CN109039625A

CN109039625A - Quantum key distribution time bit-phase decoding method, apparatus and system based on polarized orthogonal rotation

Info

Publication number: CN109039625A
Application number: CN201811267189.5A
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: CN109039625B

Abstract

A kind of quantum key distribution time bit-phase decoding method and apparatus and corresponding system based on polarized orthogonal rotation.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 polarized orthogonal rotating device, 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

Based on polarized orthogonal rotation quantum key distribution time bit-phase decoding method, Apparatus and system

Technical field

The present invention relates to optical transport private communication technology field more particularly to a kind of quantum based on polarized orthogonal rotation are close Key distributes time 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, when the present invention proposes a kind of quantum key distribution based on polarized orthogonal rotation Between 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 polarized orthogonal rotation, 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；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,

Wherein, it is rotated at least one sub-light road in the two strips optical path comprising at least one polarized orthogonal Device, the polarized orthogonal rotating device are configured for two orthogonal polarisation states point through the pulse of sub-light all the way of its transmission Not carry out polarized orthogonal rotation so that after via the polarized orthogonal rotating device, two cross-polarizations of the sub-light pulse all the way Each polarization state in state is transformed into orthogonal to that polarization state respectively, 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 method according to scheme 1 based on polarized orthogonal rotation, It is characterized in that, the two strips optical path includes that there are birefringent for two orthogonal polarisation states of the first via light pulse With two orthogonal polarisation states for the first via light pulse, there are birefringent in optical path and/or the two strips optical path Optical device, wherein a polarization state in two orthogonal polarisation states of the control first via light pulse is in beam splitting to closing Phase of the phase difference with another polarization state through the two strips optic path through the two strips optic path during beam Potential difference makes the integral multiple of two 2 π of phase differences difference, comprising:

Keep each of the two orthogonal polarisation states polarization state during beam splitting to conjunction beam through described two respectively It keeps polarization state constant when strip optic path and/or is kept after the polarized orthogonal rotating device carries out polarized orthogonal rotation Its corresponding orthogonal polarisation 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 this A polarization state in two orthogonal polarisation states is in beam splitting to the phase difference through two strips optic path during closing beam The integral multiple of 2 π is differed through the phase difference of the two strips optic path with another polarization state.

3. quantum key distribution time bit-phase decoding side based on polarized orthogonal rotation according to scheme 1 or 2 Method, which is characterized in that

The two strips optical path is configured to polarization maintaining optical fibre optical path, and two of the control first via light pulse are orthogonal partially A polarization state in polarization state is inclined with another to phase difference during closing beam through the two strips optic path in beam splitting Polarization state makes the integral multiple of two 2 π of phase differences difference through the phase difference of the two strips optic path, comprising:

Control when a polarization eigen state of polarization maintaining optical fibre transmits in a strip optical path in the two strips optical path The distance transmitted under the polarization eigen state situation and transmitted under the orthogonal polarisation state situation for being converted to the polarization eigen state away from From first distance is poor and another strip optical path that the polarization eigen state is in the two strips optical path on transmit when at this Levy the distance transmitted and the distance transmitted under the orthogonal polarisation state situation for being converted to the polarization eigen state under polarization state situation 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 decoding side based on polarized orthogonal rotation according to scheme 1 or 3 Method a, which is characterized in that 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:

The two strips optical path includes a polarized orthogonal rotating device, and each polarized orthogonal rotating device is located at institute At the midpoint on sub-light road.

5. quantum key distribution time bit-phase decoding method according to scheme 1 based on polarized orthogonal rotation, It is characterized in that, the polarized orthogonal rotating device is 90 degree of Faraday rotators or half-wave plate.

6. quantum key distribution time bit-phase decoding method according to scheme 1 based on polarized orthogonal rotation, It is characterized in that, configuring polarization maintaining optical fibre stretcher and/or birefringent at least one sub-light road in the two strips optical path Phase-modulator, wherein adjusting the first via 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 optic path The phase difference of phase difference and another polarization state through the two strips optic path difference.

7. quantum key distribution time bit-phase decoding method according to scheme 1 based on polarized orthogonal rotation, It is characterized in that, including: to second tunnel light pulse progress time bit decoding

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.

8. a kind of quantum key distribution time bit-phase decoding device based on polarized orthogonal rotation, which is characterized in that Time bit-phase decoding the device includes:

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 used to transmit the two-way sub-light pulse respectively, and for realizing the two-way sub-light pulse Relative time delay；

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.

9. quantum key distribution time bit-phase decoding device based on polarized orthogonal rotation according to scheme 8, It is characterized in that, the two strips optical path is configured to polarization maintaining optical fibre optical path, the two strips optical path and optical device thereon by into One step is configured to, when controlling a polarization eigen state of polarization maintaining optical fibre and transmitting in the strip optical path in the two strips optical path It the distance transmitted under the polarization eigen state situation and is transmitted under the orthogonal polarisation state situation for being converted to the polarization eigen state At this when being transmitted in another strip optical path that the first distance of distance is poor and the polarization eigen state is in the two strips optical path The distance transmitted under polarization eigen state situation and the distance transmitted under the orthogonal polarisation state situation for being converted to the polarization eigen state Second range difference so that first distance difference and second range difference difference beat length of polarization maintaining optical fiber integral multiple.

10. quantum key distribution time bit-phase decoding based on polarized orthogonal rotation according to scheme 8 or 9 Device, which is characterized in that

11. quantum key distribution time bit-phase decoding dress based on polarized orthogonal rotation according to scheme 8 It sets, which is characterized in that the polarized orthogonal rotating device is 90 degree of Faraday rotators or half-wave plate.

12. quantum key distribution time bit-phase decoding dress based on polarized orthogonal rotation according to scheme 8 It sets, 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.

13. quantum key distribution time bit-phase decoding dress based on polarized orthogonal rotation according to scheme 8 It sets, which is characterized in that the phase-modulator is to polarize unrelated phase-modulator；The phase-modulator is configured for logical The light pulse for crossing it randomly carries out 0 degree of phase-modulation or 180 degree phase-modulation.

14. quantum key distribution time bit-phase decoding dress based on polarized orthogonal rotation according to scheme 8 It sets, 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 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 are respectively configured for The two-way sub-light pulse-echo come through the two strips optic path from first beam splitter is returned described first Beam splitter,

Wherein first beam splitter is configured for exporting after beam is closed in the two-way sub-light pulse that will reflect back into.

15. quantum key distribution time bit-phase decoding dress based on polarized orthogonal rotation according to scheme 8 It sets, which is characterized in that first beam splitter and first bundling device and first beam splitter and described first close beam Optical device between device in optical path is that polarization keeps optical device or non-birefringent optical device.

16. quantum key distribution time bit-phase decoding dress based on polarized orthogonal rotation according to scheme 8 It sets, which is characterized in that the time bit-phase decoding device further includes the second beam splitter, the second beam splitter optical coupling To the preposition beam splitter, and it is configured for receiving second tunnel light pulse and will be after the second tunnel light pulse beam splitting Output is for carrying out time bit decoding.

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

Quantum key distribution time bit-phase based on polarized orthogonal rotation according to any one of scheme 8~16 Position decoding apparatus, is arranged in the receiving end of the quantum key distribution system, is used for time bit-phase decoding；And/or

Quantum key distribution time bit-phase based on polarized orthogonal rotation according to any one of scheme 8~16 Position decoding apparatus, is arranged in the transmitting terminal of the quantum key distribution system, is used for time bit-phase code.

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 in interferometer two-arm by using polarized orthogonal rotating device, light arteries and veins in easily controllable phase base decoding The difference of the phase difference transmitted in the two-arm of each comfortable unequal arm interferometer of two orthogonal polarisation states of punching, realizes that the two are orthogonal partially Polarization state effectively interferes output in output port simultaneously, is achieved in the immune phase base decoding function of environmental disturbances, makes it possible to Realize the immune time bit-phase code quantum key distribution solution of stable environmental disturbances.Quantum of the invention is close 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 quantum key distribution time bit-phase based on polarized orthogonal rotation of a preferred embodiment of the invention The flow chart of position coding/decoding method；

Fig. 2 is quantum key distribution time bit-phase based on polarized orthogonal rotation of a preferred embodiment of the invention The composed structure schematic diagram of position decoding apparatus；

Fig. 3 is the quantum key distribution time bit-based on polarized orthogonal rotation of another preferred embodiment of the present invention The composed structure schematic diagram of phase decoding device；

Fig. 4 is the quantum key distribution time bit-based on polarized orthogonal rotation of another preferred embodiment of the present invention The composed structure schematic diagram of phase decoding device；

Fig. 5 is the quantum key distribution time bit-based on polarized orthogonal rotation of another preferred embodiment of the present invention The composed structure schematic diagram of phase decoding device；

Fig. 6 is the quantum key distribution time bit-based on polarized orthogonal rotation of another preferred embodiment of the present invention The composed structure schematic diagram of phase decoding device.

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-phase based on polarized orthogonal rotation of a preferred embodiment of the invention Coding/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 the first via light pulse and to described Second tunnel light pulse carries out the decoding of time bit.

As skilled in the art will understand, it can regard as by two orthogonal polarisation states per light pulse all the way (for example, just The x-polarisation state and y-polarisation state of friendship) composition.Equally, the two-way sub-light pulse obtained by first via light pulse beam splitting can also be regarded as It is made of two orthogonal polarisation states identical with the first via light pulse.

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 differs the integral multiple of 2 π, the in other words first via light pulse through the phase difference of the two strips optic path Each comfortable beam splitting of two orthogonal polarisation states to the integer for closing the phase difference through two strip optic paths during beam and differing 2 π Times, it can indicate 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: keep respectively each of the two orthogonal polarisation states polarization state beam splitting extremely Close beam during through when the two strips optic path keep polarization state it is constant and/or through the polarized orthogonal rotating device into Keep its corresponding orthogonal polarisation state constant after the rotation of row polarized orthogonal；And adjustment there are the length of birefringent optical path and/ Or there are the birefringent sizes of birefringent optical device, so that a polarization state in the two orthogonal polarisation states is in beam splitting to conjunction Phase of the phase difference with another polarization state through the two strips optic path through the two strips optic path during beam Potential difference differs the integral multiple of 2 π, in other words, so that through described during each comfortable beam splitting to conjunction beam of the two orthogonal polarisation states The phase difference of two strip optic paths differs the integral multiple of 2 π.Optionally, this can be realized by following either type: i) by institute It states two strip optical paths and is configured to polarization maintaining optical fibre optical path, configure non-birefringent smooth device for the optical device in the polarization maintaining optical fibre optical path Part and/or polarization keep optical device；Ii free space optical path) is configured by one of described two strips optical path, by two strip Optical device in optical path is configured to polarization and keeps optical device.Herein, " polarization maintaining optical fibre optical path " is referred to and is transmitted using polarization maintaining optical fibre The optical path or polarization maintaining optical fibre of light pulse connect the optical path to be formed." non-birefringent optical device " refers to for different polarization state (examples Such as, two orthogonal polarisation states) optical device with identical refractive index.In addition, polarization keeps optical device alternatively referred to as to protect polarizer Part.

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

The two strips optical path is configured to polarization maintaining optical fibre optical path, controls a polarization eigen state of polarization maintaining optical fibre described two The distance transmitted under the polarization eigen state situation and intrinsic being converted to this when being transmitted in the strip optical path in strip optical path The first distance for the distance transmitted under the orthogonal polarisation state situation of polarization state is poor and the polarization eigen state is in two sub-lights The distance transmitted under the polarization eigen state situation and the eigen polarization is being converted to when transmitting in another strip optical path in road The second range difference for the distance transmitted under the orthogonal polarisation state situation of state, so that first distance difference and second range difference differ polarization-maintaining Optical fiber claps long integral multiple, so that further such that a polarization state in two orthogonal polarisation states of the first via light pulse exists Phase difference and another polarization state during beam splitting to conjunction beam through the two strips optic path is through the two strips optical path The phase difference of transmission differs the integral multiple of 2 π, in other words, so that each comfortable point of two orthogonal polarisation states of the first via light pulse Phase difference during Shu Zhihe beam through the two strips optic path 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 embodiment, carried out in the two-way sub-light pulse for being obtained to first via light pulse beam splitting At least one sub-light road configuration polarization maintaining optical fibre stretcher and/or birefringent phase modulator in two strip optical paths of transmission. Polarization maintaining optical fibre stretcher is suitable for adjusting the polarization maintaining optical fibre length of the optical path where it.Birefringent phase modulator is suitable for passing through it Two orthogonal polarisation states apply different adjustable phase-modulations, thus polarization maintaining optical fibre stretcher and/or birefringent phase tune Device processed can be provided to adjust a polarization state in two orthogonal polarisation states of 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 Difference.For example, birefringent phase modulator can be lithium niobate phase modulator, the electricity of lithium columbate crystal is applied to by controlling Pressure, the phase-modulation that be respectively subjected to by two orthogonal polarisation states of the lithium niobate phase modulator can be carried out control and Adjustment.Birefringent phase modulator can be used for influencing and adjusting two orthogonal polarisation states of the first via light pulse respectively as a result, In beam splitting to the difference of the phase difference through two strips optic path during closing beam.

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.

A kind of quantum key distribution time bit-phase based on polarized orthogonal rotation of a preferred embodiment of the invention Decoding apparatus is as shown in Fig. 2, include consisting of part: preposition beam splitter 201, (alternatively referred to as " the second beam splitting of beam splitter 202 Device "), beam splitter 203 (alternatively referred to as " the first beam splitter "), phase-modulator 204, bundling device 205 (alternatively referred to as " first close Beam device "), polarized orthogonal rotating device 206 and 207.Beam splitter 203, bundling device 205 and two strip optical paths totality between them It can be described as phase decoder.The polarized orthogonal rotating device 206 or 207 is configured for the sub-light arteries and veins all the way that will be transmitted through it Two orthogonal polarisation states of punching carry out polarized orthogonal rotation respectively, so that after via the polarized orthogonal rotating device, a way Each polarization state in two orthogonal polarisation states of light pulse is transformed into orthogonal to that polarization state respectively.

Preferably, the polarized orthogonal rotating device 206 or 207 can be 90 degree of Faraday rotators or half-wave plate. 90 degree of Faraday rotators can rotate to the sub-light pulse transmitted along polarization maintaining optical fibre slow axis to be passed along polarization maintaining optical fibre fast axle It is defeated, and/or the sub-light pulse transmitted along polarization maintaining optical fibre fast axle is rotated to and is transmitted along polarization maintaining optical fibre slow axis, to realize sub-light arteries and veins The polarized orthogonal rotation of two orthogonal polarisation states of punching.For the half-wave plate, in one of two orthogonal polarisation states of light pulse Polarization direction be arranged to the angle of the fast axle of half-wave plate or slow axis when being 45 degree, half-wave plate can be by sub-light pulse Each polarization state in two orthogonal polarisation states is transformed into orthogonal to that polarization state respectively, to realize the polarization of sub-light pulse Orthogonal rotation.

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.The optical path physical length on any sub-light road in two strip optical paths between adjusting beam splitter 203 and bundling device 205 can be passed through To realize the relative time delay of two-way sub-light pulse.This two-way sub-light arteries and veins of bundling device 205 for will come through two strip optic paths Beam output is closed in punching.

Preferably, the two strips optical path is configured as polarization maintaining optical fibre, the two strips optical path and optical device quilt thereon It is further configured to, controls a polarization eigen state of the polarization maintaining optical fibre in the strip optical path in the two strips optical path The distance transmitted under the polarization eigen state situation when transmission and in the case where being converted to the orthogonal polarisation state situation of the polarization eigen state It is transmitted in another strip optical path that the first distance of the distance of transmission is poor and the polarization eigen state is in the two strips optical path When the distance transmitted under the polarization eigen state situation and transmitted under the orthogonal polarisation state situation for being converted to the polarization eigen state Distance second range difference so that first distance difference and second range difference difference beat length of polarization maintaining optical fiber integral multiple, to make A polarization state in two orthogonal polarisation states of first via input optical pulse is obtained during beam splitting to conjunction beam through described two The phase difference of strip optic path is with another polarization state through the two strips optic path during beam splitting to conjunction beam Phase difference differs the integral multiple of 2 π.

Preferably, phase-modulator 204 is used to randomly carry out 0 degree of phase-modulation or 180 to by its sub-light pulse Spend 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 It is passed during each comfortable beam splitting to conjunction beam of two orthogonal polarisation states of the first via light pulse of position decoder through two strip optical paths Defeated phase 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, wherein Comprising at least one polarized orthogonal rotating device (for example, 90 degree at least one sub-light road in the two strips optical path Faraday rotator or half-wave plate), the polarized orthogonal rotating device is configured for the sub-light arteries and veins all the way that will be transmitted through it Two orthogonal polarisation states of punching carry out polarized orthogonal rotation respectively, so that after via the polarized orthogonal rotating device, a way Each polarization state in two orthogonal polarisation states of light pulse is transformed into orthogonal to that polarization state respectively.In addition, this two strip Optical device in optical path, including phase-modulator --- if any, optical device and/or non-birefringent smooth device are kept for polarization Part.

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 To the first via light pulse of the phase decoder each comfortable beam splitting of two orthogonal polarisation states to closing during beam through two strips The phase difference of optic path differs the integral multiple of 2 π.In addition, fiber stretcher also is used as phase-modulator use.Birefringent phase Position modulator can be located at any sub-light road in the two strips optical path, can be used for by its two of sub-light pulse just Polarization state is handed over to apply different phase-modulations.By controlling the birefringent phase modulator, pass through two of its sub-light pulse The difference for the phase-modulation that orthogonal polarisation state is respectively subjected to is adjustable.In this way, can be facilitated by utilizing birefringent phase modulator Beam is extremely closed in each comfortable beam splitting of two orthogonal polarisation states of the first via light pulse that ground influences and adjustment is input to phase decoder The difference of phase difference in the process through the two strips optic path, it is easy to accomplish the integral multiple that the difference is 2 π.The birefringent phase Position modulator can be previously described lithium niobate phase modulator.

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 a polarized orthogonal rotating device 206 and a polarized orthogonal rotating device 207.Assuming that polarization of the beam splitter into an arm is just The distance for handing over rotating device 206 is L1, the distance of polarized orthogonal rotating device 206 to bundling device in an arm is L2, beam splitting The distance of polarized orthogonal rotating device 207 of the device into another arm is L3, the polarized orthogonal rotating device 207 in another arm to The distance of bundling device is L4, and length relation preferably meets (L1-L2)-(L3-L4)=n β, and wherein n is positive integer, bears Integer or zero, β are beat length of polarization maintaining optical fiber.In this case, other optical devices in two strip optical paths cause to be input to the phase 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 decoder Phase difference differ 2 π integral multiple.In a preferred embodiment, two polarized orthogonal rotating devices can be located at The midpoint of two-arm 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.Due to the output of phase decoder according to the present invention Port only needs one, needs to increase the corresponding ring of light when the output port of phase decoder is same port with input port Shape device；When the output port of phase decoder and input port difference, optical circulator is not needed.Preferably, described first point The interferometer two-arm that beam device and described two reflecting mirrors are constituted optical path (that is, the beam splitter of phase decoder with two instead Penetrate two strip optical paths between mirror) using polarization maintaining optical fibre, the two-arm of interferometer can separately include a polarized orthogonal rotating device, Assuming that the distance of polarized orthogonal rotating device of the beam splitter into an arm is L1, the polarized orthogonal rotating device in an arm to two The distance of a reflecting mirror in a reflecting mirror is L2, and the distance of polarized orthogonal rotating device of the beam splitter into another arm is The distance of another reflecting mirror of the polarized orthogonal rotating device into two reflecting mirrors in L3, another arm is L4, it is contemplated that Along two-arm round-trip transmission, the distance that polarization maintaining optical fibre slow axis or fast axle transmission are passed through in transmission process is corresponding polarization-maintaining for sub-light pulse 2 times of fiber lengths, length relation preferably meet 2 (L1-L2) -2 (L3-L4)=n β, and wherein n is positive integer, negative integer Or zero, β is beat length of polarization maintaining optical fiber.In this case, other optical devices in two strip optical paths cause to be input to the phase decoding Phase 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 device Potential difference differs the integral multiple of 2 π.In a preferred embodiment, two polarized orthogonal rotating devices can be located at two-arm Midpoint, that is to say L1=L2 and L3=L4, length relation meets 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 distribution based on polarized orthogonal rotation of another preferred embodiment according to the present invention Time bit-phase decoding device.As shown in figure 3, phase decoder therein is using unequal arm Mach-Zender interferometer Structure.Specifically, the quantum key distribution time bit-phase decoding device includes consisting of part: preposition beam splitter 303, beam splitter 304, polarization-maintaining beam splitter 307, polarization maintaining optical fibre stretcher 309, phase-modulator 311, polarization-maintaining bundling device 312, partially Shake orthogonal rotating device 308 and polarized orthogonal rotating device 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 polarized orthogonal rotating device, such as can separately include a polarized orthogonal rotation Rotary device 308 and a polarized orthogonal rotating device 310.The light pulse of polarization-maintaining beam splitter 307 is input to through unequal arm Mach-once It is exported after the decoding of Dare 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, the pulse of sub-light all the way in the two-way sub-light pulse through the transmission of polarized orthogonal rotating device 308 and (wherein the setting sequence of polarized orthogonal rotating device 308 and polarization maintaining optical fibre stretcher 309 can for the modulation of polarization maintaining optical fibre stretcher 309 Transformation, or referred to as " sequence is unrelated "), the pulse of another way sub-light is transmitted through polarized orthogonal rotating device 310 and through phase tune 0 degree of 311 Stochastic Modulation of device processed or 180 degree phase (sequence is unrelated), through polarization-maintaining bundling device 312 after two-way sub-light pulse relative time delay It is exported after closing beam by port 313.The second tunnel light pulse input 304 beam splitting of beam splitter exported from preposition beam splitter 303 is two-way Sub-light pulse is exported through port 305 or 306 for carrying out time bit decoding.

Preferably, it is assumed that length is L1 between polarization-maintaining beam splitter 307 and polarized orthogonal rotating device 308, polarized orthogonal revolves Length is long between L2, polarization-maintaining beam splitter 307 and polarized orthogonal rotating device 310 between rotary device 308 and polarization-maintaining bundling device 312 Degree be L3, length is L4 between polarized orthogonal rotating device 310 and polarization-maintaining bundling device 312, modulation 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 distribution based on polarized orthogonal rotation of another preferred embodiment according to the present invention Time bit-phase decoding device, as shown in figure 4, phase decoder therein is using 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 point Beam device 405, polarized orthogonal rotating device 406 and 408, polarization maintaining optical fibre stretcher 407, phase-modulator 409 and polarization-maintaining close beam Device 410.

One of two ports 401 and 402 of side of preposition beam splitter 403 are as time bit-phase decoding device Input terminal, for receiving incident light pulse.Polarization-maintaining beam splitter 405 and polarization-maintaining bundling device 410 form unequal arm Mach-Zehnder Interferometer.Polarization maintaining optical fibre stretcher 407 and phase-modulator 409 can be inserted into the same arm of unequal arm Mach-Zender interferometer Or it is inserted into two arms of unequal arm Mach-Zender interferometer respectively.In unequal arm Mach-Zender interferometer two-arm at least One arm includes at least one polarized orthogonal rotating device, such as two-arm can separately include 406 He of polarized orthogonal rotating device One polarized orthogonal rotating device 408 is input to the light pulse of polarization-maintaining beam splitter 405 through unequal arm Mach-Zender interferometer It is exported after decoding 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 sub-light pulse is modulated through the transmission of polarized orthogonal rotating device 406 and polarization maintaining optical fibre stretcher 407 all the way (sequence is unrelated), the pulse of another way sub-light is through the transmission of polarized orthogonal rotating device 408 and phase modulated device 409 modulation (sequence It is unrelated), it is exported after polarization-maintaining bundling device 410 closes beam by port 411 after two-way sub-light pulse relative time delay.

Preferably, it is assumed that length is L1 ' between polarization-maintaining beam splitter 405 and polarized orthogonal rotating device 406, polarized orthogonal revolves Length is between L2 ', polarization-maintaining beam splitter 405 and polarized orthogonal rotating device 408 between rotary device 406 and polarization-maintaining bundling device 410 Length is L3 ', length is L4 ' between polarized orthogonal rotating device 408 and 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,

Wherein β is beat length of polarization maintaining optical fiber, n is integer；So that each leisure of two orthogonal polarisation states of input optical pulse is not The integral multiple that the difference of the phase difference of equiarm Mach-Zender interferometer two-arm transmission is 2 π.

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 time based on polarized orthogonal rotation of another preferred embodiment of the present invention Bit-phase decoding device, as shown in figure 5, phase decoder therein uses the structure of unequal arm Michelson's interferometer.Tool Body, which includes consisting of part: preposition beam splitter 503, beam splitter 504, polarization-maintaining beam splitter 507, polarized orthogonal rotating device 508 and 511, polarization maintaining optical fibre stretcher 509, phase-modulator 512, anti- Penetrate mirror 510 and 513.

One of two ports 501 and 502 of side of preposition beam splitter 503 are as time bit-phase decoding device Input terminal, beam splitter 504 receive through the input optical pulse all the way after preposition 503 beam splitting of beam splitter and are two ways by its beam splitting Light pulse.Polarization-maintaining beam splitter 507 and reflecting mirror 510,513 form unequal arm Michelson's interferometer, polarization maintaining optical fibre stretcher 509 It can be inserted into the same arm of unequal arm Michelson's interferometer with phase-modulator 512 or be inserted into unequal arm Michelson respectively and do Two arms of interferometer.An at least arm includes at least one polarized orthogonal rotating device in unequal arm Michelson's interferometer two-arm, Such as two-arm can separately include a polarized orthogonal rotating device 508 and a polarized orthogonal rotating device 511.It is input to polarization-maintaining The light pulse of beam splitter 507 is exported after the decoding of unequal arm Michelson's interferometer by the port 514 of polarization-maintaining beam splitter 507.? In the example, polarization-maintaining beam splitter 507 both plays the role of polarization-maintaining beam splitter, also functions to polarization-maintaining 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 After beam splitter 507 by beam splitting be the pulse of two-way sub-light, wherein all the way sub-light pulse through polarized orthogonal rotating device 508 transmit and protect It is reflected after the inclined modulation of fiber stretcher 509 (sequence is unrelated) by reflecting mirror 510, another way sub-light pulse is revolved through polarized orthogonal It is reflected after the transmission of rotary device 511 and phase modulated device 512 modulation (sequence is unrelated) by reflecting mirror 513, it is reflected The two-way sub-light pulse of relative time delay is exported after polarization-maintaining beam splitter 507 closes beam by the port 514 of polarization-maintaining beam splitter 507, or In the case where being equipped with optical circulator, can also be exported by the port of optical circulator.

Preferably, it is assumed that length is L1 " between polarization-maintaining beam splitter 507 and polarized orthogonal rotating device 508, polarized orthogonal revolves Length is length between L2 ", polarization-maintaining beam splitter 507 and polarized orthogonal rotating device 511 between rotary device 508 and reflecting mirror 510 Length is L4 " between L3 ", polarized orthogonal rotating device 511 and reflecting mirror 513, 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.

When Fig. 6 shows a kind of quantum key distribution based on polarized orthogonal rotation of another embodiment according to the present invention M- phase decoding device.As shown in fig. 6, phase decoder therein uses the structure of unequal arm Michelson's interferometer.Specifically , which includes consisting of part: preposition beam splitter 603, polarization-maintaining beam splitting Device 605, polarized orthogonal rotating device 606 and 609, polarization maintaining optical fibre stretcher 607, phase-modulator 610,608 and of reflecting mirror 611。

One of two ports 601 and 602 of side of preposition beam splitter 603 are as time bit-phase decoding device Input terminal.Polarization-maintaining beam splitter 605 and reflecting mirror 608,611 form unequal arm Michelson's interferometer.Polarization maintaining optical fibre stretcher 607 It can be inserted into the same arm of unequal arm Michelson's interferometer with phase-modulator 610 or be inserted into unequal arm Michelson respectively and do Two arms of interferometer.An at least arm includes at least one polarized orthogonal rotating dress in the two-arm of unequal arm Michelson's interferometer It sets, for example, two-arm can separately include a polarized orthogonal rotating device 606 and a polarized orthogonal rotating device 609.It is input to The light pulse of beam splitter polarization-maintaining 605 is defeated by the port 612 of polarization-maintaining beam splitter 605 after the decoding of unequal arm Michelson's interferometer Out, it or in the case where being equipped with optical circulator, can also be exported by the port of optical circulator.

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 polarizing all the way It is reflected after the orthogonal transmission of rotating device 606 and the modulation of polarization maintaining optical fibre stretcher 607 (sequence is unrelated) by reflecting mirror 608, separately Sub-light pulse is after the transmission of polarized orthogonal rotating device 609 and phase modulated device 610 modulation (sequence is unrelated) by reflecting all the way Mirror 611 reflects, and the two-way sub-light pulse of reflected relative time delay is after polarization-maintaining beam splitter 605 closes beam by polarization-maintaining beam splitting The port 612 of device 605 exports.In this example, polarization-maintaining beam splitter 605 both plays the role of polarization-maintaining beam splitter, also functions to polarization-maintaining The effect of bundling device.

Preferably, it is assumed that length is L1 " ', polarized orthogonal between polarization-maintaining beam splitter 605 and polarized orthogonal rotating device 606 Length is long between L2 " ', polarization-maintaining beam splitter 605 and polarized orthogonal rotating device 609 between rotating device 606 and reflecting mirror 608 Degree be L3 " ', length is L4 " ' between polarized orthogonal rotating device 609 and reflecting mirror 611, modulation 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 configuration quantum key distribution time bit-phase decoding device of the invention based on polarized orthogonal rotation, is used for time ratio Spy-phase decoding.It is configured alternatively, it is also possible to the transmitting terminal in quantum key distribution system of the invention based on polarized orthogonal rotation Quantum key distribution time bit-phase decoding device, be used for time bit-phase code.

The present invention in interferometer two-arm by using polarized orthogonal rotating device, light arteries and veins in easily controllable phase base decoding The difference of the phase difference transmitted in the two-arm of each comfortable unequal arm interferometer of two orthogonal polarisation states of punching.In addition, the present invention can It realizes that two orthogonal polarisation states of light pulse in the decoding of phase base effectively interfere output in output port simultaneously, is equivalent to two Orthogonal polarisation state carries out polarization diversity processing, can effectively solve interference decoding instability problem caused by polarization induction decline, real The immune stable phase angle decoding of existing environmental disturbances, without using polarization beam apparatus and two interferometers to distinguish two polarization states It is decoded, 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 polarized orthogonal rotation, which is characterized in that 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 output,

It wherein, include at least one polarized orthogonal rotating dress at least one sub-light road in the two strips optical path It sets, the polarized orthogonal rotating device is configured for distinguish through two orthogonal polarisation states of the pulse of sub-light all the way of its transmission Polarized orthogonal rotation is carried out, so that after via the polarized orthogonal rotating device, two orthogonal polarisation states of the sub-light pulse all the way In each polarization state be transformed into orthogonal to that polarization state respectively, 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 method according to claim 1 based on polarized orthogonal rotation, It is characterized in that, the two strips optical path includes that there are birefringent for two orthogonal polarisation states of the first via light pulse With two orthogonal polarisation states for the first via light pulse, there are birefringent in optical path and/or the two strips optical path Optical device, wherein a polarization state in two orthogonal polarisation states of the control first via light pulse is in beam splitting to closing Phase of the phase difference with another polarization state through the two strips optic path through the two strips optic path during beam Potential difference makes the integral multiple of two 2 π of phase differences difference, comprising:

Keep each of the two orthogonal polarisation states polarization state during beam splitting to conjunction beam through two strip respectively It keeps polarization state constant when optic path and/or keeps its right after the polarized orthogonal rotating device carries out polarized orthogonal rotation The orthogonal polarisation state answered 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 is in beam splitting to phase difference during closing beam through the two strips optic path and another One 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 decoding side according to claim 1 or 2 based on polarized orthogonal rotation Method, which is characterized in that

The two strips optical path is configured to polarization maintaining optical fibre optical path, two orthogonal polarisation states of the control first via light pulse In a polarization state in beam splitting to phase difference through two strips optic path during closing beam and another polarization state Phase difference through the two strips optic path makes the integral multiple of two 2 π of phase differences difference, comprising:

It controls when a polarization eigen state of polarization maintaining optical fibre transmits in the strip optical path in the two strips optical path at this Levy the distance transmitted and the distance transmitted under the orthogonal polarisation state situation for being converted to the polarization eigen state under polarization state situation It is intrinsic partially at this when being transmitted in another strip optical path that first distance is poor and the polarization eigen state is in the two strips optical path The second of the distance transmitted under polarization state situation and the distance transmitted under the orthogonal polarisation state situation for being converted to the polarization eigen state 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 decoding side according to claim 1 or 3 based on polarized orthogonal rotation Method a, which is characterized in that 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:

The two strips optical path includes a polarized orthogonal rotating device, and each polarized orthogonal rotating device is located at place The midpoint of optical path.

5. quantum key distribution time bit-phase decoding method according to claim 1 based on polarized orthogonal rotation, It is characterized in that, the polarized orthogonal rotating device is 90 degree of Faraday rotators or half-wave plate.

6. quantum key distribution time bit-phase decoding method according to claim 1 based on polarized orthogonal rotation, It is characterized in that, configuring polarization maintaining optical fibre stretcher and/or birefringent at least one sub-light road in the two strips optical path Phase-modulator, wherein adjusting the first via 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 optic path The phase difference of phase difference and another polarization state through the two strips optic path difference.

7. quantum key distribution time bit-phase decoding method according to claim 1 based on polarized orthogonal rotation, It is characterized in that, including: to second tunnel light pulse progress time bit decoding

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.

8. a kind of quantum key distribution time bit-phase decoding device based on polarized orthogonal rotation, which is characterized in that described Time bit-phase decoding device includes:

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 used to transmit the two-way sub-light pulse respectively, and for realizing the phase of the two-way sub-light pulse To delay；

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,

9. quantum key distribution time bit-phase decoding device according to claim 8 based on polarized orthogonal rotation, It is characterized in that, the two strips optical path is configured to polarization maintaining optical fibre optical path, the two strips optical path and optical device thereon by into One step is configured to, when controlling a polarization eigen state of polarization maintaining optical fibre and transmitting in the strip optical path in the two strips optical path It the distance transmitted under the polarization eigen state situation and is transmitted under the orthogonal polarisation state situation for being converted to the polarization eigen state At this when being transmitted in another strip optical path that the first distance of distance is poor and the polarization eigen state is in the two strips optical path The distance transmitted under polarization eigen state situation and the distance transmitted under the orthogonal polarisation state situation for being converted to the polarization eigen state Second range difference so that first distance difference and second range difference difference beat length of polarization maintaining optical fiber integral multiple.

10. quantum key distribution time bit-phase decoding based on polarized orthogonal rotation according to claim 8 or claim 9 Device, which is characterized in that

11. the quantum key distribution time bit according to claim 8 based on polarized orthogonal rotation-phase decoding dress It sets, which is characterized in that the polarized orthogonal rotating device is 90 degree of Faraday rotators or half-wave plate.

12. the quantum key distribution time bit according to claim 8 based on polarized orthogonal rotation-phase decoding dress It sets, 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.

13. the quantum key distribution time bit according to claim 8 based on polarized orthogonal rotation-phase decoding dress It sets, which is characterized in that the phase-modulator is to polarize unrelated phase-modulator；The phase-modulator is configured for logical The light pulse for crossing it randomly carries out 0 degree of phase-modulation or 180 degree phase-modulation.

14. the quantum key distribution time bit according to claim 8 based on polarized orthogonal rotation-phase decoding dress It sets, 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 are respectively configured in the future First beam splitting is returned from the two-way sub-light pulse-echo of first beam splitter come through the two strips optic path Device,

15. the quantum key distribution time bit according to claim 8 based on polarized orthogonal rotation-phase decoding dress It sets, which is characterized in that first beam splitter and first bundling device and first beam splitter and described first close beam Optical device between device in optical path is that polarization keeps optical device or non-birefringent optical device.

16. the quantum key distribution time bit according to claim 8 based on polarized orthogonal rotation-phase decoding dress It sets, which is characterized in that the time bit-phase decoding device further includes the second beam splitter, the second beam splitter optical coupling To the preposition beam splitter, and it is configured for receiving second tunnel light pulse and will be after the second tunnel light pulse beam splitting Output is for carrying out time bit decoding.

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

Quantum key distribution time bit-phase based on polarized orthogonal rotation according to any one of claim 8~16 Position decoding apparatus, is arranged in the receiving end of the quantum key distribution system, is used for time bit-phase decoding；And/or

Quantum key distribution time bit-phase based on polarized orthogonal rotation according to any one of claim 8~16 Position decoding apparatus, is arranged in the transmitting terminal of the quantum key distribution system, is used for time bit-phase code.