines in time phase coding quantum key distribution application
Unstable problem.Also, the invention enables the detector for reducing quantity can be used, thus eliminates or reduce multi-detector and produce
Raw safety issue, and appreciably reduce manufacturing cost and system complexity.
The present invention provides at least following technical scheme:
1. a kind of time phase decoding apparatus, comprising: beam splitter, two respectively through two arms and the beam splitter optical coupling
A reflection unit, at least one of be set to the beam splitter front end or be set to described two arms on phase-modulator, list
A single-photon detector, wherein
Each reflection unit is polarized orthogonal rotary reflection device, one of described two reflection units or each institute
Stating reflection unit is quarter-wave plate reflecting mirror, and the quarter-wave plate reflecting mirror is by quarter-wave plate and reflecting mirror one
Formed to body；
The single-photon detector is coupled to an end in the port for not being coupled to described two arms of the beam splitter
Mouthful, for being detected within a pulse period to the signal of continuous first time slot, the second time slot and third time slot, wherein
One pulse period includes first time slot, the second time slot and third time slot.
2. time phase decoding apparatus according to scheme 1, wherein 0 degree of the phase-modulator Stochastic Modulation or 180
Spend phase.
3. time phase decoding apparatus according to scheme 1, wherein one port is non-input port.
4. time phase decoding apparatus according to scheme 1, further include setting the single-photon detector with it is described
Optical circulator between one port of beam splitter, the optical circulator include first port, second port and third end
Mouthful, the optical circulator is coupled to one port of the beam splitter through the second port, and through the third port
It is coupled to the single-photon detector, wherein the first port is the input port of the time phase decoding apparatus, from institute
The light pulse for stating first port input is exported by the second port to the beam splitter, the light arteries and veins inputted from the second port
Punching is exported by the third port.
5. a kind of time phase decoding apparatus, comprising: optical circulator, beam splitter, respectively through two arms and the beam splitter
Two reflection units, the first single-photon detector and the second single-photon detector of optical coupling, wherein
Each reflection unit is polarized orthogonal rotary reflection device, one of described two reflection units or each institute
Stating reflection unit is quarter-wave plate reflecting mirror, and the quarter-wave plate reflecting mirror is by quarter-wave plate and reflecting mirror one
Formed to body；
The optical circulator includes first port, second port and third port, and is coupled to via the second port
A port in the port for not being coupled to described two arms of the beam splitter, the first port of the optical circulator are described
The input port of time phase decoding apparatus, the light pulse inputted by the first port of the optical circulator is by the optical circulator
Second port export to the beam splitter, by the beam splitter export to the light pulse of the second port of the optical circulator by
The third port of the optical circulator exports；
First single-photon detector is coupled to another in the port for not being coupled to described two arms of the beam splitter
A port, for being detected to the light pulse exported from another described port；
Second single-photon detector is coupled to the third port of the optical circulator, for from the optical circulator
Third port output light pulse detected,
Wherein, one in first single-photon detector and the second single-photon detector within a pulse period extremely
It is few that the signal of continuous first time slot and the second time slot is detected, first single-photon detector and the second single-photon detecting
Another surveyed in device at least detects the signal of continuous second time slot and third time slot within a pulse period,
Described in a pulse period include first time slot, the second time slot and third time slot.
6. according to time phase decoding apparatus described in scheme 5, wherein described device further includes direct current phase-modulator,
The direct current phase-modulator is set at least one of described two arms.
7. the time phase decoding apparatus according to scheme 1 or 5, wherein described two arms are polarization maintaining optical fibre optical path, right
In any quarter-wave plate reflecting mirror: the slow axis of the polarization maintaining optical fibre of coupled arm and the slow axis of its quarter-wave plate or
The angle of fast axle is 45 degree.
8. the time phase decoding apparatus according to scheme 1 or 5, wherein the beam splitter is polarization-maintaining coupler.
9. according to time phase decoding apparatus described in scheme 8, wherein the beam splitter is 2 × 2 polarization-maintaining couplers.
10. a kind of quantum key distribution system, comprising:
The time phase decoding apparatus according to any one of scheme 1~9 is arranged in the quantum key distribution system
The receiving end of system, for decoding.
The present invention makes it possible to steadily carry out volume solution to the input optical pulse of random polarization state by creative construction
Code interference, it is thus achieved that unexpected beneficial effect.Using the solution of the present invention, for the input light arteries and veins of random polarization state
Punching, which may be implemented to decode in phase base, stablizes interference output at interferometer, solves time phase coding quantum key distribution and answers
With middle polarization induction decline cause system can not steady operation the problem of.Also, the invention enables can use to reduce quantity
The safety issue that multi-detector generates thus is eliminated or reduced to detector (one or two single-photon detector), and considerable
Ground reduces manufacturing cost and system complexity.The anti-polarization induction decline for being easily achieved and applying the present invention provides a kind of when
Between phase code quantum key distribution decoding scheme.
Detailed description of the invention
Fig. 1 is the composed structure schematic diagram of the time phase decoding apparatus of one embodiment of the present invention；
Fig. 2 is the composed structure schematic diagram of the time phase decoding apparatus of another preferred embodiment of the present invention；
Fig. 3 is the figure for schematically showing the first time slot in a pulse period, the second time slot and third time slot.
Specific embodiment
Specifically describing the preferred embodiment of the present invention with reference to the accompanying drawing, wherein attached drawing constitutes the application a part, and
Together with embodiments of the present invention for illustrating the principle of the present invention.For purpose of clarity and simplification, when it may make the present invention
Theme it is smudgy when, illustrating and omitting in detail to the known function and structure of device described herein.
The time phase decoding apparatus of one embodiment of the present invention is as shown in Figure 1, include consisting of part: beam splitter
102, phase-modulator 103, quarter-wave plate reflecting mirror 104 and 105, single-photon detector 106.
Quarter-wave plate reflecting mirror includes quarter-wave plate and reflecting mirror, and the reflecting mirror is in the quarter-wave
Piece rear end is integrally formed with the quarter-wave plate.Quarter-wave plate reflecting mirror can be by quarter-wave platelet
Body surface face is plated reflecting mirror and is realized, also can plate reflecting mirror reality by transmitting 90 degree of phase phase difference of polarization maintaining optical fibre end face in fast and slow axis
It is existing.
Quarter-wave plate reflecting mirror 104 and 105 is polarized orthogonal rotary reflection device.
Here, polarized orthogonal rotary reflection device refers to that one kind can be to two orthogonal polarisation states of the light pulse reflected
Make polarized orthogonal rotary reflection, i.e. in the incident light pulse of reflection by each orthogonal polarisation state of the light pulse be transformed into and its
The reflection unit of orthogonal polarization state.For example, it is assumed that the two orthogonal polarisation states are respectively x-polarisation state and y-polarisation state, edge
The x-polarisation state of optic path to a polarized orthogonal rotary reflection device becomes after polarized orthogonal rotary reflection at reflection unit
It changes orthogonal to that polarization state i.e. y-polarisation state into, is passed through at reflection unit along the y-polarisation state of optic path to the reflection unit inclined
It shakes and is transformed into orthogonal to that polarization state i.e. x-polarisation state after orthogonal rotary reflection.
The a port 101 of 102 side of beam splitter is the input port of device.Quarter-wave plate reflecting mirror 104 and 105
Respectively through two arms (upper and lower arms in Fig. 1) and 102 optical coupling of beam splitter.Described two arms can be polarization maintaining optical fibre light
Road；In the case, the slow axis of the polarization maintaining optical fibre of each arm and the quarter-wave in corresponding quarter-wave plate reflecting mirror
The slow axis of piece or the angle of fast axle are 45 degree.Beam splitter 102 and quarter-wave plate reflecting mirror 104 and 105 constitute unequal arm and step
Ke Erxun interferometer.Phase-modulator 103 is located in described two arms on any arm (being upper arm in Fig. 1).
Beam splitter 102 is used to the beam splitting of input optical pulse all the way of incident random polarization state be two-way light pulse with respectively
It is transmitted along two arms.
Two arms for transmitting the two-way light pulse respectively.
Phase-modulator 103 is used for the light pulse (that is, one of two-way light pulse) to the arm transmission where it according to quantum
Key distribution protocol carries out phase-modulation.The phase-modulation that phase-modulator 103 carries out is determined by quantum key distribution agreement.
Time phase decoding apparatus can only include a single-photon detector, single-photon detector as shown in Figure 1
106.Single-photon detector 106 receives the light pulse signal exported by the another port of 102 side of beam splitter.One pulse period
The signal of interior output to single-photon detector 106 includes three time slots, i.e. the first time slot, the second time slot and third time slot.Monochromatic light
Sub- detector 106 is for detecting the signal in the first time slot, the second time slot and third time slot within a pulse period.
At this point, the phase-modulator can 0 degree of phase of Stochastic Modulation or 180 degree phase.
It is possible that time phase decoding apparatus includes two single-photon detectors, device further includes optical circulator at this time.
The optical circulator includes first port, second port and third port.It is illustrated by means of Fig. 1, two single photon detections
One (such as single-photon detector 106 shown in FIG. 1) in device is coupled to the another port of 102 side of beam splitter, for pair
The light pulse exported from the another port is detected.The optical circulator can be located at 102 front end of beam splitter, second port coupling
It is bonded to the port 101 of 102 side of beam splitter.The light pulse inputted from the first port of the optical circulator is defeated by its second port
Out to beam splitter 102, the light pulse inputted from the second port of the optical circulator is exported by its third port.Two single photons
Another in detector is coupled to the third port of the optical circulator, for the third port output to the optical circulator
Light pulse detected.Any of two single-photon detectors are within a pulse period at least to the first time slot and
The signal of two time slots is detected, and another in two single-photon detectors is within a pulse period at least to the second time slot
It is detected with the signal of third time slot.At this point, the phase-modulator can be direct current phase-modulator.
Time phase coded light pulses include four kinds of coded light pulses states, are two time bits of encoded light pulses respectively
State and two phase code light pulse states.As shown in figure 3, two time bits of encoded light pulse states respectively correspond first
Time slot light pulse and the second time slot light pulse；Two phase code light pulse states respectively correspond the first time slot light pulse and second
Time slot light pulse phase difference is 0 degree and the first time slot light pulse and the second time slot light pulse phase difference are the state of 180 degree.When
Between phase code four kinds of coded light pulses decoding after corresponding state are as follows: the first time slot light pulse of time bits of encoded decoding after
Become the first time slot and the second time slot former and later two sub-light pulses；Become the after time bits of encoded the second time slot light pulse decoding
Sub two light pulses before and after two time slots and third time slot；The corresponding first time slot light pulse of phase code and the second time slot light pulse phase
Become three the first time slot, the second time slot and third time slot light pulses after the state decoding that potential difference is 0 degree, wherein the second time slot
Interfere the sub-light pulse to be formed for two light pulses, from the long output of a port interference coherent phase in two ports of beam splitter；
The corresponding first time slot light pulse of phase code and the second time slot light pulse phase difference are when becoming first after the state of 180 degree decodes
Three gap, the second time slot and third time slot light pulses, wherein the second time slot is that the sub-light pulse to be formed is interfered in two light pulses,
From the long output of another port interference coherent phase in two ports of beam splitter.
In a kind of possible application, device only includes a single-photon detector, and the single-photon detector is to an arteries and veins
The signal of three time slots rushed in the period is detected.When transmitting terminal is encoded using time base, if single-photon detector only exists
First time slot has response or only has response in third time slot, then generates key according to detection result；If single-photon detector only exists
Second time slot has response or has response in two or three time slots, then detection result is given up or post-processed according to quantum key distribution
Algorithm generates decoding result.When transmitting terminal is encoded using phase base, if single-photon detector only has response, root in the second time slot
Key is generated according to detection result and the phase of phase modulator modulation；If single-photon detector is only in the first time slot or only in third
Time slot has response, or has response in two or three time slots, then detection result is given up or post-processed according to quantum key distribution and calculated
Method generates decoding result.
In alternatively possible application, device includes two single-photon detectors, respectively the first single-photon detector
With the second single-photon detector；Signal of first single-photon detector to the first time slot and the second time slot in a pulse period
It is detected, the second single-photon detector detects the signal of the second time slot and third time slot in a pulse period.
When transmitting terminal is encoded using time base, if the first single-photon detector only has response in the first time slot, according to detection result
Generate key；If the first single-photon detector only has response in the second time slot or has response, detection result house in two time slots
It abandons or decoding result is generated according to quantum key distribution post-processing algorithm.When transmitting terminal is encoded using time base, if second is single
Photon detector only has response in third time slot, then generates key according to detection result；If the second single-photon detector is only
Two time slots have response or have response in two time slots, then detection result is given up or generated according to quantum key distribution post-processing algorithm
Decoding result.When transmitting terminal is encoded using phase base, if the first single-photon detector only has response in the second time slot, according to spy
It surveys result and generates key；If the first single-photon detector only has response, detection result house in the first time slot or in two time slots
It abandons or decoding result is generated according to quantum key distribution post-processing algorithm.When transmitting terminal is encoded using phase base, if second is single
Photon detector only has response in the second time slot, generates key according to detection result；If the second single-photon detector is only in third
Time slot has response in two time slots, then detection result is given up or generates decoding knot according to quantum key distribution post-processing algorithm
Fruit.
In another possible application, device includes two single-photon detectors, respectively the first single-photon detector
With the second single-photon detector；Each of first single-photon detector and the second single-photon detector are to a pulse period
The signal of three interior time slots is detected.When transmitting terminal is encoded using time base, if the first single-photon detector is only the
One time slot has response or only has response in third time slot, then generates key according to detection result；If the first single-photon detector is only
Have response in the second time slot or in two or three time slots have response, then detection result give up or according to quantum key distribution after
Adjustment method generates decoding result.When transmitting terminal is encoded using time base, if the second single-photon detector only has in the first time slot
Response only has response in third time slot, then generates key according to detection result；If the second single-photon detector is only at second
Gap has response or has response in two or three time slots, then detection result is given up or according to the life of quantum key distribution post-processing algorithm
At decoding result.When transmitting terminal is encoded using phase base, if the first single-photon detector only has response in the second time slot, according to
Detection result generates key；If the first single-photon detector only in the first time slot or only in third time slot have response or at two or
Three time slots have response, then detection result is given up or generates decoding result according to quantum key distribution post-processing algorithm.Work as transmitting
When end is using phase base coding, if the second single-photon detector only has response in the second time slot, key is generated according to detection result；
If the second single-photon detector only in the first time slot or only has response in third time slot or has response in two or three time slots,
Detection result is given up or generates decoding result according to quantum key distribution post-processing algorithm.
When work, light pulse enters beam splitter 102 through the port 101 of beam splitter 102 and is beamed into two-way by beam splitter 102
Light pulse.It is anti-by quarter-wave plate after the phase modulated progress of device 103 phase-modulation of light pulse all the way from beam splitter 102
It penetrates mirror 104 to reflect, it is anti-that the another way light pulse from beam splitter 102 is directly transmitted to quarter-wave plate through polarization maintaining optical fibre
It penetrates mirror 105 and is reflected by quarter-wave plate reflecting mirror 105.Reflected two-way light pulse through relative time delay is through dividing
Beam device 102 closes the output optical pulse obtained after beam and is exported by another port to single-photon detector 106.It is defeated in one pulse period
It include out three time slots to the signal of single-photon detector 106.Single-photon detector 106 within a pulse period to three when
The signal of gap is detected.
Phase-modulator 103 can be birefringent phase modulator.Birefringent phase modulator is suitable for by its two
A orthogonal polarisation state applies different adjustable phase-modulations.For example, birefringent phase modulator can be lithium niobate phase tune
Device processed is applied to the voltage of lithium columbate crystal by controlling, can be orthogonal inclined to two for passing through the lithium niobate phase modulator
The phase-modulation that polarization state is respectively subjected to is controlled and is adjusted.
Although in Fig. 1, only one phase-modulator 103 is shown as being set on one of two arms, in two arms
Upper one phase-modulator of each setting is also possible.In the case where being arranged such there are two phase-modulator, two phases
The difference for the phase that modulator is modulated is determined by quantum key distribution agreement, depends on specific application.In addition, instead of at two
One of arm or both is upper to be arranged phase-modulator, phase-modulator can be arranged before beam splitter 102, before to beam splitting
Input optical pulse according to quantum key distribution agreement carry out phase-modulation.
Since two reflection units 104 and 105 are polarized orthogonal rotary reflection device, in the two-way light pulse
Per light pulse all the way: the road light pulse is through the corresponding reflection unit reflection road the Shi Gai light pulse in described two reflection units
Two orthogonal polarisation states make polarized orthogonal rotary reflection, so that after the reflection via the corresponding reflection unit, the road light pulse
Each orthogonal polarisation state be transformed into orthogonal to that polarization state.In this way, for the phase codec of Fig. 1, just using polarization
The polarized orthogonal rotary reflection at rotary reflection device is handed over, the x-polarisation state of input optical pulse is closed in beam splitter beam splitting to beam splitter
The phase difference transmitted during beam through described two arms is exactly equal to the y-polarisation state of the light pulse in beam splitter beam splitting to beam splitting
The phase difference that device transmits during closing beam through described two arms.
Although two reflection units 104 and 105 of above description are the polarized orthogonal of quarter-wave plate reflecting mirror form
Rotary reflection device, but according to circumstances, one of the two reflection units can be the polarized orthogonal rotary reflection of other forms
Device, such as following constructions 1, construction 2 or the polarized orthogonal rotary reflection device for constructing 3.
According to construction 1, polarized orthogonal rotary reflection device includes polarization beam apparatus, which has input port
, transmission optical path optically coupled to one another through a transmission optical path with two output ports of two output ports, the polarization beam apparatus
On be provided with half-wave plate, the angle for inputting the polarization direction of the light pulse of the half-wave plate and the fast axle of the half-wave plate or slow axis is 45
Degree.The transmission optical path can be formed by polarization maintaining optical fibre；In the case, light pulse is after the polarization beam apparatus beam splitting along described
Polarization maintaining optical fibre transmission, the slow axis of polarization maintaining optical fibre and the angle of the fast axle of the half-wave plate or slow axis for forming the transmission optical path are 45
Degree.Polarized orthogonal rotary reflection device with construction 1, can be by by its polarization beam splitting when for decoding apparatus of the invention
The reflection unit is couple the arm by the arm that the input port of device is coupled to decoding apparatus.
According to construction 2, polarized orthogonal rotary reflection device includes polarization beam apparatus, which has input port
, the transmission light optically coupled to one another through a transmission optical path with two output ports of two output ports, the polarization beam apparatus
Routing polarization maintaining optical fibre is formed, and the slow axis and fast axle of the polarization maintaining optical fibre keep inputting respectively two of the light pulse of the polarization maintaining optical fibre
Orthogonal polarisation state stablizes transmission --- and i.e. polarization state is constant, and two output ports of the polarization beam apparatus and the polarization maintaining optical fibre structure
Cause so that, by the polarization beam apparatus two output ports export light pulse be all coupled to the polarization maintaining optical fibre slow axis carry out
The fast axle for transmitting or being all coupled to the polarization maintaining optical fibre is transmitted.Here, it is exported by two output ports of the polarization beam apparatus
Light pulse be all coupled to the polarization maintaining optical fibre slow axis transmitted or be all coupled to the polarization maintaining optical fibre fast axle carry out transmission can
It turn 90 degrees or reverses (90+n*180) degree by polarization maintaining optical fibre torsion to realize, wherein n is integer.No matter polarization maintaining optical fibre torsion or
It does not reverse, the light pulse inputted from the slow axis of polarization maintaining optical fibre (is stablized along slow axis and transmitted) along slow axis transmission always, from polarization-maintaining
The light pulse of the fast axle input of optical fiber (is stablized along fast axle and is transmitted) along fast axle transmission always.Polarized orthogonal with construction 2
Rotary reflection device, can be by coupleeing decoding for the input port of its polarization beam apparatus when for decoding apparatus of the invention
The reflection unit is couple the arm by one arm of device.
According to construction 3, polarized orthogonal rotary reflection device includes polarization beam apparatus, which has input port
, the transmission light optically coupled to one another through a transmission optical path with two output ports of two output ports, the polarization beam apparatus
Routing is formed comprising the polarization maintaining optical fibre of 90 degree of fusion points of odd number, and each 90 degree of fusion points are by polarization maintaining optical fibre slow axis and polarization maintaining optical fibre
Fast axle alignment welding forms.Polarized orthogonal rotary reflection device with construction 3 can lead to when for decoding apparatus of the invention
It crosses and couples the arm for the reflection unit for the arm that the input port of its polarization beam apparatus is coupled to decoding apparatus.
In addition, the beam splitter 102 in Fig. 1 can be polarization-maintaining beam splitter, such as 2 × 2 polarization-maintaining couplers.
The time phase decoding apparatus of another preferred embodiment of the present invention is as shown in Fig. 2, include consisting of part: the ring of light
Shape device 202, polarization-maintaining beam splitter 203, direct current phase-modulator 204, quarter-wave plate reflecting mirror 205 and 206 and single photon
Detector 207 and 208.
One of four parts wave plate reflecting mirrors include quarter-wave plate and reflecting mirror, and the reflecting mirror is in the quarter-wave
Piece rear end is integrally formed with the quarter-wave plate.Quarter-wave plate reflecting mirror can be by quarter-wave platelet
Body surface face is plated reflecting mirror and is realized, also can plate reflecting mirror reality by transmitting 90 degree of phase phase difference of polarization maintaining optical fibre end face in fast and slow axis
It is existing.
Quarter-wave plate reflecting mirror 205 and 206 is polarized orthogonal rotary reflection device.
Optical circulator 202 includes three ports, these three ports are respectively port A, port B and port C.By optical circulator
The light pulse of 202 port A input is exported by the port B of optical circulator 202, the light arteries and veins inputted by the port B of optical circulator 202
Punching is exported by the port C of optical circulator 202.The port A of optical circulator 202 namely port 201 are the input port of device.Four points
One of wave plate reflecting mirror 205 and 206 respectively through two arms (upper and lower arms in Fig. 2) and 203 optical coupling of polarization-maintaining beam splitter.Institute
Stating two arms is polarization maintaining optical fibre optical path, the slow axis of the polarization maintaining optical fibre of each arm and four in corresponding quarter-wave plate reflecting mirror
The slow axis of/mono- wave plate or the angle of fast axle are 45 degree.Polarization-maintaining beam splitter 203 and quarter-wave plate reflecting mirror 205 and 206
Constitute unequal arm Michelson's interferometer.It (is upper in Fig. 2 that direct current phase-modulator 204, which is located at any arm in described two arms,
Arm) on.The reception of single-photon detector 208 is exported by a port of 203 side of polarization-maintaining beam splitter to the port of optical circulator 202
B is simultaneously exported by the port C of optical circulator 202 to the light pulse signal of single-photon detector 208, and single-photon detector 207 receives
The light pulse signal exported by the another port of 203 side of polarization-maintaining beam splitter.Unequal arm Michelson is dry in one pulse period
The signal of interferometer output includes three time slots, these three time slots are respectively the first time slot, the second time slot and third time slot.Single photon
One in detector 207 and 208 at least detects the signal of the first time slot and the second time slot within a pulse period,
The signal of another in single-photon detector 207 and 208 within a pulse period at least to the second time slot and third time slot
It is detected.
When work, port A namely port 201 of the light pulse through optical circulator 202 are input to optical circulator 202, by the ring of light
The light pulse that the port A of shape device 202 is input to optical circulator 202 is exported through the port B of optical circulator 202 to polarization-maintaining beam splitter
203, and two-way light pulse is beamed by polarization-maintaining beam splitter 203.Light pulse all the way from polarization-maintaining beam splitter 203 is through direct current phase
Modulator 204 is reflected after carrying out direct current phase-modulation by quarter-wave plate reflecting mirror 205, comes from polarization-maintaining beam splitter 203
Another way light pulse be directly transmitted to quarter-wave plate reflecting mirror 206 through polarization maintaining optical fibre and by quarter-wave plate reflecting mirror
206 reflect.Through the reflected two-way light pulse of relative time delay through polarization-maintaining beam splitter 203 close beam after by polarization-maintaining beam splitter
203 another port is exported to single-photon detector 207, or is exported by one port of polarization-maintaining beam splitter 203
Port B to optical circulator 202 and the port C through optical circulator 202 are exported to single-photon detector 208.Single-photon detector
207 at least detect the signal of the first time slot and the second time slot, and single-photon detector 208 is at least to the second time slot and third
The signal of time slot is detected；Alternatively, single-photon detector 207 at least visits the signal of the second time slot and third time slot
It surveys, single-photon detector 208 at least detects the signal of the first time slot and the second time slot.Phase-modulator 204 can be
Birefringent phase modulator.
Herein, term " beam splitter " and " bundling device " are used interchangeably, and beam splitter is also referred to as and as bundling device, instead
.Herein, " polarization maintaining optical fibre optical path " refers to the optical path or polarization maintaining optical fibre connection shape using polarization maintaining optical fibre transmission light pulse
At optical path.
Time phase decoding dress of the invention as described above can be configured in the receiving end of quantum key distribution system
It sets, for decoding.
By the explanation of specific embodiment, the present invention can should be reached technological means that predetermined purpose is taken and
Effect, which has, more deeply and specifically to be understood, however appended diagram is only to provide reference and description and is used, and is not used to this hair
It is bright to limit.
Claims (10)
1. a kind of time phase decoding apparatus, comprising: beam splitter, two through two arms and the beam splitter optical coupling are anti-respectively
Injection device, at least one of be set to the beam splitter front end or be set to described two arms on phase-modulator, single single
Photon detector, wherein
Each reflection unit is polarized orthogonal rotary reflection device, one of described two reflection units or each described anti-
Injection device is quarter-wave plate reflecting mirror, and the quarter-wave plate reflecting mirror is by quarter-wave plate and mirror integral
It is formed；
The single-photon detector is coupled to a port in the port for not being coupled to described two arms of the beam splitter, uses
In being detected within a pulse period to the signal of continuous first time slot, the second time slot and third time slot, wherein described
One pulse period includes first time slot, the second time slot and third time slot.
2. time phase decoding apparatus according to claim 1, wherein 0 degree of the phase-modulator Stochastic Modulation or 180
Spend phase.
3. time phase decoding apparatus according to claim 1, wherein one port is non-input port.
4. time phase decoding apparatus according to claim 1, further include setting the single-photon detector with it is described
Optical circulator between one port of beam splitter, the optical circulator include first port, second port and third end
Mouthful, the optical circulator is coupled to one port of the beam splitter through the second port, and through the third port
It is coupled to the single-photon detector, wherein the first port is the input port of the time phase decoding apparatus, from institute
The light pulse for stating first port input is exported by the second port to the beam splitter, the light arteries and veins inputted from the second port
Punching is exported by the third port.
5. a kind of time phase decoding apparatus, comprising: optical circulator, beam splitter, respectively through two arms and the beam splitter optocoupler
Two reflection units, the first single-photon detector and the second single-photon detector closed, wherein
Each reflection unit is polarized orthogonal rotary reflection device, one of described two reflection units or each described anti-
Injection device is quarter-wave plate reflecting mirror, and the quarter-wave plate reflecting mirror is by quarter-wave plate and mirror integral
It is formed；
The optical circulator includes first port, second port and third port, and is coupled to via the second port described
A port in the port for not being coupled to described two arms of beam splitter, the first port of the optical circulator are the time
The input port of phase decoding device, the light pulse inputted by the first port of the optical circulator is by the of the optical circulator
Two-port netwerk is exported to the beam splitter, exports the light pulse to the second port of the optical circulator by described by the beam splitter
The third port of optical circulator exports；
First single-photon detector is coupled to another in the port for not being coupled to described two arms of the beam splitter
Port, for being detected to the light pulse exported from another described port；
Second single-photon detector is coupled to the third port of the optical circulator, for from the of the optical circulator
The light pulse of three ports output is detected,
Wherein, one in first single-photon detector and the second single-photon detector is at least right within a pulse period
The signal of continuous first time slot and the second time slot is detected, first single-photon detector and the second single-photon detector
In another at least the signal of continuous second time slot and third time slot is detected within a pulse period, wherein institute
Stating a pulse period includes first time slot, the second time slot and third time slot.
6. time phase decoding apparatus according to claim 5, wherein described device further includes direct current phase-modulator,
The direct current phase-modulator is set at least one of described two arms.
7. time phase decoding apparatus according to claim 1 or 5, wherein described two arms are polarization maintaining optical fibre optical path, right
In any quarter-wave plate reflecting mirror: the slow axis of the polarization maintaining optical fibre of coupled arm and the slow axis of its quarter-wave plate or
The angle of fast axle is 45 degree.
8. time phase decoding apparatus according to claim 1 or 5, wherein the beam splitter is polarization-maintaining coupler.
9. time phase decoding apparatus according to claim 8, wherein the beam splitter is 2 × 2 polarization-maintaining couplers.
10. a kind of quantum key distribution system, comprising:
According to claim 1, time phase decoding apparatus described in~any one of 9 be arranged in the quantum key distribution system
The receiving end of system, for decoding.
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| CN117459153A (en) * | 2023-12-26 | 2024-01-26 | 万事通科技(杭州)有限公司 | Optical fiber channel eavesdropping detection device |
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