CN109039626A

CN109039626A - Quantum key distribution time bit-phase decoding method, apparatus and system based on 90 degree of welding difference control

Info

Publication number: CN109039626A
Application number: CN201811267203.1A
Authority: CN
Inventors: 许华醒
Original assignee: China Electronics Technology Group Corp CETC
Current assignee: China Electronics Technology Group Corp CETC
Priority date: 2018-10-29
Filing date: 2018-10-29
Publication date: 2018-12-18
Anticipated expiration: 2038-10-29
Also published as: CN109039626B

Abstract

A kind of quantum key distribution time bit-phase decoding method and apparatus and corresponding system based on 90 degree of welding difference control.This method comprises: being the first via and the second tunnel light pulse by input optical pulse beam splitting；Phase decoding is carried out to first via light pulse, the decoding of time bit is carried out to the second tunnel light pulse.Carrying out phase decoding to first via light pulse include: by first via light pulse beam splitting is the two-way sub-light pulse transmitted in two strip optical paths；Beam output will be closed after its relative time delay, at least one sub-light road includes at least one 90 degree of fusion point, the phase difference through two strip optic paths differs the integral multiple of 2 π during controlling each comfortable beam splitting of two orthogonal polarisation states extremely conjunction beam of first via light pulse, and carries out phase-modulation or during beam splitting to conjunction beam to one of two-way sub-light pulse progress phase-modulation to the first via light pulse before beam splitting.The present invention is able to achieve the immune time bit-phase code quantum key distribution scheme of environmental disturbances.

Description

Quantum key distribution time bit-phase decoding based on 90 degree of welding difference control Method, apparatus and system

Technical field

The present invention relates to when the quantum key distribution of optical transport private communication technology field more particularly to a kind of difference control Between bit-phase decoding method, apparatus and the quantum key distribution system including the device.

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 between users based on physical principles such as quantum mechanics Heisenberg uncertainty relationship, quantum non-clone principles Safely shared key, and can detecte potential eavesdropping behavior, it can be applied to the high safeties such as national defence, government affairs, finance, electric power The field of information transfer demands.

Currently, ground quantum key distribution is based primarily upon fibre channel transmission, and light pulse is in Fiber quantum transmission In the process, because there are the non-circular symmetrical, fiber core refractive index in section radially non-idealities such as uneven distribution for optical fiber fabrication, and Optical fiber is influenced by temperature, strain, bending etc. in the actual environment, generates random birefringence effect.M- phase when quantum key distribution Bit protocol is compiled using one group of time base and one group of phase base coding, time base using the time mode of two different time positions Code, phase base are encoded using two phase differences of front and back light pulse.Influenced by optical fiber random birefringence, light pulse through it is long away from When from reaching receiving end after optical fiber transmission, random variation is had occurred in polarization state.When m- phase code in the decoding of time base not By polarization state variation influenced, however phase base interfere decoding when, because of transmission fiber and encoding and decoding interferometer fiber birefringence It influences, there is polarization induction fading problem, cause decoding interference unstable, the bit error rate is caused to increase, if increasing correcting device, increase System complexity and cost are added, and stable application are difficult to strong jammings situations such as aerial optical cable, road and bridge optical cables.To quantum key M- phase encoding scheme when distribution, when how to solve phase base decoding in time bit-phase code quantum key distribution application Phase decoding interference caused by declining because of polarization induction is unstable, is to be based on to carry out phase interference decoding with realizing stability and high efficiency Existing optical cable infrastructure carries out the hot spot and problem of quantum secret communication application.

Summary of the invention

At least one in order to solve the above problem, the present invention proposes a kind of based on 90 degree of welding difference control (alternatively referred to as " phases Potential difference control ") quantum key distribution time bit-phase decoding method and apparatus.

The present invention provides at least following technical scheme:

1. a kind of quantum key distribution time bit-phase decoding method based on 90 degree of welding difference control, feature It is, which comprises

It is first via light pulse and the second tunnel light pulse by the beam splitting of input optical pulse all the way of incident random polarization state；With And

According to quantum key distribution agreement, phase decoding is carried out to the first via light pulse and to the second road Guang Mai The decoding of row time bit is rushed in,

Wherein, carrying out phase decoding to the first via light pulse includes:

It is the pulse of two-way sub-light by the first via light pulse beam splitting；And

The two-way sub-light pulse is transmitted in two strip optical paths respectively, and relative time delay is made into the two-way sub-light pulse Beam output is closed afterwards, at least one sub-light road in the two strips optical path includes at least two sections of polarization maintaining optical fibres,

It wherein, include at least one 90 degree of fusion point at least one sub-light road in the two strips optical path, 90 degree of fusion points are formed in the following manner: by the opposite rotation of two sections of polarization maintaining optical fibres at least one sub-light road It turn 90 degrees, so that the slow axis of one section of polarization maintaining optical fibre is directed at welding with the fast axle of another section of polarization maintaining optical fibre, and

A polarization state in two orthogonal polarisation states of the first via light pulse is wherein controlled in beam splitting to conjunction beam Phase difference and phase difference of another polarization state through the two strips optic path in the process through the two strips optic path So that two phase differences differ the integral multiple of 2 π, and

Wherein before the first via light pulse beam splitting, to the first via light pulse according to quantum key distribution agreement Phase-modulation is carried out, or is uploaded to during closing beam in the two strips optical path in the first via light pulse beam splitting At least one of defeated described two-way sub-light pulse carries out phase-modulation according to quantum key distribution agreement.

2. quantum key distribution time bit-phase decoding according to scheme 1 based on 90 degree of welding difference control Method, which is characterized in that the two strips optical path includes two orthogonal polarisation states for the first via light pulse in the presence of double Have in the optical path of refraction and/or the two strips optical path and exists for two orthogonal polarisation states of the first via light pulse Birefringent optical device a, wherein polarization state in two orthogonal polarisation states of the control first via light pulse is being divided Phase difference and another polarization state through the two strips optic path during Shu Zhihe beam are passed through the two strips optical path Defeated phase difference makes the integral multiple of two 2 π of phase differences difference, comprising:

It keeps uploading during each comfortable beam splitting to conjunction beam of the two orthogonal polarisation states in the two strips optical path respectively Polarization state is constant when defeated；And

Adjustment is there are the length of birefringent optical path and/or there are the birefringent sizes of birefringent optical device, so that this A polarization state in two orthogonal polarisation states beam splitting to during closing beam through two optic paths phase difference with Another polarization state differs the integral multiple of 2 π through the phase difference of the two strips optic path.

3. quantum key distribution time bit-phase solution based on 90 degree of welding difference control according to scheme 1 or 2 Code method, which is characterized in that

A polarization state in two orthogonal polarisation states of the control first via light pulse is in beam splitting to conjunction beam Phase difference and phase difference of another polarization state through the two strips optic path in the process through the two strips optic path So that two phase differences differ the integral multiple of 2 π, comprising:

A polarization eigen state of the polarization maintaining optical fibre is controlled to transmit in the strip optical path in the two strips optical path When the distance transmitted through polarization maintaining optical fibre fast axle and the distance through slow axis transmission first distance it is poor and the polarization eigen state is in institute State the distance transmitted through polarization maintaining optical fibre fast axle when being transmitted in another strip optical path in two strip optical paths and through slow axis transmission away from From second range difference so that first distance difference and second range difference difference beat length of polarization maintaining optical fiber integral multiple.

4. quantum key distribution time bit-phase solution based on 90 degree of welding difference control according to scheme 1 or 3 Code method, which is characterized in that a wherein polarization state in two orthogonal polarisation states of the control first via light pulse Phase difference and another polarization state during beam splitting to conjunction beam through the two strips optic path is through two sub-lights The phase difference of road transmission makes the integral multiple of two 2 π of phase differences difference, comprising:

The two strips optical path includes 90 degree of fusion points, and each fusion point is located at the midpoint on place sub-light road.

5. quantum key distribution time bit-phase decoding according to scheme 1 based on 90 degree of welding difference control Method, which is characterized in that polarization maintaining optical fibre stretcher and/or double is configured on at least one sub-light road in the two strips optical path Refractive phase modulator, wherein adjusting described the by the polarization maintaining optical fibre stretcher and/or the birefringent phase modulator A polarization state in two orthogonal polarisation states of light pulse is during beam splitting to conjunction beam through the two strips optical path all the way The difference of the phase difference of the phase difference of transmission and another polarization state through the two strips optic path.

6. quantum key distribution time bit-phase decoding according to scheme 1 based on 90 degree of welding difference control Method, which is characterized in that carrying out the decoding of time bit to second tunnel light pulse includes:

Second tunnel light pulse is directly exported and is used to detect；Or

Output after the second tunnel light pulse beam splitting is used to detect.

7. a kind of quantum key distribution time bit-phase decoding device based on 90 degree of welding difference control, feature It is, comprising:

Preposition beam splitter is configured for the beam splitting of input optical pulse all the way of incident random polarization state being first via light Pulse and the second tunnel light pulse；And

With the phase decoder of the preposition beam splitter optical coupling, it is configured for carrying out phase to the first via light pulse Position decoding,

The phase decoder include the first beam splitter, the first bundling device and merges with the first beam splitter optocoupler and Two strip optical paths of the first bundling device optical coupling, wherein

First beam splitter is configured for the first via light pulse beam splitting being the pulse of two-way sub-light；

The two strips optical path is configured for transmitting the two-way sub-light pulse respectively, and for realizing two way The relative time delay of light pulse, at least one sub-light road in the two strips optical path include at least two sections of polarization maintaining optical fibres；

First bundling device is configured for closing the two-way sub-light pulse after relative time delay into beam output,

Wherein in the phase decoder, the two strips optical path and optical device thereon are configured to, control this A polarization state in two orthogonal polarisation states of light pulse is during beam splitting to conjunction beam through the two strips optical path all the way The phase difference of transmission makes two phase differences differ 2 π's with another polarization state through the phase difference of the two strips optic path Integral multiple,

Wherein the phase decoder has positioned at first beam splitter front end or in the two strips optical path The phase-modulator of any sub-light road, the phase-modulator are configured for the light pulse by it according to quantum key Distribution protocol carries out phase-modulation,

Wherein light pulse output in second tunnel is used to carry out time bit decoding by the preposition beam splitter.

8. quantum key distribution time bit-phase decoding according to scheme 7 based on 90 degree of welding difference control Device, which is characterized in that the two strips optical path and optical device thereon are further constructed to, and control the polarization maintaining optical fibre The distance that one polarization eigen state transmits when transmitting in the strip optical path in the two strips optical path through polarization maintaining optical fibre fast axle With another sub-light that the first distance for the distance transmitted through slow axis is poor and the polarization eigen state is in the two strips optical path The second range difference of distance and the distance through slow axis transmission that road is transmitted when transmitting through polarization maintaining optical fibre fast axle, so that first distance The integral multiple of difference and second range difference difference beat length of polarization maintaining optical fiber.

9. quantum key distribution time bit-phase solution based on 90 degree of welding difference control according to scheme 7 or 8 Code device, which is characterized in that

10. quantum key distribution time bit-phase decoding according to scheme 7 based on 90 degree of welding difference control Device, which is characterized in that the phase decoder further include:

The polarization maintaining optical fibre stretcher of any sub-light road in the two strips optical path, the polarization maintaining optical fibre stretcher It is configured for adjusting the polarization maintaining optical fibre length of the optical path where it；And/or

The birefringent phase modulator of any sub-light road in the two strips optical path, the birefringent phase tune Device processed is configured for applying different adjustable phase-modulations to two orthogonal polarisation states of the light pulse by it.

11. quantum key distribution time bit-phase decoding according to scheme 7 based on 90 degree of welding difference control Device, which is characterized in that the phase-modulator is to polarize unrelated phase-modulator；The phase-modulator is configured for pair 0 degree of phase-modulation or 180 degree phase-modulation are randomly carried out by its light pulse.

12. quantum key distribution time bit-phase decoding according to scheme 7 based on 90 degree of welding difference control Device, which is characterized in that

The phase decoder uses the light channel structure of unequal arm Mach-Zender interferometer；Or

The phase decoder use unequal arm Michelson's interferometer light channel structure, wherein first bundling device with First beam splitter is same device, the phase decoder further include:

Two reflecting mirrors, described two reflecting mirrors are located in the two strips optical path, and being respectively used to will be from described First beam splitter is returned in the two-way sub-light pulse-echo of first beam splitter come through the two strips optic path,

The two-way sub-light pulse that wherein first beam splitter will reflect back into exports after closing beam.

13. quantum key distribution time bit-phase decoding according to scheme 7 based on 90 degree of welding difference control Device, which is characterized in that first beam splitter and first bundling device and first beam splitter and described first close Optical device between beam device in optical path is that polarization keeps optical device or non-birefringent optical device.

14. quantum key distribution time bit-phase decoding according to scheme 7 based on 90 degree of welding difference control Device, which is characterized in that it further include the second beam splitter, second beam splitter is optically coupled to the preposition beam splitter, and by It is configured to receive second tunnel light pulse and output will be used to carry out the time after the second tunnel light pulse beam splitting and compare particular solution Code.

15. a kind of quantum key distribution system characterized by comprising

Quantum key distribution time ratio based on 90 degree of welding difference control according to any one of scheme 7~14 The receiving end of the quantum key distribution system is arranged in for time bit-phase decoding in spy-phase decoding device；With/ Or

Quantum key distribution time ratio based on 90 degree of welding difference control according to any one of scheme 7~14 The transmitting terminal of the quantum key distribution system is arranged in for time bit-phase code in spy-phase decoding device.

Using the solution of the present invention, it can be achieved that multiple advantages.For example, for time bit-phase code quantum key point Hair application, the present invention is by carrying out 90 degree of weldings, easily controllable phase base decoding using to polarization maintaining optical fibre in interferometer two-arm The difference of the phase difference transmitted in the two-arm of each comfortable unequal arm interferometer of two orthogonal polarisation states of middle light pulse, realizes the two Orthogonal polarisation state effectively interferes output in output port simultaneously, is achieved in the immune phase base decoding function of environmental disturbances, makes The immune time bit-phase code quantum key distribution solution of stable environmental disturbances must be can be realized.Of the invention Quantum key distribution decoding scheme can resist polarization induction decline, while avoid the need for complicated correcting device.

Detailed description of the invention

Fig. 1 is the quantum key distribution time ratio based on 90 degree of welding difference control of a preferred embodiment of the invention Spy-phase decoding method flow chart；

Fig. 2 is the quantum key distribution time ratio based on 90 degree of welding difference control of a preferred embodiment of the invention Spy-phase decoding device composed structure schematic diagram；

Fig. 3 is the quantum key distribution time ratio based on 90 degree of welding difference control of another preferred embodiment of the present invention Spy-phase decoding device composed structure schematic diagram；

Fig. 4 is the quantum key distribution time ratio based on 90 degree of welding difference control of another preferred embodiment of the present invention Spy-phase decoding device composed structure schematic diagram；

Fig. 5 is the quantum key distribution time ratio based on 90 degree of welding difference control of another preferred embodiment of the present invention Spy-phase decoding device composed structure schematic diagram；

Fig. 6 is the quantum key distribution time ratio based on 90 degree of welding difference control of another preferred embodiment of the present invention Spy-phase decoding device composed structure schematic diagram.

Specific embodiment

Specifically describe the preferred embodiments of the invention with reference to the accompanying drawing, wherein attached drawing constitutes one of the application Point, and be used to illustrate the principle of the present invention together with embodiment of the present invention.For purpose of clarity and simplification, when it may make When subject of the present invention is smudgy, the detailed of known function and structure of device described herein is illustrated and will be saved Slightly.

A kind of quantum key distribution time bit-based on 90 degree of welding difference control of a preferred embodiment of the invention Phase decoding method as shown in Figure 1, specifically includes the following steps:

Step S101: being first via light pulse and the second tunnel by the beam splitting of input optical pulse all the way of incident random polarization state Light pulse.

Specifically, incident input optical pulse is random polarization state, it is can be linear polarization, circular polarization or oval The complete polarized light of polarization is also possible to partial poolarized light or non-polarized light.

Step S102: according to quantum key distribution agreement, phase decoding is carried out to first via light pulse and to the second road light Pulse carries out the decoding of time bit.

As skilled in the art will understand, it can regard as per light pulse all the way and be made of two orthogonal polarisation states.Together Sample, the two-way sub-light pulse obtained by first via light pulse beam splitting can also be regarded as by two identical with the first via light pulse Orthogonal polarisation state composition.

Step S103: phase decoding is carried out to first via light pulse can include:

A polarization state in two orthogonal polarisation states of the first via light pulse is wherein controlled in beam splitting to conjunction beam Phase difference and phase difference of another polarization state through the two strips optic path in the process through the two strips optic path So that two phase differences differ the integral multiple of 2 π.

In addition, carrying out phase decoding according to quantum key distribution agreement to first via light pulse for the method for Fig. 1 Carry out phase-modulation as described below in the process: before first via light pulse beam splitting, to first via light pulse according to quantum key Distribution protocol carries out phase-modulation；Alternatively, during first via light pulse beam splitting to conjunction beam, in the two strips optical path At least one of two-way sub-light pulse of upper transmission carries out phase-modulation according to quantum key distribution agreement.In first via light pulse Carrying out phase-modulation according to quantum key distribution agreement to first via light pulse before beam splitting can be by the first via light arteries and veins One of former and later two adjacent input optical pulses in punching carry out phase-modulation to realize.

Here, relative time delay and phase-modulation are carried out according to the requirement and regulation of quantum key distribution agreement, are not made herein It is described in detail.

About a polarization state in two orthogonal polarisation states for controlling the first via light pulse in beam splitting to conjunction beam Phase difference and phase difference of another polarization state through the two strips optic path in the process through the two strips optic path So that two phase differences differ the integral multiple of 2 π, for example, it is assumed that the two orthogonal polarisation states are respectively x-polarisation state and y inclined X-polarisation state is shown as Δ x in beam splitting to the phase meter through two strip optic paths during closing beam, by y-polarisation state by polarization state It is shown as Δ y in beam splitting to the phase meter through two strip optic paths during closing beam, then the two of the first via light pulse A polarization state in a orthogonal polarisation state beam splitting to during closing beam through the two strips optic path phase difference with Another polarization state makes two phase differences differ the integral multiple of 2 π through the phase difference of the two strips optic path, in other words should Phase difference through two strip optic paths during each comfortable beam splitting to conjunction beam of two orthogonal polarisation states of first via light pulse The integral multiple of 2 π is differed, can be indicated are as follows:

Δ x-Δ y=2 π * m,

Wherein m is integer, can be positive integer, negative integer or zero.

In a kind of possible embodiment, it is used for transmission the two of the two-way sub-light pulse that first via light pulse beam splitting obtains Strip optical path includes that there are birefringent optical paths for two orthogonal polarisation states of the first via light pulse, and/or at this two Sub-light road has two orthogonal polarisation states for the first via light pulse, and there are birefringent optical devices.In such case Under, a polarization state in two orthogonal polarisation states of the control first via light pulse is in beam splitting to during closing beam Phase difference and another polarization state through the two strips optic path make two through the phase difference of the two strips optic path A phase difference differs the integral multiple of 2 π, comprising: during keeping each comfortable beam splitting to conjunction beam of the two orthogonal polarisation states respectively When transmitting in the two strips optical path, polarization state is constant；And adjustment there are the length of birefringent optical path and/or exists double The birefringent size of the optical device of refraction a, so that polarization state in the two orthogonal polarisation states is in beam splitting to the process for closing beam The middle phase difference through two optic paths differs 2 π through the phase difference of the two strips optic path with another polarization state Integral multiple, in other words, so that each comfortable beam splitting of the two orthogonal polarisation states is to closing during beam through the two strips optical path The phase difference of transmission differs the integral multiple of 2 π.Optionally, this can be realized by following either type: i) by two sub-lights Road is configured to polarization maintaining optical fibre optical path, by the optical device in the polarization maintaining optical fibre optical path be configured to non-birefringent optical device and/or partially Vibration keeps optical device；Ii free space optical path) is configured by one of described two strips optical path, by the light in the two strips optical path Device is configured to polarization and keeps optical device.Herein, " polarization maintaining optical fibre optical path " refers to the light using polarization maintaining optical fibre transmission light pulse Road or polarization maintaining optical fibre connect the optical path to be formed." non-birefringent optical device " refers to for different polarization states (for example, two orthogonal Polarization state) optical device with identical refractive index.In addition, polarization keeps optical device to be alternatively referred to as polarization-maintaining optical device.

In a kind of possible embodiment, it is described control the first via light pulse two orthogonal polarisation states in one Phase difference and another polarization state of the polarization state during beam splitting to conjunction beam through the two strips optic path are through described two The phase difference of strip optic path makes the integral multiple of two 2 π of phase differences difference, comprising:

A polarization eigen state of the polarization maintaining optical fibre is controlled to transmit in the strip optical path in the two strips optical path When the distance transmitted through polarization maintaining optical fibre fast axle and the distance through slow axis transmission first distance it is poor and the polarization eigen state is in institute State the distance transmitted through polarization maintaining optical fibre fast axle when being transmitted in another strip optical path in two strip optical paths and through slow axis transmission away from From second range difference so that first distance difference and second range difference difference beat length of polarization maintaining optical fiber integral multiple so that should A polarization state in two orthogonal polarisation states of first via light pulse is during beam splitting to conjunction beam through two sub-lights The phase difference of road transmission differs the integral multiple of 2 π with another polarization state through the phase difference of the two strips optic path, changes speech It, so that through the two strips optical path during each comfortable beam splitting to conjunction beam of two orthogonal polarisation states of the first via light pulse The phase difference of transmission differs the integral multiple of 2 π.

In a kind of possible embodiment, free space optical path can be configured by two strip optical paths, by two strip Optical device in optical path is configured to non-birefringent optical device.

In a kind of possible realization, transmitted in the two-way sub-light pulse for being obtained to first via light pulse beam splitting Two strip optical paths at least one sub-light road configuration polarization maintaining optical fibre stretcher and/or birefringent phase modulator.Polarization-maintaining Fiber stretcher is suitable for adjusting the polarization maintaining optical fibre length of the optical path where it.Birefringent phase modulator is suitable for by its two A orthogonal polarisation state applies different adjustable phase-modulations, thus polarization maintaining optical fibre stretcher and/or birefringent phase modulator A polarization state in two orthogonal polarisation states of the first via light pulse can be provided to adjust in beam splitting to the process for closing beam The difference of the phase difference of the middle phase difference through the two strips optic path and another polarization state through the two strips optic path. For example, birefringent phase modulator can be lithium niobate phase modulator, the voltage of lithium columbate crystal is applied to by controlling, it can It is controlled and is adjusted with the phase-modulation being respectively subjected to two orthogonal polarisation states by the lithium niobate phase modulator. Birefringent phase modulator can be used for influencing and adjusting each comfortable beam splitting of two orthogonal polarisation states of the first via light pulse as a result, To close beam during the phase difference through the two strips optic path difference.

Carrying out phase-modulation to a light pulse can be realized by polarizing unrelated phase-modulator.Polarize unrelated phase-modulation Device is suitable for carrying out identical phase-modulation to two orthogonal polarisation states of light pulse, so referred to as polarizing unrelated.Citing and Speech, polarizing unrelated phase-modulator can be realized by two birefringent phase modulator serial or parallel connections.According to circumstances, Ke Yitong A variety of specific meanss are crossed to realize phase-modulation.For example, these means can include: the length of modulation free space optical path, or The length of modulation optical fiber, or utilize serial or parallel connection optical waveguide phase-modulator etc..For example, can be by being changed freely with motor The length of space optical path realizes desired phase-modulation.For another example, it can be modulated by the fiber stretcher using piezoelectric effect The length of optical fiber, is achieved in phase-modulation.In addition, phase-modulator can be suitable for voltage-controlled other types, pass through Apply suitable voltage to polarizing unrelated phase-modulator to carry out identical phase tune to two orthogonal polarisation states of light pulse System is, it can be achieved that desired phase-modulation.

In a preferred embodiment, phase-modulation packet is carried out according to quantum key distribution agreement to first via light pulse It includes: randomly carrying out 0 degree of phase-modulation or 180 degree phase-modulation to first via light pulse.In a preferred embodiment, right At least one of two-way sub-light pulse transmitted in the two strips optical path carries out phase tune according to quantum key distribution agreement System includes: randomly to carry out 0 degree of phase-modulation or 180 to one of two-way sub-light pulse transmitted in the two strips optical path Spend phase-modulation.Here, it randomly carries out 0 degree phase-modulation or 180 degree phase-modulation and refers to randomly to carry out being selected from 0 degree of phase Phase-modulation in modulation and 180 degree phase-modulation the two.

According to a kind of possible embodiment, including: to second tunnel light pulse progress time bit decoding will be described Second tunnel light pulse is directly exported for detecting；Or output after the second tunnel light pulse beam splitting is used to detect.

Fig. 2 shows when a kind of quantum key distribution based on 90 degree of welding difference control of a preferred embodiment of the invention Between bit-phase decoding device (may be simply referred to as " decoding apparatus "), as shown in Fig. 2, include consisting of part: preposition beam splitter 201,205,90 degree of beam splitter 202 and 203, phase-modulator 204, bundling device fusion points 206 and 207.Beam splitter 203 closes beam Device 205 and two strip optical paths between them totally can be described as phase decoder.

Preposition beam splitter 201 is used to the beam splitting of input optical pulse all the way of incident random polarization state be two-way light pulse.

Phase decoder and preposition 201 optical coupling of beam splitter, for receiving the light pulse all the way in above-mentioned two-way light pulse And phase decoding is carried out to it.For convenience, phase decoder it is received this all the way light pulse be hereinafter also referred to be first Road light pulse.

Beam splitter 202 and preposition 201 optical coupling of beam splitter, for receiving the another way light pulse in above-mentioned two-way light pulse (also known as " the second tunnel light pulse "), and output after the another way light pulse beam splitting is used to carry out time bit decoding.Here, It should be noted that beam splitter 202 is optional.The another way light pulse directly exported by preposition beam splitter 201 be used for into The decoding of row time bit is also possible.

Beam splitter 203 will be for that will be the pulse of two-way sub-light from the first via light pulse beam splitting of preposition beam splitter 201, to divide Beam output is not closed through two strip optic paths and by bundling device 205 after by this two strips optical path making relative time delay.Phase-modulator 204 for carrying out phase tune according to quantum key distribution agreement to the sub-light pulse transmitted through one of the two strip optical paths where it System.Specifically, two strip optical paths are used to transmit this two-way sub-light pulse respectively, and for realizing the opposite of this two-way sub-light pulse Delay.It can be realized by adjusting optical path physical length any in two strip optical paths between beam splitter 203 and bundling device 205 The relative time delay of two-way sub-light pulse.Beam is closed in this two-way sub-light pulse of bundling device 205 for that will come through two strip optic paths Output.

Preferably, phase-modulator 204 is used to randomly carry out 0 degree of phase-modulation or 180 degree to by its light pulse Phase-modulation.As it is known in the art, this phase modulation method is also sometimes referred to as " AC phases modulation ".

According to the present invention, in phase decoder, two strip optical paths and optical device thereon are configured to, control this first A polarization state in two orthogonal polarisation states of road light pulse is passed to during closing beam through the two strips optical path in beam splitting Defeated phase difference makes two phase differences differ the whole of 2 π with another polarization state through the phase difference of the two strips optic path Several times, in other words, so that through two strips during each comfortable beam splitting to conjunction beam of two orthogonal polarisation states of first via light pulse The phase difference of optic path differs the integral multiple of 2 π.

In this regard, an optical path depends on for two orthogonal polarisation states there may be birefringent or there is no birefringent In the type of the optical path.For example, free space optical path for input optical pulse all the way two orthogonal polarisation states there is no two-fold Penetrate, and polarization maintaining optical fibre optical path for input optical pulse all the way two orthogonal polarisation states usually exist differ greatly each other it is two-fold It penetrates.In addition, an optical device in optical path for two orthogonal polarisation states there may be birefringent or there is no birefringent, depend on In the type of the optical device.For example, a non-birefringent optical device for input optical pulse all the way two orthogonal polarisation states not There are birefringent, and a polarization keeps optical device usually to there are each other two orthogonal polarisation states of input optical pulse all the way What is differed greatly is birefringent.

For phase decoder, can optionally there be following setting:

Two strip optical paths between beam splitter and bundling device in phase decoder can be free space optical road, this two Optical device in strip optical path, including phase-modulator --- it is that non-birefringent optical device and/or polarization are kept if any Optical device.For the setting, in the case where there is polarization to keep optical device, polarization keeps optical device itself to cause to be input to the phase Phase through two strip optic paths during each comfortable beam splitting to conjunction beam of two orthogonal polarisation states of the light pulse of position decoder Potential difference differs the integral multiple of 2 π.

Two strip optical paths between beam splitter and bundling device in phase decoder are polarization maintaining optical fibre optical path, described two At least one sub-light road in sub-light road includes at least two sections of polarization maintaining optical fibres, wherein described in the two strips optical path extremely It include at least one 90 degree of fusion point in a few strip optical path, 90 degree of fusion points are formed in the following manner: by institute 90 degree of two sections of polarization maintaining optical fibre relative rotation at least one sub-light road are stated, so that the slow axis of one section of polarization maintaining optical fibre and another section of guarantor The fast axle of polarisation fibre is directed at welding.In addition, the optical device in this two strips optical path, including phase-modulator --- if there is Words keep optical device and/or non-birefringent optical device for polarization.

Phase decoder further includes fiber stretcher and/or birefringent phase modulator.Fiber stretcher can be located at phase Any sub-light road in two strip optical paths between the beam splitter and bundling device of position decoder, can be used for adjusting the son where it The polarization maintaining optical fibre length of optical path.By adjusting polarization maintaining optical fibre length by means of fiber stretcher, it may be advantageous to be easily achieved input Each comfortable beam splitting of two orthogonal polarisation states to the light pulse of the phase decoder is passed during beam through two strip optical paths to closing Defeated phase difference differs the integral multiple of 2 π.In addition, fiber stretcher also is used as phase-modulator use.Birefringent phase modulation Device can be located at any sub-light road in the two strips optical path, can be used for two orthogonal polarisation states to the light pulse by it Apply different phase-modulations.By controlling the birefringent phase modulator, pass through two orthogonal polarisation states of its light pulse The difference for the phase-modulation being respectively subjected to is adjustable.In this way, by utilizing birefringent phase modulator, it is convenient to influence and adjust Through described two during each comfortable beam splitting to conjunction beam of two orthogonal polarisation states of the whole light pulse for being input to phase decoder The difference of the phase difference of sub- optic path, it is easy to accomplish the integral multiple that the difference is 2 π.Before the birefringent phase modulator can be Lithium niobate phase modulator described in text.

Phase decoder uses the structure of unequal arm Mach-Zender interferometer, and the optical path of interferometer two-arm is (that is, phase Two strip optical paths between the beam splitter and bundling device of position decoder) use polarization maintaining optical fibre, it is assumed that and the two-arm of interferometer is wrapped respectively Containing 90 degree of fusion points 206 and 207, it is assumed that the distance of 90 degree fusion point 206 of the beam splitter into an arm is L1, in an arm The distance of 90 degree of fusion points 206 to bundling device be L2, the distance of 90 degree fusion point 207 of the beam splitter into another arm be L3, The distance of 90 degree of fusion points 207 to bundling device in another arm is L4, and length relation meets (L1-L2)-(L3-L4)=n β, wherein n is positive integer, negative integer or zero, and β is beat length of polarization maintaining optical fiber.In this case, can be input to the phase solution Through two strip optic paths during each comfortable beam splitting to conjunction beam of two orthogonal polarisation states of the first via light pulse of code device Phase difference differs the integral multiple of 2 π.In a preferred embodiment, two 90 degree of fusion points can be located in two-arm Point that is to say that L1=L2 and L3=L4, length relation meet (L1-L2)-(L3-L4)=0.

Phase decoder uses the structure of unequal arm Michelson's interferometer.At this point, the bundling device of phase decoder with Beam splitter is same device.In the case, phase decoder further includes two reflecting mirrors, the two reflecting mirrors are located at use In in two strip optical paths of the two-way sub-light pulse that the beam splitter beam splitting of transmission phase decoder obtains, it is respectively used to that phase will be come from The two-way sub-light pulse-echo of the beam splitter of position decoder come through the two strips optic path is gone back so as to by phase decoding Device closes beam output with beam splitter for the bundling device of same device.In addition, in one embodiment, phase decoder can also be with Including optical circulator (not shown).The optical circulator can be located at the beam splitter front end of phase decoder.From preposition beam splitter 201 Corresponding light pulse all the way can input from the first port of optical circulator and export from the second port of optical circulator to phase solution The conjunction beam of the beam splitter of code device, the bundling device (beam splitter with phase decoder is same device) from phase decoder exports The second port of optical circulator can be input to and exported from the third port of optical circulator.But, in another reality of the invention It applies in scheme, also can use another port (such as beam splitting in the port 514 of beam splitter 507 or Fig. 6 in Fig. 5 of beam splitter The port 612 of device 605) output port as Michelson's interferometer.Preferably, the beam splitter and described two reflecting mirrors Two arms of the interferometer constituted can separately include 90 degree of fusion points, it is assumed that 90 degree weldings of the beam splitter into an arm The distance of point is L1, the distance of a reflecting mirror of the 90 degree of fusion points in an arm into two reflecting mirrors is L2, beam splitter Distance to 90 degree fusion points in another arm is L3, another into two reflecting mirrors of 90 degree of fusion points in another arm The distance of reflecting mirror is L4, it is contemplated that light pulse is along two-arm round-trip transmission, by polarization maintaining optical fibre slow axis or fastly in transmission process The distance of axis transmission is 2 times of corresponding polarization maintaining optical fibre length, and length relation meets 2 (L1-L2) -2 (L3-L4)=n β, wherein N is positive integer, negative integer or zero, and β is beat length of polarization maintaining optical fiber.In this case, other optical devices in two strip optical paths cause Each comfortable beam splitting of two orthogonal polarisation states of the light pulse of the phase decoder is input to closing during beam through two sub-lights The phase difference of road transmission differs the integral multiple of 2 π.In a preferred embodiment, two 90 degree of fusion points can be located at The midpoint of two-arm that is to say that L1=L2 and L3=L4, length relation meet 2 (L1-L2) -2 (L3-L4)=0.

" beat length of polarization maintaining optical fiber " is concept well known in the art, refers to two polarization eigen states of polarization maintaining optical fibre along polarization maintaining optical fibre Transmission generates polarization maintaining optical fibre length corresponding to the phase difference of 2 π.

Although Fig. 2 shows phase-modulator is arranged between beam splitter 203 and bundling device 205, i.e., in beam splitting to conjunction beam One of two-way sub-light pulse obtained in the process to beam splitting carries out phase-modulation according to quantum key distribution agreement, it is also possible to , phase-modulator is set in 203 front end of beam splitter, i.e., is assisted before first via light pulse beam splitting according to quantum key distribution View carries out phase-modulation to it.Furthermore, it is also possible that phase-modulator is arranged before preposition beam splitter 201, i.e., to incidence Input optical pulse all the way carry out phase-modulation.

In addition, in beam splitter 203 and being closed although showing phase decoder in Fig. 2 with only one phase-modulator It is also possible that a phase-modulator, which is arranged, in every strip optical path in two strip optical paths between beam device 205.It is being arranged There are two in the case where phase-modulator, the difference for the phase that two phase-modulators are modulated is true by quantum key distribution agreement It is fixed.

For the embodiment of Fig. 2, beam splitter 203 and bundling device 205 preferably polarize and keep optical device.In other words, divide Beam device 203 and bundling device 205 can be polarization-maintaining beam splitter and polarization-maintaining bundling device respectively.Optical device is kept about polarization, is existed Two orthogonal polarization eigen states keep polarization state constant the light pulse of incident polarization eigen state, such as those skilled in the art Known to member.

Fig. 3 shows a kind of quantum key based on 90 degree of welding difference control of another preferred embodiment according to the present invention Distribute time bit-phase decoding device, as shown in figure 3, phase decoder therein uses unequal arm Mach Zehnder interference The structure of instrument.Specifically, the quantum key distribution time bit-phase decoding device includes consisting of part: preposition beam splitting Device 303, beam splitter 304, polarization-maintaining beam splitter 307, polarization maintaining optical fibre stretcher 309, phase-modulator 311, polarization-maintaining bundling device 312 with And two 90 degree of fusion points 308 and 310.

One of two ports 301 and 302 of side of preposition beam splitter 303 are used as quantum key distribution time bit-phase The input terminal of position decoding apparatus.Beam splitter 304 receive by the input optical pulse all the way after preposition 303 beam splitting of beam splitter and by its Beam splitting is the pulse of two-way sub-light.Polarization-maintaining beam splitter 307 and polarization-maintaining bundling device 312 constitute unequal arm Mach-Zender interferometer Component part, two strip optical paths between polarization-maintaining beam splitter 307 and polarization-maintaining bundling device 312 are (that is, unequal arm Mach-Zehnder is dry The two-arm of interferometer) it can be polarization maintaining optical fibre optical path, polarization maintaining optical fibre stretcher 309 and phase-modulator 311 can be inserted into unequal arm horse The same arm of conspicuous-Zeng Deer interferometer or two arms for being inserted into unequal arm Mach-Zender interferometer respectively.Unequal arm horse Conspicuous-Zeng Deer interferometer two-arm includes at least one 90 degree of fusion point, such as can separately include 90 degree of 308 Hes of fusion point 310.The light pulse for being input to beam splitter 307 is exported after the decoding of unequal arm Mach-Zender interferometer by port 313.

When work, port 301 or 302 of the incident light pulse through preposition beam splitter 303 is beamed into preposition beam splitter 303 Two-way light pulse (first via light pulse and the second tunnel light pulse) transmission, wherein first via light pulse inputs polarization-maintaining beam splitter 307 Beam splitting is the pulse of two-way sub-light, and the pulse of sub-light all the way in the two-way sub-light pulse is through 90 degree of transmission of fusion point 308 and polarization-maintaining light (wherein the setting sequence of 90 degree of fusion points 308 and polarization maintaining optical fibre stretcher 309 is convertible, or referred to as the fine modulation of stretcher 309 For " sequence unrelated "), the pulse of another way sub-light through 0 degree of 90 degree transmission of fusion points 310 and phase modulated 311 Stochastic Modulation of device or 180 degree phase (sequence unrelated) is exported after polarization-maintaining bundling device 312 closes beam by port 313 after two-way sub-light pulse relative time delay. The second tunnel light pulse input 304 beam splitting of beam splitter exported from preposition beam splitter 303 be the pulse of two-way sub-light through port 305 or 306 outputs are for carrying out time bit decoding.

Assuming that length is L1 between polarization-maintaining beam splitter 307 and 90 degree fusion point 308,90 degree of fusion points 308 and polarization-maintaining close beam Length is L2 between device 312, length is L3,90 degree of fusion points 310 and protects between polarization-maintaining beam splitter 307 and 90 degree fusion point 310 Length is L4 between inclined bundling device 312, modulates polarization maintaining optical fibre stretcher 309, so that length relation meets:

(L1-L3)-(L2-L4)=n β, in other words

(L1-L2)-(L3-L4)=n β,

Wherein β is beat length of polarization maintaining optical fiber, n is integer；So that two each leisures of orthogonal polarisation state of first via light pulse The integral multiple that the difference of the phase difference of unequal arm Mach-Zender interferometer two-arm transmission is 2 π.

Phase-modulator 311 is to polarize unrelated optical device.If not connecing phase-modulator 311, and stretched through polarization maintaining optical fibre Device 309 realizes that the phase-modulation function of phase-modulator 311, the above results are unaffected.

Fig. 4 shows a kind of quantum key point based on 90 degree of welding difference control of a preferred embodiment according to the present invention Time bit-phase decoding device is sent out, as shown in figure 4, phase decoder therein uses unequal arm Mach-Zender interferometer Structure.The quantum key distribution time bit-phase decoding device includes consisting of part: preposition beam splitter 403, polarization-maintaining 405,90 degree of fusion points 406 and 408 of beam splitter, polarization maintaining optical fibre stretcher 407, phase-modulator 409 and polarization-maintaining bundling device 410。

Input terminal of one of two ports 401 and 402 of side of preposition beam splitter 403 as device, for receive into The light pulse penetrated.Polarization-maintaining beam splitter 405 and polarization-maintaining bundling device 410 form unequal arm Mach-Zender interferometer.Polarization maintaining optical fibre is drawn Stretching device 407 and phase-modulator 409 can be inserted into the same arm of unequal arm Mach-Zender interferometer or is inserted into unequal arm respectively Two arms of Mach-Zender interferometer.In unequal arm Mach-Zender interferometer two-arm an at least arm include at least one 90 Fusion point is spent, such as two-arm can separately include 90 degree of fusion points 406 and 90 degree of fusion points 408, is input to polarization-maintaining point The light pulse of beam device 405 is exported after the decoding of unequal arm Mach-Zender interferometer by port 411.

When work, port 401 or 402 of the light pulse through preposition beam splitter 403 is beamed into two-way into preposition beam splitter 403 Optical pulse propagation, light pulse is directly exported by port 404 all the way；It is two that another way light pulse, which inputs 405 beam splitting of polarization-maintaining beam splitter, Way light pulse, wherein all the way sub-light pulse through the transmission of 90 degree of fusion points 406 and the modulation of polarization maintaining optical fibre stretcher 407 (sequentially without Close), the pulse of another way sub-light is through 90 degree of transmission of fusion point 408 and phase modulated device 409 modulation (sequence is unrelated), two-way sub-light It is exported after polarization-maintaining bundling device 410 closes beam by port 411 after pulse relative time delay.

Assuming that length is L1 ' between polarization-maintaining beam splitter 405 and 90 degree fusion point 406,90 degree of fusion points 406 and polarization-maintaining close beam Between device 410 length be L2 ', between polarization-maintaining beam splitter 405 and 90 degree fusion point 408 length be L3 ', 90 degree of fusion points 408 with Length is L4 ' between polarization-maintaining bundling device 410, modulates polarization maintaining optical fibre stretcher 407, so that length relation meets:

(L1 '-L3 ')-(L2 '-L4 ')=n β, in other words

(L1 '-L2 ')-(L3 '-L4 ')=n β,

Phase-modulator 409 is to polarize unrelated optical device.If not connecing phase-modulator 409, and stretched through polarization maintaining optical fibre Device 407 realizes that the phase-modulation function of phase-modulator 409, the above results are unaffected.

Fig. 5 shows a kind of quantum key distribution based on 90 degree of welding difference control of another preferred embodiment of the present invention Time bit-phase decoding device, as shown in figure 5, phase decoder therein uses the knot of unequal arm Michelson's interferometer Structure.Specifically, the quantum key distribution time bit-phase decoding device includes consisting of part: preposition beam splitter 503, It is beam splitter 504,507,90 degree of fusion points 508 and 511 of polarization-maintaining beam splitter, polarization maintaining optical fibre stretcher 509, phase-modulator 512, anti- Penetrate mirror 510 and 513.

Input terminal of one of two ports 501 and 502 of side of preposition beam splitter 503 as phase decoding device, point Beam device 504 receives through the input optical pulse all the way after preposition 503 beam splitting of beam splitter and is the pulse of two-way sub-light by its beam splitting.It protects Inclined beam splitter 507 and reflecting mirror 510,513 form unequal arm Michelson's interferometer, polarization maintaining optical fibre stretcher 509 and phase tune Device 512 processed can be inserted into unequal arm Michelson's interferometer same arm or respectively be inserted into unequal arm Michelson's interferometer two An at least arm includes at least one 90 degree of fusion point in a arm unequal arm Michelson's interferometer two-arm, such as two-arm can wrap respectively Containing 90 degree of fusion points 508 and 90 degree of fusion points 511.The light pulse of beam splitter 507 is input to through unequal arm Michael It is exported after inferior interferometer decoding by the port 514 of beam splitter 507.In this example, beam splitter 507 had both played the work of beam splitter With also functioning to the effect of bundling device.

When work, port 501 or 502 of the light pulse through preposition beam splitter 503 is beamed into two-way into preposition beam splitter 503 Optical pulse propagation, that is, first via light pulse and the second tunnel light pulse.After second tunnel light pulse is input to beam splitter 504, by beam splitting It is decoded via port 505 or the output of port 506 for time bit for the pulse of two-way sub-light.First via light pulse is input to polarization-maintaining It by beam splitting is the pulse of two-way sub-light after beam splitter 507, wherein sub-light pulse is transmitted and polarization maintaining optical fibre through 90 degree of fusion points 508 all the way It is reflected after the modulation of stretcher 509 (sequence is unrelated) by reflecting mirror 510, the pulse of another way sub-light is passed through 90 degree of fusion points 511 It is reflected after the defeated and phase modulated modulation of device 512 (sequence is unrelated) by reflecting mirror 513, the two of reflected relative time delay Way light pulse is exported after polarization-maintaining beam splitter 507 closes beam by the port 514 of polarization-maintaining beam splitter 507.

Assuming that length is L1 ", 90 degree of fusion points 508 and reflecting mirror between polarization-maintaining beam splitter 507 and 90 degree fusion point 508 Between 510 length be L2 ", between polarization-maintaining beam splitter 507 and 90 degree fusion point 511 length be L3 ", 90 degree of fusion points 511 and anti- Penetrating length between mirror 513 is L4 ", modulates polarization maintaining optical fibre stretcher 509, so that length relation meets:

2 (L1 "-L3 ") -2 (L2 "-L4 ")=n β, or

2 (L1 "-L2 ") -2 (L3 "-L4 ")=n β

Wherein β is beat length of polarization maintaining optical fiber, n is integer；So that two each leisures of orthogonal polarisation state of first via light pulse The integral multiple that the difference of the phase difference of unequal arm Michelson's interferometer two-arm transmission is 2 π.

Phase-modulator 512 is to polarize unrelated optical device.If not connecing phase-modulator 512, and stretched through polarization maintaining optical fibre Device 509 realizes that the phase-modulation function of phase-modulator 512, the above results are unaffected.

Fig. 6 shows a kind of quantum key point based on 90 degree of welding difference control of another embodiment according to the present invention M- phase decoding device when hair.As shown in fig. 6, phase decoder therein uses the structure of unequal arm Michelson's interferometer. Specifically, the quantum key distribution time bit-phase decoding device includes consisting of part: preposition beam splitter 603, polarization-maintaining Beam splitter 605,90 degree of fusion points 606 and 609, polarization maintaining optical fibre stretcher 607, phase-modulator 610, reflecting mirrors 608 and 611.

Input terminal of one of two ports 601 and 602 of side of preposition beam splitter 603 as device.Polarization-maintaining beam splitter 605 and reflecting mirror 608,611 form unequal arm Michelson's interferometer.Polarization maintaining optical fibre stretcher 607 and phase-modulator 610 can It is inserted into the same arm of unequal arm Michelson's interferometer or is inserted into two arms of unequal arm Michelson's interferometer respectively.Differ An at least arm includes at least one 90 degree of fusion point in the two-arm of arm Michelson's interferometer, for example, two-arm can separately include one A 90 degree of fusion points 606 and 90 degree of fusion points 609.The light pulse for being input to beam splitter 605 is dry through unequal arm Michelson It is exported after interferometer decoding by the port 612 of polarization-maintaining beam splitter 605.

When work, port 601 or 602 of the light pulse through preposition beam splitter 603 is beamed into two-way into preposition beam splitter 603 Optical pulse propagation, that is, first via light pulse and the second tunnel light pulse.When second tunnel light pulse is used for by the direct output in port 604 Between bit decode；It is the pulse of two-way sub-light that first via light pulse, which inputs 605 beam splitting of polarization-maintaining beam splitter, and sub-light pulse is through 90 degree all the way It is reflected after the transmission of fusion point 606 and the modulation of polarization maintaining optical fibre stretcher 607 (sequence is unrelated) by reflecting mirror 608, another way Light pulse is reflected back after 90 degree of transmission of fusion point 609 and phase modulated device 610 modulation (sequence is unrelated) by reflecting mirror 611 Come, the two-way sub-light pulse of reflected relative time delay is after polarization-maintaining beam splitter 605 closes beam by the port of polarization-maintaining beam splitter 605 612 outputs.In this example, beam splitter 605 both plays the role of beam splitter, also functions to bundling device.

Assuming that length is L1 " ', 90 degree of fusion points 606 and reflecting mirror between polarization-maintaining beam splitter 605 and 90 degree fusion point 606 Between 608 length be L2 " ', between polarization-maintaining beam splitter 605 and 90 degree fusion point 609 length be L3 " ', 90 degree of fusion points 609 with Length is L4 " ' between reflecting mirror 611, modulates polarization maintaining optical fibre stretcher 607, so that length relation meets:

2 (L1 " '-L3 " ') -2 (L2 " '-L4 " ')=n β, in other words

2 (L1 " '-L2 " ') -2 (L3 " '-L4 " ')=n β,

Wherein β is beat length of polarization maintaining optical fiber, n is integer；So that two orthogonal polarisation states of first via light pulse are respectively The integral multiple for being 2 π in the difference of the phase difference of unequal arm Michelson's interferometer two-arm transmission.

Phase-modulator 610 is to polarize unrelated optical device.If not connecing phase-modulator 610, and stretched through polarization maintaining optical fibre Device 607 realizes that the phase-modulation function of phase-modulator 610, the above results are unaffected.

Herein, term " beam splitter " and " bundling device " are used interchangeably, and beam splitter is also referred to as and as bundling device, instead ?.

In another aspect, the present invention provides a kind of quantum key distribution system, it can be in the reception of quantum key distribution system End configures quantum key distribution time bit-phase decoding device of difference control of the invention, is used for time bit-phase solution Code.When configuring the quantum key distribution of difference control of the invention alternatively, it is also possible to the transmitting terminal in quantum key distribution system Between bit-phase decoding device, be used for time bit-phase code.

The present invention is by carrying out 90 degree of weldings, easily controllable phase base decoding using to polarization maintaining optical fibre in interferometer two-arm The difference of the phase difference transmitted in the two-arm of each comfortable unequal arm interferometer of two orthogonal polarisation states of middle light pulse.In addition, this hair Bright two orthogonal polarisation states that can be realized light pulse in the decoding of phase base effectively interfere output in output port simultaneously, are equivalent to Polarization diversity processing is carried out to two orthogonal polarisation states, polarization can be effectively solved and induce the caused interference decoding of decline is unstable to ask Topic realizes the immune stable phase angle decoding of environmental disturbances, without using polarization beam apparatus and two interferometers to polarize two State is decoded respectively, in addition also eliminates the needs to correction.

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.

Although being described in detail by example embodiment, preceding description be all in all respects it is illustrative rather than It is restrictive.It should be appreciated that can be designed that range of a number of other remodeling with variant without departing from example embodiment, these Both fall within protection scope of the present invention.Therefore, protection scope of the present invention should be determined by the appended claims.

Claims

1. a kind of quantum key distribution time bit-phase decoding method based on 90 degree of welding difference control, which is characterized in that The described method includes:

It is first via light pulse and the second tunnel light pulse by the beam splitting of input optical pulse all the way of incident random polarization state；And

According to quantum key distribution agreement, to the first via light pulse carry out phase decoding and to second tunnel light pulse into The decoding of row time bit,

Wherein, carrying out phase decoding to the first via light pulse includes:

The two-way sub-light pulse is transmitted in two strip optical paths respectively, and is closed after relative time delay is made in the two-way sub-light pulse Beam exports, and at least one sub-light road in the two strips optical path includes at least two sections of polarization maintaining optical fibres,

It wherein, include at least one 90 degree of fusion point at least one sub-light road in the two strips optical path, it is described 90 degree of fusion points are formed in the following manner: by two sections of polarization maintaining optical fibre relative rotation 90 at least one sub-light road Degree, so that the slow axis of one section of polarization maintaining optical fibre is directed at welding with the fast axle of another section of polarization maintaining optical fibre, and

A polarization state in two orthogonal polarisation states of the first via light pulse is wherein controlled in beam splitting to the process for closing beam The middle phase difference through the two strips optic path makes with another polarization state through the phase difference of the two strips optic path Two phase differences differ the integral multiple of 2 π, and

Wherein before the first via light pulse beam splitting, the first via light pulse is carried out according to quantum key distribution agreement Phase-modulation, or during the first via light pulse beam splitting to conjunction beam, to what is transmitted in the two strips optical path At least one of described two-way sub-light pulse carries out phase-modulation according to quantum key distribution agreement.

2. quantum key distribution time bit-phase decoding according to claim 1 based on 90 degree of welding difference control Method, which is characterized in that the two strips optical path includes two orthogonal polarisation states for the first via light pulse in the presence of double Have in the optical path of refraction and/or the two strips optical path and exists for two orthogonal polarisation states of the first via light pulse Birefringent optical device a, wherein polarization state in two orthogonal polarisation states of the control first via light pulse is being divided Phase difference and another polarization state through the two strips optic path during Shu Zhihe beam are passed through the two strips optical path Defeated phase difference makes the integral multiple of two 2 π of phase differences difference, comprising:

During keeping each comfortable beam splitting of the two orthogonal polarisation states extremely to close beam respectively when being transmitted in the two strips optical path Polarization state is constant；And

Adjustment is there are the length of birefringent optical path and/or there are the birefringent sizes of birefringent optical device, so that the two A polarization state in orthogonal polarisation state beam splitting to during closing beam through two optic paths phase difference with it is another A polarization state differs the integral multiple of 2 π through the phase difference of the two strips optic path.

3. quantum key distribution time bit-phase solution according to claim 1 or 2 based on 90 degree of welding difference control Code method, which is characterized in that

A polarization state in two orthogonal polarisation states of the control first via light pulse is in beam splitting to the process for closing beam The middle phase difference through the two strips optic path makes with another polarization state through the phase difference of the two strips optic path Two phase differences differ the integral multiple of 2 π, comprising:

It controls when a polarization eigen state of the polarization maintaining optical fibre transmits in the strip optical path in the two strips optical path and passes through The first distance of the distance of polarization maintaining optical fibre fast axle transmission and the distance through slow axis transmission is poor and the polarization eigen state is described two The distance transmitted through polarization maintaining optical fibre fast axle and the distance through slow axis transmission when being transmitted in another strip optical path in strip optical path Second range difference, so that the integral multiple of first distance difference and second range difference difference beat length of polarization maintaining optical fiber.

4. quantum key distribution time bit-phase solution according to claim 1 or 3 based on 90 degree of welding difference control Code method, which is characterized in that a wherein polarization state in two orthogonal polarisation states of the control first via light pulse Phase difference and another polarization state during beam splitting to conjunction beam through the two strips optic path is through two sub-lights The phase difference of road transmission makes the integral multiple of two 2 π of phase differences difference, comprising:

5. quantum key distribution time bit-phase decoding according to claim 1 based on 90 degree of welding difference control Method, which is characterized in that polarization maintaining optical fibre stretcher and/or double is configured on at least one sub-light road in the two strips optical path Refractive phase modulator, wherein adjusting described the by the polarization maintaining optical fibre stretcher and/or the birefringent phase modulator A polarization state in two orthogonal polarisation states of light pulse is during beam splitting to conjunction beam through the two strips optical path all the way The difference of the phase difference of the phase difference of transmission and another polarization state through the two strips optic path.

6. quantum key distribution time bit-phase decoding according to claim 1 based on 90 degree of welding difference control Method, which is characterized in that carrying out the decoding of time bit to second tunnel light pulse includes:

Second tunnel light pulse is directly exported and is used to detect；Or

Output after the second tunnel light pulse beam splitting is used to detect.

7. a kind of quantum key distribution time bit-phase decoding device based on 90 degree of welding difference control, which is characterized in that Include:

Preposition beam splitter is configured for the beam splitting of input optical pulse all the way of incident random polarization state being first via light pulse With the second tunnel light pulse；And

With the phase decoder of the preposition beam splitter optical coupling, it is configured for carrying out phase solution to the first via light pulse Code,

The phase decoder include the first beam splitter, the first bundling device and merge with the first beam splitter optocoupler with it is described Two strip optical paths of the first bundling device optical coupling, wherein

The two strips optical path is configured for transmitting the two-way sub-light pulse respectively, and for realizing the two-way sub-light arteries and veins The relative time delay of punching, at least one sub-light road in the two strips optical path include at least two sections of polarization maintaining optical fibres；

Wherein in the phase decoder, the two strips optical path and optical device thereon are configured to, and control the first via A polarization state in two orthogonal polarisation states of light pulse is during beam splitting to conjunction beam through the two strips optic path Phase difference and another polarization state make two phase differences differ the integer of 2 π through the phase difference of the two strips optic path Times,

Wherein the phase decoder, which has, is located at first beam splitter front end or any in the two strips optical path The phase-modulator of sub-light road, the phase-modulator are configured for the light pulse by it according to quantum key distribution Agreement carries out phase-modulation,

8. quantum key distribution time bit-phase decoding according to claim 7 based on 90 degree of welding difference control Device, which is characterized in that the two strips optical path and optical device thereon are further constructed to, and control the polarization maintaining optical fibre The distance that one polarization eigen state transmits when transmitting in the strip optical path in the two strips optical path through polarization maintaining optical fibre fast axle With another sub-light that the first distance for the distance transmitted through slow axis is poor and the polarization eigen state is in the two strips optical path The second range difference of distance and the distance through slow axis transmission that road is transmitted when transmitting through polarization maintaining optical fibre fast axle, so that first distance The integral multiple of difference and second range difference difference beat length of polarization maintaining optical fiber.

9. quantum key distribution time bit-phase solution according to claim 7 or 8 based on 90 degree of welding difference control Code device, which is characterized in that

10. quantum key distribution time bit-phase decoding according to claim 7 based on 90 degree of welding difference control Device, which is characterized in that the phase decoder further include:

The polarization maintaining optical fibre stretcher of any sub-light road in the two strips optical path, the polarization maintaining optical fibre stretcher are matched Set the polarization maintaining optical fibre length for adjusting the optical path where it；And/or

The birefringent phase modulator of any sub-light road in the two strips optical path, the birefringent phase modulator It is configured for applying different adjustable phase-modulations to two orthogonal polarisation states of the light pulse by it.

11. quantum key distribution time bit-phase decoding according to claim 7 based on 90 degree of welding difference control Device, which is characterized in that the phase-modulator is to polarize unrelated phase-modulator；The phase-modulator is configured for pair 0 degree of phase-modulation or 180 degree phase-modulation are randomly carried out by its light pulse.

12. quantum key distribution time bit-phase decoding according to claim 7 based on 90 degree of welding difference control Device, which is characterized in that

The phase decoder uses the light channel structure of unequal arm Mach-Zender interferometer；Alternatively,

The phase decoder use unequal arm Michelson's interferometer light channel structure, wherein first bundling device with it is described First beam splitter is same device, the phase decoder further include:

Two reflecting mirrors, described two reflecting mirrors are located in the two strips optical path, and being respectively used to will be from described first First beam splitter is returned in the two-way sub-light pulse-echo of beam splitter come through the two strips optic path,

13. quantum key distribution time bit-phase decoding according to claim 7 based on 90 degree of welding difference control Device, which is characterized in that first beam splitter and first bundling device and first beam splitter and described first close Optical device between beam device in optical path is that polarization keeps optical device or non-birefringent optical device.

14. quantum key distribution time bit-phase decoding according to claim 7 based on 90 degree of welding difference control Device, which is characterized in that it further include the second beam splitter, second beam splitter is optically coupled to the preposition beam splitter, and by It is configured to receive second tunnel light pulse and output will be used to carry out the time after the second tunnel light pulse beam splitting and compare particular solution Code.

15. a kind of quantum key distribution system characterized by comprising

Quantum key distribution time ratio based on 90 degree of welding difference control according to any one of claim 7~14 The receiving end of the quantum key distribution system is arranged in for time bit-phase decoding in spy-phase decoding device；With/ Or

Quantum key distribution time ratio based on 90 degree of welding difference control according to any one of claim 7~14 The transmitting terminal of the quantum key distribution system is arranged in for time bit-phase code in spy-phase decoding device.