Digital twin space channel continuous variable quantum key distribution method

Abstract

The invention discloses a digital twin space channel continuous variable quantum key distribution method, and relates to the technical field of quantum information processing, and the method comprises the steps: constructing a satellite-ground link model between a satellite and a ground station according to satellite orbit parameter data and ground receiving station position information, and calculating satellite-ground link dynamic parameters; based on the satellite-ground link dynamic parameters and the atmospheric parameters, constructing an atmospheric model to simulate link attenuation loss at different moments under a single orbit in a satellite-ground link; and simulating a quantum state preparation process to adjust quantum state parameters, and calculating a key generation rate in combination with the link attenuation loss to distribute satellite-ground quantum keys. According to the method, a dynamic model is constructed based on satellite orbit parameters and ground station positions, dynamic parameters of a satellite-ground link can be calculated in real time, an atmosphere model is established to quantify link attenuation and background noise under different weather conditions, quantum state preparation parameters are adjusted, and the key generation rate is maximized on the premise that safety is guaranteed.

Description

Technical Field

[0001] The present application relates to the field of quantum information processing technology, and more specifically, to a spatial channel continuous variable quantum key distribution method for digital twins. Background Art

[0002] Quantum Key Distribution (QKD) technology, with its security characteristics based on the framework of quantum mechanics and information theory, can distribute security keys between communicating parties. Combined with the "one-time pad" encryption algorithm, it can achieve secure and confidential communication in the sense of information theory. Driven by the grand vision of a space-ground integrated quantum secure communication network, all-weather, highly stable, and high-rate space quantum secure communication has become a research hotspot in the field of quantum information. As an important branch of QKD, CV-QKD (continuous variable quantum key distribution) encodes key information in the Gaussian modulation parameters of coherent light (such as amplitude, phase or frequency) and uses balanced homodyne detection technology to achieve coherent measurement of quantum states.

[0003] In the existing technology, CV-QKD technology mainly focuses on ground-based optical fiber scenarios. Its core solutions include Gaussian modulated light sources, linear optical devices, balanced detectors and backward error correction protocols. It relies on the optical capture and tracking system of the classical laser communication link (such as satellite-borne lidar) and precision pointing control, combined with atmospheric turbulence pre-compensation algorithms (such as adaptive optics) to maintain signal stability.

[0004] However, the existing technology solutions face multiple bottlenecks in practical applications: first, the spot distortion and phase disturbance caused by atmospheric turbulence lead to quantum state degradation, reducing the signal-to-noise ratio; second, the dynamic time-varying satellite-to-ground link makes it difficult to model the channel characteristics in real time; third, the high complexity of the CV-QKD system imposes strict requirements on engineering, especially the size, power consumption and reliability of satellite-borne equipment. In addition, although the existing simulation tools can partially simulate the atmospheric channel effect, the refined modeling of multi-physical field coupling is still insufficient, which restricts the accuracy of theoretical predictions and experimental designs. Summary of the invention

[0005] In response to at least one defect or improvement need in the prior art, the present invention provides a digital twin spatial channel continuous variable quantum key distribution method, which is used to solve the problems that CV-QKD in the prior art is difficult to achieve real-time compensation under dynamic time-varying conditions, fails to fully couple the influence of atmospheric effects, resulting in a large deviation between simulation results and actual experiments, relies on channel signal-to-noise ratio and bit error rate, and cannot balance security and communication efficiency in complex channel environments.

[0006] To achieve the above object, according to a first aspect of the present invention, a method for spatial channel continuous variable quantum key distribution of digital twin is provided, comprising:

[0007] Construct a satellite-to-ground link model between the satellite and the ground station based on the satellite orbit parameter data and the ground receiving station location information, and calculate the satellite-to-ground link dynamic parameters;

[0008] Based on the dynamic parameters of the satellite-to-ground link and the atmospheric parameters, an atmospheric model is constructed to simulate the link attenuation loss at different times in a single orbit in the satellite-to-ground link.

[0009] The quantum state preparation process is simulated to adjust the quantum state parameters and the key generation rate is calculated based on the link attenuation loss to distribute the satellite-to-ground quantum key.

[0010] In a possible implementation, an atmospheric model is constructed based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate the link attenuation loss at different times in a single orbit in the satellite-to-ground link, and further includes:

[0011] Based on the dynamic parameters of the satellite-to-ground link and the atmospheric parameters, a free-space diffraction model is constructed to simulate the diffraction effect of the light beam when it propagates in free space, and the diffraction transmittance is calculated.

[0012] Based on the dynamic parameters of the satellite-to-ground link and the atmospheric parameters, an atmospheric extinction model is constructed to simulate and evaluate the impact of atmospheric conditions on signal transmission, and the atmospheric transmission efficiency at a preset elevation angle is calculated;

[0013] Based on the dynamic parameters of the satellite-to-ground link and the atmospheric parameters, an atmospheric turbulence model is constructed to simulate the influence of irregular temperature and pressure changes in the atmosphere on the beam transmission, and the transmission efficiency probability is calculated;

[0014] The link attenuation loss at different times in a single orbit is calculated based on the diffraction transmittance, atmospheric transmission efficiency, transmission efficiency probability and dynamic parameters of the satellite-to-ground link.

[0015] In a possible implementation, a free space diffraction model is constructed based on the satellite-to-ground link dynamic parameters and the atmospheric parameters to simulate the diffraction effect of a light beam propagating in free space, calculate the diffraction transmittance, and further include:

[0016] The parameters of Gaussian beam are determined based on the dynamic parameters of satellite-to-ground link and atmospheric parameters to construct a free-space diffraction model.

[0017] When the Gaussian beam is detected by a receiver of a preset telescope, the diffraction transmittance is calculated based on the Gaussian beam parameters and the receiver radius.

[0018] In a possible implementation, an atmospheric turbulence model is constructed based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate the influence of irregular temperature and pressure changes in the atmosphere on beam transmission, and the transmission efficiency probability is calculated, which also includes:

[0019] Based on the dynamic parameters of the satellite-to-ground link and the atmospheric parameters, an atmospheric turbulence model is constructed to calculate the random fluctuation degree of the center position of the light beam;

[0020] Determine the channel transmission coefficient at a preset center deflection distance according to the approximate probability distribution of the deflection distance and the random fluctuation degree of the center position of the light beam;

[0021] The transmission efficiency probability is calculated from the channel transmission coefficient using the chain rule.

[0022] In a possible implementation, simulating the quantum state preparation process to adjust the quantum state parameters and calculating the key generation rate in combination with the link attenuation loss to distribute the satellite-to-ground quantum key also includes:

[0023] Set quantum state parameters to establish a quantum state that conforms to Gaussian distribution, and use machine learning algorithms to optimize quantum state parameters;

[0024] The key generation rate is calculated based on the optimized quantum state parameters and link attenuation loss to distribute the satellite-to-ground quantum key.

[0025] In a possible implementation, the key generation rate is calculated based on the optimized quantum state parameters and link attenuation loss to distribute the satellite-to-ground quantum key, and further includes:

[0026] Calculate the total channel noise based on the optimized quantum state parameters and link attenuation loss;

[0027] Determine the mutual information between the receiving end and the transmitting end according to the covariance matrix of the receiving end and the transmitting end of the channel total noise and Gaussian modulation;

[0028] Calculate the maximum amount of information of the receiving end measurement value according to the covariance matrix;

[0029] The key generation rate is calculated based on the mutual information between the receiver and the transmitter and the maximum information amount of the receiver's measurement value to distribute the satellite-to-ground quantum key.

[0030] In a possible implementation, a satellite-to-ground link model between a satellite and a ground station is constructed according to satellite orbit parameter data and ground receiving station position information, and dynamic parameters of the satellite-to-ground link are calculated, which also includes:

[0031] Access the open source platform to obtain two lines of element set data of the satellite, and convert the two lines of element set data into satellite orbit parameter data;

[0032] It is beneficial for the preset simulation software to construct a satellite-to-ground link model between the satellite and the ground station based on the satellite orbit parameter data and the ground receiving station location information;

[0033] The satellite motion trajectory is simulated based on the satellite-to-ground link model, and the dynamic parameters of the satellite-to-ground link are calculated.

[0034] According to the second aspect of the present invention, there is also provided a digital twin spatial channel continuous variable quantum key distribution device, comprising:

[0035] A link parameter module, which is configured to construct a satellite-to-ground link model between the satellite and the ground station according to the satellite orbit parameter data and the ground receiving station position information, and calculate the satellite-to-ground link dynamic parameters;

[0036] An attenuation loss module is configured to construct an atmospheric model based on satellite-to-ground link dynamic parameters and atmospheric parameters to simulate link attenuation losses at different times in a single orbit in a satellite-to-ground link;

[0037] The key distribution module is configured to simulate the quantum state preparation process to adjust the quantum state parameters and calculate the key generation rate in combination with the link attenuation loss to distribute the satellite-to-ground quantum key.

[0038] According to the third aspect of the present invention, a digital twin spatial channel continuous variable quantum key distribution device is also provided, which includes at least one processing unit and at least one storage unit, wherein the storage unit stores a computer program, and when the computer program is executed by the processing unit, the processing unit executes the steps of any of the above-mentioned digital twin spatial channel continuous variable quantum key distribution methods.

[0039] According to the fourth aspect of the present invention, a storage medium is also provided, which stores a computer program executable by an access authentication device. When the computer program is run on the access authentication device, the access authentication device executes the steps of the spatial channel continuous variable quantum key distribution method of the digital twin described in any one of the above items.

[0040] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0041] The present invention provides a digital twin space channel continuous variable quantum key distribution method, which is based on a dynamic model constructed based on satellite orbit parameters and ground station positions, and can calculate the dynamic parameters of the satellite-to-ground link in real time. Combined with the dynamic model of atmospheric parameters, it can quantify the link attenuation and background noise under different weather conditions, and adjust the quantum state preparation parameters according to the real-time link attenuation data, so as to maximize the key generation rate while ensuring security. Starting from the real experimental scene of space quantum key distribution, the complete process of transmitter, transmission channel and key distribution protocol calculation in the satellite-to-ground communication process is simulated, which not only covers the preparation, transmission and measurement of quantum states, but also can simulate in detail various influencing factors of the atmospheric environment, such as diffraction, extinction and turbulence and other actual environmental factors, and provides a multi-parameter, multi-variable and high-confidence digital twin simulation environment. Through precise model and parameter settings, it is possible to truly simulate the real-time dynamic changes of core parameters such as the operation of quantum satellites, the satellite-to-ground quantum key distribution process, the degradation of quantum states, and the quantum key rate during space quantum key distribution. Potential problems can be identified and solved in advance, thereby reducing the attenuation and loss of single-photon signals during transmission, increasing the key generation rate, and avoiding the adverse effects of environmental noise, equipment defects, transmission losses and other factors on the security and reliability of the generated keys. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 A schematic flow chart of an embodiment of a method for spatial channel continuous variable quantum key distribution of digital twins provided by the present invention;

[0044] Figure 2 The present invention provides Figure 1 A schematic diagram of a flow chart of an embodiment of step S102;

[0045] Figure 3 The present invention provides Figure 2 A schematic diagram of a flow chart of an embodiment of step S203;

[0046] Figure 4 A schematic diagram of a flow chart of an embodiment of calculating a key generation rate and distributing satellite-to-ground quantum keys provided by the present invention;

[0047] Figure 5 The present invention provides Figure 1 A schematic flow chart of an embodiment of step S101;

[0048] 6(a), (b), (c) and (d) are schematic diagrams of the results of an embodiment of the simulation of the real-time distance and zenith angle change of the downlink communication between the Micius satellite and the Delingha, Lijiang, Xinglong and Nanshan ground stations provided by the present invention;

[0049] Figure 7 A schematic diagram of the structure of an embodiment of a spatial channel continuous variable quantum key distribution device for digital twins provided by the present invention;

[0050] Figure 8 A schematic diagram of the structure of a spatial channel continuous variable quantum key distribution device for a digital twin provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0052] The terms "first", "second", "third", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0053] See also Figure 1 , Figure 1 A flow chart of an embodiment of a method for distributing continuous variables quantum keys over a spatial channel of a digital twin provided by the present invention. In a specific embodiment of the present invention, a method for distributing continuous variables quantum keys over a spatial channel of a digital twin is disclosed, including:

[0054] S101, constructing a satellite-to-ground link model between the satellite and the ground station according to the satellite orbit parameter data and the ground receiving station position information, and calculating the satellite-to-ground link dynamic parameters;

[0055] S102, constructing an atmospheric model based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate the link attenuation loss at different times in a single orbit in the satellite-to-ground link;

[0056] S103, simulating the quantum state preparation process to adjust the quantum state parameters and calculating the key generation rate in combination with the link attenuation loss to distribute the satellite-to-ground quantum key.

[0057] In the above embodiment, firstly, based on accurate satellite orbit parameter data (such as orbit altitude, inclination, period, etc.) and geographical location information of the ground receiving station, a three-dimensional satellite-to-ground link model between the satellite and the ground receiving station is constructed using spatial geometry and physical modeling technology. Subsequently, the dynamic parameters of the satellite-to-ground link in different time periods are calculated through real-time or prediction algorithms. These parameters include but are not limited to link distance, elevation angle, line-of-sight speed, etc., which are crucial for the subsequent analysis of link characteristics.

[0058] Based on the acquired dynamic parameters of the satellite-to-ground link and combined with real-time or historical atmospheric parameters (such as temperature, humidity, air pressure, cloud distribution, etc.), a variety of high-precision atmospheric models are constructed. These models can simulate the impact of atmospheric conditions at different times within a single orbital cycle on the satellite-to-ground link, especially the link attenuation loss caused by atmospheric absorption, scattering, and turbulence effects. This is conducive to evaluating the attenuation of quantum signals during transmission, which is directly related to the efficiency and success rate of quantum key distribution.

[0059] After determining the link attenuation loss, we enter the simulation stage of the quantum state preparation process. According to the requirements of the quantum key distribution protocol, we design and adjust the parameters of the quantum state, such as the polarization, phase or amplitude of the photons, to ensure that the quantum state can resist eavesdropping and effectively convey information during transmission. Subsequently, combined with the specific values ​​of the link attenuation loss, the relevant formulas in quantum information theory are used to calculate the key generation rate under different conditions. This not only considers the loss of the quantum state during transmission, but also covers the impact of factors such as quantum noise and detector efficiency on the key generation rate. Finally, based on the calculation results, the quantum state parameters and distribution strategy are dynamically adjusted to distribute the satellite-to-ground quantum keys in the most optimized way to ensure the security and efficiency of communication.

[0060] Compared with the prior art, the digital twin space channel continuous variable quantum key distribution method provided in this embodiment can calculate the dynamic parameters of the satellite-to-ground link in real time based on the dynamic model constructed based on the satellite orbit parameters and the ground station position. Combined with the dynamic model of atmospheric parameters, it can quantify the link attenuation and background noise under different weather conditions, adjust the quantum state preparation parameters according to the real-time link attenuation data, and maximize the key generation rate under the premise of ensuring security. Starting from the real experimental scene of space quantum key distribution, the complete process of transmitter, transmission channel and key distribution protocol calculation in the satellite-to-ground communication process is simulated, which not only covers the preparation, transmission and measurement of quantum states, but also can simulate in detail various influencing factors of the atmospheric environment, such as diffraction, extinction and turbulence and other actual environmental factors, providing a multi-parameter, multi-variable and high-confidence digital twin simulation environment. Through precise model and parameter settings, it is possible to truly simulate the real-time dynamic changes of core parameters such as the operation of quantum satellites, the satellite-to-ground quantum key distribution process, the degradation of quantum states, and the quantum key rate during space quantum key distribution. Potential problems can be identified and solved in advance, thereby reducing the attenuation and loss of single-photon signals during transmission, increasing the key generation rate, and avoiding the adverse effects of environmental noise, equipment defects, transmission losses and other factors on the security and reliability of the generated keys.

[0061] See also Figure 2 , Figure 2 The present invention provides Figure 1 In some embodiments of the present invention, an atmospheric model is constructed based on the satellite-to-ground link dynamic parameters and the atmospheric parameters to simulate the link attenuation loss at different times in a single orbit in the satellite-to-ground link, and further includes:

[0062] S201. Construct a free space diffraction model based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate the diffraction effect of a light beam propagating in free space, and calculate the diffraction transmittance;

[0063] S202, constructing an atmospheric extinction model based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate and evaluate the impact of atmospheric conditions on signal transmission, and calculating the atmospheric transmission efficiency at a preset elevation angle;

[0064] S203, constructing an atmospheric turbulence model based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate the influence of irregular temperature and pressure changes in the atmosphere on light beam transmission, and calculating the transmission efficiency probability;

[0065] S204. Calculate the link attenuation loss at different times in a single orbit according to the diffraction transmittance, the atmospheric transmission efficiency, the transmission efficiency probability and the satellite-to-ground link dynamic parameters.

[0066] In the above embodiment, the establishment of the free space diffraction model is completed by MATLAB programming, the diffraction effect of light waves propagating in free space is simulated, and the diffraction transmittance is calculated. Subsequently, the establishment of the atmospheric extinction model is completed by MATLAB programming, the influence of atmospheric conditions on signal transmission is simulated and evaluated, for example: the absorption and scattering effect of different atmospheric component aerosol models (such as water vapor, carbon dioxide and ozone layer, etc.) on the light signal is calculated, and the atmospheric transmission efficiency at the preset elevation angle is calculated. Finally, the establishment of the atmospheric turbulence model is completed by MATLAB programming, the influence of irregular temperature and pressure changes in the atmosphere on the signal light transmission and the atmospheric turbulence of different intensities on the phase and amplitude disturbance of the light signal are calculated to calculate the atmospheric turbulence loss under the real channel, and the transmission efficiency probability is calculated. After the transmission channel is modeled, the satellite and ground station parameter submodules are combined through the interface of STK and MATLAB to complete the link attenuation loss calculation at different times under a single orbit, and the link attenuation loss at different times under a single orbit is obtained.

[0067] In some embodiments of the present invention, a free space diffraction model is constructed based on the satellite-to-ground link dynamic parameters and the atmospheric parameters to simulate the diffraction effect of a light beam when propagating in free space, and the diffraction transmittance is calculated, which also includes:

[0068] The parameters of Gaussian beam are determined based on the dynamic parameters of satellite-to-ground link and atmospheric parameters to construct a free-space diffraction model.

[0069] When the Gaussian beam is detected by a receiver of a preset telescope, the diffraction transmittance is calculated based on the Gaussian beam parameters and the receiver radius.

[0070] In the above embodiment, beam broadening in the free space channel refers to the phenomenon that the waist spot size of the beam gradually increases due to the diffraction effect during the propagation of the beam. In the free space channel, beam broadening is mainly caused by the diffraction effect. As the beam propagates in space, its waist spot size gradually increases, resulting in a decrease in the light intensity per unit area. In satellite quantum communications, beam broadening may cause insufficient signal strength received by the ground station, thereby affecting the efficiency of quantum key distribution. The free space diffraction model can be represented by a Gaussian beam with a field spot size of w0 and a curvature of R0 (assuming that the Gaussian beam is a collimated beam, R0 = ∞). After propagating through the free space at a distance z, beam broadening will occur under the influence of diffraction and turbulence, and the beam will be divided by a radius a. R The receiver of the circular aperture telescope detects the beam radius w d (z) can be written as:

[0071]

[0072] in, is the Rayleigh distance, and λ is the wavelength of the outgoing beam. For a collimated beam R0 = ∞, this can be simplified to:

[0073]

[0074] Due to the limited aperture a of the receiving telescope R , only a portion of the initial beam is detected. The transmittance η caused by diffraction d (z) is:

[0075]

[0076] Atmospheric transmission efficiency is affected by a variety of physical processes, including systematic effects such as atmospheric refraction, absorption and scattering, as well as random effects such as refractive index fluctuations caused by random changes in atmospheric temperature and pressure. Among the systematic effects, atmospheric refraction causes the beam path to be extended, while light extinction includes absorption and scattering, which significantly attenuate the intensity of the optical signal. Random effects cause beam intensity fluctuations, beam drift and beam expansion, resulting in fluctuations in the received signal power. The calculation of atmospheric transmission efficiency needs to take into account factors such as beam path, atmospheric model and visibility. Therefore, accurate evaluation of atmospheric transmission efficiency is crucial for the design and optimization of satellite-to-ground quantum key distribution systems. The atmospheric transmission efficiency is determined by establishing an atmospheric extinction model.

[0077] As a preferred embodiment, the preset elevation angle in the present invention is an elevation angle higher than 20 degrees. For elevation angles higher than 20 degrees, the atmospheric transmission efficiency η atm Change according to the following formula:

[0078]

[0079] Among them, θ zen is the zenith angle, η zen is the transmission efficiency at the zenith. The simulation is usually performed using the MODTRAN code, which is widely used to estimate atmospheric transmittance and radiance. For example, at a wavelength of 1550 nm, a mid-latitude summer atmospheric model, and 23 km visibility, the transmission efficiency in the zenith direction is 0.91, while when the visibility is reduced to 10 km, 5 km, and 2 km, the zenith transmission efficiency drops to 0.85, 0.75, and 0.53, respectively, indicating that visibility has a significant effect on the transmission efficiency.

[0080] See also Figure 3 , Figure 3 The present invention provides Figure 2 In some embodiments of the present invention, an atmospheric turbulence model is constructed based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate the influence of irregular temperature and pressure changes in the atmosphere on light beam transmission, and the transmission efficiency probability is calculated, which also includes:

[0081] S301, constructing an atmospheric turbulence model based on the satellite-to-ground link dynamic parameters and atmospheric parameters to calculate the random fluctuation degree of the center position of the light beam;

[0082] S302, determining a channel transmission coefficient at a preset center deflection distance according to an approximate probability distribution of the deflection distance and a random fluctuation degree of the center position of the light beam;

[0083] S303: Calculate the transmission efficiency probability according to the channel transmission coefficient using the chain rule.

[0084] In the above embodiment, after the light beam is emitted from the satellite, it will be affected by atmospheric turbulence and satellite pointing errors, causing the actual propagation path of the light beam to deviate from the ideal path, causing the center of the light beam to deviate from the center of the receiving telescope. r It represents the random fluctuation degree of the center position of the beam, which combines the influence of atmospheric turbulence and pointing error on beam propagation. r It can be written as:

[0085]

[0086] Among them, θ p It is the angle between the center of the light beam and the center line connecting the transmitter and receiver telescopes. is the variance of the beam center due to turbulence and is expressed by the following formula:

[0087]

[0088] parameter is the refractive index structure parameter that characterizes the atmospheric turbulence intensity. In an ideal situation, the approximate probability distribution of the deflection distance follows the Weibull distribution:

[0089]

[0090] When the center deflection distance r is given, the expression of the channel transmission coefficient T can be obtained. The relationship between r and T can be approximately expressed as:

[0091]

[0092] Where T0 is the maximum transmittance coefficient during channel transmission, S and λ express the scale parameter and shape parameter of the transmission channel respectively.

[0093] The transmission efficiency η in the known turbulent channel tur =T 2 When , the probability distribution of the transmission coefficient is obtained using the chain rule, as follows:

[0094]

[0095] Through the above mathematical model, MATLAB software is used for simulation.

[0096] In some embodiments of the present invention, simulating the quantum state preparation process to adjust the quantum state parameters and calculating the key generation rate in combination with the link attenuation loss to distribute the satellite-to-ground quantum key also includes:

[0097] Set quantum state parameters to establish a quantum state that conforms to Gaussian distribution, and use machine learning algorithms to optimize quantum state parameters;

[0098] The key generation rate is calculated based on the optimized quantum state parameters and link attenuation loss to distribute the satellite-to-ground quantum key.

[0099] In the above embodiment, in the process of simulating quantum state preparation, in order to efficiently generate and distribute satellite-to-ground quantum keys, we need to carefully adjust the various parameters of the quantum state and comprehensively consider the impact of link attenuation loss on the key generation rate. In the CV-QKD simulation of spatial Gaussian modulation, the transmitter (Alice) needs to prepare quantum states that conform to the Gaussian distribution, usually coherent states or compressed states. The preparation of these quantum states determines the quality of the signal and the security and efficiency of quantum communication.

[0100] In this process, common parameters include modulation variance (V A ) and the number of symbols (N). The modulation variance controls the amplitude of the coherent state or the compressed state, that is, the "strength" of the quantum signal, which directly affects the transmission distance of the signal and the signal quality at the receiving end. The number of symbols determines the amount of data sent each time, and is also a very important parameter in communication, affecting the generation rate and noise resistance of quantum keys.

[0101] The optimization of quantum state parameters using machine learning algorithms can be completed through machine learning algorithms in the prior art, and the present invention will not elaborate on this further.

[0102] According to the optimized quantum state parameters and the accurate calculation of link attenuation loss, the key generation rate can be obtained, and the satellite-to-ground quantum key can be distributed accordingly. The key generation rate is an important indicator to measure the performance of the quantum communication system, which directly determines how many secure and reliable keys can be generated. By continuously optimizing the quantum state parameters and accurately calculating the link attenuation loss, the key generation rate can be improved, thereby ensuring the efficiency and security of satellite-to-ground quantum key distribution.

[0103] See also Figure 4 , Figure 4 A schematic flow chart of an embodiment of calculating the key generation rate and distributing the satellite-to-ground quantum key provided by the present invention. In some embodiments of the present invention, the key generation rate and the satellite-to-ground quantum key are calculated based on the optimized quantum state parameters and link attenuation loss, and further include:

[0104] S401, calculating the total channel noise according to the optimized quantum state parameters and link attenuation loss;

[0105] S402, determining the mutual information between the receiving end and the transmitting end according to the covariance matrix of the receiving end and the transmitting end of the channel total noise and Gaussian modulation;

[0106] S403, calculating the maximum amount of information of the receiving end measurement value according to the covariance matrix;

[0107] S404, calculating the key generation rate based on the mutual information between the receiving end and the transmitting end and the maximum amount of information of the receiving end measurement value to distribute the satellite-to-ground quantum key.

[0108] In the above embodiment, the sender (Alice) uses a mean of 0 and a variance of V A The Gaussian random number modulates the canonical position and canonical momentum of the coherent state |α>, and the Gaussian modulated coherent state |X A +iP A >, and then send the quantum signal to the receiver (Bob) through a free-space quantum channel with the help of a transmitting telescope;

[0109] The free-space quantum channel is composed of a i} i＝1,2,..,M The transmission efficiency {T i} i＝1,2,..,M and its corresponding excess noise ε, then the channel noise in units of shot noise is described as in <t>Represents {T i } i＝1,2,..,M The average value of is: Here the probability distribution of T is <t>Compared with the previous P(η tur )same.

[0110] The receiver (Bob), with the assistance of the receiving telescope, detects any one component through homodyne detection, or detects both components simultaneously through heterodyne detection. The security key shared between the communicators is then extracted through parameter estimation, negotiation error correction, and confidentiality enhancement. The detection noise of the quantum state under homodyne detection and heterodyne detection is described as Where η is the detector efficiency, v el represents the electrical noise of the detector. Therefore, the total channel noise can be described as The measurement variance at the receiver (Bob) is described as V B =η <t>(V+x tot ), V is the total variance of the transmitter, which is equal to the modulation variance V A +1.

[0111] Therefore, the input noise value can be set by setting the excess noise ε value. First, the total noise can be set when ε=0. In this way, the attenuation under the current noise compared to the case without additional noise can be obtained by setting different noise values.

[0112] The spatial Gaussian modulation CV-QKD quantum state measurement model was established using MATLAB programming. Through relevant simulation parameters, including detection efficiency, reverse coordination parameters and detector electronic noise, the key rate calculation formula was used to accurately calculate the key generation rate within a single access orbit, and the simulation of satellite-to-ground quantum key distribution was completed based on the key generation rate.

[0113] The asymptotic key rate of free-space CVQKD under collective attack is described as,

[0114] K=(1-P)(β R I AB -x BE );

[0115] Where P represents the outage probability caused by arrival angle fluctuation, β R Represents the error correction efficiency under reverse coordination. AB and X BE They represent the mutual information between the sender (Alice) and the receiver (Bob) and the maximum amount of information that Eve can steal from the receiver (Bob) subject to the Holevo bound. The covariance matrix γ of the Gaussian modulation AB It can be expressed as:

[0116]

[0117] In the case of this EPR source, after free space channel transmission, the receiving state decays from AB to AB1. It is expressed as:

[0118]

[0119] Where I is the identity matrix, σ z is the Pauli matrix, expressed as:

[0120]

[0121] So when the covariance matrix is ​​known Under the consideration of detection efficiency η and electronic noise v el In the case of , the mutual information between the sender (Alice) and the receiver (Bob) can be further expressed as:

[0122]

[0123] The maximum amount of information Eve has about the measurement value of the receiver (Bob) BE Determined by the Hoelvo boundary

[0124]

[0125] In the formula, χ B represents Bob's measurement under homodyne detection, p(X B ) represents the probability distribution of the measurement under homodyne detection, represents the quantum state of Eve’s eavesdropping under homodyne detection, and S(·) represents the von Neumann entropy of the quantum state ρ. Under Gaussian modulation, χ BE The mathematical calculation of information volume can be simplified to the following equation:

[0126]

[0127] in,

[0128] To obtain χ BE The value of , we need to find the covariance matrix The symplectic eigenvalues ​​λ1 and λ2 of The symplectic eigenvalues ​​λ3, λ4 and λ5, then the parameter λ i The expression is:

[0129]

[0130] After each parameter is transmitted through the free space channel, the equivalent expression is:

[0131]

[0132]

[0133] Communication interruption is closely related to beam drift. When the focus is not in the receiving fiber core, communication interruption occurs. This is because due to the high directivity of laser transmission, when the arrival angle of the image jitter on the receiving aperture plane fluctuates greatly, communication interruption may occur. At present, we temporarily discuss the feasibility of CV-QKD under the communication protocol using GG02 under ideal conditions, assuming that the probability of communication interruption is 0, that is, it is not affected by the interruption probability during the satellite-to-ground communication process. Then the key rate formula is:

[0134] K=β B I AB -X BE .

[0135] See also Figure 5 , Figure 5 The present invention provides Figure 1 In some embodiments of the present invention, a satellite-to-ground link model between a satellite and a ground station is constructed according to satellite orbit parameter data and ground receiving station position information, and dynamic parameters of the satellite-to-ground link are calculated, further comprising:

[0136] S501, accessing the open source platform to obtain two lines of element set data of the satellite, and converting the two lines of element set data into satellite orbit parameter data;

[0137] S502, facilitating the preset simulation software to construct a satellite-to-ground link model between the satellite and the ground station according to the satellite orbit parameter data and the ground receiving station position information;

[0138] S503: Simulate the satellite motion trajectory based on the satellite-to-ground link model and calculate the satellite-to-ground link dynamic parameters.

[0139] In the above embodiment, by accessing open source platforms such as LEOLabs, Find-Satellites, SatNOGS, AGSATTrack, N2YO, JSatTrak, Look4Sat and CELESTRAK, the two-line element set (Two-Line Orbital Element, TLE) data released by the relevant satellite is obtained to obtain the orbital parameters of the specified satellite (taking Mozi as an example), and the satellite orbital parameters are collected. Next, based on the collected parameter data, the satellite and ground station scenes are established using STK simulation software, the satellite motion orbit model is constructed using STK simulation software, and the dynamic parameters of the satellite-to-ground link are calculated by STK software, including but not limited to satellite-to-ground access time, link distance and zenith angle calculation. According to the calculation results, the distance change relationship between the satellite and the ground station is analyzed, and the co-viewing time window between the satellite and the ground receiving station is determined, thereby realizing the simulation of the physical link between the satellite and the ground station.

[0140] The common view time window refers to the time period in which the satellite and the ground station can directly "see" each other at the same time and in the same spatial orientation. It is one of the core constraints in the design of satellite communication links, which directly affects the continuity of signal transmission and the efficiency of key generation. It can ensure that signal transmission meets the requirements of quantum protocols in terms of temporal and spatial consistency. Through dynamic window selection and parameter adjustment, it can minimize environmental attenuation and noise interference. By limiting the communication period, it can significantly reduce the risk of eavesdropping and illegal access.

[0141] Please refer to Figures 6(a), (b), (c) and (d), which are schematic diagrams of the results of an embodiment of the simulation of the real-time distance and zenith angle change of the downlink of the Micius satellite and the ground stations in Delingha, Lijiang, Xinglong and Nanshan provided by the present invention. In a specific embodiment of the present invention, the communication process between the satellite and the ground station is simulated. First, the design orbit parameter TLE data of the Chinese quantum science experimental satellite "Micius" is obtained through the CelesTrak public satellite data website, as shown in the following table:

[0142] Table 1. Micius TLE data

[0143]

[0144] The orbit altitude of the Micius satellite is 496.6km, and the scene is the communication between the Micius satellite and the Lijiang / Delingha / Xinglong / Nanshan ground stations. The parameters to be extracted include: the second line "16354.569 (first group)", which represents the TLE ephemeris; the third line mainly extracts: orbital inclination 97.3698 (second group), ascending node right ascension 268.1064 (third group), orbital eccentricity 0013349 (fourth group), perigee argument 175.8929 (fifth group), mean anomaly 309.019 (sixth group). Combined with the location information of Lijiang ground station (26°41'38.151"N, 100°1'45.5484"E, 3233m above sea level), Delingha ground station (43°28'40.4976"N, 87°11'15.7518"E, 2050m above sea level), Xinglong ground station (40°23'45.12"N, 117°34'38.85"E, 890m above sea level), Nanshan ground station (43°51′57.2″N, 87°34′18.8″E, 2088m above sea level).

[0145] The horizontal axes of Figure 6 (a), (b), (c) and (d), i.e. the total communication time between the satellite and the ground station, are 439 s for Delingha, 437 s for Lijiang, 290 s for Nanshan and 252 s for Xinglong respectively.

[0146] In order to better implement the spatial channel continuous variable quantum key distribution method of the digital twin in the embodiment of the present invention, based on the spatial channel continuous variable quantum key distribution method of the digital twin, correspondingly, please refer to Figure 7 , Figure 7 This is a structural schematic diagram of an embodiment of a digital twin spatial channel continuous variable quantum key distribution device provided by the present invention. The embodiment of the present invention provides a digital twin spatial channel continuous variable quantum key distribution device 700, including:

[0147] A link parameter module 710, which is configured to construct a satellite-to-ground link model between the satellite and the ground station according to the satellite orbit parameter data and the ground receiving station position information, and calculate the satellite-to-ground link dynamic parameters;

[0148] An attenuation loss module 720 is configured to construct an atmospheric model based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate the link attenuation loss at different times in a single orbit in the satellite-to-ground link;

[0149] The key distribution module 730 is configured to simulate the quantum state preparation process to adjust the quantum state parameters and calculate the key generation rate in combination with the link attenuation loss to distribute the satellite-to-ground quantum key.

[0150] It should be noted here that: the device 700 provided in the above embodiment can implement the technical solutions described in the above method embodiments. The specific implementation principles of the above modules or units can refer to the corresponding contents in the above method embodiments, which will not be repeated here.

[0151] See also Figure 8 , Figure 8 A schematic diagram of the structure of a digital twin spatial channel continuous variable quantum key distribution device provided by an embodiment of the present invention. Based on the above-mentioned digital twin spatial channel continuous variable quantum key distribution method, the present invention also provides a digital twin spatial channel continuous variable quantum key distribution device, and the digital twin spatial channel continuous variable quantum key distribution device can be a computing device such as a mobile terminal, a desktop computer, a notebook, a PDA and a server. The digital twin spatial channel continuous variable quantum key distribution device 800 includes a processor 810, a memory 820 and a display 830. Figure 8 Only some components of the digital twin spatial channel continuous variable quantum key distribution device are shown, but it should be understood that it is not required to implement all of the shown components, and more or fewer components may be implemented instead.

[0152] In some embodiments, the memory 820 may be an internal storage unit of the digital twin spatial channel continuous variable quantum key distribution device 800, such as a hard disk or memory of the digital twin spatial channel continuous variable quantum key distribution device 800. In other embodiments, the memory 820 may also be an external storage device of the digital twin spatial channel continuous variable quantum key distribution device 800, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the digital twin spatial channel continuous variable quantum key distribution device 800. Further, the memory 820 may also include both the internal storage unit of the digital twin spatial channel continuous variable quantum key distribution device 800 and an external storage device. The memory 820 is used to store application software and various types of data installed in the digital twin spatial channel continuous variable quantum key distribution device 800, such as the program code of the digital twin spatial channel continuous variable quantum key distribution device 800. The memory 820 can also be used to temporarily store data that has been output or is to be output. In one embodiment, the memory 820 stores a digital twin spatial channel continuous variable quantum key distribution program 840, which can be executed by the processor 810, thereby realizing the digital twin spatial channel continuous variable quantum key distribution method of each embodiment of the present application.

[0153] In some embodiments, the processor 810 can be a central processing unit (CPU), a microprocessor or other data processing chip, used to run the program code stored in the memory 820 or process data, such as executing the spatial channel continuous variable quantum key distribution method of the digital twin.

[0154] In some embodiments, the display 830 may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, and an OLED (Organic Light-Emitting Diode) touch device. The display 830 is used to display information on the digital twin spatial channel continuous variable quantum key distribution device 800 and to display a visual user interface. The components 810-830 of the digital twin spatial channel continuous variable quantum key distribution device 800 communicate with each other via a system bus.

[0155] In one embodiment, when the processor 810 executes the digital twin spatial channel continuous variable quantum key distribution program 840 in the memory 820, the steps in the digital twin spatial channel continuous variable quantum key distribution method as described above are implemented.

[0156] This embodiment also provides a computer-readable storage medium on which a spatial channel continuous variable quantum key distribution program of a digital twin is stored. When the spatial channel continuous variable quantum key distribution program of the digital twin is executed by a processor, the following steps are implemented:

[0157] Construct a satellite-to-ground link model between the satellite and the ground station based on the satellite orbit parameter data and the ground receiving station location information, and calculate the satellite-to-ground link dynamic parameters;

[0158] Based on the dynamic parameters of the satellite-to-ground link and the atmospheric parameters, an atmospheric model is constructed to simulate the link attenuation loss at different times in a single orbit in the satellite-to-ground link.

[0159] The quantum state preparation process is simulated to adjust the quantum state parameters and the key generation rate is calculated based on the link attenuation loss to distribute the satellite-to-ground quantum key.

[0160] In summary, the present invention provides a digital twin space channel continuous variable quantum key distribution method, which is based on the dynamic model constructed by satellite orbit parameters and ground station positions, and can calculate the dynamic parameters of the satellite-to-ground link in real time. Combined with the dynamic model of atmospheric parameters, it can quantify the link attenuation and background noise under different weather conditions, and adjust the quantum state preparation parameters according to the real-time link attenuation data, so as to maximize the key generation rate while ensuring security. Starting from the real experimental scene of space quantum key distribution, the complete process of transmitter, transmission channel and key distribution protocol calculation in the satellite-to-ground communication process is simulated, which not only covers the preparation, transmission and measurement of quantum states, but also can simulate in detail various influencing factors of the atmospheric environment, such as diffraction, extinction and turbulence and other actual environmental factors, and provides a multi-parameter, multi-variable and high-confidence digital twin simulation environment. Through precise model and parameter settings, it is possible to truly simulate the real-time dynamic changes of core parameters such as the operation of quantum satellites, the satellite-to-ground quantum key distribution process, the degradation of quantum states, and the quantum key rate during space quantum key distribution. Potential problems can be identified and solved in advance, thereby reducing the attenuation and loss of single-photon signals during transmission, increasing the key generation rate, and avoiding the adverse effects of environmental noise, equipment defects, transmission losses and other factors on the security and reliability of the generated keys.

[0161] The present application also provides a computer-readable storage medium on which a computer program is stored, and when the program is executed by a processor, the steps of the above method are implemented. The computer-readable storage medium may include, but is not limited to, any type of disk, including a floppy disk, an optical disk, a DVD, a CD-ROM, a micro drive, and a magneto-optical disk, a ROM, a RAM, an EPROM, an EEPROM, a DRAM, a VRAM, a flash memory device, a magnetic card or an optical card, a nanosystem (including a molecular memory IC), or any type of medium or device suitable for storing instructions and / or data.

[0162] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0163] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0164] In the several embodiments provided in the present application, it should be understood that the disclosed devices can be implemented in other ways. For example, the device embodiments described above are only schematic, such as the division of the units, which is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some service interfaces, and the indirect coupling or communication connection of devices or units can be electrical or other forms.

[0165] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0166] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0167] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a memory, including a number of instructions to enable a computer device (which can be a personal computer, server or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned memory includes: U disk, read-only memory (ROM), random access memory (RAM), mobile hard disk, disk or optical disk and other media that can store program code.

[0168] A person of ordinary skill in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable memory, which can include: a flash drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0169] The above is only an exemplary embodiment of the present disclosure, and the scope of the present disclosure cannot be limited thereto. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the specification and practicing the disclosure here, those skilled in the art will easily think of the implementation scheme of the present disclosure. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the technical field not recorded in the present disclosure. The description and examples are regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

[0170] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0171] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.< / t> < / t> < / t>

Claims

1. A digital twin spatial channel continuous variable quantum key distribution method, characterized in that: include: Construct a satellite-to-ground link model between the satellite and the ground station based on the satellite orbit parameter data and the ground receiving station location information, and calculate the satellite-to-ground link dynamic parameters; Based on the satellite-to-ground link dynamic parameters and atmospheric parameters, an atmospheric model is constructed to simulate the link attenuation loss at different times in a single orbit in the satellite-to-ground link; The quantum state preparation process is simulated to adjust the quantum state parameters and the key generation rate is calculated in combination with the link attenuation loss to distribute the satellite-to-ground quantum key.

2. The spatial channel continuous variable quantum key distribution method of digital twin according to claim 1, characterized in that: The step of constructing an atmospheric model based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate link attenuation losses at different times in a single orbit in the satellite-to-ground link also includes: Based on the satellite-to-ground link dynamic parameters and atmospheric parameters, a free space diffraction model is constructed to simulate the diffraction effect of a light beam when propagating in free space, and the diffraction transmittance is calculated; Based on the satellite-to-ground link dynamic parameters and atmospheric parameters, an atmospheric extinction model is constructed to simulate and evaluate the impact of atmospheric conditions on signal transmission, and the atmospheric transmission efficiency at a preset elevation angle is calculated; Based on the satellite-to-ground link dynamic parameters and atmospheric parameters, an atmospheric turbulence model is constructed to simulate the influence of irregular temperature and pressure changes in the atmosphere on light beam transmission, and the transmission efficiency probability is calculated; The link attenuation loss at different times in a single orbit is calculated according to the diffraction transmittance, the atmospheric transmission efficiency, the transmission efficiency probability and the satellite-to-ground link dynamic parameters.

3. The spatial channel continuous variable quantum key distribution method of digital twin according to claim 2, characterized in that: The method of constructing a free space diffraction model based on the satellite-to-ground link dynamic parameters and the atmospheric parameters to simulate the diffraction effect of the light beam when propagating in the free space and calculate the diffraction transmittance also includes: Based on the satellite-to-ground link dynamic parameters and atmospheric parameters, Gaussian beam parameters are determined to construct a free space diffraction model; When the Gaussian beam is detected by a receiver of a preset telescope, the diffraction transmittance is calculated according to the Gaussian beam parameters and the receiver radius.

4. The spatial channel continuous variable quantum key distribution method of digital twin according to claim 2, characterized in that: The atmospheric turbulence model is constructed based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate the influence of irregular temperature and pressure changes in the atmosphere on light beam transmission, and calculate the transmission efficiency probability, and further includes: Based on the satellite-to-ground link dynamic parameters and atmospheric parameters, an atmospheric turbulence model is constructed to calculate the random fluctuation degree of the center position of the light beam; Determining the channel transmission coefficient at a preset center deflection distance according to the approximate probability distribution of the deflection distance and the degree of random fluctuation of the center position of the light beam; The transmission efficiency probability is calculated based on the channel transmission coefficient using the chain rule.

5. The spatial channel continuous variable quantum key distribution method of digital twin according to claim 1, characterized in that: The simulation of the quantum state preparation process adjusts the quantum state parameters and calculates the key generation rate in combination with the link attenuation loss to distribute the satellite-to-ground quantum key, and also includes: Setting quantum state parameters to establish a quantum state that conforms to a Gaussian distribution, and optimizing the quantum state parameters using a machine learning algorithm; The satellite-to-ground quantum key is distributed by calculating the key generation rate based on the optimized quantum state parameters and the link attenuation loss.

6. The spatial channel continuous variable quantum key distribution method of digital twin according to claim 5, characterized in that: The method of calculating the key generation rate according to the optimized quantum state parameters and the link attenuation loss and distributing the satellite-to-ground quantum key also includes: Calculate the total channel noise according to the optimized quantum state parameters and the link attenuation loss; Determine the mutual information between the receiving end and the transmitting end according to the covariance matrix of the receiving end and the transmitting end of the channel total noise and Gaussian modulation; Calculate the maximum amount of information of the receiving end measurement value according to the covariance matrix; The key generation rate is calculated based on the mutual information between the receiving end and the transmitting end and the maximum amount of information of the receiving end measurement value to distribute the satellite-to-ground quantum key.

7. The spatial channel continuous variable quantum key distribution method of digital twin according to claim 1, characterized in that: The method of constructing a satellite-to-ground link model between the satellite and the ground station according to the satellite orbit parameter data and the ground receiving station position information, and calculating the satellite-to-ground link dynamic parameters, further includes: Accessing an open source platform to obtain two lines of element set data of a satellite, and converting the two lines of element set data into satellite orbit parameter data; It is beneficial for the preset simulation software to construct a satellite-to-ground link model between the satellite and the ground station according to the satellite orbit parameter data and the ground receiving station position information; The satellite motion trajectory is simulated based on the satellite-to-ground link model, and the satellite-to-ground link dynamic parameters are calculated.

8. A digital twin spatial channel continuous variable quantum key distribution device, characterized in that: include: A link parameter module, which is configured to construct a satellite-to-ground link model between the satellite and the ground station according to the satellite orbit parameter data and the ground receiving station position information, and calculate the satellite-to-ground link dynamic parameters; An attenuation loss module is configured to construct an atmospheric model based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate the link attenuation loss at different times in a single orbit in the satellite-to-ground link; The key distribution module is configured to simulate the quantum state preparation process to adjust the quantum state parameters and calculate the key generation rate in combination with the link attenuation loss to distribute the satellite-to-ground quantum key.

9. A digital twin spatial channel continuous variable quantum key distribution device, characterized in that: It includes at least one processing unit and at least one storage unit, wherein the storage unit stores a computer program, and when the computer program is executed by the processing unit, the processing unit executes the steps of the spatial channel continuous variable quantum key distribution method of the digital twin according to any one of claims 1 to 7.

10. A storage medium, characterized in that: It stores a computer program that can be executed by an access authentication device. When the computer program runs on the access authentication device, the access authentication device executes the steps of the spatial channel continuous variable quantum key distribution method of the digital twin according to any one of claims 1 to 7.

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