CN110492991A - Method for parameter estimation and system based on free space CVQKD system - Google Patents
Method for parameter estimation and system based on free space CVQKD system Download PDFInfo
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Abstract
The present invention provides a kind of method for parameter estimation and system based on free space CVQKD system, the subchannel of atmospheric channel is divided, atmospheric channel is divided into several sub-channels by the scintillation index of receiving end local oscillator light intensity, while obtaining the shot noise of subchannel；Estimation to system relevant parameter obtains the estimated value of the relevant parameter under different subchannels by parameter Estimation according to the subchannel divided, then according to estimates of parameters computation key rate, judges whether channel is safe with this；Cipher key-extraction is carried out, by rear selection method, retains and biggish subchannel is contributed to key rate, therefrom extract key, obtain the final key of system.The present invention carries out subchannel division by the atmospheric channel to free space CVQKD system, obtains the estimates of parameters and real-time cipher key rate under each sub-channels, and combine rear selection technique lifting system performance.
Description
Technical Field
The invention relates to the technical field of information security, in particular to a parameter estimation method and a parameter estimation system based on a free space CVQKD system, in particular to a parameter estimation method for continuous variable quantum key distribution, which is designed based on free space Gaussian modulation coherent state continuous variable quantum key distribution (GMCS CVQKD).
Background
Continuous variable quantum key distribution is a technology different from traditional communication, and the unconditional safety of communication is realized mainly by using an uncertainty principle and a quantum state unclonable theorem. The optical fiber channel CVQKD attracts many researchers to participate in research because of its potential advantages compatible with existing optical communication technologies. In order to make the free space CVQKD and the optical fiber channel CVQKD better merge and develop, research on continuous variable quantum key distribution under the free space channel has become one of the research hotspots of the CVQKD in recent years.
CVQKD generally includes two phases: (1) quantum information transmission stage: the quantum signal is transmitted through a quantum channel and then measured by a zero/heterodyne detector; (2) classical information post-processing stage: part of the data is evaluated for system security by applying parameter estimation, and the rest part extracts a final key by technologies such as reverse negotiation, privacy enhancement and the like. And the parameter estimation is used as a key loop in the post-processing stage of the CVQKD classical information, which helps the communication parties to evaluate the actual safety of the system and obtain parameters relevant for subsequent processing. In the case where the quantum channel is estimated by a legitimate correspondent, the principles of quantum mechanics impose an upper bound on the information that may be revealed to a potential eavesdropper. However, the study of free-space channel CVQKD parameter estimation methods is currently almost blank. The transmittance of the free-space channel fluctuates randomly in time compared to the optical fiber channel, and therefore, the parameter estimation method of the optical fiber channel CVQKD cannot be directly applied to the free-space channel CVQKD.
The prior art related to the present application is patent document CN104539582A, which discloses a continuous variable quantum key distribution security defense method, including: step A: shot noise monitoring, namely evaluating shot noise variance by monitoring local oscillator light intensity of a receiving end in real time; and B: calculating a key rate, namely calculating an operation key rate according to the real-time shot noise variance estimated in the step A; the two steps are executed simultaneously and in parallel. The method is used for monitoring the local oscillation light at the receiving end of the CVQKD system, acquiring the shot noise variance during the operation of the system, and acquiring the real-time operation key rate of the system by combining a parameter estimation method so as to provide safety early warning for the safety of the system. However, the above patent document is designed for a constant transmittance, and is applied only to an optical fiber channel.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a parameter estimation method and system based on a free space CVQKD system.
The invention provides a parameter estimation system based on a free space CVQKD system, which comprises:
a sub-channel division module: the receiving end separates the optical signal sent by the sending end to obtain signal light and local oscillator light, and divides an atmospheric channel into a plurality of sub-channels through the flicker index of the local oscillator light to obtain shot noise of each sub-channel;
a parameter estimation module: the receiving end detects the signal light to obtain initial correlation information, parameter evaluation is carried out on each sub-channel based on the initial correlation information to obtain a parameter estimation value, and a key rate is calculated by combining the parameter estimation value and shot noise;
a key selection module: and extracting the key rate, and selecting the key rate of each sub-channel to obtain a final key.
The invention provides a parameter estimation method based on a free space CVQKD system, which comprises the following steps:
a sub-channel dividing step: the receiving end separates the optical signal sent by the sending end to obtain signal light and local oscillator light, and divides an atmospheric channel into a plurality of sub-channels through the flicker index of the local oscillator light to obtain shot noise of each sub-channel;
a parameter estimation step: the receiving end detects the signal light to obtain initial correlation information, parameter evaluation is carried out on each sub-channel based on the initial correlation information to obtain a parameter estimation value, and a key rate is calculated by combining the parameter estimation value and shot noise;
and a key selection step: and extracting the key rate, and selecting the key rate of each sub-channel to obtain a final key.
Preferably, the transmitting end modulates the coherent state signal by using a gaussian random number to form a modulated quantum signal, and transmits the quantum signal to the receiving end through an atmospheric channel;
the receiving end divides the local oscillator light through the beam splitter, divides the atmospheric channel into M sub-channels according to the flicker index monitoring of the light intensity of the local oscillator light, obtains the shot noise of each sub-channel, and records as { N }k}k＝1,2,…,MWhere k denotes the kth sub-channel, NkRepresents the shot noise of the kth sub-channel and M represents the total number of sub-channels.
Preferably, the flicker index is a ratio of a light intensity fluctuation variance of the local oscillator light to a light intensity mean square, and is calculated by the following formula:
wherein,a flicker index representing the intensity of the local oscillator light;
r represents a deviation value of the centroid of the received beam from the center of the receive aperture;
l represents a transmission distance;
I2(r, L) represents instantaneous local oscillator light intensity under real-time monitoring;
i (r, L) represents the instantaneous local oscillator light intensity under real-time monitoring;
u represents a voltage signal corresponding to the instantaneous light intensity after photoelectric conversion;
<. > indicates that statistical averages were made.
Preferably, the sending end sends the shared data { x to the receiving endi}i＝1,2,…,NAfter the receiving end receives the shared data after detecting, extracting the storage data { y of each sub-channeli}i＝1,2,…,NObtaining parameter estimation dataThe following relationships are satisfied:
wherein, tkRepresenting the correlation coefficient of the sending end data and the receiving end data on the k-th sub-channel;
xkrepresents the sender data on the k-th sub-channel;
ykrepresents the receiving end data on the k-th sub-channel;
zkrepresenting noise on the k-th sub-channel, satisfying a mean of zero, variance(ii) a gaussian distribution;
eta represents the detection efficiency obtained by the pre-selection measurement of the receiving end;
velrepresenting electrical noise resulting from a preselected measurement at the receiving end;
Tkrepresents the transmittance of the k-th sub-channel;
εkrepresents the over-noise of the k-th sub-channel;
Nkis the shot noise of the k-th sub-channel.
Preferably, the estimate of the parameter is obtained by:
wherein,an estimated value representing a correlation coefficient between the transmitter data and the receiver data on the kth sub-channel;
is shown at the k-thOn a subchannel, in M groups of dataRandomly selected m groups of data for parameter evaluation;
representing the noise z on the k-th sub-channelkAn estimate of the variance of (c);
representing the signal modulation variance estimate in the kth subchannel.
Preferably, the estimated value of the parameter of the kth sub-channel is obtained by the following formula:
wherein,an estimate representing a signal modulation variance within the kth subchannel;
an estimated value representing the channel transmittance of the kth sub-channel;
representing an estimate of the over-noise of the k-th sub-channel,
representing an estimate of the total noise of the k-th sub-channel.
Preferably, the estimated value of the parameter of the atmospheric channel is obtained by the following formula:
wherein,represents the average transmittance of the atmospheric channel;
m' represents the channel transmittance distribution number of the atmospheric subchannel;
indicates the channel transmittance TkA corresponding probability;
represents the over-noise epsilonkA corresponding probability;
representing total noiseA corresponding probability;
representing modulation varianceA corresponding probability;
representing the average over-noise of the atmospheric channel;
is the signal mean modulation variance;
is an atmospheric channelTotal noise;
is the total noise of the kth subchannel.
Preferably, the K sub-channel key rate K(k)And the system key rate K is calculated as follows:
K＝(1-P)(βIAB-χBE) (6b)
wherein, K(k)Represents the k-th sub-channel key rate;
β represents the reverse negotiation efficiency;
representing the mutual information quantity between the sending end and the receiving end on the kth sub-channel;
representing the mutual information quantity between the eavesdropper and the receiving end on the kth sub-channel;
k represents the system key rate;
IABrepresenting the mutual information quantity between a sending end and a receiving end in the system;
χBErepresenting the mutual information quantity between an eavesdropper and a receiving end in the system; pkRepresenting a communication outage probability for the kth sub-channel;
p represents the system communication outage probability.
Preferably, the first and second electrodes are formed of a metal,
wherein,
g (x) denotes Shannon entropy, g (x) ═ x +1 log2(x+1)-xlog2x；
A sine eigenvalue representing the covariance matrix on the kth subchannel;
λithe sincerous eigenvalues of the system covariance matrix are represented;
in particular, the amount of the solvent to be used,
in the k-th sub-channel,
wherein "+" in the formula (9-a) meansThe value of (A), "-" indicatesA value of (d);
wherein,
represents the linear noise of the k-th sub-channel,
Ak、Bk、CK、DKare respectively used as a reference for simplifying formula operation in the k-th sub-channel, and have no specific
Refers to a meaning;
χhrepresenting receiver probe noise,. chih＝[(1-η)+vel]/η
In the case of an atmospheric air channel,
wherein,
wherein "+" in the formula (10-c) means λ3The value of (A) (-) represents λ4A value of (d);
which represents the linear noise of the atmospheric channel,
χhrepresenting receiver probe noise,. chih＝[(1-η)+vel]/η；
A. B, C, D are respectively used as the index for simplifying formula operation in the atmosphere channel, and have no specific reference meaning;
calculating formula (6-a) according to formulas (7-a), (8-a), (9-a) - (9-d) can obtain the key rate of each subchannel, and calculating formula (6-b) according to formulas (7-b), (8-b), (10-a) - (10-d) can obtain the average key rate of the atmospheric channel.
Preferably, the detection of the signal light by the receiving end is accomplished by a detector, wherein the detector is a calibrated Homodyne detector; the estimates of the parameter estimates include channel transmittance, channel over-noise, modulation variance, and channel total noise.
Compared with the prior art, the invention has the following beneficial effects:
1. the method is based on the channel characteristics of the atmospheric channel and continuous variable quantum key distribution, obtains the shot noise of the sub-channel by dividing the sub-channel, carries out parameter estimation, and can accurately judge whether the system running state is safe, so that a receiving end selects to extract the key after carrying out the sub-channel;
2. the method for processing the received data at the receiving end is simple and efficient to realize and has good application prospect in a free space CVQKD system.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic reference diagram of a free space CVQKD system;
FIG. 2 is a flow chart of the present invention.
The figures show that: and Alice: a sending end; and Bob: a receiving end; src: a light source; RNG: a random number generator; mod: a modulator; PC: a polarization controller; BS: a beam splitter; HD: a Homodyne detector; t: a channel transmittance; p: probability corresponding to channel transmittance; t isi: channel transmittance of the ith subchannel;probability corresponding to the ith sub-channel transmittance; epsilon: excessive noise; eta: detecting efficiency of a detector at a receiving end; v: receiving end noise variance; xA，PA: a sequence of Gaussian random numbers; delta XA: canonical position before modulation; delta PA: positive moment before modulation; x: canonical position after modulation; p: regular momentum after modulation; x (p): receiving a measurement of the regular position (momentum) of the end; g, F0: and the receiving end assists the quantum state detected by the Homodyne.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
The invention provides a parameter estimation method based on a free space CVQKD system, which comprises the following steps:
a sub-channel dividing step: the receiving end separates the optical signal sent by the sending end to obtain signal light and local oscillator light, and divides an atmospheric channel into a plurality of sub-channels through the flicker index of the local oscillator light to obtain shot noise of each sub-channel;
a parameter estimation step: the receiving end detects the signal light to obtain initial correlation information, parameter evaluation is carried out on each sub-channel based on the initial correlation information to obtain a parameter estimation value, and a key rate is calculated by combining the parameter estimation value and shot noise;
and a key selection step: and extracting the key rate, and selecting the key rate of each sub-channel to obtain a final key.
Specifically, the transmitting end modulates coherent state signals by using Gaussian random numbers to form modulated quantum signals, and transmits the quantum signals to the receiving end through an atmospheric channel;
the receiving end divides the local oscillator light through the beam splitter, divides the atmospheric channel into M sub-channels according to the flicker index monitoring of the light intensity of the local oscillator light, obtains the shot noise of each sub-channel, and records as { N }k}k＝1,2,…,MWhere k denotes the kth sub-channel, NkRepresents the shot noise of the kth sub-channel and M represents the total number of sub-channels.
Specifically, the flicker index is a ratio of a light intensity fluctuation variance of the local oscillation light to a light intensity mean square, and is calculated by the following formula:
wherein,a flicker index representing the intensity of the local oscillator light;
r represents a deviation value of the centroid of the received beam from the center of the receive aperture;
l represents a transmission distance;
i (r, L) represents the instantaneous local oscillator light intensity under real-time monitoring; i is2(r, L) represents the square of the instantaneous local oscillator light intensity under real-time monitoring;
u represents a voltage signal corresponding to the instantaneous light intensity after photoelectric conversion;
<. > indicates that statistical averages were made.
Specifically, the sending end sends shared data { x to the receiving endi}i＝1,2,…,NAfter the receiving end receives the shared data after detecting, extracting the storage data { y of each sub-channeli}i＝1,2,…,NObtaining parameter estimation dataThe following relationships are satisfied:
wherein, tkRepresenting the correlation coefficient of the sending end data and the receiving end data on the k-th sub-channel;
xkrepresents the sender data on the k-th sub-channel;
ykrepresents the receiving end data on the k-th sub-channel;
zkrepresenting noise on the k-th sub-channel, satisfying a mean of zero, variance(ii) a gaussian distribution;
eta represents the detection efficiency obtained by the pre-selection measurement of the receiving end;
velrepresenting electrical noise resulting from a preselected measurement at the receiving end;
Tkrepresents the transmittance of the k-th sub-channel;
εkrepresents the over-noise of the k-th sub-channel;
Nkis the shot noise of the k-th sub-channel.
Specifically, the estimated value of the parameter is obtained by the following formula:
wherein,an estimated value representing a correlation coefficient between the transmitter data and the receiver data on the kth sub-channel;
represented on the k-th sub-channel in M groups of dataRandomly selected m groups of data for parameter evaluation;
representing the noise z on the k-th sub-channelkAn estimate of the variance of (c);
representing the signal modulation variance estimate in the kth subchannel.
Specifically, the estimated value of the parameter of the kth sub-channel is obtained by the following formula:
wherein,an estimate representing a signal modulation variance within the kth subchannel;
an estimated value representing the channel transmittance of the kth sub-channel;
representing an estimate of the over-noise of the k-th sub-channel,
representing an estimate of the total noise of the k-th sub-channel.
Specifically, the estimated value of the parameter of the atmospheric channel is obtained by the following formula:
wherein,represents the average transmittance of the atmospheric channel;
m' represents the channel transmittance distribution number of the atmospheric subchannel;
indicates the channel transmittance TkA corresponding probability;
represents the over-noise epsilonkA corresponding probability;
representing total noiseA corresponding probability;
representing modulation varianceA corresponding probability;
representing the average over-noise of the atmospheric channel;
is the signal mean modulation variance;
is the total noise of the atmospheric channel;
is the total noise of the kth subchannel.
In particular, the K-th sub-channel key rate K(k)And the system key rate K is calculated as follows:
K＝(1-P)(βIAB-χBE) (6b)
wherein, K(k)Represents the k-th sub-channel key rate;
β represents the reverse negotiation efficiency;
representing the mutual information quantity between the sending end and the receiving end on the kth sub-channel;
representing the mutual information quantity between the eavesdropper and the receiving end on the kth sub-channel;
k represents the system key rate;
IABrepresenting the mutual information quantity between a sending end and a receiving end in the system;
χBErepresenting the mutual information quantity between an eavesdropper and a receiving end in the system;
Pkrepresenting a communication outage probability for the kth sub-channel;
p represents the system communication outage probability.
Specifically, the detection of the signal light by the receiving end is completed by a detector, wherein the detector is a calibrated Homodyne detector; the estimates of the parameter estimates include channel transmittance, channel over-noise, modulation variance, and channel total noise.
The invention provides a parameter estimation system based on a free space CVQKD system, which comprises:
a sub-channel division module: the receiving end separates the optical signal sent by the sending end to obtain signal light and local oscillator light, and divides an atmospheric channel into a plurality of sub-channels through the flicker index of the local oscillator light to obtain shot noise of each sub-channel;
a parameter estimation module: the receiving end detects the signal light to obtain initial correlation information, parameter evaluation is carried out on each sub-channel based on the initial correlation information to obtain a parameter estimation value, and a key rate is calculated by combining the parameter estimation value and shot noise;
a key selection module: and extracting the key rate, and selecting the key rate of each sub-channel to obtain a final key.
The invention is further elucidated with reference to the following figures.
The invention aims to provide a parameter estimation method based on a free space CVQKD system, which is designed based on a Gaussian modulation coherent state continuous variable quantum key distribution (GMCS CVQKD) system and is designed aiming at random variation of transmittance and excessive noise in a free space channel, wherein the continuous variable quantum key distribution technology becomes an important branch of a communication technology due to the advantages of unconditional safety and the like on physics, and as a key ring in a CVQKD classical information post-processing stage, parameter estimation helps both communication parties to evaluate the actual safety of the system and obtain parameters related to subsequent processing, so that the parameters become a very important part in a system data processing module. The receiving end preprocesses the atmospheric channel, namely sub-channel division of the atmospheric channel; firstly, parameter estimation is carried out on each sub-channel, unsafe sub-channels are abandoned, and then sub-channels which contribute a larger key rate are screened out through a post-selection method, so that a final key of the system is obtained.
As shown in fig. 1, the present invention provides a parameter estimation method based on a free space continuous variable quantum key distribution system, which includes the following steps: sub-channel division, parameter estimation and post-selection. The transmitting end (Alice end) transmits the coherent state signal light and the local oscillator light which are subjected to Gaussian modulation to the receiving end (Bob end) through an atmospheric channel by time division multiplexing and polarization multiplexing.
And a sub-channel division stage: the method comprises the steps that a Bob end separates signal light and local oscillation light sent by an Alice end through polarization demultiplexing, then partial local oscillation light is separated through a beam splitter, corresponding voltage signals are obtained through a photoelectric converter, and a flicker index is obtained through a formula (1)According to the flicker index of the local oscillator light intensity toIs centeredThe range is divided into a sub-channel, and the shot noise of the sub-channel is obtained through a shot noise variance calibration technology.
A parameter estimation stage: the Bob end detects the quantum signal light through a Homodyne detector to obtain initial correlation information, then the Bob end and the Alice end use part of the information to perform parameter evaluation on an atmospheric channel to obtain modulation variance, channel transmittance, noise passing and total noise parameters on each sub-channel, and calculate sub-channel key rate and system key rate by combining shot noise and negotiation efficiency so as to judge the safety of the CVQKD system.
And a post-selection stage: and screening the sub-channels with the key rate higher than the safety threshold value according to the key rate of the sub-channels in the parameter estimation stage to be used as candidate channels for key extraction, and then selecting the sub-channels with larger contribution to the key to extract the final key by combining a post-selection technology.
Through the process, the sub-channel key rate and the system key rate can be obtained through parameter estimation when the CVQKD system runs, on one hand, the system safety can be judged, and on the other hand, the system key rate is improved by combining with a post-selection technology.
Preferably, the above-mentioned phases are performed simultaneously. The method comprises the steps that a sender completes Gaussian modulation on coherent states through amplitude modulation and phase modulation, and then sends quantum signals and local oscillator light to a receiving end through an atmospheric channel through polarization multiplexing and time division multiplexing; after a receiving end receives quantum signals and local oscillator light sent by a sending end through polarization demultiplexing, a part of local oscillator light is divided through a beam splitter, then corresponding voltage signals are obtained through photoelectric conversion, a corresponding flicker index is obtained through calculation according to a formula (1), meanwhile, corresponding shot noise is obtained through a calibrated Homodyne detector, and then, an atmospheric channel is divided into a plurality of sub-channels through the receiving end according to the flicker index. The data negotiation between the sending end and the receiving end is a reverse negotiation process.
As shown in fig. 2, the present invention is implemented by the following steps:
step 1: the transmitting end modulates coherent state signals by using Gaussian random numbers and transmits the modulated quantum signals to the receiving end through an atmospheric channel; the receiving end divides a part of received local oscillation light through the beam splitter, then divides the atmospheric channel into M sub-channels according to the flicker index monitoring of the local oscillation light intensity, and simultaneously obtains the shot noise value { N ] of each sub-channelk}k＝1,2,…,M；
Step 2: the receiving end completes the detection of the quantum signal through the detector to obtain the key data. After the sending end and the receiving end finish data negotiation, the sending end sends shared data { x to the receiving end through a classical channeli}i＝1,2,…,NAfter receiving the shared data, the receiving end extracts the corresponding data { y stored by the quantum channeli}i＝1,2,…,N；
And step 3: the receiving end transmits the data { (x)i,yi)}i＝1,2,…,NCorresponding to the M sub-channels divided in the step 1 to obtainThen obtaining parameters such as transmittance parameters, modulation variance parameters and noise passing parameters of each sub-channel by a parameter estimation method, calculating the key rate of the sub-channel by combining the negotiation efficiency, and then judging whether the communication at the stage and the communication at the time are safe or not according to the key rate of the sub-channel;
and 4, step 4: and the receiving end screens out the sub-channels which have larger contribution to the system key rate by a post-selection method in the sub-channel range of which the key rate is higher than the safety threshold value, and extracts the final key from the sub-channels.
The above steps are performed simultaneously.
Preferably, said step 1, in particular:
the sub-channels of the atmospheric channel are divided according to the flicker index of the light intensity of the local oscillatorReal-time monitoring of, thenIs centeredRanging from one sub-channel to the flicker indexThe calculation is as follows:
wherein, I (r, L) represents the instantaneous light intensity, U represents the voltage signal corresponding to the light intensity after photoelectric conversion, L represents the statistical average, and r represents the deviation between the receiving beam and the receiving aperture.
Preferably, said step 3, in particular:
alice end and Bob end exchange m groups of data in each sub-channelFor parameter estimation, the following relationship is satisfied under the gaussian model for the kth sub-channel:
yk＝tkxk+zk (2)
wherein,zkmean value of zero and varianceOf Gaussian noise, η and velIs the detection efficiency and electrical noise of the Bob terminal, TkIs the transmittance of the kth sub-channel, εkIs the over-noise of the k-th sub-channel, NkIs the shot noise of the k-th sub-channel.
Obtaining the estimated value of the coefficient in the formula (2) according to the maximum likelihood estimation theory,
wherein,is the modulation variance estimate for the channel in the kth subchannel.
By the parameter evaluation method, the estimation value of the related parameter of the kth sub-channel is further obtained,
therefore, the estimated value of the relevant parameter of the air channel is,
wherein,is the average transmission rate of the atmospheric channel,is the average over-noise of the atmospheric channel,is the signal-averaged modulation variance and,is a big air letterThe total noise of the road is the noise,is the total noise of the kth subchannel.
Preferably, said step 3, in particular:
k sub-channel key rate K(k)And the system key rate K is such that,
wherein,
and,
the key rate of each sub-channel can be obtained by calculation according to the formulas (7-a), (8-a) and (9-a) - (9-d), and the average key rate of the atmospheric channel can be obtained by calculation according to the formulas (7-b), (8-b) and (10-a) - (10-d).
Those skilled in the art will appreciate that, in addition to implementing the systems, apparatus, and individual modules thereof provided by the present invention in purely computer readable program code, the same procedures can be implemented entirely by logically programming method steps into logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system, the device and the modules thereof provided by the present invention can be considered as a hardware component, and the modules included in the system, the device and the modules thereof for implementing various programs can also be considered as structures in the hardware component; modules for performing various functions may also be considered to be both software programs for performing the methods and structures within hardware components.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (10)
1. A parameter estimation method based on a free space CVQKD system is characterized by comprising the following steps:
a sub-channel dividing step: the receiving end separates the optical signal sent by the sending end to obtain signal light and local oscillator light, and divides an atmospheric channel into a plurality of sub-channels through the flicker index of the local oscillator light to obtain shot noise of each sub-channel;
a parameter estimation step: the receiving end detects the signal light to obtain initial correlation information, parameter evaluation is carried out on each sub-channel based on the initial correlation information to obtain a parameter estimation value, and a key rate is calculated by combining the parameter estimation value and shot noise;
and a key selection step: and extracting the key rate, and selecting the key rate of each sub-channel to obtain a final key.
2. The parameter estimation method based on the free space CVQKD system according to claim 1, characterized in that the transmitting end modulates coherent state signals using Gaussian random numbers to form modulated quantum signals, and transmits the quantum signals to the receiving end through an atmospheric channel;
the receiving end divides the local oscillator light through the beam splitter, divides the atmospheric channel into M sub-channels according to the flicker index monitoring of the light intensity of the local oscillator light, obtains the shot noise of each sub-channel, and records as { N }k}k＝1,2,…,MWhere k denotes the kth sub-channel, NkRepresents the shot noise of the kth sub-channel and M represents the total number of sub-channels.
3. The free-space CVQKD system-based parameter estimation method of claim 1 wherein said flicker index is a ratio of a light intensity fluctuation variance of local oscillator light to a light intensity mean square, calculated by:
wherein,a flicker index representing the intensity of the local oscillator light;
r represents a deviation value of the centroid of the received beam from the center of the receive aperture;
l represents a transmission distance;
i (r, L) represents the instantaneous local oscillator light intensity under real-time monitoring;
I2(r, L) represents the square of the instantaneous local oscillator light intensity under real-time monitoring;
u represents a voltage signal corresponding to the instantaneous light intensity after photoelectric conversion;
<. > indicates that statistical averages were made.
4. The parameter estimation method based on the free-space CVQKD system according to claim 1, characterized in that the transmitting end sends shared data { x ] to the receiving endi}i＝1,2,…,NAfter the receiving end receives the shared data after detecting, extracting the storage data { y of each sub-channeli}i＝1,2,…,NObtaining parameter estimation dataThe following relationship is satisfied:
wherein, tkRepresenting the correlation coefficient of the sending end data and the receiving end data on the k-th sub-channel;
xkrepresents the sender data on the k-th sub-channel;
ykrepresents the receiving end data on the k-th sub-channel;
zkrepresenting noise on the k-th sub-channel, satisfying a mean of zero, variance(ii) a gaussian distribution of;
eta represents the detection efficiency obtained by the pre-selection measurement of the receiving end;
velrepresenting electrical noise resulting from a preselected measurement at the receiving end;
Tkrepresents the transmittance of the k-th sub-channel;
εkrepresents the over-noise of the k-th sub-channel;
Nkis the shot noise of the k-th sub-channel.
5. The method for parameter estimation based on a free-space CVQKD system according to claim 4, wherein the estimated values of the parameters are obtained by:
wherein,an estimated value representing a correlation coefficient between the transmitter data and the receiver data on the kth sub-channel;
represented on the k-th sub-channel in M groups of dataThe m groups of data for parameter evaluation are randomly selected;
representing the noise z on the k-th sub-channelkAn estimate of the variance of (c);
representing the signal modulation variance estimate in the kth subchannel.
6. The method for parameter estimation based on a free-space CVQKD system according to claim 5, wherein the estimated value of the parameter of the kth sub-channel is obtained by:
wherein,an estimate representing a signal modulation variance within the kth subchannel;
an estimated value representing the channel transmittance of the kth sub-channel;
representing an estimate of the over-noise of the k-th sub-channel,
representing an estimate of the total noise of the k-th sub-channel.
7. The free-space CVQKD system-based parameter estimation method according to claim 6, characterized in that the estimated values of the parameters of the atmospheric channel are obtained by:
wherein,represents the average transmittance of the atmospheric channel;
m' represents the channel transmittance distribution number of the atmospheric subchannel;
indicates the channel transmittance TkA corresponding probability;
represents the over-noise epsilonkA corresponding probability;
representing total noiseA corresponding probability;
representing modulation varianceA corresponding probability;
representing the average over-noise of the atmospheric channel;
is the signal mean modulation variance;
is the total noise of the atmospheric channel;
is the total noise of the kth subchannel.
8. The method for parameter estimation based on a free-space CVQKD system according to claim 7, characterized in that the kth sub-channel key rate K(k)And the system key rate K is calculated as follows:
K＝(1-P)(βIAB-χBE)(6b)
wherein, K(k)Represents the k-th sub-channel key rate;
β represents the reverse negotiation efficiency;
representing the mutual information quantity between the sending end and the receiving end on the kth sub-channel;
representing the mutual information quantity between the eavesdropper and the receiving end on the kth sub-channel;
k represents the system key rate;
IABrepresenting the mutual information quantity between a sending end and a receiving end in the system;
χBErepresenting the mutual information quantity between an eavesdropper and a receiving end in the system;
Pkrepresenting a communication outage probability for the kth sub-channel;
p represents the system communication outage probability.
9. The method for parameter estimation based on a free-space CVQKD system according to claim 1, wherein the detection of signal light by the receiving end is accomplished by a detector of quantum signals, said detector being a calibrated Homodyne detector; the estimates of the parameter estimates include channel transmittance, channel over-noise, modulation variance, and channel total noise.
10. A parameter estimation system based on a free-space CVQKD system, comprising:
a sub-channel division module: the receiving end separates the optical signal sent by the sending end to obtain signal light and local oscillator light, and divides an atmospheric channel into a plurality of sub-channels through the flicker index of the local oscillator light to obtain shot noise of each sub-channel;
a parameter estimation module: the receiving end detects the signal light to obtain initial correlation information, parameter evaluation is carried out on each sub-channel based on the initial correlation information to obtain a parameter estimation value, and a key rate is calculated by combining the parameter estimation value and shot noise;
a key selection module: and extracting the key rate, and selecting the key rate of each sub-channel to obtain a final key.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113055167A (en) * | 2021-03-22 | 2021-06-29 | 上海循态信息科技有限公司 | Defense method and system based on security vulnerability in chip CVQKD actual system |
| CN113225273A (en) * | 2021-03-25 | 2021-08-06 | 中国人民解放军国防科技大学 | CS-based free space CV-QKD channel parameter estimation method |
| CN114239840A (en) * | 2021-12-15 | 2022-03-25 | 北京百度网讯科技有限公司 | Quantum channel noise coefficient estimation method and device, electronic device and medium |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20150055961A1 (en) * | 2004-08-04 | 2015-02-26 | U.S. Army Research Laboratory | System and method for quantum based information transfer |
| US20170070290A1 (en) * | 2014-04-04 | 2017-03-09 | Nxgen Partners Ip, Llc | System and method for communication using orbital angular momentum with multiple layer overlay modulation |
| CN108683462A (en) * | 2018-07-31 | 2018-10-19 | 深圳大学 | A kind of encryption method and system of free space optical communication data |
| CN109039475A (en) * | 2018-07-11 | 2018-12-18 | 上海循态信息科技有限公司 | Continuous variable quantum key delivering method and system based on free space |
-
2019
- 2019-04-18 CN CN201910314197.9A patent/CN110492991B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20150055961A1 (en) * | 2004-08-04 | 2015-02-26 | U.S. Army Research Laboratory | System and method for quantum based information transfer |
| US20170070290A1 (en) * | 2014-04-04 | 2017-03-09 | Nxgen Partners Ip, Llc | System and method for communication using orbital angular momentum with multiple layer overlay modulation |
| CN109039475A (en) * | 2018-07-11 | 2018-12-18 | 上海循态信息科技有限公司 | Continuous variable quantum key delivering method and system based on free space |
| CN108683462A (en) * | 2018-07-31 | 2018-10-19 | 深圳大学 | A kind of encryption method and system of free space optical communication data |
Non-Patent Citations (3)
| Title |
|---|
| CHAI GENG ETAL.: "Parameter estimation of atmospheric continuous-variable quantum key distribution", 《PHYSICAL REVIEW A》 * |
| WEI ZHAO ETAL.: "Performance analysis of the satellite-to-ground continuous-variable quantum key distribution with orthogonal frequency division multiplexed modulation", 《QUANTUM INFORMATION PROCESSING 》 * |
| 李菲 等: "实际大气中闪烁指数测量的数据处理", 《强激光与粒子束》 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113055167A (en) * | 2021-03-22 | 2021-06-29 | 上海循态信息科技有限公司 | Defense method and system based on security vulnerability in chip CVQKD actual system |
| CN113055167B (en) * | 2021-03-22 | 2022-06-03 | 上海循态量子科技有限公司 | Defense method and system based on security vulnerability in chip CVQKD actual system |
| CN113225273A (en) * | 2021-03-25 | 2021-08-06 | 中国人民解放军国防科技大学 | CS-based free space CV-QKD channel parameter estimation method |
| CN113225273B (en) * | 2021-03-25 | 2022-10-11 | 中国人民解放军国防科技大学 | CS-based free space CV-QKD channel parameter estimation method |
| CN114239840A (en) * | 2021-12-15 | 2022-03-25 | 北京百度网讯科技有限公司 | Quantum channel noise coefficient estimation method and device, electronic device and medium |
| CN114239840B (en) * | 2021-12-15 | 2024-07-26 | 北京百度网讯科技有限公司 | Quantum channel noise coefficient estimation method and device, electronic equipment and medium |
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