CN107437966B - Both ends polarization state initial method based on phase-modulated polarized state coding QKD system - Google Patents
Both ends polarization state initial method based on phase-modulated polarized state coding QKD system Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2589—Bidirectional transmission
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/27—Arrangements for networking
- H04B10/275—Ring-type networks
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/516—Details of coding or modulation
- H04B10/548—Phase or frequency modulation
- H04B10/556—Digital modulation, e.g. differential phase shift keying [DPSK] or frequency shift keying [FSK]
- H04B10/5561—Digital phase modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/70—Photonic quantum communication
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Abstract
The invention discloses a kind of both ends polarization state initial methods based on phase-modulated polarized state coding QKD system, it include: that the voltage of second phase modulator is fixed as 0, from 0 to 2 π of phase of first phase modulator is looped through, first Polarization Controller constantly changes the polarization state of light, until the count value in the first single-photon detector and the second single-photon detector remains unchanged；The voltage of first phase modulator is fixed as 0, and from 0 to 2 π of phase of second phase modulator is looped through, and the second Polarization Controller constantly changes the polarization state of light, until the count value in the first single-photon detector and the second single-photon detector remains unchanged；The voltage of first phase modulator and the voltage of second phase modulator are fixed as 0, and third Polarization Controller constantly changes the polarization state of light, until the second single-photon detector count value reaches maximum value；The present invention realizes the coordinate alignment of the quick polarization state in system both ends, and guarantees system self-recovery and stability.
Description
Technical field
The present invention relates to phase-modulated polarized states to encode QKD system field, and in particular to one kind is based on phase-modulated polarized
The both ends polarization state initial method of state coding QKD system.
Background technique
Sum of the quantum key dispatching system (QKD) of phase-modulated polarized coding respectively in connection with phase code QKD system
The advantage of polarization encoder QKD system has good application scenarios.And the same polarization encoder of phase-modulated polarized coding QKD system
QKD system is identical, needs to initialize before carrying out quantum-key distribution, i.e., by the light coordinate axis of transmitting terminal and receiving end
Alignment, because guaranteeing that the polarization state of light is identical with the measurement state of receiving end coordinate system in transmitting terminal coordinate system.
Only one general quantum radiant of the QKD system of phase-modulated polarized coding, the realization of polarization state are to utilize
The phase-modulator of system realizes the modulation of each polarization state, that is, modulating different phases can be realized different polarization states.Into
The stability of the polarization state of the light of phase-modulator needs to guarantee, usually with measuring device that the measuring polarization state of light is good, it
The stabilization of polarization state is realized in transmission with polarization maintaining optical fibre afterwards, even has polarization maintaining optical fibre in actual use, the polarization state of light also has
Change, need to re-measure, demarcates.The method is unable to the stability and flexibility of matching system, and additional measuring device, increases
The complexity and cost of system.How each device realization both ends polarization state in the QKD system of phase-modulated polarized coding is utilized
Initialization operation and the problem of do not need additional measuring device, be current urgent need to resolve.
Summary of the invention
It is a kind of based on phase-modulation the technical problem to be solved by the present invention is to provide in view of the above shortcomings of the prior art
Polarization state encodes the both ends polarization state initial method of QKD system, based on the both ends of phase-modulated polarized state coding QKD system
Polarization state initial method realizes the coordinate alignment of the quick polarization state in system both ends, and has cast out the fiber crops of additional measuring device
It is tired, and can influence according to environment to system, the alignment of real-time perfoming both ends light coordinate axis, guarantee system self-reparability and
Stability.
To realize the above-mentioned technical purpose, the technical scheme adopted by the invention is as follows:
A kind of both ends polarization state initial method based on phase-modulated polarized state coding QKD system, including phase-modulation
Polarization state encodes QKD system, and the phase-modulated polarized state coding QKD system includes transmitting terminal, receiving end and host computer, described
Transmitting terminal is connected with receiving end by fiber channel, the transmitting terminal and receiving end with upper mechatronics；The transmitting terminal
Including laser, the first Polarization Controller, first annular device, the first polarization beam apparatus, first phase modulator, attenuator and
One control circuit, the receiving end include the second Polarization Controller, the second circulator, the second polarization beam apparatus, second phase tune
Device, third Polarization Controller, third polarization beam apparatus, the first single-photon detector, the second single-photon detector and the second control processed
Circuit processed, specifically includes the following steps:
Step 1: the voltage of second phase modulator being fixed as 0, host computer is by first control circuit to first phase
Modulator issues control instruction, and the voltage of first phase modulator is looped through from minimum value to maximum value, i.e. first phase tune
From 0 to 2 π of phase of device processed is looped through, meanwhile, host computer issues the first Polarization Controller by first control circuit and controls
Instruction is to make the first Polarization Controller constantly change the polarization state of light, when the first single-photon detector and the second single photon detection
When count value in device remains constant, the first Polarization Controller stops changing the polarization state of light；
Step 2: the voltage of first phase modulator being fixed as 0, host computer is by second control circuit to second phase
Modulator issues control instruction, and the voltage of second phase modulator is looped through from minimum value to maximum value, i.e. second phase tune
From 0 to 2 π of phase of device processed is looped through, meanwhile, host computer issues the second Polarization Controller by second control circuit and controls
Instruction is to make the second Polarization Controller constantly change the polarization state of light, when the first single-photon detector and the second single photon detection
When count value in device remains constant, the second Polarization Controller stops changing the polarization state of light；
Step 3: the voltage of the voltage of first phase modulator and second phase modulator being fixed as 0, host computer is logical
It crosses second control circuit and control instruction is issued to make third Polarization Controller constantly change the inclined of light to third Polarization Controller
Polarization state, when the count value of the first single-photon detector reaches minimum value, the count value of the second single-photon detector reaches maximum
When value, third Polarization Controller stops changing the polarization state of light；
Step 4: host computer issues control instruction to the first Polarization Controller again by first control circuit to make the
One Polarization Controller constantly changes the polarization state of light, the count value in the first single-photon detector and the second single-photon detector
When equal, the first Polarization Controller stops changing the polarization state of light；
Step 5: host computer issues control instruction to third Polarization Controller again by second control circuit to make the
Three Polarization Controllers constantly change the polarization state of light, and when the count value of the first single-photon detector reaches minimum value, second is single
When the count value of photon detector reaches maximum value, third Polarization Controller stops changing the polarization state of light, phase-modulated polarized
State encodes the receiving end of QKD system and the polarization state of transmitting terminal is initialized and completed.
Technical solution as a further improvement of that present invention, the host computer are electrically connected with first control circuit, and described
One control circuit is electrically connected with laser, the first Polarization Controller and first phase modulator respectively, first polarization beam splitting
Device connects to constitute transmitting terminal sagnac ring by two polarization maintaining optical fibres with first phase modulator；The laser is for producing
Raw pulsed light, first Polarization Controller for changing light polarization state and light is incident on first annular device, described first
Polarization beam apparatus is used to the polarised light of first annular device incidence being divided into horizontal polarization light and orthogonal polarized light, first phase
Position modulator is used to modulate the phase of polarised light clockwise or counterclockwise direction, and first polarization beam apparatus is in the future
It is emitted to attenuator from horizontal polarization light and orthogonal polarized light the remittance first annular device of merga pass of first phase modulator, is decayed
Device is with then decaying light intensity and the light issued passes through fibre channel transmission to receiving end.
Technical solution as a further improvement of that present invention, the host computer are electrically connected with second control circuit, and described
Two control circuits respectively with the second Polarization Controller, third Polarization Controller, second phase modulator, the first single-photon detector
It is electrically connected with the second single-photon detector, second polarization beam apparatus and second phase modulator are connected by two polarization maintaining optical fibres
It connects to constitute receiving end sagnac ring；Second Polarization Controller for changing light polarization state and light is incident on second
Circulator, second polarization beam apparatus are used to the polarised light of the second circulator incidence being divided into horizontal polarization light and vertical polarization
Light, the second phase modulator are used to modulate the phase of polarised light clockwise or counterclockwise direction, second polarization
Beam splitter is used to horizontal polarization light and orthogonal polarized light remittance the second circulator of merga pass from second phase modulator
Be mapped to third Polarization Controller, third Polarization Controller for changing light polarization state and light is incident on third polarization beam splitting
Device, third polarization beam apparatus are used to incident polarised light being divided into horizontal polarization light and orthogonal polarized light, first single photon
Detector is used to detect the polarised light of horizontal state of polarization, and the second single-photon detector is used to detect the polarised light of perpendicular polarisation state.
It is inclined that the present invention using the related device of the QKD system of phase-modulated polarized coding realizes the quick light in system both ends
The coordinate of polarization state is aligned, and has cast out the trouble of additional measuring device, save the cost, and can be according to environment to the shadow of system
It rings, the alignment of real-time perfoming both ends light coordinate axis guarantees the self-reparability and stability of system.
Detailed description of the invention
Fig. 1 is the structural schematic diagram that phase-modulated polarized state of the invention encodes QKD system.
Fig. 2 is the curve synoptic diagram for the corresponding relationship that phase of the invention and polarization state count.
Fig. 3 is operational flowchart of the invention.
Specific embodiment
Specific embodiments of the present invention are made to Fig. 3 below according to Fig. 1 and being illustrated:
Adjustable Polarization Controller there are three tools in phase-modulated polarized state coding QKD system based on sagnac ring,
Effect is respectively: the first Polarization Controller is to guarantee that the light for entering Sagnac ring is 45 ° of polarization state incidences, the second Polarization Controller
It is the 45 ° of polarization state incidences of light for guaranteeing to enter the Sagnac ring of receiving end, third Polarization Controller is to guarantee to enter two single photons
The stability of 45 ° of polarization states of incidence of detector light.How the initialization of both ends polarization state is realized using each device in system
The problem of operation is urgent need to resolve of the invention.
Referring to Fig. 1, a kind of phase-modulated polarized state coding QKD system, including transmitting terminal, receiving end and host computer, it is described
Transmitting terminal is connected with receiving end by fiber channel, the transmitting terminal and receiving end with upper mechatronics.
The transmitting terminal includes laser, the first Polarization Controller, first annular device, the first polarization beam apparatus, the first phase
Position modulator, attenuator and first control circuit, the host computer are electrically connected with first control circuit, the first control circuit
It is electrically connected respectively with laser, the first Polarization Controller and first phase modulator, first polarization beam apparatus and the first phase
Position modulator is by two polarization maintaining optical fibre (i.e. the optical path 1 and optical path 2 of transmitting terminal) connections to constitute transmitting terminal sagnac ring；Institute
It states laser and is used to pulsed light being turned into 0 ° of linearly polarized light or 45 ° of lines for generating pulsed light, first Polarization Controller
Polarised light is simultaneously incident on first annular device, and first polarization beam apparatus is used to the polarised light of first annular device incidence being divided into water
Flat polarised light and orthogonal polarized light, the first phase modulator are used to modulate polarised light clockwise or counterclockwise direction
Phase, first polarization beam apparatus is for converging horizontal polarization light and orthogonal polarized light from first phase modulator
And attenuator is emitted to by first annular device, attenuator is with then decaying light intensity and the light issued passed through fiber channel
It is transferred to receiving end.
The receiving end includes the second Polarization Controller, the second circulator, the second polarization beam apparatus, second phase modulation
Device, third Polarization Controller, third polarization beam apparatus, the first single-photon detector, the second single-photon detector and the second control
Circuit, the host computer are electrically connected with second control circuit, the second control circuit respectively with the second Polarization Controller, third
Polarization Controller, second phase modulator, the first single-photon detector and the electrical connection of the second single-photon detector, described second partially
Vibration beam splitter and second phase modulator connect to constitute by two polarization maintaining optical fibres (i.e. the optical path 1 and optical path 2 of receiving end)
Receiving end sagnac ring；Second Polarization Controller for changing light polarization state and light is incident on the second circulator, institute
The second polarization beam apparatus is stated for the polarised light of the second circulator incidence to be divided into horizontal polarization light and orthogonal polarized light, described the
Two phase modulator is used to modulate the phase of polarised light clockwise or counterclockwise direction, and second polarization beam apparatus is used for
It is inclined that horizontal polarization light and orthogonal polarized light remittance the second circulator of merga pass from second phase modulator is emitted to third
Shake controller, third Polarization Controller for changing light polarization state and light is incident on third polarization beam apparatus, third polarization
Beam splitter is used for for incident polarised light to be divided into horizontal polarization light and orthogonal polarized light, first single-photon detector and
Second single-photon detector is respectively used to the polarised light of detection horizontal state of polarization and the polarised light of perpendicular polarisation state.
Solid arrow in Fig. 1 is optic path direction, and dotted arrow is automatically controlled signal, and a branch of quantum light is inclined by first
Enter the first polarization beam apparatus after vibration controller and first annular device, quantum light is divided into polarization state by the first polarization beam apparatus at this time
Orthogonal two-way light, respectively along the optical path 1 and the propagation of optical path 2 in Fig. 1, and the path of optical path 2 is longer than optical path 1, two-beam edge
Opposite direction passes through first phase modulator, but passes through circuit design, only propagates along the optical path of transmitting terminal 1 in the present embodiment
Pulsed light by corresponding phase on first phase modulator tune, what the pulsed light that the optical path 2 of transmitting terminal is propagated added always is
Stationary phase, two-beam reach the first polarization beam apparatus multiplex by same paths opposite direction at phase information tune simultaneously
The polarization state of system, the sagnac ring for similarly reaching receiving end is also same mode, the polarised light modulated by both ends phase difference
Entering third polarization beam apparatus after the second circulator reaches the adjustment of third Polarization Controller, to respectively enter polarization state orthogonal
Two-way single-photon detector, i.e. the first single-photon detector and the second single-photon detector.First single-photon detector and second
Single-photon detector can be regarded as respectively representing detection horizontal state of polarization and perpendicular polarisation state, the first single-photon detector and second
Count results are fed back to host computer by second control circuit by single-photon detector, can be obtained in optical path in phase and polarization state
Counting corresponding relationship, as shown in Fig. 2, the abscissa in Fig. 2 represents the tune of first phase modulator and second phase modulator
Phase difference processed, ordinate represent the count value of detector；When the phase of first phase modulator or second phase modulator from 0 to
2 π change, and sine wave occurs in the counting of the correspondence polarization state on the first single-photon detector and the second single-photon detector, and does not have
When having phase change, the counting of the first single-photon detector and the second single-photon detector is two straight lines, i.e., count value begins
Constant eventually, the not variation of amplitude is not influenced by the phase change of first phase modulator or second phase modulator.
Method provided by the invention is proposed for above-mentioned phase-modulated polarized state coding QKD system, is a kind of utilization
Polarization Controller adjusts plus the method for single-photon detector feedback photons polarization state, in order to realize the first Polarization Controller, second
Polarization Controller and third Polarization Controller reach 45 ° of linearly polarized light incidences (bad measurement), can use phase-modulated polarized state
It encodes the first single-photon detector for measuring polarization state in QKD system and the second single-photon detector algorithm for design is realized, specifically
Thought be: the first Polarization Controller is first arranged to 0 ° of linearly polarized light incidence, i.e., is adjusted to the polarised light that transmitting terminal comes out
Horizontal direction light (good measurement, because be set as that light after glancing incidence walks completely is the optical path 2 of transmitting terminal, i.e., no phase modulation, then
The counting of first single-photon detector and the second single-photon detector does not change with phase change), then by the second Polarization Control
Device is set as 0 ° of linearly polarized light incidence, is that (principle enters horizon light with the first Polarization Controller, the level of being set as the light of receiving end
Penetrate that rear light walks completely is the optical path 2 of receiving end, i.e., no phase modulation), then third Polarization Controller is set as 0 ° of linearly polarized light and is entered
It penetrates, then the optical path of receiving end and transmitting terminal is at this time to be raised the first Polarization Controller in 0 referential with 0 ° of referential
Linearly polarized light at 45 ° is incident (to be fixed as 0 for the first phase modulator at both ends and second phase modularot voltage at this time, by the
The count value of one single-photon detector and the second single-photon detector is equal to be judged, because the polarised light in 45 ° of directions is in level
It is equal with the component in vertical sounding), then the state of the second Polarization Controller at this time is also 45 ° of incidences, third is adjusted at this time
Polarization Controller makes the counting of the first single-photon detector close to dark counting level, i.e. minimum value, the second single-photon detector
Count value reach maximum value, (because the optical path 1 and optical path 2 of transmitting terminal are all when 45 ° of polarised lights incident first polarization beam apparatus
The optical path 1 and optical path 2 of receiving end have light when having light or 45 ° of polarised lights second polarization beam apparatus of incidence, then system both ends
Light all passes through first phase modulator and first phase modulator phase modulation, and first phase modulator and first phase modulator tune
The phase of system is identical (i.e. the first phase modulator at both ends and second phase modularot voltage are fixed as 0), namely uses phase
Same base and state, at this time by QKD agreement it is found that can be visited completely on only one detector when both ends use identical base and state
Photon is measured, Polarization Controller is adjusted by third, makes light therethrough horizontally or vertically light, only one spy of such case
Light can be detected by surveying on device) i.e. the both ends coordinate initialization completion specific process of such as Fig. 3:
Referring to Fig. 3, a kind of both ends polarization state initial method based on phase-modulated polarized state coding QKD system, specifically
The following steps are included:
Step 1: the voltage of second phase modulator being fixed as 0, host computer is by first control circuit to first phase
Modulator issues control instruction, and the voltage of first phase modulator is looped through from minimum value to maximum value, i.e. first phase tune
From 0 to 2 π of phase of device processed is looped through, meanwhile, host computer issues the first Polarization Controller by first control circuit and controls
Instruction is to make the first Polarization Controller constantly change the polarization state of light, when the first single-photon detector and the second single photon detection
When count value in device remains constant, i.e. two slope of a curves are 0 in Fig. 2, and the first Polarization Controller stops changing
The polarization state of light；At this time regardless of the phase of first phase modulator changes, the first single-photon detector and the second single photon
Count value in detector remains constant；The first Polarization Controller is arranged to 0 ° of linearly polarized light incidence；
Step 2: the voltage of first phase modulator being fixed as 0, host computer is by second control circuit to second phase
Modulator issues control instruction, and the voltage of second phase modulator is looped through from minimum value to maximum value, i.e. second phase tune
From 0 to 2 π of phase of device processed is looped through, meanwhile, host computer issues the second Polarization Controller by second control circuit and controls
Instruction is to make the second Polarization Controller constantly change the polarization state of light, until two curves become straight line in Fig. 2；I.e. when first
When count value in single-photon detector and the second single-photon detector remains constant, the stopping of the second Polarization Controller changes
The polarization state of darkening；The second Polarization Controller is set as 0 ° of linearly polarized light incidence；
Step 3: the voltage of the voltage of first phase modulator and second phase modulator being fixed as 0, host computer is logical
It crosses second control circuit and control instruction is issued to make third Polarization Controller constantly change the inclined of light to third Polarization Controller
Polarization state, when the count value of the first single-photon detector is close to 0(i.e. minimum value), the count value of the second single-photon detector reaches
When maximum value, third Polarization Controller stops changing the polarization state of light；Third Polarization Controller is set as 0 ° of linearly polarized light to enter
It penetrates；
Step 4: host computer issues control instruction to the first Polarization Controller again by first control circuit to make the
One Polarization Controller constantly changes the polarization state of light, the count value in the first single-photon detector and the second single-photon detector
When equal, the first Polarization Controller stops changing the polarization state of light；The first Polarization Controller is raised in 0 referential at 45 °
Linearly polarized light is incident；
Step 5: host computer issues control instruction to third Polarization Controller again by second control circuit to make the
Three Polarization Controllers constantly change the polarization state of light, when the count value of the first single-photon detector is close to 0(i.e. minimum value), the
When the count value of two single-photon detectors reaches maximum value, third Polarization Controller stops changing the polarization state of light, phase-modulation
Polarization state encodes the receiving end of QKD system and the polarization state of transmitting terminal is initialized and completed.
This method realizes system receiving terminal and hair using the related device and algorithm of phase-modulated polarized state coding QKD system
It penetrates and the coordinate of quick polarization state is held to be aligned, cast out the trouble of additional measuring device, and can be according to environment to system
It influences, the alignment of real-time perfoming both ends light coordinate axis guarantees the self-reparability and stability of system.
Protection scope of the present invention includes but is not limited to embodiment of above, and protection scope of the present invention is with claims
Subject to, replacement, deformation, the improvement that those skilled in the art that any pair of this technology is made is readily apparent that each fall within of the invention
Protection scope.
Claims (1)
1. a kind of both ends polarization state initial method based on phase-modulated polarized state coding QKD system, including phase-modulation are inclined
Polarization state encodes QKD system, and the phase-modulated polarized state coding QKD system includes transmitting terminal, receiving end and host computer, the hair
End is penetrated to be connected with receiving end by fiber channel, the transmitting terminal and receiving end with upper mechatronics；The transmitting terminal packet
Include laser, the first Polarization Controller, first annular device, the first polarization beam apparatus, first phase modulator, attenuator and first
Control circuit, the receiving end include the second Polarization Controller, the second circulator, the second polarization beam apparatus, second phase modulation
Device, third Polarization Controller, third polarization beam apparatus, the first single-photon detector, the second single-photon detector and the second control
Circuit；
It is characterized by:
The host computer is electrically connected with first control circuit, the first control circuit respectively with laser, the first Polarization Control
Device and the electrical connection of first phase modulator, first polarization beam apparatus and first phase modulator are connected by two polarization maintaining optical fibres
It connects to constitute transmitting terminal sagnac ring；The laser for generating pulsed light, first Polarization Controller for changing
Light is simultaneously incident on first annular device by the polarization state of light, and first polarization beam apparatus is used for the polarization of first annular device incidence
Light is divided into horizontal polarization light and orthogonal polarized light, and the first phase modulator is for modulating clockwise or counterclockwise direction
Polarised light phase, first polarization beam apparatus be used for by the horizontal polarization light from first phase modulator and it is vertical partially
The vibration light remittance first annular device of merga pass is emitted to attenuator, and attenuator is with then decaying light intensity and the light issued passes through light
Fine transmission is to receiving end；Two polarization maintaining optical fibre length wherein in transmitting terminal sagnac ring are different, and short polarization maintaining optical fibre passes
Defeated pulsed light is used for by corresponding phase on first phase modulator tune, and the pulsed light of long polarization maintaining optical fibre transmission adds always
Be stationary phase；
The host computer is electrically connected with second control circuit, the second control circuit respectively with the second Polarization Controller, third
Polarization Controller, second phase modulator, the first single-photon detector and the electrical connection of the second single-photon detector, described second partially
Vibration beam splitter connects to constitute receiving end sagnac ring by two polarization maintaining optical fibres with second phase modulator；Described second partially
Vibration controller for changing light polarization state and light is incident on the second circulator, second polarization beam apparatus is used for second
The polarised light of circulator incidence is divided into horizontal polarization light and orthogonal polarized light, and the second phase modulator is for modulating clockwise
Or the phase of the polarised light in counter clockwise direction, second polarization beam apparatus is used for will be from the level of second phase modulator
Polarised light and orthogonal polarized light remittance the second circulator of merga pass are emitted to third Polarization Controller, and third Polarization Controller is used for
Change the polarization state of light and light is incident on third polarization beam apparatus, third polarization beam apparatus is used to for incident polarised light being divided into
Horizontal polarization light and orthogonal polarized light, first single-photon detector are used to detect the polarised light of horizontal state of polarization, and second is single
Photon detector is used to detect the polarised light of perpendicular polarisation state；Wherein two polarization maintaining optical fibre length in receiving end sagnac ring are not
Together, the pulsed light of short polarization maintaining optical fibre transmission is used for by corresponding phase on second phase modulator tune, and long polarization maintaining optical fibre passes
What defeated pulsed light added always is stationary phase；
Specifically includes the following steps:
Step 1: the voltage of second phase modulator being fixed as 0, host computer modulates first phase by first control circuit
Device issues control instruction, and the voltage of first phase modulator is looped through from minimum value to maximum value, i.e. first phase modulator
From 0 to 2 π of phase loop through, meanwhile, host computer by first control circuit to the first Polarization Controller issue control instruction
To make the first Polarization Controller constantly change the polarization state of light, when in the first single-photon detector and the second single-photon detector
Count value when remaining constant, the first Polarization Controller stops changing the polarization state of light；
Step 2: the voltage of first phase modulator being fixed as 0, host computer modulates second phase by second control circuit
Device issues control instruction, and the voltage of second phase modulator is looped through from minimum value to maximum value, i.e. second phase modulator
From 0 to 2 π of phase loop through, meanwhile, host computer by second control circuit to the second Polarization Controller issue control instruction
To make the second Polarization Controller constantly change the polarization state of light, when in the first single-photon detector and the second single-photon detector
Count value when remaining constant, the second Polarization Controller stops changing the polarization state of light；
Step 3: the voltage of the voltage of first phase modulator and second phase modulator being fixed as 0, host computer passes through the
The polarization state that two control circuits issue control instruction to third Polarization Controller to make third Polarization Controller constantly change light,
When the count value of the first single-photon detector reaches minimum value, when the count value of the second single-photon detector reaches maximum value,
Third Polarization Controller stops changing the polarization state of light；
Step 4: host computer again by first control circuit to the first Polarization Controller issue control instruction to make first partially
Vibration controller constantly changes the polarization state of light, when the count value in the first single-photon detector and the second single-photon detector is equal
When, the first Polarization Controller stops changing the polarization state of light；
Step 5: host computer issues control instruction to third Polarization Controller again by second control circuit to keep third inclined
Vibration controller constantly changes the polarization state of light, when the count value of the first single-photon detector reaches minimum value, the second single photon
When the count value of detector reaches maximum value, third Polarization Controller stops changing the polarization state of light, and phase-modulated polarized state is compiled
The receiving end of code QKD system and the polarization state of transmitting terminal are initialized and are completed.
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| CN108282465B (en) * | 2017-12-28 | 2020-08-18 | 中国人民解放军战略支援部队信息工程大学 | Quantum secret communication anti-attack detection method and device for sine gate-controlled filtering type GHz single-photon detector |
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