Measurement equipment adaptive continuous variable quantum key distribution method, receiving device and system

Abstract

The invention provides a continuous variable quantum key distribution method, receiving device and system for self-adaption of measurement equipment, and belongs to the field of continuous variable quantum key distribution. The method comprises an evaluation link, an optimization link and a code forming link. Obtaining a signal-to-noise ratio parameter of an evaluation data system in an evaluation link; in the optimization link, a system working mode and an optimal beam splitting parameter are selected according to the signal-to-noise ratio parameter of the system; when the signal-to-noise ratio is low, a homodyne detection working mode is selected; otherwise, selecting a heterodyne detection working mode; and in the coding link, an optimal security key is extracted according to the optimal beam splitting parameter, and part of quantum data is randomly extracted for parameter estimation in the next round of evaluation link. The device utilizes a tunable interference unit to realize selection of optimal beam splitting parameters. The system comprises a transmitting end, a receiving end, a system damage compensation unit, a self-adaptive parameter optimization unit and a key extraction unit. According to the invention, the flexibility of the detection process of the receiving end in an actual system can be effectively improved, and the system security code rate optimization is realized.

Description

Technical Field

[0001] The present invention belongs to the field of continuous variable quantum key distribution, and specifically relates to a measurement device adaptive continuous variable quantum key distribution method, a receiving device and a system. Background Art

[0002] Continuous variable quantum key distribution technology uses the canonical component of the light field as the information carrier and can achieve unconditional and secure key distribution. This technology has the advantages of low cost, high reliability, and good compatibility with existing telecommunications devices, and has shown great potential in long-distance transmission and large-scale applications within the metropolitan area.

[0003] Heterodyne detection is a commonly used detection method in continuous variable quantum key distribution technology. In heterodyne detection, the quantum signal is first divided into two parts by a 50:50 beam splitter, and then two homodyne detectors are used to measure the x and p components of the signal respectively. Its advantage is that the two canonical components of the quantum state can be obtained at the same time without switching the measurement basis. Thanks to the above characteristics, heterodyne detection is the current mainstream receiving scheme for continuous variable quantum key distribution.

[0004] However, heterodyne detection is limited by non-idealities in practical applications.

[0005] Symmetry of heterodyne detection: Ideally, a heterodyne detector consists of a beam splitter with a transmittance of 50% and two ideal homodyne detectors with exactly the same characteristics. However, in actual systems, the beam splitting ratio of the beam splitter is often not exactly 50:50, and the detectors also have inevitable defects: limited detection efficiency and electrical noise. In the actual production process of heterodyne detectors, the defects of the two homodyne detectors that make up each heterodyne detector may be different, resulting in different heterodyne detectors having different asymmetries. This will seriously reduce the performance of heterodyne detection in actual systems and introduce security vulnerabilities - this puts forward the need for adaptive adjustment of heterodyne detector parameters.

[0006] System signal-to-noise ratio: Compared with homodyne detection, since a 50:50 beam splitter is added to the heterodyne detection device to split the quantum signal and realize the simultaneous measurement of the two canonical components of the quantum state, the beam splitter will introduce an additional 3dB loss to the entire receiving device. In addition, if the beam splitting ratio of the beam splitter is not exactly 50:50, or the insertion loss is greater than 3dB due to its own non-ideality, this will also increase the loss in the heterodyne detection process. This additional loss directly leads to a reduction in signal energy, thereby reducing the signal-to-noise ratio at the receiving end. Summary of the invention

[0007] The present invention provides a measurement device-adaptive continuous variable quantum key distribution method, a receiving device and a system, which can effectively improve the flexibility of the receiving end detection process in an actual system and achieve the optimization of the system security code rate.

[0008] The present invention provides a measurement device adaptive continuous variable quantum key distribution method. The method includes three parts: evaluation, optimization and coding, as follows:

[0009] In the evaluation phase, the transmitter prepares a transmitter evaluation signal sequence according to the transmitter first evaluation data sequence and the transmitter second evaluation data sequence; and transmits the transmitter evaluation signal sequence to the receiver through the quantum channel; the receiver performs tunable beam splitting on each received evaluation signal according to the first beam splitting parameter to obtain the receiver first evaluation signal sequence and the receiver second evaluation signal sequence, and then performs the first balance detection and the second balance detection on the receiver first evaluation signal sequence and the receiver second evaluation signal sequence to obtain the receiver first evaluation data sequence and the receiver second evaluation data sequence; the receiver performs the first balance detection and the second balance detection on the receiver first evaluation data sequence and the receiver second evaluation data sequence The first evaluation data sequence is processed to obtain a third evaluation data sequence of the receiving end and a fourth evaluation data sequence of the receiving end, and the third evaluation data sequence of the receiving end and the fourth evaluation data sequence of the receiving end are transmitted to the transmitting end through a classical channel; the transmitting end evaluates the signal-to-noise ratio of the first balanced detection and the second balanced detection according to the first evaluation data sequence of the transmitting end, the second evaluation data sequence of the transmitting end, the third evaluation data sequence of the receiving end and the fourth evaluation data sequence of the receiving end, obtains a first signal-to-noise ratio parameter of the evaluation data and a second signal-to-noise ratio parameter of the evaluation data, and sends the first signal-to-noise ratio parameter of the evaluation data and the second signal-to-noise ratio parameter of the evaluation data to the receiving end through a classical channel;

[0010] In the optimization phase, the receiving end selects the system working mode according to the first signal-to-noise ratio parameter of the received evaluation data, the second signal-to-noise ratio parameter of the evaluation data, and the signal-to-noise ratio threshold parameter, and transmits the system working mode to the sending end through the classical channel; the system working mode includes the first working mode and the second working mode; the receiving end calculates the security code rate of the system under different beam splitting parameters according to the system working mode, and obtains the second beam splitting parameter that makes the system security code rate the highest;

[0011] In the coding stage, the transmitting end prepares a transmitting end quantum signal sequence according to the transmitting end first secret data sequence and the transmitting end second secret data sequence; and transmits the transmitting end quantum signal sequence to the receiving end through a quantum channel; the receiving end performs tunable beam splitting on each received quantum signal according to the second beam splitting parameter to obtain the receiving end first quantum signal sequence and the receiving end second quantum signal sequence, and obtains the receiving end first secret data sequence and the receiving end second secret data sequence by performing first balance detection and second balance detection on the receiving end first quantum signal sequence and the receiving end second quantum signal sequence; the receiving end obtains the receiving end third secret data sequence and the receiving end fourth secret data sequence by performing data processing on the receiving end first secret data sequence and the receiving end second secret data sequence, and extracts the receiving end fifth secret data sequence and the receiving end fifth secret data sequence from the receiving end third secret data sequence and the receiving end fourth secret data sequence by random sampling according to the random sampling parameter. six secret data sequences; the receiving end transmits the fifth secret data sequence of the receiving end, the sixth secret data sequence of the receiving end and the random sampling parameter to the sending end through the classical channel; the sending end calculates the security key extraction parameter according to the random sampling parameter, the first secret data sequence of the sending end, the second secret data sequence of the sending end, the fifth secret data sequence of the receiving end and the sixth secret data sequence of the receiving end, and transmits the security key extraction parameter to the receiving end through the classical channel; the sending end and the receiving end extract the key according to the security key extraction parameter and the system working mode; in the first working mode, the first secret data sequence of the sending end and the third secret data sequence of the receiving end are used as a group, and the second secret data sequence of the sending end and the fourth secret data sequence of the receiving end are used as a group to extract the key; in the second working mode, only the first secret data sequence of the sending end and the third secret data sequence of the receiving end are used as a group to extract the key, and the second secret data sequence of the sending end and the fourth secret data sequence of the receiving end are discarded.

[0012] In the above coding link, the first secret data sequence and the second secret data sequence of the sending end can be used as the first evaluation data sequence and the second evaluation data sequence of the sending end in the next round of evaluation link; the fifth secret data sequence and the sixth secret data sequence of the receiving end can be used as the third evaluation data sequence and the fourth evaluation data sequence of the receiving end in the next round of evaluation link; the second beam splitting parameter can be used as the first beam splitting parameter in the next round of evaluation link.

[0013] Therefore, this method can make the key distribution system work in a cycle, continuously evaluate the system working status and obtain the maximum security code rate. The specific principle is: the first beam parameter of the first round of key distribution can be set to 1:1; after the first round of key distribution is completed, in each subsequent round of key distribution, the sender can evaluate the signal-to-noise ratio of the first balance detection and the second balance detection in this round of key distribution based on the sender's first secret data sequence, the sender's second secret data sequence, the receiver's fifth secret data sequence and the receiver's sixth secret data sequence generated in the previous round of key distribution coding link, and obtain the evaluation data first signal-to-noise ratio parameter and the evaluation data second signal-to-noise ratio parameter.

[0014] The present invention provides a continuous variable quantum key distribution receiving device with self-adaptive measurement equipment. The device comprises two parts: a tunable beam splitting unit and a homodyne detection unit:

[0015] The tunable beam splitting unit includes a first tunable beam splitter and a second tunable beam splitter. The first tunable beam splitter splits the quantum signal at the receiving end into a first quantum signal at the receiving end and a second quantum signal at the receiving end. The second tunable beam splitter splits the local oscillator light signal at the receiving end into a first local oscillator light signal at the receiving end and a second local oscillator light signal at the receiving end, and then sends the split quantum signal and the split local oscillator light signal to the heterodyne detection unit.

[0016] The heterodyne detection unit includes a first homodyne detector and a second homodyne detector. The first homodyne detector receives the first quantum signal at the receiving end and the third local oscillation light signal at the receiving end, and differentially outputs the first output electrical signal at the receiving end after coupling interference and photoelectric detection. The second homodyne detector receives the second quantum signal at the receiving end and the first local oscillation light signal at the receiving end, and differentially outputs the second output electrical signal at the receiving end after coupling interference and photoelectric detection.

[0017] The tunable beam splitter is the most critical device for realizing tunable beam splitting. It consists of a first balanced beam splitter, a second balanced beam splitter, a first reflector, a second reflector and a phase shifter. Applying an electric field to the phase shifter can realize free tuning of the splitting ratio.

[0018] For an integrated chip system, the first reflector and the second reflector are not needed, and the optical signal is confined in the waveguide for transmission.

[0019] After the tunable beam splitting is completed, the phase of the first local oscillation optical signal at the receiving end is changed by π / 2 to obtain the third local oscillation optical signal at the receiving end, and send it to the heterodyne detection unit.

[0020] In the heterodyne detection unit, the first homodyne detector includes a first symmetrical beam splitter, a first photodiode, a second photodiode and a first differential device, and the second homodyne detector includes a second symmetrical beam splitter, a third photodiode, a fourth photodiode and a second differential device.

[0021] A measurement device adaptive continuous variable quantum key distribution system includes five parts: a transmitter, a receiver, a system damage compensation unit, an adaptive parameter optimization unit and a key extraction unit:

[0022] At the transmitting end, in the evaluation phase, the transmitting end prepares a transmitting end evaluation signal and a transmitting end reference signal according to the transmitting end evaluation data and the transmitting end reference data, multiplexes the transmitting end evaluation signal with the reference signal, and sends the evaluation multiplexed signal to the quantum channel for transmission; in the coding phase, the transmitting end prepares a transmitting end quantum signal and a transmitting end reference signal according to the transmitting end quantum data and the transmitting end reference data, multiplexes the transmitting end quantum signal with the transmitting end reference signal, and sends the coding multiplexed signal to the quantum channel for transmission.

[0023] The receiving end is used to receive the multiplexed signal from the quantum channel and demultiplex the evaluation multiplexed signal and the coding multiplexed signal; in the evaluation link, the receiving end evaluation signal and the receiving end reference signal are demultiplexed, and the receiving end evaluation signal and the receiving end reference signal are tunably split according to the first beam splitting parameter by the continuous variable quantum key distribution receiving device adaptive to the measuring device, and then balanced detection is performed to obtain the receiving end output evaluation data and the receiving end output reference data; in the coding link, the receiving end quantum signal and the receiving end reference signal are demultiplexed, and the receiving end quantum signal and the receiving end reference signal are tunably split according to the second beam splitting parameter by the continuous variable quantum key distribution receiving device adaptive to the measuring device, and then balanced detection is performed to obtain the receiving end output quantum data and the receiving end output reference data.

[0024] The system damage compensation unit processes the receiving end output evaluation data and the receiving end output quantum data based on the receiving end reference data, so as to maximize the correlation between the sending end and the receiving end data and improve the signal-to-noise ratio parameter of the continuous variable quantum key distribution system.

[0025] The adaptive parameter optimization unit obtains the system working mode parameters based on the signal-to-noise ratio parameters obtained in the evaluation link, calculates the second beam splitting parameters that make the system security code rate the highest, and transmits the system working mode parameters and the second beam splitting parameters to the receiving end of the coding link.

[0026] The key extraction unit completes parameter estimation, information coordination and private key amplification according to the quantum data of the sending end or the evaluation data output by the receiving end and the quantum data output by the receiving end, calculates the security key extraction parameters, selects the system working mode according to the extraction parameters, and performs key extraction.

[0027] The beneficial effects of the present invention are as follows:

[0028] (1) The continuous variable quantum key distribution method, receiving device and system with adaptive measurement equipment can select the appropriate working mode by evaluating the actual signal-to-noise ratio of the system, thus ensuring a high signal-to-noise ratio of the system and improving the flexibility of detection.

[0029] (2) The measurement device is adaptive to the continuous variable quantum key distribution method, receiving device and system. Under different working modes, the security code rate under different beam splitting parameters is calculated, and the optimal beam splitting parameters are selected to complete adaptive beam splitting to maximize the security code rate.

[0030] (3) The measurement device’s adaptive continuous variable quantum key distribution method, receiving device, and system allow the system to work cyclically, continuously evaluate, and optimize through close coordination between each round of key distribution, thereby improving the system’s operating efficiency.

[0031] (4) The measurement equipment-adaptive continuous variable quantum key distribution method, receiving device and system are applicable to different quantum key distribution schemes, have strong applicability and scalability, and provide important technical support for the construction of future quantum networks. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The first round of key distribution flow chart of the continuous variable quantum key distribution method for measuring device adaptation of the present invention;

[0033] Figure 2 This is a key distribution flow chart for the second round of the continuous variable quantum key distribution method for measuring device adaptation of the present invention;

[0034] Figure 3 It is a schematic diagram of the first round of key distribution evaluation and optimization in the continuous variable quantum key distribution method with adaptive measurement equipment of the present invention;

[0035] Figure 4 A schematic diagram of the key distribution coding link and the next round of evaluation link in the continuous variable quantum key distribution method for measuring device adaptation of the present invention;

[0036] Figure 5 A schematic diagram of a key extraction method in different working modes in the continuous variable quantum key distribution method for measuring device adaptation of the present invention;

[0037] Figure 6 A schematic diagram of a continuous variable quantum key distribution receiving device adapted to the measurement device of the present invention;

[0038] Figure 7 The structure diagram of the tunable beam splitting unit in the continuous variable quantum key distribution receiving device of the measuring device of the present invention is as follows;

[0039] Figure 8A schematic diagram of a continuous variable quantum key distribution system for measuring device adaptation of the present invention; DETAILED DESCRIPTION

[0040] In order to facilitate those skilled in the art to understand and implement the present invention, the present invention will be described in more detail below with reference to the accompanying drawings and embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0041] The present invention discloses a measurement device adaptive continuous variable quantum key distribution method, receiving device and system, which are more flexible and have better system performance than the detection method of the receiving end in the traditional key distribution process, and are of great significance to the quantum key distribution technology.

[0042] The measurement device adaptive continuous variable quantum key distribution method includes three parts: evaluation, optimization and coding. In the method, the first round of key distribution process is as follows: Figure 1 shown.

[0043] The evaluation phase includes six processes: evaluation signal preparation, evaluation signal transmission, evaluation signal reception, evaluation signal processing, evaluation signal disclosure and system working status evaluation. After the evaluation phase is completed, the evaluation data system signal-to-noise ratio parameters are obtained, and the system signal-to-noise ratio parameters are used in the subsequent optimization phase;

[0044] The optimization phase compares the received system signal-to-noise ratio parameter with the signal-to-noise ratio threshold parameter, selects the system working mode, and reports it to the transmitter. The transmitter calculates the security code rate under different beam splitting parameters, selects the fractional parameter with the highest security code rate, and uses it as the optimal beam splitting parameter for subsequent coding phases.

[0045] The coding process includes six processes: quantum signal preparation, quantum signal transmission, quantum signal reception, quantum signal processing, signal-to-noise ratio and security code rate calculation, and security key extraction. During the quantum signal reception process, the optimal beam splitting parameters obtained in the optimization process are used to maximize the security code rate and finally extract the security key.

[0046] After the first round of key distribution is completed, the key distribution process for the second round is as follows Figure 2 shown.

[0047] In the evaluation phase, it is no longer necessary to prepare, transmit and receive evaluation signals separately. Instead, the quantum signals prepared, transmitted and received in the previous round of coding phase are used as the evaluation signals for this round of key distribution. The evaluation signals are made public, and the system working status of this round of key distribution is evaluated based on the signal-to-noise ratio calculated in the previous round of coding phase. The system signal-to-noise ratio parameters are obtained for subsequent optimization phases.

[0048] The optimization process is the same as the first round of key distribution;

[0049] The signal-to-noise ratio calculated in the coding phase is used for the evaluation phase of the next round of key distribution;

[0050] This forms a cycle, allowing the system to continue working.

[0051] like Figure 3 As shown in the figure, the specific implementation process of the first round of key distribution evaluation and optimization is as follows:

[0052] In the evaluation phase, the transmitter prepares a transmitter evaluation signal sequence according to a transmitter evaluation data sequence 1 and a transmitter evaluation data sequence 2. The data sequence is electrical data, and the signal sequence is an optical signal. The electrical data is modulated onto the optical signal using a modulator, and the signal is transmitted to the receiver through a quantum channel. The receiver first performs tunable beam splitting on the evaluation signal based on the beam splitting parameter 1. In the first round of key distribution, the beam splitting parameter 1 is set to 1:1 to obtain a receiver evaluation signal sequence 1 and a receiver evaluation signal sequence 2. Balanced detection and data processing are performed on the receiver evaluation signal sequence 1 and the receiver evaluation signal sequence 2 to obtain a receiver evaluation data sequence 3 and a receiver evaluation data sequence 4. The receiver evaluation data sequence is transmitted to the transmitter through a classical channel. The transmitter calculates the signal-to-noise ratio of two balanced detections according to the transmitter evaluation data sequence 1, the transmitter evaluation data sequence 2, the receiver evaluation data sequence 3, and the receiver evaluation data sequence 4, and transmits the calculation results to the receiver.

[0053] In the optimization phase, the receiving end selects the system working mode based on the signal-to-noise ratio and signal-to-noise ratio threshold parameters of the two balanced detections, obtains the working mode parameters, calculates the safety code rate under different beam splitting parameters, and selects the beam splitting parameter when the safety code rate is the largest as beam splitting parameter 2.

[0054] like Figure 4 As shown in the figure, the specific implementation process of the key distribution coding link and the subsequent evaluation link is as follows:

[0055] In the coding stage, the transmitter prepares a transmitter quantum signal sequence according to a transmitter secret data sequence 1 and a transmitter secret data sequence 2, and transmits the sequence to the receiver through a quantum channel; the receiver first performs tunable beam splitting on the quantum signal based on the beam splitting parameter 2 obtained in the optimization stage to obtain a receiver quantum signal sequence 1 and a receiver evaluation quantum sequence 2, performs balance detection and data processing on the receiver quantum signal sequence 1 and the receiver quantum signal sequence 2 to obtain a receiver quantum data sequence 3 and a receiver quantum data sequence 4, and then performs random sampling to obtain a receiver quantum data sequence 5 and a receiver quantum data sequence 6, and transmits the receiver evaluation quantum data sequence to the transmitter through a classical channel; the transmitter calculates the signal-to-noise ratio of two balance detections and the system security code rate according to the transmitter evaluation data sequence 1, the transmitter evaluation data sequence 2, the receiver evaluation data sequence 5 and the receiver evaluation data sequence 6, and transmits the calculation results to the receiver; the transmitter and the receiver extract the key according to the transmitter evaluation data sequence 1, the transmitter evaluation data sequence 2, the receiver evaluation data sequence 3, the receiver evaluation data sequence 4 and the system working mode parameters.

[0056] like Figure 5 As shown in the figure, the specific method of extracting the key in the coding stage under different working mode parameters is as follows:

[0057] In the first working mode, i.e., the "heterodyne detection" mode, the transmitter and the receiver extract the key based on the transmitter's secret data sequence 1 and the receiver's quantum data sequence 3 as a group, and the transmitter's secret data sequence 2 and the receiver's secret data sequence 4 as a group;

[0058] In the second working mode, namely the "homodyne detection" mode, the sender and the receiver extract the key based on the sender's secret data sequence 1 and the receiver's quantum data sequence 3 as a group, and discard the sender's secret data sequence 2 and the receiver's quantum data sequence 4.

[0059] like Figure 6 As shown, the adaptive receiving device of the measuring device is composed of a tunable interference unit and two groups of homodyne detection units. The specific process of realizing the adaptive measurement of quantum signals at the receiving end is as follows:

[0060] The tunable interference unit of the receiving device receives the quantum signal and the local oscillator optical signal. The tunable unit is composed of a tunable beam splitter 1 and a tunable beam splitter 2. The tunable beam splitter BS1 performs tunable beam splitting on the quantum signal to obtain a quantum signal 1 and a quantum signal 2. The tunable beam splitter BS2 performs tunable beam splitting on the local oscillator optical signal to obtain a local oscillator optical signal 1 and a local oscillator optical signal 2, and changes the phase of the local oscillator optical signal 1 by π / 2 to obtain a local oscillator optical signal 3, which is sent to the homodyne detection unit together with the other three split signals.

[0061] The homodyne detection unit is divided into two groups, each of which consists of a symmetrical beam splitter, two photodiodes and a differential device. In the first group of homodyne detection, quantum signal 1 and local oscillator light signal 3 are coupled and interfered in the symmetrical beam splitter BS3 to obtain coupling signal 1 and coupling signal 2, which are then photoelectrically detected by photodiodes PD1 and PD2 to obtain detection data 1 and detection data 2, and finally the two groups of data are passed through the differential device to obtain output data 1; in the second group of homodyne detection, quantum signal 2 and local oscillator light signal 2 are coupled and interfered in the symmetrical beam splitter BS4 to obtain coupling signal 3 and coupling signal 4, which are then photoelectrically detected by photodiodes PD3 and PD4 to obtain detection data 3 and detection data 4, and finally the two groups of data are passed through the differential device to obtain output data 2;

[0062] like Figure 7 As shown in the figure, the tunable beam splitter is implemented using a Mach-Zehnder (MZI) interferometer, which consists of two 50:50 beam splitters (BS1 and BS2), two mirrors (M1 and M2), and a phase shifter (PS). The phase shifter is implemented by an electro-optic modulator. By applying an electric field to the phase shifter to induce birefringence in the crystal, the phase of the transmitted light is changed, and then the phase of the two interference signals can be adjusted to change the beam splitting ratio.

[0063] The specific working principle of the tunable beam splitting structure is as follows:

[0064] First, define the signal:

[0065] After passing through the first symmetrical beam splitter BS1 of the MZI, the output signal is

[0066]

[0067] The phase difference is introduced between the two arms of the MZI. That is, the signal input into the interference structure of the second symmetrical beam splitter BS2 of the MZI is: The output is:

[0068]

[0069] Arrange the two output signals into a structure of magnitude and phase:

[0070]

[0071] Therefore, the phase difference between the two output signals is Relationship between amplitude and phase difference The size of the MZI can be changed by changing the phase difference between the two arms of the MZI. to change the splitting ratio.

[0072] like Figure 8 As shown, the measurement device adaptive continuous variable quantum key distribution system has the following specific implementation process:

[0073] Step 1: The transmitter prepares an evaluation signal and a reference signal, or a quantum signal and a reference signal, according to the current link of the system;

[0074] First, the laser at the sending end generates the original signal light;

[0075] Then, the original signal light is split into two beams, and the modulator modulates the two original signal lights respectively according to the input evaluation data and the input reference data, or the input quantum data and the input reference data;

[0076] Finally, the modulated evaluation signal light and quantum signal are passed through an attenuator to attenuate the signal light power to a level that meets the requirements of the quantum system, thereby obtaining the required evaluation signal and quantum signal;

[0077] Step 2: multiplexing the evaluation signal and the reference signal, or the quantum signal and the reference signal, and sending them to the quantum channel to be transmitted to the receiving end;

[0078] Step 3: The receiving end demultiplexes the multiplexed signal, and uses the adaptive receiving device of the measuring device to detect the evaluation signal and the reference signal, or the quantum signal and the reference signal to obtain output data;

[0079] Step 4: The system damage compensation unit processes the output evaluation data and the output quantum data based on the reference data to maximize the signal-to-noise ratio parameter of the system;

[0080] Step 5: Use the sender data and output data after system damage compensation to perform security analysis and key extraction;

[0081] In the actual experiment, the security analysis process is as follows: According to the modulation variance data of the sending end and the detection data of the receiving end, the two components x of the quantum state of each end are calculated respectively. A 、x B 、p A and p B The variance and covariance between , write the final covariance matrix:

[0082]

[0083] Calculate the final security code rate according to the covariance matrix;

[0084] The sender and the receiver use their respective data under the maximum security code rate to extract the key.

Claims

1. A measurement device adaptive continuous variable quantum key distribution method, characterized in that: The quantum key distribution method comprises: In the evaluation phase, the transmitting end prepares a transmitting end evaluation signal sequence according to a transmitting end first evaluation data sequence and a transmitting end second evaluation data sequence; the transmitting end evaluation signal sequence is transmitted to the receiving end through a quantum channel; the receiving end performs tunable beam splitting on each received evaluation signal according to a first beam splitting parameter to obtain a receiving end first evaluation signal sequence and a receiving end second evaluation signal sequence; and obtains a receiving end first evaluation data sequence and a receiving end second evaluation data sequence by performing a first balance detection and a second balance detection on the receiving end first evaluation signal sequence and the receiving end second evaluation signal sequence; the receiving end performs a tunable beam splitting on each received evaluation signal according to a first beam splitting parameter to obtain a receiving end first evaluation signal sequence and a receiving end second evaluation signal sequence; The data sequence is processed to obtain a third evaluation data sequence of the receiving end and a fourth evaluation data sequence of the receiving end; and the third evaluation data sequence of the receiving end and the fourth evaluation data sequence of the receiving end are transmitted to the transmitting end through a classical channel; the transmitting end evaluates the signal-to-noise ratio of the first balanced detection and the second balanced detection according to the first evaluation data sequence of the transmitting end, the second evaluation data sequence of the transmitting end, the third evaluation data sequence of the receiving end and the fourth evaluation data sequence of the receiving end, and obtains a first signal-to-noise ratio parameter of the evaluation data and a second signal-to-noise ratio parameter of the evaluation data; the transmitting end sends the first signal-to-noise ratio parameter of the evaluation data and the second signal-to-noise ratio parameter of the evaluation data to the receiving end through the classical channel; In the optimization phase, the receiving end selects the system working mode according to the first signal-to-noise ratio parameter of the evaluation data, the second signal-to-noise ratio parameter of the evaluation data, and the signal-to-noise ratio threshold parameter; and transmits the system working mode to the sending end through the classical channel; the system working mode includes the first working mode and the second working mode; the receiving end calculates the security code rate of the system under different beam splitting parameters according to the system working mode, and obtains the second beam splitting parameter that makes the system security code rate the highest; In the coding stage, the transmitting end prepares a transmitting end quantum signal sequence according to the transmitting end first secret data sequence and the transmitting end second secret data sequence; the transmitting end quantum signal sequence is transmitted to the receiving end through a quantum channel; the receiving end performs tunable beam splitting on each received quantum signal according to the second beam splitting parameter to obtain the receiving end first quantum signal sequence and the receiving end second quantum signal sequence; and obtains the receiving end first secret data sequence and the receiving end second secret data sequence by performing first balance detection and second balance detection on the receiving end first quantum signal sequence and the receiving end second quantum signal sequence; the receiving end obtains the receiving end third secret data sequence and the receiving end fourth secret data sequence by performing data processing on the receiving end first secret data sequence and the receiving end second secret data sequence; and extracts the receiving end fifth secret data sequence and the receiving end sixth secret data sequence from the receiving end third secret data sequence and the receiving end fourth secret data sequence by random sampling according to the random sampling parameter; The receiving end transmits the fifth secret data sequence of the receiving end, the sixth secret data sequence of the receiving end and the random sampling parameter to the sending end through the classical channel; the sending end calculates the security key extraction parameter according to the random sampling parameter, the first secret data sequence of the sending end, the second secret data sequence of the sending end, the fifth secret data sequence of the receiving end and the sixth secret data sequence of the receiving end; and transmits the security key extraction parameter to the receiving end through the classical channel; the sending end and the receiving end perform key extraction according to the security key extraction parameter and the system working mode; in the first working mode, the key extraction extracts the key by taking the first secret data sequence of the sending end and the third secret data sequence of the receiving end as a group, and the second secret data sequence of the sending end and the fourth secret data sequence of the receiving end as a group; in the second working mode, the key extraction extracts the key by taking only the first secret data sequence of the sending end and the third secret data sequence of the receiving end as a group, and discarding the second secret data sequence of the sending end and the fourth secret data sequence of the receiving end.

2. The coding process according to claim 1, characterized in that: The first secret data sequence and the second secret data sequence of the sending end can be used as the first evaluation data sequence and the second evaluation data sequence of the sending end in the next round of the evaluation link, and the fifth secret data sequence and the sixth secret data sequence of the receiving end can be used as the third evaluation data sequence and the fourth evaluation data sequence of the receiving end in the next round of the evaluation link; the second beam splitting parameter can be used as the first beam splitting parameter in the next round of the evaluation link.

3. The evaluation process according to claim 1, characterized in that: The first beam parameter of the first round of key distribution can be 1:1; after the first round of key distribution is completed, the sending end in each subsequent round of key distribution can evaluate the signal-to-noise ratio of the first balanced detection and the second balanced detection in this round of key distribution based on the sending end first secret data sequence, the sending end second secret data sequence, the receiving end fifth secret data sequence and the receiving end sixth secret data sequence generated in the coding link of the previous round of key distribution, and obtain the evaluation data first signal-to-noise ratio parameter and the evaluation data second signal-to-noise ratio parameter.

4. A measurement device adaptive continuous variable quantum key distribution receiving device, characterized in that: The continuous variable quantum key distribution receiving device comprises: The tunable beam splitting unit comprises a first tunable beam splitter and a second tunable beam splitter, wherein the first tunable beam splitter splits the quantum signal at the receiving end into a first quantum signal at the receiving end and a second quantum signal at the receiving end, and the second tunable beam splitter splits the local oscillator optical signal at the receiving end into a first local oscillator optical signal at the receiving end and a second local oscillator optical signal at the receiving end, and then sends the split quantum signal and the split local oscillator optical signal to the heterodyne detection unit. The heterodyne detection unit includes a first homodyne detector and a second homodyne detector, wherein the first homodyne detector receives the first quantum signal at the receiving end and the third local oscillation light signal at the receiving end, and differentially outputs the first output electrical signal at the receiving end after coupling interference and photoelectric detection; the second homodyne detector receives the second quantum signal at the receiving end and the first local oscillation light signal at the receiving end, and differentially outputs the second output electrical signal at the receiving end after coupling interference and photoelectric detection.

5. The tunable beam splitting unit according to claim 4, characterized in that: The tunable beam splitter is composed of a first balanced beam splitter, a second balanced beam splitter, a first reflector, a second reflector and a phase shifter; an electric field is applied to the phase shifter to achieve a tunable beam splitting ratio.

6. The tunable beam splitter according to claim 5, characterized in that: The integrated chip system does not need to use the first reflector and the second reflector, and the optical signal is bound in the waveguide for transmission.

7. The third local oscillation optical signal at the receiving end according to claim 4, characterized in that: It is obtained by changing the phase of the first local oscillation optical signal at the receiving end by π / 2 and then sent to the heterodyne detection unit.

8. The heterodyne detection unit according to claim 4, characterized in that: The first homodyne detector includes a first symmetrical beam splitter, a first photodiode, a second photodiode and a first differential device, and the second homodyne detector includes a second symmetrical beam splitter, a third photodiode, a fourth photodiode and a second differential device.

9. A measurement device adaptive continuous variable quantum key distribution system, characterized in that: The continuous variable quantum key distribution system comprises: At the transmitting end, for the evaluation link, the transmitting end prepares a transmitting end evaluation signal and a transmitting end reference signal according to the transmitting end evaluation data and the transmitting end reference data, multiplexes the transmitting end evaluation signal with the reference signal, and sends the evaluation multiplexed signal to the quantum channel for transmission; for the coding link, the transmitting end prepares a transmitting end quantum signal and a transmitting end reference signal according to the transmitting end quantum data and the transmitting end reference data, multiplexes the transmitting end quantum signal with the transmitting end reference signal, and sends the coding multiplexed signal to the quantum channel for transmission. A receiving end is used to receive a multiplexed signal from a quantum channel and demultiplex the evaluation multiplexed signal and the coding multiplexed signal; for the evaluation link, the demultiplexing obtains a receiving end evaluation signal and a receiving end reference signal, and the receiving end evaluation signal and the receiving end reference signal are respectively tunably split by a continuous variable quantum key distribution receiving device adaptive to the measuring device according to the first beam splitting parameter, and then a balanced detection is performed to obtain receiving end output evaluation data and receiving end output reference data; for the coding link, the demultiplexing obtains a receiving end quantum signal and a receiving end reference signal, and the receiving end quantum signal and the receiving end reference signal are respectively tunably split by a continuous variable quantum key distribution receiving device adaptive to the measuring device according to the second beam splitting parameter, and then a balanced detection is performed to obtain receiving end output quantum data and receiving end output reference data. A system damage compensation unit performs data processing on the receiving end output evaluation data and the receiving end output quantum data based on the receiving end reference data, so as to maximize the correlation between the sending end and the receiving end data and improve the signal-to-noise ratio parameter of the continuous variable quantum key distribution system. The adaptive parameter optimization unit obtains the system working mode parameter based on the signal-to-noise ratio parameter obtained in the evaluation link, calculates the second beam splitting parameter that makes the system security code rate the highest, and transmits the system working mode parameter and the second beam splitting parameter to the receiving end of the coding link. The key extraction unit is used to complete parameter estimation, information coordination and private key amplification according to the sending end quantum data and the receiving end output evaluation data and the receiving end output quantum data, calculate the security key extraction parameters, select the system working mode according to the extraction parameters, and perform key extraction.

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