CN203590241U - Decoy state quantum light source generating device of high-speed polarization encoding - Google Patents
Decoy state quantum light source generating device of high-speed polarization encoding Download PDFInfo
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- CN203590241U CN203590241U CN201320816535.7U CN201320816535U CN203590241U CN 203590241 U CN203590241 U CN 203590241U CN 201320816535 U CN201320816535 U CN 201320816535U CN 203590241 U CN203590241 U CN 203590241U
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Abstract
The utility model discloses a decoy state quantum light source generating device of high-speed polarization encoding. The device provided by the utility model comprises a high-speed logic control chip, a decoy state light pulse driver module, a high-speed phase modulator driver module, a laser diode, a high-speed phase modulation and polarization rotation module and an optical attenuator, wherein the decoy state light pulse driver module receives a control signal from the high-speed logic control chip, modulates and generates decoy state electric pulse signals of three impulse amplitudes according to proportional requirement of a decoy state quantum light source embodiment and drives the lasing diode to output decoy state optical pulse of three light intensities; the decoy state electric pulse signals pass through the high-speed phase modulation and polarization rotation module and four polarization states of linearly polarized base and circularly polarized base are modulated at random by a high-speed phase modulator; and the signals are attenuated to the single photon level by the optical attenuator. Any one of nine quantum states including three average photon number intensities and four polarizations can be generated by high-speed random modulation. The device provided by the utility model is small in size, has a compact structure, is easy to integrate and can be adopted to effectively raise safety level.
Description
Technical field
The utility model belongs to quantum key distribution class, is specifically related to a kind of preparation of trick quantum state of quantum key distribution (QKD) system that is applicable to high speed polarization encoder, i.e. the trick state quantum light source generation device of high speed polarization encoder.
Background technology
Quantum cryptography comes from Bennett in 1984 and Brassard proposes " BB84 agreement ", cipher mode compared to tradition based on algorithm complex, quantum key distribution (Quantum Key Distribution, QKD) fail safe is to be guaranteed by basic physics theory, because of but the communication mode being perfectly safe that cannot be cracked.The QKD system of existing main flow mainly contains following three kinds of forecast scheme configurations: the QKD scheme of the phase code based on " plug & play ", the QKD scheme based on polarization encoder and based on the right QKD scheme of entangled photons.Based on the right QKD scheme of entangled photons, at present also in the experimental study stage, the practical application implementation of distance also has a segment distance.Phase code QKD scheme based on " plug & play " has the advantage of polarization compensation because of its system configuration; But, due to quantum state light source with single-photon detector all a side who communicates by letter, information loads sequential and is limited to the time jitter of single-photon detector, this scheme is not suitable for the high speed QKD that exceedes GHz.QKD scheme light source based on polarization encoder is in respectively with single-photon detector the two ends of communicating by letter, belong to communication end to end, thereby not there is not the time upper control limit of " plug & play " phase code QKD scheme, be suitable for high speed quantum key distribution.
Although more than the QKD scheme traffic rate based on polarization encoder can reach GHz, this scheme implements to still need a lot of ACTIVE CONTROL elements in technology so far, controls difficulty large, also lacks high speed polarization encoder module.In recent years, the fast development of single-photon detecting survey technology, for example, the auto-balanced detection method based on nearest proposition or sinusoidal door Detection Techniques, the detection rate of near-infrared single photon detector has risen to higher than 2GHz, substantially reaches the speed limit of the response photon of InGaAs avalanche diode.In the situation that GHz high-speed single photon Detection Techniques constantly promote, people need realization badly and can reach the quantum coding solution of equal speed, to improve the one-tenth code check of quantum cryptography.
Single-photon source is the important component part of QKD system, and communicating pair will be loaded into ciphertext in the phase place or polarization information of single photon.At present, real single-photon source implements to also have very long distance apart from through engineering approaches, what in present stage experiment and practical project implementing process, use is mostly the weak coherent light source through overdamping, this light source adopts the very ripe semiconductor laser diode of existing communication system, has that cost is low, volume is little, be easy to the features such as integrated.But, because this light source is not desirable single-photon source, in each photon pulse, have certain multi-photon probability, and actual (imperfect) quantum channel exists certain photon loss, listener-in separates attack (PNS attack) method by number of photons and implements not found eavesdropping.For stopping this security breaches, scientists has proposed trick state quantum coding scheme, makes the weak coherent light source equally can be for the QKD without security breaches.Inveigle state scheme require transmitting terminal take special ratios (specifically according to counting statistics fluctuation optimal design) produce at random every average pulse number of photons as μ=0, the light pulse signal of μ=0.2, μ=0.6; Wherein, corresponding zero photon state in μ=0, μ=0.6 respective signal state, the corresponding state of inveigling in μ=0.2.This scheme requirement, the light pulse of signal state is with the light pulse of trick state except average photon number has difference, and other characteristic parameters are all identical.In existing system, conventionally utilize two laser diodes to produce respectively signal state and inveigle state, owing to having adopted two laser diodes, the optical signature parameters such as the light signal centre wavelength of launching, spectral width, pulse duration are difficult to be consistent, assailant just can distinguish signal state and inveigle state by means of this inconsistency, thereby has security breaches.On the other hand, the inconsistency of centre wavelength and spectral width can cause light signal to have polarization dispersion in long-distance optical fiber transmission, reduce the detection efficient of receiving terminal single-photon detector, and then reduction system becomes code efficiency.
Polarization encoder QKD scheme adopts four laser diodes to add that four polarizers encode, modulation produces a pair of " the inclined to one side base of line " (45 ° of line polarisations and 135 ° of line polarisations) and a pair of " the inclined to one side base of circle " (left-handed rotatory polarization and dextrorotation rotatory polarization), receiving terminal recycles corresponding polarisation based decoding, completes thus the transmission of information.Here with four laser diodes, produce four polarization states equally, the inconsistent shortcoming of centre wavelength and spectral width highlights again.In conjunction with inveigling state scheme, system needs eight laser diodes altogether, and the complexity that this has increased system has undoubtedly reduced system compact degree, is unfavorable for that the through engineering approaches of QKD system is integrated.
How realizing trick state quantum coding is at a high speed the key of current QKD technology to the development of the high one-tenth of high speed code efficiency.
Utility model content
The purpose of this utility model is the preparation of a kind of trick quantum state that is applicable to high speed polarization encoder QKD system of proposing for the deficiencies in the prior art, i.e. the trick state quantum light source generation device of high speed polarization encoder
, itsthe technical barriers such as the trick state signal generation that exists in High Speed System, polarization state Stochastic Modulation, high-speed narrow pulse generation, the coupling of high-speed radio-frequency electric pulse, system sequence logic control have been solved.
The purpose of this utility model is achieved in that
A kind of trick state quantum light source generation device of high speed polarization encoder, this device comprises high speed logic control chip, inveigle state light pulse driver module, high-speed phase modulator driver module, laser diode, high-speed phase modulating polarization rotary module and optical attenuator, described high speed logic control chip one tunnel connects inveigles state light pulse driver module, one tunnel connects high-speed phase modulator driver module, inveigle state light pulse driver module to connect laser diode, laser diode output optical signal connects high-speed phase modulating polarization rotary module by optical fiber, high-speed phase modulator driver module connects high-speed phase modulating polarization rotary module, high-speed phase modulating polarization rotary module connects optical attenuator, wherein, high speed logic control chip is control core, inveigle state light pulse driver module to receive the control signal from high speed logic control module, according to the proportion requirement Stochastic Modulation of inveigling state quantum light source embodiment, produce the trick state electric impulse signal of three kinds of pulse amplitudes, the trick state light pulse of three kinds of light intensity of driving laser diode output, inveigle the high-speed phase modulator Stochastic Modulation of state light pulse signal in high-speed phase modulating polarization rotary module to go out " the inclined to one side base of line " and " the inclined to one side base of circle " totally four kinds of polarization states, high-speed phase modulator is driven by high-speed phase modulator driver module, through optical attenuator, every pulsed light subnumber is decayed to single photon level again and produce three kinds of optical power intensity, four kinds of polarization states totally nine kinds of quantum states.
Described trick state light pulse driver module comprises high-speed, true random-number expansion module and inveigles state electric pulse generation module, described high-speed, true random-number is expanded module and is connected trick state electric pulse generation module, inveigle state electric pulse generation module to receive high-speed, true random-number and expand the true random number signal that module produces, according to the proportion requirement of inveigling state quantum light source embodiment, produce at random three kinds of electric impulse signals that pulse amplitude is different, driving laser diode carries out the direct modulation of three kinds of intensity, and by the light pulse signal of three kinds of states of laser diode output: window pulse, the light pulse signal of every pulsed light intensity 1:3.
Described trick state electric pulse generation module consists of the first electric pulse generation module, the first electric pulse generation module, broadband power synthesizer and RF cascade driver, described the first electric pulse generation module and the second electric pulse generation module be random produces the narrow electric impulse signal of two kinds of different amplitudes or equal output electric pulse signals not, through broadband power synthesizer, is coupled as road output after RF cascade driver amplifies again.
Described high-speed phase modulator driver module expands module by high-speed, true random-number and four states form with mechanical-electronic pulse generation module, described high-speed, true random-number is expanded module and is connected four states with mechanical-electronic pulse generation module, described four states receive high speed random number with mechanical-electronic pulse generation module and expand the true random number signal that module produces, according to the four kinds of electric impulse signals that output pulse amplitude is different that require of phase-modulated polarized rotation light path, drive high-speed phase modulator to carry out the direct modulation of four kinds of phase places.
Described high-speed phase modulating polarization rotary module consists of high-speed phase modulator and phase-modulated polarized rotation light path, described high-speed phase modulator is connected with phase-modulated polarized rotation light path by optical fiber, phase-modulated polarized rotation light path receives the trick state light pulse signal of laser diode output, by optical controller part, be divided into the orhtogonal linear polarizaiton light that two-way amplitude equates, initial phase is identical and be called " A light ", " B light ", wherein only " A light " accepts the modulation of high-speed phase modulator; Its high-speed phase modulator is driven by high-speed phase modulator driver module, modulation described " A light " produces four kinds of different phase shifts, described " A light " superposes at phase-modulated polarized rotating light way outlet after the optical path of equal length with " B light ", random output " the inclined to one side base of line " and " the inclined to one side base of circle " totally four kinds of polarization states after stack.
Described phase-modulated polarized rotation light path is structure or " the Plug & Play " structure based on faraday-Sagnac loop, input light can be carried out to Polarization Control and is divided into the orhtogonal linear polarizaiton light that two-way amplitude equates, initial phase is identical; Can guarantee two-way light when delivery outlet superposes by the optical path of equal length; High-speed phase modulator is only modulated " A light " in phase-modulated polarized rotation light path, and " B light " is not modulated.
Described four states consist of four electric pulse generation modules, broadband power synthesizer and RF cascade driver with mechanical-electronic pulse generation module, the random rectangle electric impulse signal that produces four kinds of different amplitudes of described four electric pulse generation modules, is coupled as road output after RF cascade driver amplifies again through broadband power synthesizer.
Described electric pulse generation module comprises amplitude stabilization control module, clock alignment module, Short pulse generation module, pulse amplitude control module and digital control module, the output digit signals that described amplitude stabilization control module is expanded module by high-speed, true random-number carries out amplitude stabilization control the constant signal of output amplitude, again through the time delay of clock alignment module fine registration, and according to application requirements, produce narrow pulse signal or rectangular pulse signal by Short pulse generation module, finally by pulse amplitude control module, described pulse signal is carried out the continuous control of amplitude, digital control module produces control signal to aforesaid module automation control.
The driving semaphore request of described high-speed phase modulator is: light pulse is modulated to electric pulse " flat-top " middle position, and electric pulse " top width " is greater than light pulse " bottom width ", and electric pulse " bottom width " is less than the difference of light pulse cycle and light pulse " bottom width ".
Structural design of the present utility model guarantees only to need a laser diode just can produce three kinds of average photon number intensity, four kinds of polarization states any one in totally nine kinds of quantum states up to GHz or higher speed Stochastic Modulation, and the optical characteristics such as different quantum state centre wavelength, spectral width, pulse duration all has consistency.Its volume is little, compact conformation, be easy to integrated.In traditional scheme, utilize eight laser diodes to produce the scheme of nine kinds of quantum states, the utility model has solved the inconsistent difficult problems of optical characteristics such as different quantum state centre wavelengths in long-term puzzlement polarization encoder QKD system, spectral width, pulse duration, effectively evade the quantum based on above-mentioned inconsistency that QKD system may exist future and attacked, improved system safety grade.
Accompanying drawing explanation
Fig. 1 is the utility model apparatus structure schematic diagram;
Fig. 2 is that the utility model is inveigled state electric pulse generation module structural representation;
Fig. 3 is the phase-modulated polarized rotating light line structure schematic diagram of the utility model based on faraday-Sagnac (Faraday-Sagnac) ring structure;
Fig. 4 is the phase-modulated polarized rotating light line structure schematic diagram of the utility model based on " Plug & Play " structure;
Fig. 5 is that the utility model four states are with mechanical-electronic pulse generation module structural representation;
Fig. 6 is the utility model electric pulse generation module structural representation;
Fig. 7 is that the utility model high-speed phase modulator drives electric pulse timing diagram;
Fig. 8 is the light pulse of the utility model high-speed phase modulators modulate and driving electric pulse parameter figure.
Embodiment
Below in conjunction with accompanying drawing, by embodiment, the utility model is described in further detail, so that technical staff's of the same trade understanding.
Embodiment
Consult Fig. 1, the utility model device comprises high speed logic control chip, inveigle state light pulse driver module, high-speed phase modulator driver module, laser diode, high-speed phase modulating polarization rotary module and optical attenuator, described high speed logic control chip one tunnel connects inveigles state light pulse driver module, one tunnel connects high-speed phase modulator driver module, inveigle state light pulse driver module to connect laser diode, laser diode output optical signal connects high-speed phase modulating polarization rotary module by optical fiber, high-speed phase modulator driver module connects high-speed phase modulating polarization rotary module, high-speed phase modulating polarization rotary module connects optical attenuator, wherein said trick state light pulse driver module receives the control signal from high speed logic control chip, according to the proportion requirement Stochastic Modulation of inveigling state quantum light source embodiment, produce the trick state electric impulse signal of three kinds of pulse amplitudes, drive the trick state light pulse of three kinds of light intensity of described laser diode output, described trick state light pulse signal goes out " the inclined to one side base of line " (45 ° of linear polarization and 135 ° of linear polarization) and " the inclined to one side base of circle " (left-handed rotatory polarization and dextrorotation rotatory polarization) totally four kinds of polarization states through high-speed phase modulating polarization rotary module by high-speed phase modulator Stochastic Modulation, through optical attenuator, decay to single photon level again and can prepare three kinds of optical power intensity, four kinds of polarization states are any one in totally nine kinds of quantum states.
Consult Fig. 1-8, the concrete enforcement of the utility model comprises the steps:
1. inveigle state optical pulse generation: as shown in Figure 1, inveigle state light pulse driver module to comprise high-speed, true random-number expansion module and inveigle state electric pulse generation module, described trick state electric pulse generation module receives high-speed, true random-number and expands the 2 bit true random signals that module produces, according to the proportion requirement of inveigling state quantum light source embodiment, produce at random 3 kinds of electric impulse signals that pulse amplitude is different and be coupled into a road output, through RF cascade driver, amplify driving laser diode again and carry out the direct modulation of three kinds of intensity, can export window pulse by laser diode, the light pulse signal of every pulsed light intensity 1:3.
High-speed, true random-number is expanded module and is produced two-way high-speed, true random-number signal, and according to random 00,01,10 the 3 groups of random signals that produce of the proportion requirement of inveigling state quantum light source embodiment, concrete ratio is according to counting statistics fluctuation optimal design.When random number series is 00, PORT 1 and PORT 2 all do not trigger, and now inveigle the output of state electric pulse generation module no signal, and respective laser diodes is also without optical pulse generation, corresponding to 0 photon state of inveigling in state scheme; When random number series is 01, trigger PORT 1, now inveigle state electric pulse generation module to produce the short pulse signal that pulse amplitude is V1, through RF cascade driver drives laser diode, produce the light signal that average light power is P1, corresponding to the trick state of inveigling in state scheme; When random number columns is 10, trigger PORT 2, now inveigle state electric pulse generation module produce pulse amplitude be V2(V2>V1) short pulse signal, through RF cascade driver drives laser diode, producing average light power is P2(P2=3P1) light signal, corresponding to the signal state of inveigling in state scheme.
As shown in Figure 2, described trick state electric pulse generation module consists of electric pulse generation module 1～2, broadband power synthesizer and RF cascade driver.Described electric pulse generation module 1 and electric pulse generation module 2 produce respectively the narrow electric impulse signal of two kinds of different amplitudes, through described broadband power synthesizer, are coupled as road output after RF cascade driver amplifies again.
This step has solved a coupling difficult problem for high speed short pulse, and along with the lifting of system repetition rate, the design of circuit need to adopt the method for designing of radio circuit.In low speed scheme, the PCB layout that signal coupling conventionally adopts directly connected method is inadvisable.This step adopts RF cascade driver that higher isolation is exported and guaranteed in undistorted two paths of signals coupling, realizes transmission line 50 ohms impedance match of two paths of signals input and output simultaneously.RF cascade driver requires bandwidth wide as far as possible, and inband flatness is high, with reduce signal by time the pulse duration broadening effect that occurs, specifically can adopt resistance-type (Resistive) power combiner or Reactive power combiner.
2. " the inclined to one side base of line " and " the inclined to one side base of circle " preparation: high-speed phase modulating polarization rotary module of the present utility model consists of high-speed phase modulator and phase-modulated polarized rotation light path, the trick state light pulse signal of laser diode output enters phase-modulated polarized rotation light path, by optics control, be divided into the orhtogonal linear polarizaiton light (being called " A light ", " B light ") that two-way amplitude equates, initial phase is identical, wherein only " A light " accepts the modulation of described high-speed phase modulator.High-speed phase modulator is driven by the random electric impulse signal that produces four kinds of different amplitudes of described high-speed phase modulator driver module, modulation described " A light " produces 0 at random, pi/2, π, 3 pi/2s amount to four kinds of different phase shifts, " A light " superposes at phase-modulated polarized rotating light way outlet after the optical path of equal length with " B light " subsequently, according to the orthogonal linearly polarized light superposition principle of wave of direction of vibration, have after the poor cross line polarisation of out of phase superposes and can export at random " the inclined to one side base of line " and " the inclined to one side base of circle " totally four kinds of polarization states.
Phase-modulated polarized rotation light path in described high-speed phase modulating polarization rotary module has following characteristic: input light can be carried out to Polarization Control and is divided into the orhtogonal linear polarizaiton light that two-way amplitude equates, initial phase is identical; Can design and guarantee that two-way light passes through equal length optical path when delivery outlet superposes by optical texture; High-speed phase modulator is only modulated " A light " in phase-modulated polarized rotation light path, and " B light " is not modulated.Phase-modulated polarized rotation light path selects structure based on faraday-Sagnac (Faraday-Sagnac) ring or " Plug & Play " optical texture and other to have the light path of above-mentioned optical function.
As shown in Figure 3, phase-modulated polarized rotation light path is the structure based on faraday-Sagnac (Faraday-Sagnac) ring, by optical path, selects module, Polarization Control module, four port polarization beam splitters (PBS), faraday rotation mirror (FM), monomode fiber, polarization maintaining optical fibre to form.The trick state light pulse signal of laser diode output is selected module to be coupled into Polarization Control module through optical path and is produced line polarisation, described line polarisation polarization direction and four port PBS crystal inside S light directions angle at 45 °, guarantee to be divided into through the linearly polarized light of four port PBS port one incidents the orhtogonal linear polarizaiton light that two bundle amplitudes equate, initial phase is identical.Wherein through the linearly polarized light (being called for short " B light ") of four port PBS transmissions, through a section single-mould fiber, enter FM, FM is back to four port PBS by incident light polarization state half-twist Bing Yanyuan road, identical with the path that light is walked of FM outgoing owing to entering FM, adopt monomode fiber can realize polarization state auto-compensation; " B light " will be propagated counterclockwise along Sagnac (Sagnac) ring by 4 port outputs after four port PBS reflections, when high-speed phase modulator, not accept modulation, finally return to four port PBS.The linearly polarized light (being called for short " A light ") of another Lu Jingsi port PBS reflection is along propagating and meet at four port PBS at synchronization and " B light " with " B light " antipodal light path, and unique difference is that " A light " accept modulation when through high-speed phase modulator.Because " A light " and " B light " all encircle one-way transmission along Sagnac (Sagnac), this path does not have polarization compensation effect, thereby the optical fiber connecting between four port PBS and high-speed phase modulator adopts the polarization maintaining optical fibre with polarization maintenance effect, high-speed phase modulator adopts protects higher fast phase-modulator, and while guaranteeing linearly polarized light along the transmission of Sagnac (Sagnac) ring, polarization state is constant.Two-way crossed polarized light is through behind identical path, in the stack of four port PBS port one places, according to the orthogonal linearly polarized light superposition principle of wave of direction of vibration, determine synthetic polarisation of light state, synthetic Guang Zaiyanyuan returns on road through Polarization Control module and by optical path and selects module 3 ports to export.
As shown in Figure 4, phase-modulated polarized rotation light path is the optical texture based on " Plug & Play ", by optical path, selects module, Polarization Control module, polarization beam apparatus 1(PBS1), polarization beam apparatus 1(PBS2), faraday rotation mirror (FM), monomode fiber, polarization maintaining optical fibre form.The trick state light pulse signal of described laser diode output is selected module to be coupled into Polarization Control module through optical path and is produced line polarisation, line polarisation polarization direction and PBS1 crystal inside S light direction angle at 45 °, guarantee that through the linearly polarized light of PBS1 incident, being divided into the orhtogonal linear polarizaiton light that two bundle amplitudes equate, initial phase is identical transmits (long and short two arm forms by polarization maintaining optical fibre) along the long and short two arm of " Plug & Play " light path respectively.Wherein through the linearly polarized light (being called for short " B light ") of PBS1 transmission, along galianconism, transmit and be coupled into a section single-mould fiber by PBS entering FM, FM returns to incident light polarization state half-twist Yan Yuan road through PBS2 and enters the long-armed of " Plug & Play " light path and return to PBS1 exit.Another road enters long-armed through the linearly polarized light (being called for short " A light ") of PBS1 reflection, along meeting at PBS1 with " B light " antipodal propagated and at synchronization and " B light ", difference is that " A light " accept modulation when through high-speed phase modulator, two-way crossed polarized light is through behind identical path, at PBS1 place, superpose, according to the orthogonal linearly polarized light superposition principle of wave of direction of vibration, determine synthetic polarisation of light state, synthetic Guang Zaiyanyuan returns on road through Polarization Control module and by optical path and selects module 3 ports to export.In the present embodiment, the long and short two arm that connects high-speed phase modulator all adopt polarization maintaining optical fibre with guarantee line polarisation polarization keep effect.
The principle of high-speed phase modulator is that the refractive index of fiber waveguide is proportional to the effect of the variation of extra electric field based on linear electro-optic effect (pockeles effect).Electro optic effect makes the fiber waveguide refractive index linear change in high-speed phase modulator, causes producing phase shifts by the light wave of this waveguide, thereby realizes phase-modulation.By load the voltage signal of different amplitudes on high-speed phase modulator, can realize the continuous modulation to input light phase.
Described high-speed phase modulator driver module expands module by high-speed, true random-number and four states form with mechanical-electronic pulse generation module, described high-speed, true random-number is expanded module and is accepted the 2bit random controling signal that high speed logic control chip produces, random triggering PORT1～4 port is produced the rectangle electric impulse signal of four kinds of different amplitudes with mechanical-electronic pulse generation module by four states, drive high-speed phase modulator to four kinds of different phase shifts of modulation optical pulse generation.Table 1 has listed that synthetic polarization state, two-way orhtogonal linear polarizaiton light phase are poor, relation (the wherein V of high-speed phase modulators modulate voltage and random signal
∏for high-speed phase modulator produces the corresponding half-wave voltage of π phase shift):
| Random signal | High-speed phase modularot voltage | Two-way orhtogonal linear polarizaiton light phase is poor | Synthetic polarization state |
| 00 | 0 | 0 | 45 ° of linearly polarized lights |
| 01 |
 |
 |
Left circularly polarized light |
| 10 |
 |
 |
135 ° of linearly polarized lights |
| 11 |
 |
 |
Right-circularly polarized light |
Table 1 high-speed phase modulating polarization rotary module output polarization state, two-way orhtogonal linear polarizaiton light phase are poor, the relation of PM modulation voltage and random signal
As shown in Table 1, when random signal is 00, high-speed phase modulator driver module Non voltage output, now high-speed phase modulator does not produce phase shift, and two-way orhtogonal linear polarizaiton light phase is poor is 0, and synthetic polarization state is 45 ° of linearly polarized lights; When random signal is 01, high-speed phase modulator driver module generation amplitude is V
π/ 2 pulse signal, now two-way orhtogonal linear polarizaiton light phase is poor is pi/2, synthetic polarization state is left circularly polarized light; When random signal is 10, high-speed phase modulator driver module generation amplitude is V
πpulse signal, now two-way orhtogonal linear polarizaiton light phase is poor is π, synthetic polarization state is 135 ° of linearly polarized lights; When random signal is 11, high-speed phase modulator driver module generation amplitude is 3V
π/ 2 pulse signal, now two-way orhtogonal linear polarizaiton light phase is poor is 3 pi/2s, synthetic polarization state is right-circularly polarized light.Wherein, 45 ° of linearly polarized lights and 135 ° of linearly polarized lights form pair of orthogonal base, are called " the inclined to one side base of line "; Left circularly polarized light and right-circularly polarized light form orthogonal basis, are called " the inclined to one side base of circle ", are prepared into thus the two pairs of polarisation based totally four kinds of polarization states that meet polarization encoder QKD system requirements.
As shown in Figure 5, four states consist of electric pulse generation module (four), broadband power synthesizer and RF cascade driver with mechanical-electronic pulse generation module, described electric pulse generation module 3～6 produces respectively the rectangle electric impulse signal of four kinds of different amplitudes, through described broadband power synthesizer, be coupled as road output after RF cascade driver amplifies again, produce at random 0, V
π/ 2, V
π,3V
π/ 2 the electric impulse signal of totally four kinds of different voltage amplitudes drive high-speed phase modulator.
As shown in Figure 6, electric pulse generation module comprises amplitude stabilization control module, clock alignment module, Short pulse generation module, pulse amplitude control module and digital control module, the output digit signals that described amplitude stabilization control module is expanded module by high-speed, true random-number carries out amplitude stabilization control output, again through the time delay of clock alignment module fine registration, and according to application requirements, produce narrow pulse signal or rectangular pulse signal by Short pulse generation module, wherein narrow pulse signal is used for inveigling state electric pulse generation module, rectangular pulse signal is used for four states with mechanical-electronic pulse generation module.Finally by pulse amplitude control module paired pulses amplitude, carry out continuous control to meet the requirement of disparate modules, described digital control module produces the automation control of the responsible above-mentioned module of control signal.
3. high-speed phase modulator driving signal control: as shown in Figure 7, square waveform is that phase-modulation drives electric pulse, and Gaussian waveform (solid line) is " A light " pulse, and Gaussian waveform (dotted line) is " B light " pulse.Diagram light pulse is respectively trick state light signal, signal state light signal, the zero photon state light signal of inveigling in state scheme from left to right, (above-mentioned sequence does not represent real sequence to zero photon state, in actual implementation process, the modulation timing completely random of three kinds of light signals).The voltage amplitude that the pulse of diagram modulation electric is respectively the generation of high-speed phase modulator driver module is from left to right V
π/ 2, V
π,3V
π/ 2,0 rectangle electric pulse (above-mentioned sequence does not represent real sequence, in actual implementation process, and four kinds of modulation voltage sequential completely randoms).
As shown in Figure 8, the modulation electric pulse the non-ideal impulse that load due to high-speed phase modulator, but exist the rise/fall of certain hour length along (T
r/ T
f); Meanwhile, the light pulse that high-speed phase modulator passes through is generally Gaussian waveform, and typical halfwidth is 30ps.When light pulse be modulated to drive electric pulse rise/fall along time, there will be the corresponding modulation electric pulse amplitude of light pulse diverse location difference, it is the phase shift difference that light pulse diverse location produces, and then light pulse polarization state is inconsistent to make to superpose synthetic at phase-modulated polarized rotating light way outlet place, precision prepared by polarisation-affecting state.On the other hand, all there is unavoidable time jitter in light pulse and modulation electric pulse, when be modulated to rise/fall along time, time jitter can be aggravated the inconsistency of output polarization state.Therefore, high-speed phase modulator is strictly controlled by light pulse and modulation electric pulse parameter and sequential: require light pulse to be modulated to centre " flat-top " centering portions of electric pulse, electric pulse " top width " (δ) is greater than described light pulse " bottom width " (г) simultaneously, make modulation electric pulse produce identical phase shift to whole Gauss-pulse, reach the modulation completely to light pulse.By above means, eliminate electrical pulse time shake and the impact of amplitude jitter on modulation inconsistency.Electric pulse " bottom width " is less than the difference of light pulse cycle and light pulse " bottom width ", and assurance high-speed phase modulator is only modulated " A light " along phase-modulated polarized rotation light path.
4. light signal strength decay:
" the inclined to one side base of line " produces three kinds of light pulse intensity, four kinds of polarization states totally nine kinds of light pulse signals with " the inclined to one side base of circle ", by after fibre optic attenuator by quantum state light signal, comprise average photon number decay to single photon level, it is μ=0.2 and μ=0.6 that the light pulse that is 1:3 by intensity decays to every average pulse number of photons, prepares three kinds of light pulse intensity, four kinds of polarization states, 9 kinds of quantum states altogether.
The utility model has been realized the quantum state preparation that is applicable to high speed polarization encoder QKD system, for quantum secret communication provides solution to higher rate development.
Claims (8)
1. the trick state quantum light source generation device of a high speed polarization encoder, it is characterized in that this device comprises high speed logic control chip, inveigle state light pulse driver module, high-speed phase modulator driver module, laser diode, high-speed phase modulating polarization rotary module and optical attenuator, described high speed logic control chip one tunnel connects inveigles state light pulse driver module, one tunnel connects high-speed phase modulator driver module, inveigle state light pulse driver module to connect laser diode, laser diode output optical signal connects high-speed phase modulating polarization rotary module by optical fiber, high-speed phase modulator driver module connects high-speed phase modulating polarization rotary module, high-speed phase modulating polarization rotary module connects optical attenuator.
2. trick state quantum light source generation device according to claim 1, it is characterized in that described trick state light pulse driver module comprises high-speed, true random-number expansion module and inveigles state electric pulse generation module, described high-speed, true random-number is expanded module and is connected trick state electric pulse generation module.
3. trick state quantum light source generation device according to claim 2, it is characterized in that described trick state electric pulse generation module consists of the first electric pulse generation module, the second electric pulse generation module, broadband power synthesizer and RF cascade driver, described the first electric pulse generation module and the second electric pulse generation module produce the narrow electric impulse signal of two kinds of different amplitudes or equal output electric pulse signals not, through broadband power synthesizer, are coupled as road output after RF cascade driver amplifies again.
4. trick state quantum light source generation device according to claim 1, it is characterized in that described high-speed phase modulator driver module is expanded module by high-speed, true random-number and four states form with mechanical-electronic pulse generation module, described high-speed, true random-number is expanded module and is connected four states with mechanical-electronic pulse generation module.
5. trick state quantum light source generation device according to claim 1, it is characterized in that described high-speed phase modulating polarization rotary module consists of high-speed phase modulator and phase-modulated polarized rotation light path, described high-speed phase modulator is connected with phase-modulated polarized rotation light path by optical fiber.
6. trick state quantum light source generation device according to claim 5, is characterized in that described phase-modulated polarized rotation light path is structure or " the Plug & Play " structure based on faraday-Sagnac loop.
7. trick state quantum light source generation device according to claim 4, it is characterized in that described four states consist of four electric pulse generation modules, broadband power synthesizer and RF cascade driver with mechanical-electronic pulse generation module, the random rectangle electric impulse signal that produces four kinds of different amplitudes of described four electric pulse generation modules, is coupled as road output after RF cascade driver amplifies again through broadband power synthesizer.
8. according to the trick state quantum light source generation device described in claim 3 or 7, it is characterized in that described electric pulse generation module comprises amplitude stabilization control module, clock alignment module, Short pulse generation module, pulse amplitude control module and digital control module, digital control module connects respectively amplitude stabilization control module, clock alignment module, Short pulse generation module and pulse amplitude control module.
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| CN111969404A (en) * | 2020-10-21 | 2020-11-20 | 国开启科量子技术(北京)有限公司 | Method and device for preparing decoy state without intensity modulator |
| CN112217575A (en) * | 2019-07-12 | 2021-01-12 | 科大国盾量子技术股份有限公司 | Method and system for calibrating light intensity ratio of decoy state optical signal and signal state optical signal |
| CN114338020A (en) * | 2022-03-15 | 2022-04-12 | 浙江九州量子信息技术股份有限公司 | Quantum key distribution coding device |
| CN114465717A (en) * | 2021-12-31 | 2022-05-10 | 华南师范大学 | Quantum key distribution system and method capable of controlling pulse delay |
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| CN112217575A (en) * | 2019-07-12 | 2021-01-12 | 科大国盾量子技术股份有限公司 | Method and system for calibrating light intensity ratio of decoy state optical signal and signal state optical signal |
| CN111969404A (en) * | 2020-10-21 | 2020-11-20 | 国开启科量子技术(北京)有限公司 | Method and device for preparing decoy state without intensity modulator |
| CN111969404B (en) * | 2020-10-21 | 2022-02-22 | 国开启科量子技术(北京)有限公司 | Method and device for preparing decoy state without intensity modulator |
| CN114465717A (en) * | 2021-12-31 | 2022-05-10 | 华南师范大学 | Quantum key distribution system and method capable of controlling pulse delay |
| CN114465717B (en) * | 2021-12-31 | 2023-06-30 | 华南师范大学 | Quantum key distribution system capable of controlling pulse delay and method thereof |
| CN114338020A (en) * | 2022-03-15 | 2022-04-12 | 浙江九州量子信息技术股份有限公司 | Quantum key distribution coding device |
| CN114338020B (en) * | 2022-03-15 | 2022-06-24 | 浙江九州量子信息技术股份有限公司 | Quantum key distribution coding device |
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