CN115373632A - Quantum random number generation system based on laser phase fluctuation of polarization - Google Patents
Quantum random number generation system based on laser phase fluctuation of polarization Download PDFInfo
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Abstract
The invention discloses a quantum random number generating system based on polarization laser phase fluctuation, which relates to the field of quantum random numbers and comprises a pulse laser module, a light intensity stabilizing module, an interference module, a detection module, an analog-to-digital conversion module and a data post-processing module which are sequentially connected, wherein the pulse laser module, the light intensity stabilizing module and the interference module are sequentially connected through a polarization maintaining optical fiber, the pulse laser module is used for preparing two paths of light pulses, one path of light pulse is coupled into a fast axis of the polarization maintaining optical fiber, the other path of light pulse is coupled into a slow axis of the polarization maintaining optical fiber, and the interference module rotates and then couples the polarization directions of the two paths of light pulses to realize interference. The invention carries out interference measurement by two independent lasers, and replaces the laser self-interference technology in the prior art; the distributed feedback laser is selected, so that a good interference effect can be realized; the invention realizes interference measurement by a rotary coupling mode and can eliminate the influence of polarization fluctuation on interference effect.
Description
Technical Field
The invention relates to the field of quantum random numbers, in particular to a quantum random number generation system based on polarization laser phase fluctuation.
Background
Random numbers are basic resources for science and engineering, and have important applications in simulation and cryptography. The generation of classical random numbers is often based on deterministic algorithms or predictable complex physical phenomena, which are easy to use, but at the same time, security threats exist in the generation process of random numbers. The random numbers generated in these ways are called pseudo-random numbers, which cannot meet the security requirements in highly confidential applications. In contrast, a quantum random number generator can be referred to as a true random number generator, and the random number output by the quantum random number generator is measured from a variable having an intrinsic random characteristic in a quantum physical system.
At present, quantum random number generation is one of the most mature techniques in quantum technology, and various generation methods can be selected, for example, earlier practical quantum random number generators mostly adopt a single-photon scheme. In recent years, a laser phase fluctuation scheme and a vacuum scheme become research hotspots of quantum random numbers, and the two schemes have the common characteristic that a high-speed photoelectric detector is adopted to replace a traditional single-photon detector, so that the generation rate of the random numbers is not limited by the saturation counting rate of the single-photon detector any more, and the random number reaches Gbps magnitude.
The prior art "quantum random number generation device, method and generator for suppressing noise" (CN 202010198459.2) "uses a narrow linewidth laser as an entropy source, performs self-interference through an unequal arm mach-zehnder interferometer, and eliminates the light intensity bias term in the measured value by using a method of homodyne detection or difference after analog-to-digital conversion, thereby having the effect of suppressing laser intensity noise, but the technique has some problems, for example:
1. the laser self-interference method adopted by the technology can cause the phase correlation of front and rear pulses to influence the self-coherence coefficient of original data, and when the generation rate of the original data is high (about 50 Mbps), the self-coherence coefficients of two adjacent items of the original data are obviously improved, so that the quality and the generation rate of random numbers are limited;
2. in order to reduce the correlation between adjacent pulses, the optical path difference between two arms of the interferometer needs to be larger than the coherence length of light, which makes the device complicated and is not beneficial to realizing integration;
3. the technology uses an SFP laser or an SLED light source as an entropy source, the SFP laser is a common device in optical communication, high-frequency light pulses can be emitted at low cost, but the center frequency of light is unstable, the line width is wide, and a good interference effect cannot be achieved; SLED spectrum is wider, self-interference effect is also poor, SFP laser or SLED light source is not ideal entropy source in laser phase fluctuation scheme.
In the prior art, a quantum random number generation method and a system based on difference after detection (CN 202210671742.1) adopts two lasers with similar frequencies for interference, and combines a proper data post-processing method, so that the problem of relevance between two adjacent measurements can be solved. The technology also separates quantum noise from classical noise in the data post-processing process, so that the minimum entropy is improved, but at the same time, the technology has problems, such as: the technology does not consider the influence of polarization fluctuation on the interference result, and the optimal interference effect can be achieved only when the polarization directions of the two beams of light are completely the same. In a high-precision photoelectric system, a single-mode optical fiber needs to be subjected to polarization calibration every tens of minutes, and particularly in an integrated quantum random number generator, the bending and jitter of the optical fiber have a non-negligible influence on polarization.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a quantum random number generation system based on polarization laser phase fluctuation, which solves a series of problems caused by the current laser self-interference method, the problem of improper selection of an ideal entropy source in a laser phase fluctuation scheme and the problem of influence caused by polarization fluctuation in the interference process. The invention carries out interference measurement by two independent lasers, and replaces the laser self-interference technology in the prior art; the distributed feedback laser is selected, so that a good interference effect can be realized; the invention realizes interference measurement by using a rotary coupling mode in a polarization-maintaining light path, and can eliminate the influence of polarization fluctuation on interference effect.
The technical scheme is as follows: a quantum random number generating system based on polarization laser phase fluctuation comprises a pulse laser module, a light intensity stabilizing module, an interference module, a detection module, an analog-to-digital conversion module and a data post-processing module which are sequentially connected, wherein the pulse laser module, the light intensity stabilizing module and the interference module are sequentially connected through a polarization maintaining optical fiber;
the pulse laser module is used for preparing two paths of light pulses, wherein one path of light pulse is coupled into the fast axis of the polarization maintaining optical fiber and is expressed as
The other path of light pulse is coupled into the slow axis of the polarization maintaining fiber and is expressed as
Wherein mu and upsilon respectively represent the light intensity of the two paths of light pulses, i is an imaginary unit,
the phase difference between the two paths of light pulses;
the light intensity stabilizing module is used for attenuating two paths of light pulses;
the interference module couples the polarization directions of the two paths of light pulses after rotating, so that the light pulses transmitted by the fast axis of the polarization maintaining optical fiber interfere with the light pulses transmitted by the slow axis of the polarization maintaining optical fiber;
the detection module converts an optical signal obtained after interference into an analog electric signal;
the analog-to-digital conversion module converts the analog electric signal into a digital electric signal;
and the data post-processing module processes the original data.
Furthermore, the two optical pulses prepared by the pulse laser module are high-extinction-ratio optical pulses, the duty ratios and the frequencies of the two optical pulses are the same, the optical frequency errors of the two optical pulses are within a GHz level, the duty ratios of the two prepared optical pulses are both 50%, and the light intensity stabilizing module is used for attenuating the two optical pulses until the light intensity difference of the attenuated two optical pulses is within 5%.
Further, the pulse laser module comprises a first pulse laser and a second pulse laser, the light intensity stabilizing module comprises a first optical attenuator and a second optical attenuator, and the interference module comprises a polarization-maintaining beam splitter and a polarization beam splitter which are connected through a polarization-maintaining optical fiber;
the first pulse laser, the first optical attenuator and the polarization-maintaining beam splitter are connected in sequence through polarization-maintaining optical fibers, and the second pulse laser, the second optical attenuator and the polarization-maintaining beam splitter are connected in sequence through polarization-maintaining optical fibers;
the first pulse laser and the second pulse laser are used for preparing two paths of optical pulses with high extinction ratio and sending the optical pulses to the corresponding optical attenuators;
the first optical attenuator and the second optical attenuator attenuate received optical pulses, and the attenuated optical pulses are sent to the polarization-maintaining beam splitter;
the polarization-maintaining beam splitter is a polarization-maintaining input and output beam splitter and is used for coupling two paths of light pulses into one polarization-maintaining optical fiber;
the polarization beam splitter is used for realizing interference after the polarization directions of the two paths of light pulses are rotated.
Further, the polarization beam splitter is a 45 ° polarization beam splitter, the polarization directions of the two light pulses are rotated by 45 °, and the 45 ° rotation matrix is expressed as:
further, the detection module includes a first photodetector, the first photodetector is connected to the polarization beam splitter, and an optical signal obtained by the polarization beam splitter after interference is represented as:
the first photodetector is configured to convert an optical signal obtained after the interference into an analog electrical signal, where the intensity of the converted analog electrical signal is represented as:
wherein L is 1 Represents the firstElectrical noise of a photodetector, B is the conversion ratio of the first photodetector;
the analog-to-digital conversion module is an analog-to-digital converter;
the data post-processing module is a computer.
Further, the detection module includes a second photodetector, a third photodetector and a differential amplifier, the second photodetector is connected to the polarization beam splitter and the differential amplifier, the third photodetector is connected to the polarization beam splitter and the differential amplifier, and an optical signal obtained after the polarization beam splitter implements interference is represented as:
the second photodetector and the third photodetector are used for converting optical signals obtained after interference into analog electric signals, and the intensity of the converted analog electric signals is represented as:
wherein L is 2 、L 3 Respectively representing the electrical noise of the second photoelectric detector and the third photoelectric detector, and C is the conversion ratio of the second photoelectric detector and the third photoelectric detector;
the analog electrical signals are differenced, the difference being expressed as:
wherein Δ L represents a difference in electrical noise of the second photodetector and the third photodetector;
the analog-to-digital conversion module is an analog-to-digital converter;
the data post-processing module is a computer.
Furthermore, the pulse laser module further comprises a first temperature control device and a second temperature control device, the first temperature control device is connected with the first pulse laser, the first temperature control device is used for adjusting the center frequency of the first pulse laser, the second temperature control device is connected with the second pulse laser, and the second temperature control device is used for adjusting the center frequency of the second pulse laser.
The invention has the beneficial effects that:
1. according to the invention, two independent lasers are adopted for interference measurement, and compared with the current technical scheme, an interferometer is not needed any more, and the arm length difference stability of the interferometer is not needed to be controlled by a temperature control or feedback system, so that the system structure is simplified, and the system integration is favorably realized;
2. according to the invention, through the working mode of pulse + pulse, the correlation between adjacent pulses is eliminated, the quality of original data is improved, the self-coherence coefficient is not limited by the sampling interval of a detection end, and the generation rate of random numbers is improved;
3. the distributed feedback laser is selected and controlled by pulse driving current, so that the distributed feedback laser is narrow in line width and good in stability, and can achieve a good interference effect;
4. the invention realizes interference measurement by using a rotary coupling mode in a polarization-maintaining light path, realizes the generation of quantum random numbers on the premise of eliminating the influence of polarization fluctuation on interference effect, improves the randomness of original data, and can obtain higher random number generation rate under the condition of the same post-processing rate.
Drawings
FIG. 1 is a schematic diagram of a polarization-based laser phase fluctuation quantum random number generation system according to the present invention;
FIG. 2 is a schematic structural view of embodiment 1;
fig. 3 is a schematic structural diagram of embodiment 2.
Detailed Description
The invention is further described below with reference to the following figures and examples:
a method for a quantum random number generating system based on polarized laser phase fluctuation, the method comprising the steps of:
step 1: preparing two paths of optical pulses with high extinction ratio, wherein the duty ratios and the frequencies of the two paths of optical pulses are the same, the optical frequency errors of the two paths of optical pulses are within GHz magnitude, the duty ratios of the two paths of optical pulses are both 50%, the duty ratios and the frequencies of the optical pulses are determined by driving currents generated by the pulses, and the two paths of optical pulses are transmitted through a polarization maintaining optical fiber to perform an attenuation step, wherein one path of optical pulse is coupled into a fast axis of the polarization maintaining optical fiber, the other path of optical pulse is coupled into a slow axis of the polarization maintaining optical fiber, and the optical pulses can be prepared through a pulse laser;
step 2: attenuating the two paths of optical pulses until the light intensity difference of the attenuated two paths of optical pulses is within 5 percent, so that the intensities of the two paths of optical pulses are similar, and transmitting the attenuated optical pulses through a polarization maintaining optical fiber to perform an interference step;
and step 3: adjusting the delay time of the two paths of optical pulses to enable the two paths of optical pulses to reach an interference device at the same time, coupling the polarization directions of the two paths of optical pulses after the polarization directions are rotated by the interference device, wherein the rotation angle is 45 degrees, and enabling the optical pulses transmitted by the fast axis of the polarization maintaining optical fiber to interfere with the optical pulses transmitted by the slow axis of the polarization maintaining optical fiber;
and 4, step 4: converting the optical signal obtained after interference into an analog electrical signal, and then converting the analog electrical signal into a digital electrical signal;
and 5: extracting random numbers by using a method proved by strict safety, such as Toeplitz matrix extraction, to obtain quantum random numbers;
step 6: the randomness of the random numbers is tested by NIST and other standard randomness tests.
When the analog electric signal is converted into the digital electric signal, the analog electric signal is sampled firstly, the sampling frequency of analog-to-digital conversion is equal to the frequency of the optical pulse, then the sampling result is quantized by using a limited number of amplitude values, the quantization result is subjected to binary coding, and the analog-to-digital conversion can be completed by using an analog-to-digital converter.
Taking a group of analog electric signal data containing data amount a, removing the maximum value and minimum value of b%, using n-bit analog-to-digital converter, dividing the rest part into 2 according to the voltage distribution range n Each analog electric signal is converted into any binary number between 000 … 00-111 … 11 according to the signal intensity, the invention selects 100M, b selects 0.5, n selects 8.
In step 4, the analog electrical signal needs to eliminate the influence of the classical noise, the probability distribution of the analog electrical signal intensity without the influence of the classical noise is in standard arcsine curve distribution, and the standard arcsine curve distribution is represented as:
wherein the boundary value of the standard arcsine distribution curve is A;
wherein q is the analog electrical signal strength.
As shown in fig. 1, the system for generating quantum random number based on polarization laser phase fluctuation of the present invention comprises a pulse laser module, a light intensity stabilizing module, an interference module, a detection module, an analog-to-digital conversion module and a data post-processing module which are connected in sequence, in order to eliminate the influence of polarization fluctuation on interference effect, the present invention uses a polarization maintaining fiber to transmit light pulse, the polarization direction is not changed in the light pulse transmission process due to the use of the polarization maintaining fiber, the pulse laser module, the light intensity stabilizing module and the interference module are connected in sequence through the polarization maintaining fiber, the interference module is connected with the detection module through the fiber, and the detection module, the analog-to-digital conversion module and the data post-processing module are connected in sequence through a wire;
pulse laser moduleThe method is used for preparing two paths of light pulses with high extinction ratio, the duty ratio and the frequency of the two paths of light pulses are the same, the duty ratio and the frequency of the light pulses are determined by the driving current of a pulse laser module, the light frequency error of the two paths of light pulses is within a GHz magnitude, the duty ratios of the two paths of prepared light pulses are both 50%, one path of light pulse is coupled into a polarization maintaining optical fiber fast axis and is expressed as
The other path of light pulse is coupled into the slow axis of the polarization maintaining fiber and is expressed as
Wherein mu and upsilon respectively represent the light intensity of the two paths of light pulses, i is an imaginary unit,
is the phase difference between two light pulses>Is the right vector representation in the dirac notation.
The light intensity stabilizing module is used for attenuating the two paths of light pulses until the light intensity difference of the two paths of attenuated light pulses is within 5%, the light intensity stabilizing module receives the light pulses emitted by the pulse laser module, detects the light intensity of the light pulses, compares the detected light intensity with the set original light intensity, and regulates and controls the intensity of the light pulses in an active feedback mode;
the interference module couples the polarization directions of the two paths of light pulses after rotating, the rotating angle is 45 degrees, so that the light pulses transmitted by the fast axis of the polarization maintaining optical fiber interfere with the light pulses transmitted by the slow axis of the polarization maintaining optical fiber, the intensity of the light signals obtained after interference is controlled by the phase difference between the two paths of light pulses, and in order to eliminate the influence of polarization fluctuation on the interference effect, the polarization maintaining optical fiber is used for transmitting the light pulses;
the detection module converts an optical signal obtained after interference into an analog electrical signal, can detect the intensity of the optical signal output by the interference module, and requires good linearity, wide detection range and low bottom noise in order to ensure the detection accuracy;
the analog-to-digital conversion module converts the analog electric signal into a digital electric signal, and the threshold value of the digital electric signal can be adjusted according to the intensity distribution of the analog electric signal;
the data post-processing module is used for processing the original data by using a randomness extraction algorithm proved by strict information security, and the data post-processing module is high in required speed and good in stability.
Example 1
As shown in fig. 2, the pulse laser module includes a first pulse laser and a second pulse laser, the light intensity stabilizing module includes a first optical attenuator and a second optical attenuator, and the interference module includes a polarization-maintaining beam splitter and a polarization beam splitter connected by a polarization-maintaining fiber.
The first pulse laser, the first optical attenuator and the polarization-preserving beam splitter are connected in sequence through polarization-preserving fibers, and the second pulse laser, the second optical attenuator and the polarization-preserving beam splitter are connected in sequence through polarization-preserving fibers.
The first pulse laser and the second pulse laser are used for preparing two paths of optical pulses with high extinction ratio and sending the optical pulses to the corresponding optical attenuators, the duty ratios and the frequencies of the two paths of optical pulses are the same, the duty ratios and the frequencies of the optical pulses are determined by the driving current of the pulse lasers, the optical pulses sent out by the lasers contain the influences of spontaneous radiation and stimulated radiation, when the driving voltage is close to a light emitting threshold, the generated laser light intensity is weak, the laser line width is wide, and the phase fluctuation is most obvious. The invention can select distributed feedback laser and control by pulse drive current.
The first optical attenuator and the second optical attenuator attenuate received optical pulses until the light intensity difference of the two paths of attenuated optical pulses is within 5%, and the attenuated optical pulses are sent to the polarization-maintaining beam splitter.
The polarization-maintaining beam splitter is a beam splitter for polarization-maintaining input and output and is used for coupling two paths of light pulses into one polarization-maintaining optical fiber.
The polarization beam splitter is used for coupling the two paths of light pulses after the polarization directions of the light pulses rotate, so that the light pulses transmitted by the fast axis of the polarization maintaining fiber interfere with the light pulses transmitted by the slow axis of the polarization maintaining fiber.
The polarization beam splitter is a 45-degree 2 x 1 polarization beam splitter, 2 input ports and 1 output port, the polarization directions of the two paths of light pulses rotate by 45 degrees, and a 45-degree rotation matrix is expressed as follows:
after rotation, 50 percent of the optical pulses input from the two input ports are coupled into the output port respectively to realize interference, and the optical signals obtained after the polarization beam splitter realizes interference are represented as follows:
the detection module comprises a first photoelectric detector, the first photoelectric detector is connected with the polarization beam splitter through an optical fiber, the first photoelectric detector is used for converting an optical signal obtained after interference into an analog electric signal, and the intensity of the converted analog electric signal is represented as follows:
wherein L is 1 Representing the electrical noise of the first photodetector, and B is the conversion ratio of the first photodetector.
The photoelectric detector of the invention can select PIN photodiode and avalanche photodiode.
The analog-to-digital conversion module is an analog-to-digital converter, the analog-to-digital converter is connected with the first photoelectric detector through a lead, and the analog-to-digital converter is used for converting an analog electric signal into a digital electric signal. The analog-to-digital conversion module can also adopt an oscilloscope.
The data post-processing module is a computer, and the computer is connected with the analog-to-digital converter through a wire and used for processing the original data.
The pulse laser module also comprises a first temperature control device and a second temperature control device, wherein the first temperature control device is connected with the first pulse laser and is used for adjusting the central frequency of the first pulse laser, the second temperature control device is connected with the second pulse laser and is used for adjusting the central frequency of the second pulse laser, and the temperature control device can adopt an active feedback semiconductor refrigerator.
Example 2
As shown in fig. 3, the pulse laser module includes a first pulse laser and a second pulse laser, the light intensity stabilizing module includes a first optical attenuator and a second optical attenuator, and the interference module includes a polarization-maintaining beam splitter and a polarization beam splitter connected by a polarization-maintaining fiber.
The first pulse laser, the first optical attenuator and the polarization-maintaining beam splitter are connected in sequence through polarization-maintaining optical fibers, and the second pulse laser, the second optical attenuator and the polarization-maintaining beam splitter are connected in sequence through polarization-maintaining optical fibers.
The first pulse laser and the second pulse laser are used for preparing two paths of optical pulses with high extinction ratio and sending the optical pulses to the corresponding optical attenuators, the duty ratios and the frequencies of the two paths of optical pulses are the same, the duty ratios and the frequencies of the optical pulses are determined by the driving current of the pulse lasers, the optical pulses sent out by the lasers contain the influences of spontaneous radiation and stimulated radiation, when the driving voltage is close to a light emitting threshold, the generated laser light intensity is weak, the laser line width is wide, and the phase fluctuation is most obvious. The invention can select distributed feedback laser and control by pulse drive current.
The first optical attenuator and the second optical attenuator attenuate received optical pulses until the light intensity difference of the two paths of attenuated optical pulses is within 5%, and the attenuated optical pulses are sent to the polarization-maintaining beam splitter.
The polarization-maintaining beam splitter is a beam splitter for polarization-maintaining input and output and is used for coupling two paths of light pulses into one polarization-maintaining optical fiber.
The polarization beam splitter is used for coupling the two paths of light pulses after the polarization directions of the light pulses rotate, so that the light pulses transmitted by the fast axis of the polarization maintaining fiber interfere with the light pulses transmitted by the slow axis of the polarization maintaining fiber.
The polarization beam splitter is a 45-degree 2 multiplied by 2 polarization beam splitter, 2 input ports and 2 output ports, the polarization direction of two light pulses is rotated by 45 degrees, and a 45-degree rotation matrix is expressed as follows:
after rotation, 50 percent of the optical pulses input from the two input ports are coupled into the two output ports respectively to realize interference, and optical signals obtained after the polarization beam splitter realizes interference are expressed as follows:
the detection module comprises a second photoelectric detector, a third photoelectric detector and a differential amplifier, the second photoelectric detector is connected with the polarization beam splitter through optical fibers, the second photoelectric detector is connected with the differential amplifier through a lead, the third photoelectric detector is connected with the polarization beam splitter through the optical fibers, and the third photoelectric detector is connected with the differential amplifier through a lead. The intensity of the analog electric signals output by the second photoelectric detector and the third photoelectric detector is in direct proportion to the intensity of the received optical signal obtained after interference, the differential amplifier performs difference on the analog electric signals output by the two photoelectric detectors to eliminate the light intensity offset part, so that offset elimination processing is not needed in the data post-processing process, and the post-processing process is simplified.
The second photoelectric detector and the third photoelectric detector are used for converting optical signals obtained after interference into analog electric signals, and the intensity of the converted analog electric signals is represented as:
wherein L is 2 、L 3 Respectively representAnd C is the conversion ratio of the second photoelectric detector and the third photoelectric detector.
The photoelectric detector can select PIN photodiode and avalanche photodiode.
The analog electrical signals are differenced, the difference being expressed as:
wherein Δ L represents a difference in electrical noise of the second photodetector and the third photodetector;
the analog-to-digital conversion module is an analog-to-digital converter, the analog-to-digital converter is connected with the differential amplifier through a lead, and the analog-to-digital converter is used for converting an analog electric signal into a digital electric signal. The analog-to-digital conversion module can also adopt an oscilloscope.
The data post-processing module is a computer, and the computer is connected with the analog-to-digital converter through a wire and used for processing the original data.
The pulse laser module also comprises a first temperature control device and a second temperature control device, wherein the first temperature control device is connected with the first pulse laser and is used for adjusting the central frequency of the first pulse laser, the second temperature control device is connected with the second pulse laser and is used for adjusting the central frequency of the second pulse laser, and the temperature control device can adopt an active feedback semiconductor refrigerator.
Claims (7)
1. A quantum random number generating system based on polarization laser phase fluctuation is characterized by comprising a pulse laser module, a light intensity stabilizing module, an interference module, a detection module, an analog-to-digital conversion module and a data post-processing module which are sequentially connected, wherein the pulse laser module, the light intensity stabilizing module and the interference module are sequentially connected through a polarization maintaining optical fiber;
the pulse laser module is used for preparing two paths of light pulses, wherein one path of light pulse is coupled into a fast axis of the polarization maintaining optical fiber and is represented as
The other path of light pulse is coupled into the slow axis of the polarization maintaining fiber and is expressed as
Wherein mu and upsilon respectively represent the light intensity of the two paths of light pulses, i is an imaginary unit,
the phase difference between the two paths of light pulses;
the light intensity stabilizing module is used for attenuating two paths of light pulses;
the interference module couples the polarization directions of the two paths of light pulses after rotating so that the light pulses transmitted by the fast axis of the polarization maintaining optical fiber interfere with the light pulses transmitted by the slow axis of the polarization maintaining optical fiber;
the detection module converts an optical signal obtained after interference into an analog electric signal;
the analog-to-digital conversion module converts the analog electric signal into a digital electric signal;
and the data post-processing module processes the original data.
2. The system for generating quantum random numbers based on polarized laser phase fluctuation according to claim 1, wherein the two optical pulses prepared by the pulse laser module are high extinction ratio optical pulses, duty ratios and frequencies of the two optical pulses are the same, optical frequency errors of the two optical pulses are within GHz magnitude, duty ratios of the prepared two optical pulses are both 50%, and the light intensity stabilizing module is used for attenuating the two optical pulses until light intensity differences of the attenuated two optical pulses are within 5%.
3. The system according to claim 1, wherein the pulsed laser module comprises a first pulsed laser and a second pulsed laser, the optical intensity stabilization module comprises a first optical attenuator and a second optical attenuator, and the interference module comprises a polarization-maintaining beam splitter and a polarization beam splitter connected by a polarization-maintaining fiber;
the first pulse laser, the first optical attenuator and the polarization-maintaining beam splitter are connected in sequence through polarization-maintaining optical fibers, and the second pulse laser, the second optical attenuator and the polarization-maintaining beam splitter are connected in sequence through polarization-maintaining optical fibers;
the first pulse laser and the second pulse laser are used for preparing two paths of optical pulses with high extinction ratio and sending the optical pulses to the corresponding optical attenuators;
the first optical attenuator and the second optical attenuator attenuate received optical pulses, and the attenuated optical pulses are sent to the polarization-maintaining beam splitter;
the polarization-maintaining beam splitter is a polarization-maintaining input and output beam splitter and is used for coupling two paths of light pulses into one polarization-maintaining optical fiber;
the polarization beam splitter is used for realizing interference after the polarization directions of the two paths of light pulses are rotated.
4. The system of claim 3, wherein the polarization beam splitter is a 45 ° polarization beam splitter, the polarization direction of the two light pulses is rotated by 45 °, and the 45 ° rotation matrix is expressed as:
5. the system according to claim 3, wherein the detection module comprises a first photodetector, the first photodetector is connected to the polarization beam splitter, and the polarization beam splitter implements interference to obtain an optical signal represented as:
the first photodetector is configured to convert an optical signal obtained after the interference into an analog electrical signal, where the intensity of the converted analog electrical signal is represented as:
wherein L is 1 Representing the electrical noise of the first photodetector, B being the conversion ratio of the first photodetector;
the analog-to-digital conversion module is an analog-to-digital converter;
the data post-processing module is a computer.
6. The system according to claim 3, wherein the detection module comprises a second photodetector, a third photodetector and a differential amplifier, the second photodetector is connected to the polarization beam splitter and the differential amplifier, the third photodetector is connected to the polarization beam splitter and the differential amplifier, and the polarization beam splitter implements the interference to obtain an optical signal represented as:
the second photodetector and the third photodetector are used for converting optical signals obtained after interference into analog electric signals, and the intensity of the converted analog electric signals is represented as:
wherein L is 2 、L 3 Respectively representing the electrical noise of the second photoelectric detector and the third photoelectric detector, and C is the conversion ratio of the second photoelectric detector and the third photoelectric detector;
the analog electrical signals are differenced, the difference being expressed as:
wherein Δ L represents a difference in electrical noise of the second photodetector and the third photodetector;
the analog-to-digital conversion module is an analog-to-digital converter;
the data post-processing module is a computer.
7. The system of claim 3, wherein the pulsed laser module further comprises a first temperature control device and a second temperature control device, the first temperature control device is connected to the first pulsed laser, the first temperature control device is configured to adjust the center frequency of the first pulsed laser, the second temperature control device is connected to the second pulsed laser, and the second temperature control device is configured to adjust the center frequency of the second pulsed laser.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115801254A (en) * | 2023-02-07 | 2023-03-14 | 合肥硅臻芯片技术有限公司 | Quantum key distribution method, transmitting terminal and quantum key distribution system |
| CN116719509A (en) * | 2023-08-09 | 2023-09-08 | 北京正道量子科技有限公司 | Quantum random number generator based on phase noise |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115801254A (en) * | 2023-02-07 | 2023-03-14 | 合肥硅臻芯片技术有限公司 | Quantum key distribution method, transmitting terminal and quantum key distribution system |
| CN115801254B (en) * | 2023-02-07 | 2023-04-18 | 合肥硅臻芯片技术有限公司 | Quantum key distribution method, transmitting terminal and quantum key distribution system |
| CN116719509A (en) * | 2023-08-09 | 2023-09-08 | 北京正道量子科技有限公司 | Quantum random number generator based on phase noise |
| CN116719509B (en) * | 2023-08-09 | 2023-09-29 | 北京正道量子科技有限公司 | Quantum random number generator based on phase noise |
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