CN205961140U - Plug -and -play quantum key distribution system and transmitting terminal and receiving terminal based on time phase coding - Google Patents

Abstract

The utility model discloses a plug -and -play quantum key distribution system and transmitting terminal and receiving terminal based on time phase coding. Wherein the plug -and -play quantum key distribution system includes smooth transmitting terminal and the receiving terminal of connecting each other, and the coding module in the transmitting terminal includes Z basic vector time coding module and the phase coding module of handling with arbitrary order to light signal encode, and wherein the phase coding module is X basic vector phase coding module, decoder module in the receiving terminal with the coding module suits. The utility model discloses use the time after improving phase coding can realize that the encoding and decoding of superelevation contrast improve into the code check.

Description

A kind of based on when m- phase code plug and play quantum key dissemination system and Transmitting terminal and receiving terminal

Technical field

The utility model is related to quantum key distribution field, particularly to a kind of based on when m- phase code insert Use quantum key distribution system.

Background technology

Quantum secret communication is as the new research being combined with quantum mechanics, electronic information science and computer technology Field, has enjoyed the concern of people from all walks of life.In order to ensure the safe transmission of data, between user, must assure that safe key is handed over Change.Nowadays, quantum key distribution has become as the effective way of the key distribution being perfectly safe by public passage.With The secrecy principle of traditional classical cryptographic communication is different, quantum key distribution by the use of quantum-mechanical general principle as support, Such as Heisenberg uncertainty principle, quantum non-clone principle etc., the random key realizing unconditional security is shared.

Many QKD equipment can be operated in free space or optical fiber, the transmission medium such as planar optical waveguide field.QKD system Including generation light source, coding and decoding, detection, data acquisition extraction, Data Post etc..In optical fiber QKD system, generally adopt Polarization encoder and two kinds of coding forms of phase code.Under long range propagation, phase code QKD stability is compared to polarization encoder QKD system stability is higher, and phase code has more advantage than polarization encoder.Phase code QKD system generally adopts unequal arm horse Conspicuous Zehnder interferometer is built or is built using the unequal arm Michelson's interferometer of 90 degree of rotation faraday's speculums.

Generally in the quantum channel that unequal arm Mach-Zehnder interferometer is constituted, preferably interfere contrast for obtaining, Ask that two Mach-Zehnder interferometers are as symmetrical as possible, this is extremely difficult in practical operation, therefore Gisin et al. proposed in 1997 years " plug and play " type experimental program, (document:Muller A,Herzog T,HuttnerB,etal."plug and play" systems forquantum cryptography[J].Applied physics Letters,1997,70:793-795). The program mainly adopts three 90 degree rotation faraday's speculums, and light-pulse generator is divided into two-way through coupler, and light pulse is at three Roundtrip in 90 degree of rotation faraday's speculums, through all light paths once, polarization is compensated automatically, disappears for each light pulse Except influence of fiber birefringence.The operating frequency of this system reaches 1KHZ, and when improving operating frequency, the bit error rate also raises.For solving This difficult problem, obtains higher key production rate, and Gisin et al. was carried out to " plug and play " type experimental program in 1998 again Improve (document:Ribordy G,Gautier J D,Gisin N,et al.Automated"plug and play"quantum Key distribution [J] .Electronics Letters, 1998,34：2116—2117).Mainly adopt one Arm Mach-Zehnder interferometer and one 90 degree rotation faraday's speculums constitute reciprocation type light path.Main 90 degree of rotation farads of application Incident light is reflected by speculum, and its polarization just ratates 90 degrees, thus overcoming the two-fold of optical fiber during long-distance transmissions Penetrate the polarization drift that effect is brought.90 degree of rotation faraday's speculums constitute reciprocation type with unequal arm Mach-Zehnder interferometer simultaneously Loop, it is achieved thereby that the auto-compensation of phase place.

Referring to Fig. 1, this phase code quantum key distribution system, the transmitting terminal (Alice end) including mutual light connects and Receiving terminal (Bob end), wherein all devices at Bob end and optical fiber are all to protect inclined, the light-pulse generator of light source module in Bob end 100 transmitting linear polarizations light pulses, through circulator 101 enter coupler 107 and be divided into two bundle horizontal polarization light pulses (| H >), two-beam pulse respectively through the long-armed and galianconism in unequal arm intervention module, wherein through long-armed light pulse A through phase place Modulator 106 process after by protect inclined polarization beam apparatus 105 reflect after with vertical polarization light pulse (| V>) form output, through too short The light pulse B of arm directly with horizontal polarization light pulse (| H>) form is by protecting inclined polarization beam apparatus 105 transmission output.Protect and wilfully shake The effect of beam splitter be can by the horizontal polarization light pulse of a road reflection end (| H>) go to vertical polarization light pulse (| V>) on Transmission or by vertical polarization light pulse (| V>) go to horizontal polarization light pulse (| H>) upper transmission.

Two-beam pulse reaches 90 degree of rotation faraday's speculums 103 at Alice end by quantum channel 102, reflected Polarization direction ratates 90 degrees two-beam arteries and veins respectively afterwards.

Light pulse A after reflection be horizontal polarization light pulse (| H>) it is transmitted into coupler through protecting inclined polarization beam apparatus 105 107；Light pulse B reflection after be changed into vertical polarization light pulse (| V>) process through the phase-modulator 104 of transmitting terminal coding module Afterwards, through protect the reflection of inclined polarization beam apparatus 105 be changed into horizontal polarization light pulse (| H>) enter the light arteries and veins after coupler 107 and reflection Rush A to interfere；Single-photon detector 108 and single-photon detector 109 are arrived separately at according to interference information difference.

This system needs to add phase-modulator in the measurement part of receiving terminal, for selecting X measurement basic vector or Y measurement base Arrow, the phase-modulator being added can bring extra insertion loss to reduce into code check, and device itself also has intrinsic problem, leads Cause to interfere contrast not high enough, reduce into code check.

Propose using a pair of unequal arm based on four port polarization beam splitters in Chinese patent ZL200610170557.5 Faraday's Michelson's interferometer is realizing the phase code of Polarization Control, the quantum key distribution of Polarization Detection.Above-mentioned patent The use of a pair one-to-one encoding/decoding device is a pair of unequal arm interferometer using sender and recipient, this requires to lead to The arm length difference (the long-armed difference with galianconism) of letter both sides' unequal arm interferometer is equal, but existing process and external environment impact, It is difficult to accomplish to ensure two unequal arm Mach-Zehnder interferometer arm length difference phase stabilizations for a long time.

In sum, prior art is primarily present following problem：

1. the phase code QKD system of existing unequal arm Mach-Zehnder interferometer requires communicating pair unequal arm Mach Zeng De The arm length difference (the long-armed difference with galianconism) of interferometer is equal.But existing process and external environment impact, when being difficult to accomplish long Between ensure two unequal arm Mach-Zehnder interferometer arm length difference phase stabilizations.

2. existing phase code system needs to add phase-modulator in the measurement part of receiving terminal, brings extra declining Subtract, reduce into code check.

3. existing phase code system needs to produce the selection with the non-equilibrium basic vector of dynamoelectric signal active control at a high speed, thus The accurate modulation of the repetition rate of impact system and phase place and reduce into code check.

Utility model content

The utility model provides a kind of transmitting terminal of quantum key distribution system, m- phase when adopting improved in transmitting terminal Position coded system improves into code check, can simplify the hardware requirement of Bob end decoding process accordingly.

A kind of based on when m- phase code plug and play quantum key dissemination system transmitting terminal, including for being formed 90 degree of reflected light path rotate faraday's speculums and are arranged in coding module on reflected light path, and it is right that described coding module includes Optical signal carries out Z basic vector time encoding module and the phase code module of corresponding encoded process, and described phase code module is X base Arrow phase code module.

The utility model will based on when m- PE system combine in plug and play system, for coding module The circuit part sending control signal can adopt existing hardware framework, during phase code, compiles only with X basic vector phase place Code, only carries out phase code with a phase-modulator in transmitting terminal, is not provided with phase-modulator in receiving terminal, and then reduces phase The insertion loss that the device of position modulator brings in itself, moreover, is also avoided that the external hardware because of phase-modulator simultaneously Control and cause into the low situation of code check, and then improve into code check in decoding.

Preferably, described X basic vector phase code module is phase-modulator, described Z basic vector time encoding module is strong Degree modulator.

Existing hardware framework, optical system itself can be adopted for X basic vector phase code and Z basic vector time encoding With coding flow process.

For the relation between Z basic vector time encoding module and phase code module, also adopt existing mode, that is, encode When randomly choose basic vector, with the probability selection z basic vector time encoding of P, with the probability selection phase code of 1-P.The value of P according to Practical application needs to set, and must is fulfilled for 0 ＜ P ＜ 1.

Preferably, described transmitting terminal is additionally provided with being arranged on reflected light path in order to implement the intensity of reflected light modulation inveigled Device.

Preferably, described intensity of reflected light modulator is located between 90 degree of rotation faraday's speculums and coding module. Intensity of reflected light modulator is utilized to implement to inveigle before the coding.

Intensity of reflected light modulator passes through to change the transmission that light intensity realizes " trick state " optical signal, can guarantee that single photon composition Efficiency do not changed by attacker, and single photon composition is the effective one-tenth that can extract safe key in quantum key distribution system Point.Accordingly, light produced by the light source of receiving terminal be weak coherent light.Described intensity of reflected light modulator is to 90 degree of rotary process The optical signal that speculum is reflected back is drawn to carry out intensity modulated to change single photon composition and multi-photon in the light pulse of output The ratio of composition.

Reflected light path initiates from 90 degree of rotation faraday's speculums, and intensity of reflected light modulator can act on before the coding It is also possible to act on the optical signal after coding after coding on optical signal, phase-modulator and intensity modulator can be according to not yet It is arranged sequentially on reflected light path together.

Preferably, described intensity of reflected light modulator, phase-modulator and intensity modulator are sequentially arranged in reflected light Lu Shang.

The utility model also provide a kind of based on when m- phase code plug and play quantum key dissemination system reception End, including for sending the light source of optical signal and receiving the decoding mould detecting from transmitting terminal coded light signal to transmitting terminal Block, described decoder module includes Z basic vector time detecting module and the phase detection module that optical signal is carried out with corresponding decoding process, Wherein phase detection module is X basic vector phase detection module.

Described Z basic vector time detecting module includes：

The beam splitting module being split for optical signal after transmitting terminal is encoded；And

It is connected with beam splitting module first output end to carry out the single-photon detector that the Z basic vector time detects；

Described phase detection module connects the second output end of beam splitting module.

Preferably, described beam splitting module is beam splitter.

The splitting ratio of beam splitter can arbitrarily change as needed.According to the indivisible characteristic of single photon pulses, real After transmitting terminal coding on border, optical signal only (can include the first output end from the output of one of output port after beam splitting module Mouth and the second output port), or exporting from the first output end, or exporting from the second output end, and due to splitting ratio not With also different from the probability of different output port output.

After transmitting terminal coding, optical signal enters corresponding detection after beam splitting module after different output port output Device, now enters different detectors and illustrates to have selected corresponding detection basic vector.For example：Reach after the first output port Carry out the single-photon detector that the Z basic vector time detects, then mean that have selected Z basic vector is detected, through the second output port Reach the single-photon detector in phase detection module afterwards, then mean to have selected X basic vector.

In the utility model, beam splitter is interpreted as, achievable beam splitting or close bundle different according to optical signal direction of transfer Device, in the same manner, the first output end, the second output end refer to along the optical signal direction of transfer from transmitting terminal, if along receiving terminal extremely The optical signal direction of transfer of transmitting terminal, the second output end also can be considered input.

Beam splitter is the optical element of fixing splitting ratio, without electric signal control, can improve into code check further, needs When changing splitting ratio, directly change the beam splitter of different splitting ratios.

Preferably, beam splitter exports light energy and the light energy exporting to phase detection module to single-photon detector Unequal, for example export and be more than output to the light energy of phase detection module to the light energy of single-photon detector.It is achieved in that Non-equilibrium basic vector decoding, is conducive to improving into code check.

Described phase detection module includes the unequal arm intervention module being arranged between beam splitting module and light source and is used for Detect the detector module that unequal arm intervention module exports optical signal；Wherein light source, unequal arm intervention module and detector module Between three, light path selection is carried out by circulator.

Unequal arm intervention module receives another road output of beam splitting module, and circulator is mainly used in light path and selects, light Source (carries out, by optical circulator, the signal that Path selection makes light source send by wherein one paths when sending optical signal to transmitting terminal Light is transferred to transmitting terminal after unequal arm interferometer), and receive when detecting optical signal after the coding of transmitting terminal transmitting then By another paths, (carrying out Path selection by optical circulator makes the flashlight that receiving terminal returns pass after unequal arm interferometer It is defeated by detector module).

Described unequal arm intervention module is unequal arm Mach-Zehnder interferometer or the unequal arm based on Michelson principle is done Interferometer.

Optionally, the single-photon detector in detector module is two, separately detects and interferes from unequal arm The different result of interference of two kinds of module.

Preferably, single-photon detector in detector module is one, from two kinds of unequal arm intervention module not It is multiplexed to this same single-photon detector by corresponding light path element with result of interference.

As decoder module, the optical signal that wherein unequal arm intervention module is exported, should under the premise of not having specified otherwise It is interpreted as receiving after the coding of transmitting terminal transmitting the optical signal after optical signal, being exported to single-photon detector.

As further preferred, the single-photon detector in described decoder module is one, the of described beam splitting module The output of one output end, and two kinds of different result of interference that unequal arm intervention module is exported are equal by corresponding light path element Coupled to this same single-photon detector.Whole decoder module only one of which single-photon detector, reduce further hardware Expense.

When described unequal arm intervention module adopts unequal arm Mach-Zehnder interferometer：

Alternatively, in described unequal arm intervention module, long and short arm two ends are passed through respectively near circulator one The beam splitter of side and the polarization beam apparatus coupling away from circulator side, are provided with 90 degree of polarization rotators and time delay on long-armed Line.

Alternatively, in described unequal arm intervention module, long and short arm two ends are respectively by corresponding beam splitting Device couples, and is provided only with delay line on long-armed.Eliminate 90 degree of polarization rotators.

Two single-photon detectors in detector module are respectively the first single-photon detector and the second single-photon detector, In the beam splitter of circulator side, wherein one output end connects the first single-photon detector by the first detection branch road, another Output termination circulator is detecting branch road access the second single-photon detector by second, and another interface of circulator connects light source.

When detector module adopts a single-photon detector, first detects the output coupling of branch road and the second detection branch road Same single-photon detector is entered after conjunction.

Such as first detection branch road passes through the inclined polarization beam apparatus of guarantor (or beam splitter) after a delay line and is coupled into the second spy Survey branch road, after the first detection branch road and the second detection branch road coupling, enter same single-photon detector.In the same manner, delay line can also It is arranged on the second detection branch road, or two detection branch roads are all arranged, as long as can differentiate i.e. on the time reaching detector Can.

When whole decoder module adopts a single-photon detector, the first output end of described beam splitting module connects the 3rd Detect branch road, coupled with the 3rd detection branch road through a beam splitter again after the first detection branch road and the second detection branch road coupling, Article three, detection branch road enters same single-photon detector.

The described unequal arm interferometer based on Michelson principle, including the one 90 degree rotation faraday's speculum, second 90 degree rotate faraday's speculum, polarization beam apparatus, delay line and half-wave plate；And the fast axle of half-wave plate or slow-axis direction and polarization Either polarization base in two polarization bases of beam splitter becomes 22.5 degree or -22.5 degree angles；

Wherein it is derived from the reflected light path of transmitting terminal, it is anti-that a road is transmitted through the one 90 degree of rotation faraday through polarization beam apparatus Penetrate mirror, another road is reflected through delay line to the 2nd 90 degree of rotation faraday's speculum through polarization beam apparatus, from the one 90 degree The reflected light of rotation faraday's speculum and the 2nd 90 degree of rotation faraday's speculum is after polarization beam apparatus coupling by annular Device enters detector module through half-wave plate, and another interface of circulator connects light source.

In this scheme, detector module includes polarization beam apparatus and two single-photon detectors, and the output of half-wave plate is through partially Shaking is divided into two-way to respectively enter corresponding single-photon detector after beam splitter.

The utility model also provide a kind of based on when m- phase code plug and play quantum key dissemination system, including The mutually transmitting terminal of light connects and receiving terminal, the coding module in transmitting terminal includes optical signal is carried out with the Z of corresponding encoded process Basic vector time encoding module and phase code module, wherein phase code module are X basic vector phase code module；In receiving terminal Decoder module is adapted with described coding module.

In the utility model plug and play quantum key dissemination system, the improvement further with regard to transmitting terminal and receiving terminal is equal Can be according to the transmitting terminal of the utility model offer and receiving terminal.

The utility model plug and play quantum key dissemination system adopts unequal arm interferometer and one 90 degree rotation farads Speculum constitutes toward trans loop, and its principle of interference is similar with Sagnac ring.Can realize ensureing that unequal arm is interfered for a long time Instrument arm length difference phase stabilization.Two light pulses transmit one back and forth between the side of sending and receiving, and each light pulse is through all Light path once, reaches self compensation effect.So system architecture is simpler, becomes code check higher.

Existing phase code system needs to add phase-modulator in the measurement part of receiving terminal, for selecting X or Y to measure Basic vector, the phase-modulator being added can bring extra insertion loss to reduce into code check.The utility model does not need in receiving terminal Plus phase-modulator.The when m- phase code adopting is main as measuring basic vector, Z basic vector time encoding using Z basic vector and X basic vector Being modulated by the random intensity to two light pulses of intensity modulator (will be close for the intensity modulation of one of light pulse In 0 vacuum state, thus realizing randomly generating only first light pulse or only second light pulse, and then realize Z base Arrow time encoding), X basic vector coding is realized by phase-modulator.

Existing phase code system needs to produce at a high speed with the non-equilibrium base of dynamoelectric signal active control using signal generator The selection of arrow, relatively costly, and because device performance itself limits the accurate modulation of system phase, thus reducing into code check. The utility model can change reflected light as needed and enter Z basic vector time detecting module beam splitting ratio, need not actively modulate i.e. The efficient QKD scheme of the passively non-equilibrium basic vector of achievable measurement end.

For interfering, contrast is not high enough, and the utility model can realize superelevation contrast from Z basic vector time encoding Encoding and decoding, thus improve into code check.

Brief description

Fig. 1 is the principle schematic of prior art plug and play quantum key dissemination system；

Fig. 2 is the principle schematic of the plug and play quantum key dissemination system of embodiment 1；

Fig. 3 is the principle schematic of embodiment 2；

Fig. 4 is the principle schematic of embodiment 3；

Fig. 5 is the principle schematic of embodiment 4；

Fig. 6 is the principle schematic of embodiment 5.

Specific embodiment

Referring to Fig. 2, the utility model plug and play quantum key dissemination system, the Alice end including light connects and Bob End, is quantum channel between Alice end and Bob end, its transmission form can be optical fiber, free space, planar optical waveguide etc..

Alice end includes：90 degree of rotation faraday's speculums 9 and coding module, coding module is along reflection light direction successively It is the phase-modulator 8 as X basic vector phase code module, and the intensity modulator 7 as Z basic vector time encoding module, X basic vector phase code or Z basic vector time encoding is adopted at random during coding.

Bob end includes light source module and decoder module, and wherein decoder module includes Z basic vector time detecting module and X base Arrow detecting module.

The present embodiment light source module adopts light-pulse generator 1, is perfect single-photon source or the weak coherent light source combining trick state, Z basic vector time detecting module includes beam splitting module and single-photon detector 12.

In the present embodiment, beam splitting module can be using realizing the device of beam splitting/combining function, as preferably employing beam splitter 6, its splitting ratio can arbitrarily select as needed, and for improving into code check, the light energy entering single-photon detector 12 should be greater than Or the light energy less than entrance X basic vector detecting module.

Beam splitter 6 is the optical element of fixing splitting ratio, without electric signal control, can improve into code check further, needs When changing splitting ratio, directly change the beam splitter of different splitting ratios.

X basic vector detecting module includes unequal arm intervention module, circulator 2 and single-photon detector 10 (the second single photon Detector) and single-photon detector 11 (the first single-photon detector).Wherein unequal arm intervention module can be unequal arm Mach Zehnder interferometer or Michelson's interferometer.The present embodiment adopts unequal arm Mach-Zehnder interferometer, mainly by beam splitting Device 3,90 degree of polarization rotators 4, delay line, polarization beam apparatus 5 are constituted.

Polarization beam apparatus 5 can be replaced with beam splitter, but now needs to remove 90 degree of polarization rotators 4, interferes after replacement Efficiency will reduce half.

During the work of the present embodiment quantum key distribution system, light-pulse generator 1 sends the light pulse of linear polarization through annular Device 2 is input to beam splitter 3.

The long-armed of unequal arm intervention module is passed through in wherein one tunnel light pulse of beam splitter 3 output, through 90 degree of polarization rotations Its polarization state is ratated 90 degrees rear input polarization beam splitter 5 by device 4, only has orthogonal polarized light arteries and veins after polarization beam apparatus 5 reflection Punching (i.e. | V>Light) output.The galianconism of unequal arm intervention module is passed through in another road light pulse of beam splitter 3 output, is directly entered defeated Enter to polarization beam apparatus 5, after polarization beam apparatus 5 transmission only have horizontal polarization light pulse (i.e. | H>Light) output.

Two-beam pulse polarizes orthogonal smooth arteries and veins respectively through synthesizing a road after the reflection of polarization beam apparatus 5 and transmission Punching, then pass sequentially through beam splitter 6 and quantum channel 13, reach Alice end, and sequentially pass through intensity modulator 7, phase-modulator 8 reach 90 degree of rotation faraday's speculums 9, and intensity modulator 7 and phase-modulator 8 are inoperative during this period.Through 90 degree After rotation faraday's speculum 9 effect, the flat polarized optical pulse of raw water (| H>) become vertical polarization light pulse (| V>), former vertically inclined Shake light pulse (| V>) become horizontal polarization light (| H>).Backtracking reaches coding module and is encoded, and randomly chooses during coding Basic vector, with the probability selection z basic vector time encoding of P, with the probability selection x basic vector phase code of 1-P.

When selecting z basic vector time encoding, what intensity modulator 7 was random carries out intensity modulated to two light pulses, will wherein The vacuum state close to zero for the intensity modulation of one light pulse, thus realize Z basic vector time encoding.

When selecting x basic vector phase code, phase-modulator 8 carries out phase-modulation to one of two light pulses makes two The effective phase difference 0 of light pulse or pi, that is, carry out X basic vector phase code, returns to Bob end by quantum channel 13 after coding.

Light pulse after beam splitter 6, beam splitter 6 first output end order photon detector 12, the second output termination is partially Shake beam splitter 5.

When selection carries out the detection of Z basic vector, detected by the single-photon detector 12 being connected with the first output end.

When selection carries out the detection of X basic vector, polarize the reflection through polarization beam apparatus 5 for the orthogonal two-beam pulse and transmission Walk the long-armed of unequal arm intervention module and galianconism respectively, wherein：

Vertical polarization light pulse (| V>) become after 90 degree of polarization rotators 4 horizontal polarization light pulse (| H>) and input Beam splitter 3, horizontal polarization light pulse (| H>) then directly input beam splitter 3.

Two-way light pulse interferes at beam splitter 3, if phase difference is 0 before interfering, light is through circulator 2 to list Photon detector 10 (the second single-photon detector), if phase difference is pi before interfering, reaches single-photon detector 11 (first Single-photon detector), it is achieved thereby that detecting under X basic vector.

Detecting under Z basic vector is that receiving light pulse arrival time changes into bit value, and detecting under X basic vector is according to phase difference not Change into bit value with reaching different detectors, after generating bit value, basic vector comparison, error correction, privacy are carried out by classical channel The last handling processes such as amplification ultimately generate quantum key.

Embodiment 2

In the present embodiment, it is that polarization beam apparatus 5 beam splitter 5a replaces with the difference of embodiment 1, saves simultaneously 90 degree of polarization rotators, arm portion former delay line 4a retains, and transfer portion is referring to Fig. 3.

Embodiment 3

In the present embodiment, it is unequal arm intervention module and related single photon detection to the difference of embodiment 1 Device, the unequal arm interferometer in the present embodiment, unequal arm MZ interferometer being instead based on Michelson principle is realized, right accordingly Single-photon detector has carried out adaptive improvement.

Referring to Fig. 4, light-pulse generator 1 sends linear polarization light pulse and reaches polarization beam apparatus 15 after circulator 2, and it is saturating The flat polarized optical pulse of jetting (| H>), reflective vertical polarized optical pulse (| V>).

Horizontal polarization light pulse (| H>) walk long-armed, through 90 degree of rotation faraday's speculums 16 (the after delay line 4a time delay 2 90 degree of rotation faraday's speculums) reflection, horizontal polarization light pulse (| H>) become vertical polarization light pulse (| V>) through polarization Beam splitter 15 reflection output.Reach Alice end after 90 degree of rotation faraday's speculums, vertical polarization light pulse (| V>) be changed into Horizontal polarization light pulse (| H>) walk galianconism through polarization beam apparatus 15 transmission again and reach 90 degree to rotate faraday's speculums 17 (the One 90 degree rotation faraday's speculums), reflected, polarization state be changed into vertical polarization light pulse (| V>) anti-through polarization beam apparatus 15 Penetrate output and arrive circulator 2.

In the same manner reflective vertical polarized optical pulse (| V>) walk galianconism through 90 degree rotation faraday's speculums 17 reflect, polarization state Be changed into horizontal polarization light pulse (| H>) export arrival Alice end through polarization beam apparatus 15 transmission, through 90 degree of rotation faraday's reflections Horizontal polarization light pulse after mirror (| H>) be changed into vertical polarization light pulse (| V>), reflect through polarization beam apparatus 15 and walk long-armed arrival 90 degree rotation faraday's speculums 16, reflected polarization state be changed into horizontal polarization light pulse (| H>) through polarization beam apparatus 15 transmission Export circulator 2.

The orthogonal light pulse of two bundle polarizations synthesizes a road and reaches half-wave plate 18, the now fast axle of half-wave plate through circulator Or slow-axis direction becomes 22.5 degree or -22.5 degree angles with the either polarization base in two polarization bases of polarization beam apparatus 15, equivalent Polarization beam apparatus 19 are made to be changed into the projection measurement under+45 °/- 45 ° basic vectors from the projection measurement H/V basic vector.Light pulse reaches Polarization beam apparatus 19 interfere, different polarization states arrival different single photon detections different according to phase-modulator institute phase modulation potential difference Device.If phase difference is 0, horizontal polarization light pulse (| H>) reaching single-photon detector 20, phase difference is pi, orthogonal polarized light arteries and veins Punching (| V>) reach single-photon detector 21.

Embodiment 4

Referring to Fig. 5, in the present embodiment, it is X basic vector detecting module is improved with the difference of embodiment 1, Two single-photon detectors in X basic vector detecting module are replaced with same single-photon detector, so by reduces cost.

At Bob end, when two bundle polarization identical reflection light pulses interfere on beam splitter, due to Alice end phase place Modulator has completed X basic vector phase code, and the effective phase difference therefore making two reflection light pulses is 0 or pi.

If phase difference is 0, walks galianconism and reach the inclined polarization beam apparatus 14 (or adopting beam splitter) of guarantor through transmission through circulator 2 Export to single-photon detector 22.

If phase difference is pi, after walking the long-armed 4b time delay through delay line, reach protect inclined polarization beam apparatus 14 (or using point Bundle device) reflected output is to single-photon detector 22.

The present embodiment improvement project is distinguished out of phase difference using two moment and is reached single-photon detector 22.In monochromatic light Add a synchronous timing signal before sub- detector 22, detect arrival time, if no-delay, phase difference is 0 arrival single photon Detector 22, if there being time delay, phase difference reaches single-photon detector 22 for pi.The present embodiment improvement project also can be with embodiment 2nd, 3 combine, protect inclined polarization beam apparatus 14 when wherein combining with embodiment 2 and replace with beam splitter.Wherein mutually tie with embodiment 3 Protect inclined polarization beam apparatus 14 during conjunction and replace with polarization beam apparatus.

Embodiment 5

Referring to Fig. 6, in the present embodiment, it is decoder module is improved with the difference of embodiment 4, will own Single-photon detector is replaced with same single-photon detector, so will further decrease cost.

In the decoder module at Bob end, anti-through beam splitter 6 through the light pulse of z basic vector time encoding from Alice end Reach beam splitter 23 after penetrating away the long-armed 4c time delay through delay line, reflected export to single-photon detector 22.

From Alice end through X basic vector phase code two-beam pulse, after unequal arm interferometer, two bundles are partially Polarization state identical light pulse interferes, if phase difference is 0, walk galianconism reach through circulator 2 protect inclined polarization beam apparatus 14 (or Using beam splitter), export through transmission and reach single-photon detector 22 to beam splitter 23.

If phase difference is pi, reaches after walking the long-armed 4b time delay through delay line and protect inclined polarization beam apparatus 14 and (or adopt beam splitting Device) reflected output to beam splitter 23 reach single-photon detector 22.

The present embodiment improvement project distinguishes using four moment that (flashlight through time encoding divides two to arrive around moment Reach to make a distinction, the flashlight through phase code also divides two to reach to make a distinction around moment) under different basic vectors Detect, the present embodiment improvement project also can be combined with embodiment 2,3, protects inclined polarization beam splitting with embodiment 2 when wherein combining Device 14 replaces with beam splitter.Protect inclined polarization beam apparatus 14 when wherein combining with embodiment 3 and replace with polarization beam apparatus.

Embodiment 6

In the present embodiment, it is Alice end in addition to intensity modulator 7 with the difference of embodiment 1,90 degree of rotations Add between faraday's speculum 9 and phase-modulator 8 and adjust for another intensity of reflected light realizing " trick state " light source output Device processed, the optical signal that this intensity of reflected light modulator can be reflected back to 90 degree of rotation faraday's speculums 9 at random carries out intensity tune System is with the ratio of the random monochromatic light subconstiuent changing in output optical signal and multi-photon composition.

Inveigle state agreement thought be attacked based on PNS in attacker different by efficiency to single photon and multi-photon Consideration.In order to find attacker's attack, Alice end sends the light source of different light intensity at random, and wherein multi-photon becomes with single photon Part ratio is different, and attacker adopts the light source of which kind of intensity due to cannot distinguish between Alice side, then multi-photon can not be led to Cross efficiency to carry out adapting to adjust, thus can not ensure that different light sources reach the statistics at Bob ends and all keep constant simultaneously.Compare For, attacker can only ensure that the light source of single intensity reaches the statistics of Bob.Then, by providing " trick state " light source Method can ensure that the efficiency of single photon composition is not changed by attacker, and single photon composition is can in quantum key distribution system To extract the active ingredient of safe key.

The present embodiment improvement project also can be combined with embodiment 2～5, corresponding light-pulse generator (laser instrument) issued light For weak coherent light.

Embodiment 7

In the present embodiment, and the difference of embodiment 1 is to adopt fiber optic communication between Alice end and Bob end, now 90 degree of polarization rotators 4 can be removed, and the beam splitter 3 of embodiment 1 and polarization beam apparatus 5 are changed to polarization-maintaining beam splitter and guarantor respectively Polarization beam apparatus partially, wherein polarization-maintaining beam splitter and the tail optical fiber protected used by inclined polarization beam apparatus are polarization maintaining optical fibres.Respective annular device 2 is Protect inclined circulator, and its tail optical fiber is polarization maintaining optical fibre.Preferably, the present embodiment light-pulse generator sends the light arteries and veins of horizontal polarization Punching.

The present embodiment improvement project also can be combined with embodiment 4,5.

Claims (14)

1. a kind of based on when m- phase code plug and play quantum key dissemination system transmitting terminal, including anti-for being formed Penetrate 90 degree of rotation faraday's speculums of light path and be arranged in coding module on reflected light path, described coding module is included to light Signal carries out the Z basic vector time encoding module of corresponding encoded process and phase code module it is characterised in that described phase code It is X basic vector phase code module in module.

2. as claimed in claim 1 based on when m- phase code plug and play quantum key dissemination system transmitting terminal, its It is characterised by, described X basic vector phase code module is phase-modulator, described Z basic vector time encoding module is intensity modulator.

3. as claimed in claim 1 or 2 based on when m- phase code plug and play quantum key dissemination system transmission End it is characterised in that described transmitting terminal be additionally provided be arranged on reflected light path in order to implement inveigle intensity of reflected light modulator.

4. as claimed in claim 3 based on when m- phase code plug and play quantum key dissemination system transmitting terminal, its It is characterised by, described intensity of reflected light modulator, phase-modulator and intensity modulator are sequentially arranged on reflected light path.

5. a kind of based on when m- phase code plug and play quantum key dissemination system receiving terminal, including for transmission End sends the light source of optical signal and receives the decoder module detecting from transmitting terminal coded light signal, and described decoder module includes Optical signal is carried out with the Z basic vector time detecting module of corresponding decoding process and phase detection module it is characterised in that described phase place Detecting module is X basic vector phase detection module.

6. as claimed in claim 5 based on when m- phase code plug and play quantum key dissemination system receiving terminal, its It is characterised by, described Z basic vector time detecting module includes：

The beam splitting module being split for optical signal after transmitting terminal is encoded；And

It is connected with beam splitting module first output end to carry out the single-photon detector that the Z basic vector time detects；

Described phase detection module connects the second output end of beam splitting module.

7. as claimed in claim 6 based on when m- phase code plug and play quantum key dissemination system receiving terminal, its It is characterised by, described beam splitting module is beam splitter.

8. as claimed in claim 7 based on when m- phase code plug and play quantum key dissemination system receiving terminal, its It is characterised by, beam splitter exports unequal with the light energy exporting to phase detection module to the light energy of single-photon detector.

9. as claimed in claim 7 based on when m- phase code plug and play quantum key dissemination system receiving terminal, its It is characterised by, described phase detection module includes the unequal arm intervention module being arranged between beam splitting module and light source and is used for Detect the detector module that unequal arm intervention module exports optical signal；Wherein light source, unequal arm intervention module and detector module Between three, light path selection is carried out by circulator.

10. as claimed in claim 9 based on when m- phase code plug and play quantum key dissemination system receiving terminal, It is characterized in that, described unequal arm intervention module is unequal arm Mach-Zehnder interferometer or the unequal arm based on Michelson principle Interferometer.

11. as claimed in claim 9 based on when m- phase code plug and play quantum key dissemination system receiving terminal, It is characterized in that, it is provided with two single-photon detectors in detector module, separately detect two kinds from unequal arm intervention module Different result of interference.

12. as claimed in claim 9 based on when m- phase code plug and play quantum key dissemination system receiving terminal, It is characterized in that, the single-photon detector in detector module is one, from two kinds of different interference of unequal arm intervention module Result is multiplexed to this same single-photon detector by corresponding light path element.

13. as claimed in claim 9 based on when m- phase code plug and play quantum key dissemination system receiving terminal, It is characterized in that, the single-photon detector in described decoder module is one, the output of described beam splitting module first output end, with And two kinds of different result of interference that unequal arm intervention module is exported are all coupled to this same list by corresponding light path element Photon detector.

14. a kind of based on when m- phase code plug and play quantum key dissemination system, including the transmitting terminal of mutual light connects And receiving terminal, the coding module in transmitting terminal include optical signal is carried out corresponding encoded process Z basic vector time encoding module and Phase code module is it is characterised in that wherein phase code module is X basic vector phase code module；Decoding mould in receiving terminal Block is adapted with described coding module.