A digital-twinning spatial channel continuous-variable quantum key distribution method

Abstract

The application discloses a digital-twin spatial channel continuous variable quantum key distribution method, and relates to the technical field of quantum information processing.The method comprises the following steps: constructing a satellite-ground station link model between a satellite and a ground station according to satellite orbit parameter data and ground station position information, and calculating satellite-ground station link dynamic parameters; constructing an atmospheric model based on the satellite-ground station link dynamic parameters and atmospheric parameters to simulate link attenuation loss at different times under a single orbit in the satellite-ground station link; simulating quantum state preparation process to adjust quantum state parameters and combining the link attenuation loss to calculate key generation rate to distribute satellite-ground station quantum keys.The dynamic model constructed based on satellite orbit parameters and ground station positions can calculate satellite-ground station link dynamic parameters in real time, and can establish an atmospheric model to quantify link attenuation and background noise under different weather conditions, adjust quantum state preparation parameters, and maximize key generation rate under the premise of ensuring security.

Description

Technical Field

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

[0002] Quantum Key Distribution (QKD), with its security properties based on quantum mechanics and information theory, can distribute secure 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. CV-QKD (continuous variable quantum key distribution), as an important branch of QKD, encodes key information in the Gaussian modulation parameters (such as amplitude, phase, or frequency) of coherent light and uses balanced homodyne detection technology to achieve coherent measurement of quantum states.

[0003] In existing technologies, 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 classic laser communication link (such as satellite-borne lidar) and precise pointing control, combined with atmospheric turbulence pre-compensation algorithms (such as adaptive optics) to maintain signal stability.

[0004] However, existing technology solutions face multiple bottlenecks in practical application: First, spot distortion and phase perturbations caused by atmospheric turbulence lead to quantum state degradation, reducing the signal-to-noise ratio; second, the dynamic time-varying nature of the satellite-to-ground link makes real-time channel characteristics difficult to model; and third, the high complexity of CV-QKD systems imposes stringent engineering requirements, particularly regarding the size, power consumption, and reliability of onboard equipment. Furthermore, while existing simulation tools can partially simulate atmospheric channel effects, they lack the ability to accurately model multi-physics coupling, limiting 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 in the prior art that CV-QKD 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, depends on the 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 objectives, according to a first aspect of the present invention, a method for continuous variable quantum key distribution over a spatial channel of a digital twin is provided, comprising:

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

[0008] An atmospheric model is constructed based on the dynamic parameters of the satellite-to-ground link and the atmospheric parameters to simulate the link attenuation loss at different times in a single orbit of 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 in combination with the link attenuation loss to distribute the satellite-to-ground quantum key.

[0010] In one 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 of the satellite-to-ground link, further comprising:

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

[0012] Based on the dynamic parameters of the satellite-to-ground link 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.

[0013] Based on the dynamic parameters of the satellite-to-ground link and atmospheric parameters, an atmospheric turbulence model is constructed to simulate the impact of irregular temperature and pressure changes in the atmosphere on 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 one possible implementation, a free-space diffraction model is constructed based on the dynamic parameters of the satellite-to-ground link and atmospheric parameters to simulate the diffraction effect of a light beam propagating in free space and calculate the diffraction transmittance, which also includes:

[0016] The free-space diffraction model is constructed by determining the Gaussian beam parameters based on the satellite-to-ground link dynamic parameters and atmospheric parameters.

[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 one possible implementation, an atmospheric turbulence model is constructed based on the dynamic parameters of the satellite-to-ground link and atmospheric parameters to simulate the impact of irregular temperature and pressure changes in the atmosphere on beam transmission and calculate the transmission efficiency probability. This also includes:

[0019] An atmospheric turbulence model is constructed based on the dynamic parameters of the satellite-to-ground link and atmospheric parameters to calculate the degree of random fluctuation of the beam center position.

[0020] Determine the channel transmission coefficient at a preset center deflection distance based on the approximate probability distribution of the deflection distance and the degree of random fluctuation 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 one possible implementation, simulating the quantum state preparation process to adjust quantum state parameters and calculating the key generation rate in combination with 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 the Gaussian distribution, and use machine learning algorithms to optimize the 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 one 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, further comprising:

[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 based on the covariance matrix of the receiving end and the transmitting end of the channel total noise and Gaussian modulation;

[0028] Calculate the maximum information content of the receiving end measurement value based on 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 one possible implementation, a satellite-to-ground link model between the satellite and the ground station is constructed based on the satellite orbit parameter data and the ground receiving station position information, and dynamic parameters of the satellite-to-ground link are calculated, further comprising:

[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 helpful for the preset simulation software to build 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 a second aspect of the present invention, a digital twin spatial channel continuous variable quantum key distribution device is also provided, comprising:

[0035] a link parameter module configured 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 position information, and calculate the dynamic parameters of the satellite-to-ground link;

[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 of the 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. When the computer program is executed by the processing unit, the processing unit performs the steps of the digital twin spatial channel continuous variable quantum key distribution method described in any one of the above items.

[0039] According to the fourth aspect of the present invention, a storage medium is also provided, which stores a computer program that can be executed 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. Based on a dynamic model constructed based on satellite orbit parameters and ground station positions, it 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, adjust the quantum state preparation parameters according to the real-time link attenuation data, and maximize the key generation rate while ensuring security. Starting from the real experimental scenario 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. It 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. 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 creative work.

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

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

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

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

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

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

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

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

[0051] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of 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 may be combined with each other as long as they do not conflict with each other.

[0052] The terms "first," "second," "third," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

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

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

[0055] S102, 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 of 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-described embodiment, a three-dimensional satellite-to-ground link model between the satellite and the ground receiving station is first constructed using spatial geometry and physical modeling techniques based on precise satellite orbit parameter data (such as orbital altitude, inclination, and period) and the geographic location of the ground receiving station. Subsequently, dynamic parameters of the satellite-to-ground link are calculated over different time periods using real-time or predictive algorithms. These parameters include, but are not limited to, link distance, elevation angle, and line-of-sight velocity, which are crucial for 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, the simulation phase of the quantum state preparation process begins. Based on the requirements of the quantum key distribution protocol, quantum state parameters, such as the polarization, phase, or amplitude of the photons, are designed and adjusted to ensure that the quantum state is both eavesdropper-resistant and effectively conveys information during transmission. Subsequently, based on the specific values ​​of the link attenuation loss and using relevant formulas from quantum information theory, the key generation rate under different conditions is calculated. This not only takes into account the loss of the quantum state during transmission, but also factors such as quantum noise and detector efficiency that affect the key generation rate. Finally, based on the calculated results, the quantum state parameters and distribution strategy are dynamically adjusted to optimally distribute the satellite-to-ground quantum key, ensuring the security and efficiency of communications.

[0060] Compared with the existing technology, this embodiment provides a digital twin space channel continuous variable quantum key distribution method. Based on the dynamic model constructed based on satellite orbit parameters and ground station positions, it 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, adjust the quantum state preparation parameters according to the real-time link attenuation data, and maximize the key generation rate while ensuring security. Starting from the real experimental scenario of space quantum key distribution, it simulates the complete process of the transmitter, transmission channel, and key distribution protocol calculation in the satellite-to-ground communication process. It 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, turbulence and other actual environmental factors, providing a multi-parameter, multi-variable, 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 FIG. 1 is a flow chart of an embodiment of step S102 in FIG. 1 . In some embodiments of the present invention, constructing an atmospheric model based on satellite-to-ground link dynamic parameters and atmospheric parameters to simulate link attenuation loss at different times in a single orbit of the satellite-to-ground link 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. Construct an atmospheric turbulence model based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate the impact of irregular temperature and pressure changes in the atmosphere on light beam transmission, and calculate the transmission efficiency probability.

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

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

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

[0068] The free-space diffraction model is constructed by determining the Gaussian beam parameters based on the satellite-to-ground link dynamic parameters and atmospheric parameters.

[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 a free-space channel refers to the phenomenon that the waist spot size of a light beam gradually increases due to the diffraction effect during its propagation. In a free-space channel, beam broadening is mainly caused by the diffraction effect. As the light 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 free space at a distance z, beam broadening will occur under the influence of diffraction and turbulence. The beam is diffracted by a beam with a radius of 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 finite 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 light beam path to be extended, while light extinction includes absorption and scattering, which significantly attenuate the light signal intensity. Random effects cause light 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 the beam path, atmospheric model, and visibility. Therefore, accurately evaluating the 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. This simulation is typically performed using the MODTRAN code, which is widely used to estimate atmospheric transmittance and radiance. For example, at a wavelength of 1550 nm, using a mid-latitude summer atmospheric model and 23 km visibility, the transmission efficiency at the zenith is 0.91. However, when visibility decreases 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 impact on transmission efficiency.

[0080] See also Figure 3 , Figure 3 The present invention provides Figure 2 FIG. 1 is a flow chart of an embodiment of step S203 in FIG. 1 . In some embodiments of the present invention, an atmospheric turbulence model is constructed based on satellite-to-ground link dynamic parameters and atmospheric parameters to simulate the effects of irregular temperature and pressure changes in the atmosphere on light beam transmission, and to calculate the transmission efficiency probability, further comprising:

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

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

[0083] S303: Calculate the transmission efficiency probability based on 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 degree of random fluctuation of the center position of the beam, which combines the effects 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 as follows:

[0087]

[0088] parameter is the refractive index structure parameter that characterizes the intensity of atmospheric turbulence. In ideal conditions, 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 under the known turbulent channel tur =T 2 When , the chain rule is used to obtain the probability distribution of the transmission coefficient, which is 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 quantum state parameters and calculating the key generation rate in combination with link attenuation loss to distribute satellite-to-ground quantum keys further includes:

[0097] Set quantum state parameters to establish a quantum state that conforms to the Gaussian distribution, and use machine learning algorithms to optimize the 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-mentioned embodiments, during the simulation of quantum state preparation, in order to efficiently generate and distribute satellite-to-ground quantum keys, it is necessary to carefully adjust the various parameters of the quantum state and comprehensively consider the impact of link attenuation 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, typically coherent states or compressed states. The preparation of these quantum states determines the signal quality, as well as 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 or squeezed states, or the "strength" of the quantum signal, which directly affects the signal's transmission distance and quality at the receiving end. The number of symbols determines the amount of data transmitted each time and is a crucial parameter in communications, influencing the quantum key generation rate and noise immunity.

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

[0102] Based on the optimized quantum state parameters and the precise calculation of link attenuation loss, the key generation rate can be calculated, which is then used to distribute quantum keys between the satellite and the ground. The key generation rate is an important indicator of quantum communication system performance, directly determining the number of secure and reliable keys that can be generated. By continuously optimizing quantum state parameters and accurately calculating link attenuation loss, the key generation rate can be improved, thereby ensuring the efficiency and security of quantum key distribution between the satellite and the ground.

[0103] See also Figure 4 , Figure 4 This is a 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, calculating the key generation rate and distributing the satellite-to-ground quantum key based on optimized quantum state parameters and link attenuation loss also includes:

[0104] S401, calculating the total channel noise based on 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 total channel noise and the covariance matrix of the Gaussian modulated receiving end and the transmitting end;

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

[0107] S404: Calculate the key generation rate based on the mutual information between the receiving end and the transmitting end and the maximum information amount 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 uses the transmitting telescope to send the quantum signal to the receiving end (Bob) through the free-space quantum channel;

[0109] The free-space quantum channel is composed of a quantum network satisfying the probability distribution {p i} i＝1,2,..,M The transmission efficiency {T i} i＝1,2,..,M and its corresponding excess noise ε, the channel noise in units of shot noise is described as in <t>Represents {T i } i＝1,2,..,M The average value of , that is: Here the probability distribution of T is <t>Compared with the above 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 privacy enhancement. The detection noise of the quantum state under homodyne and heterodyne detection is described as Where η represents 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 size of 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 when there is no additional noise can be obtained by setting the size of different noise values.

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

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

[0114] K=(1-P)(β R I AB -χ BE );

[0115] Where P represents the probability of outage 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. AB It can be expressed as:

[0116]

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

[0118]

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

[0120]

[0121] Therefore, 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) χ BE Determined by the Hoelvo boundary

[0124]

[0125] Where, 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 eavesdropping under homodyne detection, 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 the parameters are transmitted through the free space channel, the equivalent expressions are:

[0131]

[0132]

[0133] Communication interruption is closely related to beam drift. When the focus is not within the receiving fiber core, communication interruption occurs. This is because due to the high directivity of laser transmission, when the arrival angle fluctuates significantly, which manifests as image jitter on the receiving aperture plane, communication interruption may occur. For now, we will temporarily discuss the feasibility of CV-QKD under ideal conditions using the GG02 communication protocol, assuming that the communication interruption probability is 0, that is, the satellite-to-ground communication process is not affected by the interruption probability. 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 based on 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. Access an open source platform to obtain two lines of element set data of a satellite, and convert 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 based on the satellite orbit parameter data and the ground receiving station location information;

[0138] S503 , simulating the satellite motion trajectory based on the satellite-to-ground link model, and calculating 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 orbital element (TLE) data released by the relevant satellite is obtained to obtain the orbital parameters of the specified satellite (taking Micius as an example), thereby completing the acquisition of satellite orbital parameters. Next, based on the collected parameter data, the satellite and ground station scene is 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 using 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 common view 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 period of time 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, directly affecting 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, environmental attenuation and noise interference can be minimized. By limiting the communication period, the risk of eavesdropping and illegal access can be significantly reduced.

[0141] Please refer to Figures 6(a), (b), (c), and (d). Figures 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 between 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 Micius satellite orbits at an altitude of 496.6 km. The scenario involves communication between the Micius satellite and the Lijiang, Delingha, Xinglong, and Nanshan ground stations. The parameters to be extracted include: the second row, "16354.569" (first group), representing the TLE ephemeris; the third row, primarily: orbital inclination 97.3698 (second group), ascending node right ascension 268.1064 (third group), orbital eccentricity 0013349 (fourth group), argument of perigee 175.8929 (fifth group), and 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), and Nanshan ground station (43°51'57.2"N, 87°34'18.8"E, 2088m above sea level).

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

[0146] In order to better implement the digital twin spatial channel continuous variable quantum key distribution method in the embodiment of the present invention, based on the digital twin spatial channel continuous variable quantum key distribution method, please refer to Figure 7 , Figure 7 This is a structural diagram of an embodiment of a digital twin spatial channel continuous variable quantum key distribution device provided by the present invention. This 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 configured 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 position information, and calculate the dynamic parameters of the satellite-to-ground link;

[0148] An attenuation loss module 720 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 of 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 be found in 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. The digital twin spatial channel continuous variable quantum key distribution device can be a computing device such as a mobile terminal, desktop computer, notebook, PDA, and 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 can 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 can 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. Furthermore, the memory 820 can 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 for installing 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 about 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 can be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, or an OLED (Organic Light-Emitting Diode) touchscreen. The display 830 is used to display information about the digital twin spatial channel continuous variable quantum key distribution device 800 and to display a visual user interface. 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 further provides a computer-readable storage medium on which a digital twin spatial channel continuous variable quantum key distribution program is stored. When the digital twin spatial channel continuous variable quantum key distribution program 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 satellite orbit parameter data and ground receiving station location information, and calculate the dynamic parameters of the satellite-to-ground link;

[0158] An atmospheric model is constructed based on the dynamic parameters of the satellite-to-ground link and the atmospheric parameters to simulate the link attenuation loss at different times in a single orbit of 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 in combination with 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. Based on the dynamic model constructed based on satellite orbit parameters and ground station positions, it 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, adjust the quantum state preparation parameters according to the real-time link attenuation data, and maximize the key generation rate while ensuring security. Starting from the real experimental scenario 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. It 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.

[0161] The present application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above method. 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 microdrive, 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 this application is not limited by the order of the actions described, because according to this 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 this application.

[0163] In the above embodiments, the description of each embodiment has its own focus. 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 this application, it should be understood that the disclosed devices can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, 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 interface, and the indirect coupling or communication connection of the device or unit can be electrical or other forms.

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

[0166] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or 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 for enabling a computer device (which can be a personal computer, server or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned memory includes: various media that can store program codes, such as a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk.

[0168] Those skilled in the art will 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 may 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 cannot be used to limit the scope of the present disclosure. 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 herein, those skilled in the art will easily think of the implementation scheme of the present disclosure. This application is intended to cover any variation, 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 art that are not recorded in the present disclosure. The description and examples are to be 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 can 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 merely 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 scope of protection 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 satellite orbit parameter data and ground receiving station location information, and calculate the dynamic parameters of the satellite-to-ground link; An atmospheric model is constructed based on the satellite-to-ground link dynamic parameters and atmospheric parameters to simulate link attenuation losses at different times in a single orbit of the satellite-to-ground link; 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; 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 of the satellite-to-ground link further 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.

2. The spatial channel continuous variable quantum key distribution method for digital twins according to claim 1, characterized in that: The method further includes: constructing 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 when propagating in free space, and calculating the diffraction transmittance. Determine Gaussian beam parameters based on the satellite-to-ground link dynamic parameters and atmospheric parameters 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.

3. The spatial channel continuous variable quantum key distribution method for digital twins according to claim 1, characterized in that: The step of 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 calculate the transmission efficiency probability further includes: An atmospheric turbulence model is constructed based on the satellite-to-ground link dynamic parameters and atmospheric parameters to calculate the degree of random fluctuation of the center position of the light beam; Determining the channel transmission coefficient at a preset center deflection distance based on an approximate probability distribution of the deflection distance and a 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.

4. The spatial channel continuous variable quantum key distribution method for digital twins 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, further comprising: 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.

5. The spatial channel continuous variable quantum key distribution method for digital twins according to claim 4 is characterized in that: The method further includes calculating the key generation rate based on the optimized quantum state parameters and the link attenuation loss to distribute the satellite-to-ground quantum key. Calculating the total channel noise based on the optimized quantum state parameters and the link attenuation loss; 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; Calculating 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 information amount of the receiving end measurement value to distribute the satellite-to-ground quantum key.

6. The spatial channel continuous variable quantum key distribution method for digital twins according to claim 1, characterized in that: The method of constructing 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 position information, and calculating the dynamic parameters of the satellite-to-ground link, 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; Facilitating 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; 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.

7. A digital twin spatial channel continuous variable quantum key distribution device, characterized in that: include: a link parameter module configured 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 position information, and calculate the dynamic parameters of the satellite-to-ground link; an attenuation loss module, 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 of the satellite-to-ground link; A key distribution module is configured to simulate the quantum state preparation process to adjust the quantum state parameters and calculate the key generation rate based on the link attenuation loss to distribute the satellite-to-ground quantum key; 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 of the satellite-to-ground link further 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.

8. 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. 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 6.

9. 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 6.

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