CN107947930A - The modulation compensated system of continuous variable quantum key distribution and its implementation - Google Patents
The modulation compensated system of continuous variable quantum key distribution and its implementation Download PDFInfo
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- CN107947930A CN107947930A CN201711472465.7A CN201711472465A CN107947930A CN 107947930 A CN107947930 A CN 107947930A CN 201711472465 A CN201711472465 A CN 201711472465A CN 107947930 A CN107947930 A CN 107947930A
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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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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2627—Modulators
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2649—Demodulators
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0852—Quantum cryptography
- H04L9/0858—Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding
Abstract
The invention discloses a kind of modulation compensated system of continuous variable quantum key distribution and its implementation, quantum key transmitting terminal to be modulated quantum signal, is changed into multiple subcarrier forms and sends to quantum key receiving terminal；Quantum key receiving terminal is acquired and handles to the signal sent, and result is sent to I/Q rectification building-out post-processing modules；I/Q rectification building-outs post-processing module is docked received signal using least mean square algorithm and is handled.The present invention can overcome the modulation defect in the presence of quantum key distribution system, uneven in particular for I/Q, further increase the physical security of the continuous variable quantum key distribution system based on Orthogonal Frequency Division Multiplexing.
Description
Technical field
The invention belongs to Fiber quantum field of communication technology, is related to a kind of continuous variable quantum based on Orthogonal Frequency Division Multiplexing
Key distributes modulation compensated system and its implementation.
Background technology
Quantum key distribution can make two distant locations secure shared key in fly-by-night quantum channel, its safety
Property is ensured by quantum-mechanical uncertainty principle and quantum non-clone principle.At present quantum key distribution be broadly divided into from
Dissipate variable and continuous variable two types.Compared with discrete variable quantum key distribution, its amount of continuous variable quantum key distribution
Sub- state is easier to prepare, and can incorporate in existing fibre system, and can use the homodyne detection or heterodyne of high efficiency, low cost
Detection technique, this causes continuous variable quantum key distribution system to be easier to enter commercialization field.However, continuous variable quantum
Negotiation efficiency is relatively low when key is distributed in long haul communication, and its key rate needs into one in the range of considerable communication distance
Step improves.OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) leads in quantum
Letter field has obtained great development.Continuous variable quantum key distribution system based on Orthogonal Frequency Division Multiplexing can the amount of effectively improving
The safe key rate of sub- communication network.But there is also many inevitably modulation defects, such as in modulated process for the program
Amplitude imbalance and phase quadrature error (I/Q is uneven) of appearance etc..Therefore, how to estimate and produced by Compensation Modulation process
Signal defect be particularly important.
The content of the invention
To achieve the above object, the present invention provides a kind of modulation compensated system of continuous variable quantum key distribution and its realization
Method, solves the problems, such as to modulate defect in the continuous variable quantum key distribution system of Orthogonal Frequency Division Multiplexing in the prior art.
The technical solution adopted in the present invention is the modulation compensated system of continuous variable quantum key distribution, including：
Quantum key transmitting terminal, generates for key, quantum signal is modulated, and by modulated signal throughput
Subchannel sends to quantum key receiving terminal and locates after the modulation flaw indication that modulated process occurs is sent to I/Q rectification building-outs
Manage module；
Quantum key receiving terminal, for receiving and detecting quantum signal, and after feedback information is passed to I/Q rectification building-outs
Processing module；
I/Q rectification building-out post-processing modules, for gathering the modulation flaw indication and quantum of the transmission of quantum key transmitting terminal
The feedback information that secret key receiving terminal is sent, detects I/Q imbalances degree using least mean square algorithm and is corrected, finally reached
Compensation to modulating defect.
Further, the quantum key transmitting terminal includes：
Pulse laser, for producing pulse coherence light；
Beam splitter, for pulse coherence light to be separated into the flashlight of 1% Quantum Level and the local oscillator of 99% Quantum Level
Light；
Radio frequency OFDM transmitting terminals, for the binary serial data of input to be first passed through quadrature amplitude modulation mapping, then by string
And change, it is loaded into by Fourier transformation in orthogonal sub-carriers and forms ofdm signal；
Mach-Zehnder modulator, the radio frequency OFDM signal for radio frequency OFDM transmitting terminals to be sent are modulated to beam splitter production
In the area of light of 1% raw quantum luminous intensity, flashlight is divided into amplitude and phase on the Y-branch device of Mach-Zehnder modulator
Identical two-beam, and as fiber waveguide is transmitted on upper and lower two branch, in modulated process, Mach-Zehnder
Modulator is inevitably present the unbalanced defects of I/Q；
Adjustable attenuator, for by Mach-Zehnder modulator send to flashlight carry out decaying to suitable light intensity levels,
Light intensity levels are configured according to the difference of handled flashlight, and the flashlight decayed is sent to polarization coupled
Device；
Field-programmable gate array data acquisition card, for receiving the modulation flaw indication of Mach-Zehnder modulator, and by its
As training sequence symbols, send to I/Q corrections and channel equalization；
Polarizing coupler, believes for the flashlight received and the separated local oscillator optocoupler of beam splitter to be synthesized quantum all the way
Number, and throughput subchannel transmission is to quantum key receiving terminal.
Further, the quantum key receiving terminal includes：
Ofdm demodulator, turns electric signal operation for the optical signal to quantum channel transmission into traveling optical signal, and passes through
Signal is further become digital signal and carries out Fast Fourier Transform (FFT) by the analog-digital converter inside ofdm demodulator, further according to
The amounts of compensation on signals that decision-feedback obtains is handled, and is sent after finally modulating signals into polarization beam apparatus；
Polarization beam apparatus, for by ofdm demodulator send to quantum signal be divided into 10% flashlight and 90% local oscillator
Light；
Local oscillator laser, for producing local oscillator light, and the flashlight sent with polarization beam apparatus is interfered, and difference passes through
The path difference that local oscillator light and flashlight pass through is realized, and is sent to zero-difference detection device；
Zero-difference detection device, for receiving the letter received from the local oscillator light that local oscillator laser produces with polarization beam apparatus
Number coherent light obtained from the interference of light and the flashlight received from polarization beam apparatus carry out homodyne detection, obtain randomly selected
The measurement result of quadrature component, and testing result is sent to field-programmable gate array data collecting card；
Field-programmable gate array data collecting card, send to I/Q corrections and channel for zero-difference detection device to be collected signal
Equilibrium, as known feedback signal, obtains the IQ imbalances parameter and channel transfer function at current time, for next
The IQ corrections of a OFDM data symbol and channel equalization.
Further, it is described to be included based on I/Q rectification building-out post-processing modules：
I/Q is corrected and channel equalization, for receiving the training sequence symbols of field-programmable gate array data acquisition card transmission
The known feedback signal sent with field-programmable gate array data collecting card, it is uneven to estimate modulated signal with least mean square algorithm
Weighing apparatus degree, finally carries out constellation point judgement to obtained complex signal, using nearest value as decision value, and calculates corresponding mend
The amount of repaying is sent to decision-feedback；
Decision-feedback, for receiving compensation rate information and passing to ofdm demodulator.
Further, the model Thorlabs OPG1015 ps optical impulses generators of the pulse laser, Mach-
The model BP-ABC substrate bias controllers of zehnder modulators, field-programmable gate array data acquisition card by Xilinx VC707 with
FMC176 is composed, the model Thorlabs PBC980PM-FC light beam couplers of polarizing coupler.
Further, the model Thorlabs PDA435A balance amplification photodetectors of the zero-difference detection device, it is existing
Field programmable gate array data collecting card is composed of Xilinx VC707 and FMC176.
Another technical solution of the present invention is the realization side of the modulation compensated system of continuous variable quantum key distribution
Method, specifically follows the steps below：
Step 1: pulse laser produces pulse coherence light is separated into flashlight and local oscillator light by beam splitter；Penetrate at the same time
The serial data of input is first passed through quadrature amplitude modulation mapping by frequency OFDM transmitting terminals, then by serioparallel exchange, by Fourier transformation plus
It is downloaded in orthogonal sub-carriers and forms ofdm signal, Mach-Zehnder modulator receives the multicarrier from radio frequency OFDM transmitting terminals
Signal and the quantum optical signal from beam splitter, and radio frequency OFDM signal is modulated to beam splitter in Mach-Zehnder modulator
In the area of light of the 1% quantum luminous intensity produced, the optical signal of some subcarrier forms of formation, modulated process inevitably produces
The unbalanced defects of I/Q are given birth to, field-programmable gate array data acquisition card will receive modulation flaw indication and be transferred to I/Q corrections
With channel equalization to Compensation Modulation defect；Decayed after the flashlight that Mach-Zehnder modulator is sent by adjustable attenuator
Couple in polarizing coupler to suitable light intensity levels, then with the local oscillator light that beam splitter is sent, and sent by quantum channel
To quantum key receiving terminal；
Step 2: in quantum signal receiving terminal, quantum signal recovers the modulation condition of signal by ofdm demodulator, then passes through
Cross polarization beam apparatus and be divided into flashlight and local oscillator light, flashlight carries out coupling merga pass zero with the local oscillator light that local oscillator laser is sent
Gap detector is detected and send testing result to field-programmable gate array data collecting card, and data are as feedback signal by passing through
Allusion quotation transmission is contrasted to I/Q corrections and channel equalization and the training sequence symbols of field-programmable gate array data acquisition card
And detection；
Step 3: I/Q rectification building-outs module send the signal that field-programmable gate array data acquisition card collects to I/Q schools
Just and channel equalization；The modulation flaw indication that I/Q is corrected and channel equalization is collected using least mean square algorithm processing, then will
To compensation after result be transferred to decision-feedback, decision-feedback is by the correction result received by classical transmission to amount
The ofdm demodulator of subsignal receiving terminal, lacks to distribute Mach-Zehnder modulator in modulation compensated system to key
Fall into and compensate.
The invention has the advantages that the collection of field programmable gate array (FPGA) data acquisition card is based on orthogonal frequency division multiplexing
With the modulated signal of the continuous variable quantum key distribution of technology, I/Q modulation letters are received with I/Q rectification building-outs post-processing module
Number, modulated signal deviation is estimated first, and then data are handled with least mean square algorithm.Data flow after processing passes to
Decision-feedback, is demodulated and compensates to signal in quantum key receiving terminal.The present invention has Real-time Feedback, and compensation is sluggish low
Advantage, effectively reduces modulation present in continuous variable quantum key distribution using I/Q rectification building-out post-processing modules and lacks
The influence to communication system is fallen into, improves the maximum transmission distance and system safe key rate of communication.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
There is attached drawing needed in technology description to be briefly described, it should be apparent that, drawings in the following description are only this
Some embodiments of invention, for those of ordinary skill in the art, without creative efforts, can be with
Other attached drawings are obtained according to these attached drawings.
Fig. 1 is the structure diagram of the embodiment of the present invention；
Fig. 2 is schematic diagram of the quantum key transmitting terminal with quantum key receiving terminal of the embodiment of the present invention.
In figure, 1. pulse lasers, 2. beam splitters, 3. radio frequency OFDM transmitting terminals, 4. Mach-Zehnder modulators, 5. is adjustable
Attenuator, 6. field programmable gate arrays (FPGA) data acquisition card, 7. polarizing couplers, 8.OFDM demodulators, 9. polarizations point
Beam device, 10. local oscillator lasers, 11. zero-difference detection devices, 12. field programmable gate arrays (FPGA) data collecting card, 13.I/Q schools
Just and channel equalization, 14. decision-feedbacks.
Embodiment
Below in conjunction with the attached drawing in the embodiment of the present invention, the technical solution in the embodiment of the present invention is carried out clear, complete
Site preparation describes, it is clear that described embodiment is only part of the embodiment of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, those of ordinary skill in the art are obtained every other without making creative work
Embodiment, belongs to the scope of protection of the invention.
The modulation compensated system of continuous variable quantum key distribution based on Orthogonal Frequency Division Multiplexing, as shown in Figs. 1-2, including：
Quantum key transmitting terminal, generates for key, quantum signal is modulated, and by modulated signal throughput
Subchannel sends to quantum key receiving terminal and locates after the modulation flaw indication that modulated process occurs is sent to I/Q rectification building-outs
Manage module；
Quantum key receiving terminal, for receiving and detecting quantum signal, and after feedback information is passed to I/Q rectification building-outs
Processing module；
I/Q rectification building-out post-processing modules, for gathering the modulation flaw indication and quantum of the transmission of quantum key transmitting terminal
The feedback information that secret key receiving terminal is sent, detects I/Q imbalances degree using least mean square algorithm and is corrected, finally reached
Compensation to modulating defect.
Quantum key transmitting terminal includes：
Pulse laser 1, for producing pulse coherence light；
Beam splitter 2, for pulse coherence light to be separated into the flashlight of 1% Quantum Level and the local oscillator of 99% Quantum Level
Light, and local oscillator light plays the role of flashlight to amplify its intensity；
Radio frequency OFDM transmitting terminals 3, for the binary serial data of input to be first passed through quadrature amplitude modulation mapping, then by string
And change, it is loaded into by Fourier transformation in orthogonal sub-carriers and forms ofdm signal；
Mach-Zehnder modulator 4, the radio frequency OFDM signal for radio frequency OFDM transmitting terminals 3 to be sent are modulated to beam splitter 2
In the area of light of the 1% quantum luminous intensity produced, flashlight is divided into amplitude and phase on the Y-branch device of Mach-Zehnder modulator 4
The identical two-beam in position, and as fiber waveguide is transmitted on upper and lower two branch, in modulated process, due to by mould
Intend the influence of the factors such as trueness error and the temperature drift of device, Mach-Zehnder modulator 4 is inevitably present I/Q imbalances
The defects of；
Adjustable attenuator 5, for by Mach-Zehnder modulator 4 send to flashlight carry out decaying to suitable light intensity water
Flat, light intensity levels are configured according to the difference of handled flashlight, and the flashlight decayed is sent to polarization coupling
Clutch 7；
Field-programmable gate array data acquisition card 6, for receiving the modulation flaw indication of Mach-Zehnder modulator 4, and will
It is sent to I/Q corrections and channel equalization 13 as training sequence symbols；
Polarizing coupler 7, believes for the flashlight received and the separated local oscillator optocoupler of beam splitter 2 to be synthesized quantum all the way
Number, and throughput subchannel transmission is to quantum key receiving terminal.
Quantum key receiving terminal, including：
Ofdm demodulator 8, turns electric signal operation for the optical signal to quantum channel transmission into traveling optical signal, and passes through
Signal is further become digital signal and carries out Fast Fourier Transform (FFT) by the analog-digital converter inside ofdm demodulator 8, then root
The amounts of compensation on signals obtained according to decision-feedback 14 is handled, and is sent after finally modulating signals into polarization beam apparatus 9；
Polarization beam apparatus 9, for by ofdm demodulator 8 send to quantum signal be divided into 10% flashlight and 90% sheet
Shake light；
Local oscillator laser 10, for producing local oscillator light, and the flashlight sent with polarization beam apparatus 9 is interfered, difference
The path difference passed through by local oscillator light and flashlight is realized, and is sent to zero-difference detection device 11；
Zero-difference detection device 11, for being connect to receiving the local oscillator light produced from local oscillator laser 10 with polarization beam apparatus 9
Coherent light obtained from the signal interference of light of receipts and the flashlight received from polarization beam apparatus 9 carry out homodyne detection, obtain with
The measurement result of the quadrature component of machine selection, and testing result is sent to field-programmable gate array data collecting card 12；
Field-programmable gate array data collecting card 12, for by zero-difference detection device 11 collect signal send to I/Q correction and
Channel equalization 13, as known feedback signal, obtains the IQ imbalances parameter and channel transfer function at current time, uses
In the IQ corrections of next OFDM data symbol and channel equalization.
Based on I/Q rectification building-out post-processing modules, including：
I/Q is corrected and channel equalization 13, for receiving the training sequence symbol of the transmission of field-programmable gate array data acquisition card 6
Number and field-programmable gate array data collecting card 12 send known feedback signal, with least mean square algorithm estimate modulated signal
Uneven degree, detailed process are that I/Q corrections and channel equalization 13 utilize known instruction on programmable gate array data acquisition card 6
Practice the I/Q imbalances that are worth to of known feedback signal in the value and field-programmable gate array data collecting card 12 of sequence symbol to join
The initial estimate H of number G and channel transfer function, then, the G and H that I/Q corrections are obtained with channel equalization 13 according to initial estimation
I/Q corrections and channel equalization are carried out to OFDM data symbol, constellation point judgement finally is carried out to obtained complex signal, using most
Near value calculates corresponding compensation rate and send to decision-feedback 14 as decision value；
Decision-feedback 14, for receiving compensation rate information and passing to ofdm demodulator 8.
The transmission medium that quantum channel is formed for single mode optical fiber or free space, single mode optical fiber attenuation coefficient are stablized, about
It is relatively low for 0.2dB/km, strong antijamming capability, cost；The transmission medium that classical channel is formed for classical wireless, wired or optical fiber.
Pulse laser 1 uses Thorlabs OPG1015 ps optical impulses generators, can generate less than equal to 3ps, frequency
Rate is the laser pulse of 10GHz.
Mach-Zehnder modulator 4 uses BP-ABC substrate bias controllers, can support common single polarization intensity modulator or IQ tune
Device processed, there is provided SPCI standard control instructions, simulation, digital modulation are applicable at the same time.
Polarizing coupler 7 uses Thorlabs PBC980PM-FC light beam couplers, by two beam cross-polarization optocouplers
It is incorporated into an optical fiber.High Extinction Ratio (>18dB), low-loss (<2dB).
Zero-difference detection device 11 is more than using Thorlabs PDA435A balance amplification photodetectors, common-mode rejection ratio
20dB, bandwidth is up to 350MHz.
Field-programmable gate array data acquisition card 6, field-programmable gate array data collecting card 12 are by Xilinx VC707
It is composed with FMC176, can neatly changes clock frequency, can meet high-speed real-time streaming, there is real-time
Well, the features such as speed is fast, precision is high.
A kind of implementation method of the modulation compensated system of continuous variable quantum key distribution is close using a kind of continuous variable quantum
Key distributes modulation compensated system, specifically follows the steps below：
Step 1: pulse laser 1 produces pulse coherence light is separated into flashlight and local oscillator light by beam splitter 2；At the same time
The serial data of input is first passed through quadrature amplitude modulation mapping by radio frequency OFDM transmitting terminals 3, then by serioparallel exchange, by Fourier transformation
It is loaded into orthogonal sub-carriers and forms ofdm signal, Mach-Zehnder modulator 4 is received from the more of radio frequency OFDM transmitting terminals 3
Carrier signal and the quantum optical signal from beam splitter 2, and be modulated to radio frequency OFDM signal in Mach-Zehnder modulator 4
In the area of light for the 1% quantum luminous intensity that beam splitter 2 produces, the optical signal of some subcarrier forms of formation, modulated process can not
What is avoided generates the unbalanced defects of I/Q, and field-programmable gate array data acquisition card 6 will receive modulation flaw indication transmission
To I/Q corrections and channel equalization 13 to Compensation Modulation defect；By can after the flashlight that Mach-Zehnder modulator 4 is sent
Controlled attenuator 5 decays to suitable light intensity levels, then is coupled with the local oscillator light that beam splitter 2 is sent in polarizing coupler 7, and leads to
Quantum channel is crossed to send to quantum key receiving terminal；
Step 2: in quantum signal receiving terminal, quantum signal recovers the modulation condition of signal by ofdm demodulator 8, then
It is divided into flashlight and local oscillator light by polarization beam apparatus 9, flashlight is coupled simultaneously with the local oscillator light that local oscillator laser 10 is sent
It is detected by zero-difference detection device 11 and send testing result to field-programmable gate array data collecting card 12, data is as anti-
Feedback signal is corrected by classical transmission to I/Q and channel equalization 13 and the training sequence of field-programmable gate array data acquisition card 6
Row symbol is contrasted and detected；
Step 3: I/Q rectification building-outs module send the signal that field-programmable gate array data acquisition card 12 collects to I/Q
Correction and channel equalization 13；The modulation flaw indication that I/Q is corrected and channel equalization 13 is collected using least mean square algorithm processing,
The result after obtained compensation is transferred to decision-feedback 14 again, decision-feedback 14 believes the correction result received by classics
Road is transferred to the ofdm demodulator 8 of quantum signal receiving terminal, is modulated to distribute Mach-Zehnder in modulation compensated system to key
The defects of device 4 occurs compensates.
Each embodiment in this specification is described using relevant mode, identical similar portion between each embodiment
Divide mutually referring to what each embodiment stressed is the difference with other embodiment.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the scope of the present invention.It is all
Any modification, equivalent replacement, improvement and so within the spirit and principles in the present invention, are all contained in protection scope of the present invention
It is interior.
Claims (7)
1. the modulation compensated system of continuous variable quantum key distribution, it is characterised in that including：
Quantum key transmitting terminal, generates for key, quantum signal is modulated, and modulated signal is believed by quantum
Road, which sends to quantum key receiving terminal and send the modulation flaw indication that modulated process occurs to I/Q rectification building-outs, post-processes mould
Block；
Quantum key receiving terminal, the post processing of I/Q rectification building-outs is passed to for receiving and detecting quantum signal, and by feedback information
Module；
I/Q rectification building-out post-processing modules, for gathering the modulation flaw indication and quantum key of the transmission of quantum key transmitting terminal
The feedback information that receiving terminal is sent, detects I/Q imbalances degree using least mean square algorithm and is corrected, finally reach and exchange
The compensation of defect processed.
2. the modulation compensated system of continuous variable quantum key distribution according to claim 1, it is characterised in that the quantum
Key transmitting terminal includes：
Pulse laser (1), for producing pulse coherence light；
Beam splitter (2), for pulse coherence light to be separated into the flashlight of 1% Quantum Level and the local oscillator of 99% Quantum Level
Light；
Radio frequency OFDM transmitting terminals (3), for the binary serial data of input to be first passed through quadrature amplitude modulation mapping, then by string simultaneously
Conversion, is loaded into orthogonal sub-carriers by Fourier transformation and forms ofdm signal；
Mach-Zehnder modulator (4), the radio frequency OFDM signal for radio frequency OFDM transmitting terminals (3) to be sent are modulated to beam splitter
(2) in the area of light of the 1% quantum luminous intensity produced, flashlight is divided on the Y-branch device of Mach-Zehnder modulator (4) to shake
Width and the identical two-beam of phase, and as fiber waveguide is transmitted on upper and lower two branch, in modulated process, horse
Conspicuous-zehnder modulators (4) are inevitably present the unbalanced defects of I/Q；
Adjustable attenuator (5), for by Mach-Zehnder modulator (4) send to flashlight carry out decaying to suitable light intensity water
Flat, light intensity levels are configured according to the difference of handled flashlight, and the flashlight decayed is sent to polarization coupling
Clutch (7)；
Field-programmable gate array data acquisition card (6), for receiving the modulation flaw indication of Mach-Zehnder modulator (4), and will
It is sent to I/Q corrections and channel equalization (13) as training sequence symbols；
Polarizing coupler (7), believes for the flashlight received and the separated local oscillator optocoupler of beam splitter (2) to be synthesized quantum all the way
Number, and throughput subchannel transmission is to quantum key receiving terminal.
3. the modulation compensated system of continuous variable quantum key distribution according to claim 1, it is characterised in that the quantum
Key reception end includes：
Ofdm demodulator (8), turns electric signal operation for the optical signal to quantum channel transmission into traveling optical signal, and passes through OFDM
Signal is further become digital signal and carries out Fast Fourier Transform (FFT) by the internal analog-digital converter of demodulator (8), further according to
The amounts of compensation on signals that decision-feedback (14) obtains is handled, and is sent after finally modulating signals into polarization beam apparatus (9)；
Polarization beam apparatus (9), for by ofdm demodulator (8) send to quantum signal be divided into 10% flashlight and 90% sheet
Shake light；
Local oscillator laser (10), for producing local oscillator light, and the flashlight sent with polarization beam apparatus (9) is interfered, difference
The path difference passed through by local oscillator light and flashlight is realized, and is sent to zero-difference detection device (11)；
Zero-difference detection device (11), for receiving the local oscillator light and polarization beam apparatus (9) that come from local oscillator laser (10) and produce
Coherent light obtained from the received signal interference of light and the flashlight received from polarization beam apparatus (9) carry out homodyne detection, obtain
The measurement result of randomly selected quadrature component is obtained, and testing result is sent to field-programmable gate array data collecting card
(12)；
Field-programmable gate array data collecting card (12), for by zero-difference detection device (11) collect signal send to I/Q correction and
Channel equalization (13), as known feedback signal, obtains the IQ imbalances parameter and channel transfer function at current time,
IQ corrections and channel equalization for next OFDM data symbol.
4. the modulation compensated system of continuous variable quantum key distribution according to claim 1, it is characterised in that described to be based on
I/Q rectification building-out post-processing modules include：
I/Q is corrected and channel equalization (13), for receiving the training sequence symbol of field-programmable gate array data acquisition card (6) transmission
Number and field-programmable gate array data collecting card (12) send known feedback signal, with least mean square algorithm estimate modulation letter
Number uneven degree, finally carries out constellation point judgement to obtained complex signal, using nearest value as decision value, and calculates
Corresponding compensation rate is sent to decision-feedback (14)；
Decision-feedback (14), for receiving compensation rate information and passing to ofdm demodulator (8).
5. the modulation compensated system of continuous variable quantum key distribution according to claim 2, it is characterised in that the pulse
The model Thorlabs OPG1015 ps optical impulses generators of laser (1), the model of Mach-Zehnder modulator (4)
BP-ABC substrate bias controllers, field-programmable gate array data acquisition card (6) are composed of Xilinx VC707 and FMC176, partially
Shake the model Thorlabs PBC980PM-FC light beam couplers of coupler (7).
6. the modulation compensated system of continuous variable quantum key distribution according to claim 3, it is characterised in that the homodyne
The model Thorlabs PDA435A balance amplification photodetectors of detector (11), field-programmable gate array data collecting card
(12) it is composed of Xilinx VC707 and FMC176.
A kind of 7. realization side of modulation compensated system of continuous variable quantum key distribution as described in claim 1-6 any one
Method, it is characterised in that specifically follow the steps below：
Step 1: pulse laser (1) produces pulse coherence light is separated into flashlight and local oscillator light by beam splitter (2)；At the same time
The serial data of input is first passed through quadrature amplitude modulation mapping by radio frequency OFDM transmitting terminals (3), then by serioparallel exchange, is become by Fourier
Change to be loaded into orthogonal sub-carriers and form ofdm signal, Mach-Zehnder modulator (4) is received from radio frequency OFDM transmitting terminals
(3) multi-carrier signal and the quantum optical signal from beam splitter (2), and by radio frequency OFDM in Mach-Zehnder modulator (4)
In the area of light for the 1% quantum luminous intensity that signal modulation is produced to beam splitter (2), the optical signal of some subcarrier forms of formation,
Modulated process inevitably generates the unbalanced defects of I/Q, and field-programmable gate array data acquisition card (6) will receive tune
Flaw indication processed is transferred to I/Q corrections and channel equalization (13) to Compensation Modulation defect；Mach-Zehnder modulator (4) is sent
Flashlight after suitable light intensity levels are decayed to by adjustable attenuator (5), then the local oscillator light sent with beam splitter (2) exists
Coupling in polarizing coupler (7), and sent by quantum channel to quantum key receiving terminal；
Step 2: in quantum signal receiving terminal, quantum signal recovers the modulation condition of signal by ofdm demodulator (8), then passes through
Cross polarization beam apparatus (9) and be divided into flashlight and local oscillator light, flashlight is coupled with the local oscillator light that local oscillator laser (10) is sent
And it is detected by zero-difference detection device (11) and send testing result to field-programmable gate array data collecting card (12), data
As feedback signal by classical transmission to I/Q corrections and channel equalization (13) and field-programmable gate array data acquisition card
(6) training sequence symbols are contrasted and detected；
Step 3: I/Q rectification building-outs module send the signal that field-programmable gate array data acquisition card (12) collects to I/Q schools
Just with channel equalization (13)；The modulation defect letter that I/Q is corrected and channel equalization (13) is collected using least mean square algorithm processing
Number, then the result after obtained compensation is transferred to decision-feedback (14), decision-feedback (14) leads to the correction result received
Ofdm demodulator (8) of the classical transmission to quantum signal receiving terminal is crossed, to distribute horse in modulation compensated system to key
The defects of conspicuous-zehnder modulators (4) occur compensates.
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