CN114337847A - Independent quantum key distribution system of continuous variable measurement equipment and phase compensation method - Google Patents

Independent quantum key distribution system of continuous variable measurement equipment and phase compensation method Download PDF

Info

Publication number
CN114337847A
CN114337847A CN202111670733.2A CN202111670733A CN114337847A CN 114337847 A CN114337847 A CN 114337847A CN 202111670733 A CN202111670733 A CN 202111670733A CN 114337847 A CN114337847 A CN 114337847A
Authority
CN
China
Prior art keywords
phase
light
beam splitter
module
pulse
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202111670733.2A
Other languages
Chinese (zh)
Other versions
CN114337847B (en
Inventor
李永民
田岩
王旭阳
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shanxi University
Original Assignee
Shanxi University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shanxi University filed Critical Shanxi University
Priority to CN202111670733.2A priority Critical patent/CN114337847B/en
Publication of CN114337847A publication Critical patent/CN114337847A/en
Application granted granted Critical
Publication of CN114337847B publication Critical patent/CN114337847B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Landscapes

  • Optical Communication System (AREA)

Abstract

The invention belongs to the technical field of quantum communication, and particularly relates to a continuous variable measurement device independent quantum key distribution system and a phase compensation method. In order to eliminate all side channel attacks on a measuring end in an actual continuous variable quantum key distribution system, the system comprises two sending ends Alice and Bob and a receiving end Charlie. The transmitting end mainly comprises a laser module, an optical phase locking module, a pulse chopping module, a signal light modulation module and a time division multiplexing and polarization multiplexing module. The receiving end mainly comprises a polarization demultiplexing module, a clock recovery module, an optical delay module, a 90-degree optical mixer module and a continuous variable Bell state measuring module. The phase compensation method comprises four parts of optical phase locking, slow drift phase estimation, real-time phase feedback and orthogonal component remapping, and can realize continuous variable Bell state measurement of remote independent quantum states.

Description

Independent quantum key distribution system of continuous variable measurement equipment and phase compensation method
Technical Field
The invention belongs to the technical field of quantum communication, and particularly relates to a continuous variable measurement device independent quantum key distribution system and a phase compensation method.
Background
Information security is a foundation for healthy development of modern society, and with the development of economy and technology, the requirements of people on communication security are higher and higher. The quantum key distribution can realize the sharing of the secure key between two remote legal communication parties through an insecure quantum channel, and the security of the secure key distribution is ensured by the basic principle of quantum mechanics. The quantum key distribution is combined with a one-time pad cipher system, and unconditional and safe secret communication can be realized.
The quantum key distribution mainly comprises two technical approaches of discrete variable quantum key distribution and continuous variable quantum key distribution, and has advantages. The continuous variable quantum key distribution protocol encodes key information on orthogonal components of a quantized light field, and a balanced homodyne detector with low cost and high detection efficiency is used for measuring quantum states, so that the method is more easily compatible with the conventional optical fiber communication network technology. The encoding mode of encoding information in an infinite dimensional Hilbert space enables continuous variable quantum key distribution to provide higher key rates in a metropolitan area. Furthermore, due to the spatial and temporal filtering characteristics of the local oscillator Light (LO), continuously variable quantum key distribution is robust to various noise photons in the quantum channel.
In a real-world environment, differences between actual physical devices and ideal models of quantum key distribution can cause various security holes, and accordingly various targeted attacks can be caused. For example, a number of attacks against practical probes have been proposed: wavelength attack, calibration attack, LO fluctuation attack, saturation attack, and the like. Inspired by entanglement exchange thought, a quantum key distribution protocol irrelevant to the measurement equipment is provided, and the quantum signals sent by Alice and Bob are interfered by introducing an untrusted third party Charlie, so that Bell state measurement is realized. Measurement device-independent quantum key distribution can naturally eliminate all side channel attacks against the detection device, which is one of the main security holes in the implementation process of quantum key distribution.
Compared with the breakthrough progress of the independent quantum key distribution of the discrete variable measurement equipment, the independent quantum key distribution of the continuous variable measurement equipment has made remarkable progress on theoretical research. In addition, in 2015, principle experimental verification was performed on independent quantum key distribution of continuous variable measurement equipment, but in the experimental demonstration, two senders of Alice and Bob use the same laser source, which is not suitable for a real independent quantum key distribution scene of measurement equipment. On the other hand, the experiment utilized two short-range lossless free-space quantum channels and modeled the link loss by reducing the modulation variance of the signal. At present, no public report is found in complete experimental verification of independent quantum key distribution of continuous variable measurement equipment based on long-distance communication single-mode optical fiber.
The experimental implementation of the independent quantum key distribution of the continuous variable measurement device based on the long-distance optical fiber mainly faces two key challenges. The first is how to accurately establish a reliable phase reference between two spatially separated independent lasers and achieve continuous variable bell state measurements. It is noted that the phase control of continuous variable bell-state measurements is more complex than that of discrete variable bell-state measurements, since continuous variable bell-state measurements not only require single photon horizontal interference between two distant independent lasers, but also require dual-homodyne detection to measure a pair of conjugated quadrature components simultaneously. This requires precise control of the relative phase between the signal light of the dual-homodyne detection and the LO light.
Another problem arises from the unreliable and imperfect balanced homodyne detector at the Charlie end. The imperfect quantum efficiency of a balanced homodyne detector is equivalent to loss of the optical path, inevitably introducing vacuum fluctuation noise, which is equivalent to total detection noise together with the electronic noise of the detector, which the eavesdropper can fully control and use to mask her attack. Therefore, the performance of the continuously variable measurement device independent quantum key distribution depends to a large extent on the detection efficiency of the balanced homodyne detector.
Disclosure of Invention
The invention aims to provide a continuous variable measurement equipment independent quantum key distribution system to avoid all side channel attacks caused by defects of a system measurement end in a real environment, and provides a phase compensation method of the continuous variable measurement equipment independent quantum key distribution system to solve the problem of phase drift in the system and realize reliable continuous variable Bell state measurement.
In order to achieve the purpose, the invention adopts the following technical scheme:
a continuous variable measurement equipment independent quantum key distribution system comprises a sending end Alice, a sending end Bob and a receiving end Charlie;
the sending end Alice comprises a first laser, a first beam splitter, an acousto-optic modulator, a pulse chopping module, a second beam splitter, a first signal light modulation module, a first delay line, a first attenuator, a second attenuator and a first polarization beam combiner, wherein the pulse chopping module comprises a first amplitude modulator and a second amplitude modulator which are connected in series, and the first signal light modulation module comprises a third amplitude modulator and a first phase modulator which are sequentially arranged;
the first laser provides continuous single-frequency light, the continuous single-frequency light is divided into two parts by the first beam splitter, one part of the continuous single-frequency light is subjected to frequency shifting by the acousto-optic modulator, the other part of the continuous single-frequency light is chopped into pulse light with a high extinction ratio by the pulse chopping module, the pulse light with the high extinction ratio is divided into signal pulse light and phase reference pulse light by the second beam splitter, the signal pulse light sequentially passes through the first signal light modulation module, the first delay line and the first attenuator and enters the first polarization beam combiner, and the phase reference pulse light enters the first polarization beam combiner through the second attenuator;
the transmitting end Bob comprises a second laser, a third beam splitter, a fourth beam splitter, a photoelectric detector, a frequency locking module, a second pulse chopping module, a fifth beam splitter, a second signal light modulation module, a second delay line, a third attenuator and a second polarization beam combiner, the second pulse chopping module comprises two cascaded fourth amplitude modulators and fifth amplitude modulators, and the second signal light modulation module comprises a sixth amplitude modulator and a second phase modulator which are sequentially arranged;
the third beam splitter receives continuous single-frequency light from the acousto-optic modulator, the second laser provides continuous single-frequency light, the continuous single-frequency light is divided into two parts through the fourth beam splitter, one part of the continuous single-frequency light is transmitted to the third beam splitter to interfere with the continuous single-frequency light from the acousto-optic modulator, the photoelectric detector detects a light beat signal, and the frequency locking module extracts an error signal from an electric signal converted from the light beat signal and feeds the error signal back to the second laser for frequency locking; the other part of continuous single-frequency light is chopped into high-extinction-ratio pulse light by the second pulse chopping module, the high-extinction-ratio pulse light is divided into signal pulse light and LO pulse light by the fifth beam splitter, the signal pulse light sequentially passes through the second signal light modulation module, the second delay line and the third attenuator and enters the second polarization beam combiner, and the LO pulse light enters the second polarization beam combiner;
the receiving end Charlie comprises a first polarization demultiplexing module, a second polarization demultiplexing module, a sixth beam splitter, a clock recovery module, a third delay line, a fourth delay line, a seventh beam splitter, an optical mixer module and a continuous variable Bell state measurement module, wherein the first polarization multiplexing module comprises a first polarization controller, a first optical fiber collimator, a first polarization beam splitter and a second optical fiber collimator, the second polarization demultiplexing module comprises a second polarization controller, a third optical fiber collimator, a second polarization beam splitter and a fourth optical fiber collimator, the optical mixer module comprises a 90-degree optical mixer, a first balanced homodyne detector and a second balanced homodyne detector, and the continuous variable Bell state measurement module comprises an eighth beam splitter, a third phase modulator, a fifth optical fiber collimator, a sixth optical fiber collimator, a first beam splitter, a second beam splitter, a clock recovery module, a third delay line, a fourth delay line, a seventh optical fiber collimator, a continuous variable Bell state measurement module, The third beam splitting slice, the third balanced homodyne detector and the fourth balanced homodyne detector;
the first polarization controller is used for adjusting the polarization directions of the signal pulse light and the phase reference pulse light of the transmitting end Alice, the first optical fiber collimator is used for coupling the signal pulse light and the phase reference pulse light of the transmitting end Alice to a free space, the first polarization beam splitter is used for polarization demultiplexing of the signal pulse light and the phase reference pulse light, the signal pulse light enters the continuous variable Bell state measuring module, and the phase reference pulse light is coupled to the optical fiber again through the second optical fiber collimator and enters the optical mixer module through the fourth delay line;
the second polarization controller is used for adjusting the polarization directions of signal pulse light and LO pulse light of a sending end Bob, the third optical fiber collimator couples the signal pulse light and the LO pulse light of the sending end Bob to a free space, the second polarization beam splitter polarizes and demultiplexes the signal pulse light and the LO pulse light, the signal pulse light enters the continuous variable Bell state measuring module, the LO pulse light is coupled to an optical fiber again through a fourth optical fiber collimator and enters a sixth beam splitter, the LO pulse light is divided into two parts by the sixth beam splitter, one part enters the clock recovery module, the other part enters a seventh beam splitter through a third delay line, the LO pulse light is divided into two parts by the seventh beam splitter, one part enters the optical mixer module, and the other part enters the continuous variable Bell state measuring module;
in the optical mixer module, the phase reference pulse light from the fourth delay line enters a 90-degree optical mixer, the LO pulse light from the seventh beam splitter enters a 90-degree optical mixer, the first balanced homodyne detector and the second balanced homodyne detector are respectively connected with the 90-degree optical mixer, and the orthogonal amplitude component X of the phase reference pulse is respectively measuredRAnd quadrature phase component PR；
In the continuous variable Bell state measurement module, LO pulse light from a seventh beam splitter is divided into two parts by an eighth beam splitter, one part enters a third balanced homodyne detector through a fifth optical fiber collimator and a second beam splitter, and the other part enters a fourth balanced homodyne detector through a third phase modulator, a sixth optical fiber collimator and a third beam splitter; the signal pulse light from the second polarization beam splitter is divided into two parts by the first beam splitter, one part enters the third balanced homodyne detector through the second beam splitter, and the other part enters the fourth balanced homodyne detector through the third beam splitter; the first beam splitter of the signal pulse light from the first polarization beam splitter is divided into two parts, and one part enters the third plane through the second beam splitterThe other part of the balanced zero-beat detector enters a fourth balanced zero-beat detector through a third beam splitter; the third balanced homodyne detector and the fourth balanced homodyne detector respectively measure orthogonal amplitude components X of the signal light fieldCAnd quadrature phase component PC。
Further, the first beam splitter divides the continuous single-frequency light into two parts of 90% and 10%, 10% of the continuous single-frequency light is shifted upwards by the acousto-optic modulator by the frequency of 80MHz, and 90% of the continuous single-frequency light is chopped into high-extinction-ratio pulse light with the repetition rate of 500kHz, the pulse width of 50ns and the extinction ratio of 80dB by the pulse chopping module;
the second beam splitter divides the high extinction ratio pulsed light of the transmitting end Alice into 1% signal pulsed light and 99% phase reference pulsed light;
the third beam splitter is an 50/50 beam splitter;
the fourth beam splitter divides the continuous single-frequency light provided by the second laser into two parts, namely 10% and 90%, the 10% continuous single-frequency light is transmitted to the third beam splitter and interferes with the continuous single-frequency light from the acousto-optic modulator, and the 90% continuous single-frequency light is chopped into pulsed light with a high extinction ratio by the second pulse chopping module;
the fifth beam splitter divides the high extinction ratio pulsed light of the transmitting end Bob into 1% signal pulsed light and 99% LO pulsed light;
the sixth beam splitter divides the LO pulse light from the fourth optical fiber collimator into two parts, namely 90% and 10%, the 10% LO pulse light enters the clock recovery module, and the 90% LO pulse light enters the seventh beam splitter through the third delay line;
the seventh beam splitter divides the LO pulse light into 10% and 90% parts, the 10% LO pulse light enters the light mixer module, and the 90% LO pulse light enters the continuous variable Bell state measuring module;
the eighth beam splitter divides the LO pulse light entering the continuous variable Bell state measurement module into two parts, namely 50% and 50%.
Further, the first beam splitting sheet, the second beam splitting sheet and the third beam splitting sheet are all free spaces 50: 50 bundling pieces.
Further, the continuous variable Bell state measurement module further comprises a plurality of high-reflection mirrors for adjusting the light path to enable the light to be completely incident to the third balanced homodyne detector and the fourth balanced homodyne detector.
A phase compensation method of a continuous variable measurement device independent quantum key distribution system comprises the following steps:
(1) according to the environment of a system, a sending end Alice and a sending end Bob firstly determine the length of a single data block, then divide each data block into a plurality of data packets, and insert 1 phase calibration frame into each data packet;
(2) and the sending end Alice and the sending end Bob determine the optimal phase calibration frame length.
(3) The frequency of the second laser and the frequency of the first laser are locked through the frequency locking module, and the relative phase of the phase reference pulse and the LO pulse is kept unchanged within the duration time of a single optical pulse;
(4) the receiving end Charlie respectively records the peak sampling voltages of the electric pulses output by the first balanced homodyne detector and the second balanced homodyne detector as XR、PRAnd calculating the fast-varying phase difference between each phase reference pulse and LO pulse in real time
Figure BDA0003452901490000071
(5) The receiving end Charlie samples output signals of the third balanced homodyne detector and the fourth balanced homodyne detector, extracts measurement voltage values corresponding to all phase calibration frames in the current data block, and calculates slow-drifting phase corresponding to the current data block of the system according to the measurement voltage values and the fast-changing phase difference delta theta corresponding to the phase calibration frames obtained in the step (4)
Figure BDA0003452901490000072
(6) Receiving end Charlie through slow drifting phase
Figure BDA0003452901490000073
Calculating corresponding compensation voltage value, loading the compensation voltage value to the third phase modulator to compensate the compensation voltage value to the next data block, and making the third balanced homodyne probeThe detector and the fourth balanced zero-beat detector simultaneously measure orthogonal components X 'which are perpendicular to each other'C、PC′；
(7) Repeating the steps (4) to (6) to ensure that each data block except the first data block can compensate the compensation voltage value corresponding to the current slow drift phase in real time, and the third balanced zero-beat detector and the fourth balanced zero-beat detector always measure orthogonal components X 'which are perpendicular to each other'C、PC′；
(8) After the data transmission is finished, the receiving end Charlie transmits the fast variable phase delta theta and the slow drifting phase through the classical channel
Figure BDA0003452901490000074
Sending to sending end Alice, slowly drifting phase
Figure BDA0003452901490000075
Sending the data to a sending end Bob;
(9) the sending end Alice and the sending end Bob respectively carry out comparison on respective original data (X)A,PA)、(XB,PB) Orthogonal component remapping is performed to obtain phase-rotated data (X'A,P′A)、(X′B,P′B)；
(10) After the phase correction is completed, the sending end Alice and the sending end Bob perform data displacement operation on the respective data to generate correlation to obtain a bare code, and then perform parameter estimation, data coordination and privacy amplification to generate a final secret key.
Further, the specific step of determining the length of a single data block in step (1) is: the duration of a single data block is at least 1 order of magnitude less than the phase drift rate of the system, at least to ensure that the slow drift phase value remains constant for the duration of two preceding and following data blocks.
Further, the optimal phase calibration frame length in the step (2) should be combined with the length of the data block to balance the phase estimation precision and the system overhead;
the phase calibration frame of the sending end Bob is respectively modulated into 0,
Figure BDA0003452901490000081
The number of each type of optical pulse is determined according to the length of the optimal phase calibration frame determined by the actual situation, and the amplitude of the corresponding optical pulse in the sending end Alice data packet is modulated to be 0; the phase calibration frame of the sending end Alice is respectively modulated into 0,
Figure BDA0003452901490000082
The number of each type of optical pulse is determined according to the length of the optimal phase calibration frame determined by the actual situation, and the amplitude of the corresponding optical pulse in the data packet of the sending end Bob is modulated to be 0.
Further, the slow drift phase corresponding to the current data block of the system is calculated in the step (5)
Figure BDA0003452901490000083
Figure BDA0003452901490000084
The method comprises the following specific steps:
Figure BDA0003452901490000085
respectively indicating the relative phase drift of the Alice signal pulse and the LO pulse light at the third balanced homodyne detector and the fourth balanced homodyne detector, which are introduced due to the fluctuation of the system optical path length, and respectively modulating the Alice phase to 0 and the LO phase at the third balanced homodyne detector and the fourth balanced homodyne detector
Figure BDA0003452901490000086
The sampling voltage values corresponding to the two types of phase calibration pulses are respectively marked as
Figure BDA0003452901490000087
Obtaining a current slow-drift phase
Figure BDA0003452901490000088
Estimated value of (a):
Figure BDA0003452901490000089
Figure BDA00034529014900000810
wherein, Delta theta1、Δθ2The fast-changing phase measured by a 90-degree optical mixer is used for obtaining a plurality of slow-drifting phase estimation values in each data block, then probability statistics and Gaussian fitting are carried out on all the estimation values, and a phase value corresponding to the maximum probability distribution is extracted and used as a slow-drifting phase
Figure BDA0003452901490000091
The final estimate of (d);
Figure BDA0003452901490000092
respectively showing the relative phase drift of Bob signal light and LO pulse light at the transmitting end, which is introduced by the fluctuation of the system optical path length, at the third and fourth balanced homodyne detectors, respectively modulating the phase to 0,
Figure BDA0003452901490000093
The average voltage values corresponding to the three types of phase calibration pulses are respectively recorded as
Figure BDA0003452901490000094
Obtaining the current slow-drifting phase by using the three groups of voltage values
Figure BDA0003452901490000095
Estimated value of (a):
Figure BDA0003452901490000096
further, in the step (6), the receiving end Charlie passes through the slow drift phase
Figure BDA0003452901490000097
Calculating a corresponding compensation voltage value, wherein the formula is as follows:
Figure BDA0003452901490000098
wherein VπIs the half-wave voltage of the third phase modulator,
Figure BDA0003452901490000099
indicating the phase of the compensation.
Further, the formula of the orthogonal component remapping in step (9) is:
Figure BDA00034529014900000910
at this time, the orthogonal components after the rotation of the sending end Alice and the sending end Bob are completely matched with the result of the measurement of the Charlie continuous variable bell state at the receiving end, that is:
Figure BDA0003452901490000101
compared with the prior art, the invention has the following advantages:
the irrelevant quantum key distribution system of the continuous variable measurement equipment and the phase compensation method thereof can eliminate all side channel attacks aiming at a measurement end in an actual continuous variable quantum key distribution system. The phase compensation method can reliably realize the continuous variable Bell state measurement of the remote independent quantum state by combining optical phase locking, slow drift phase estimation, real-time phase feedback and orthogonal component remapping. The method has the characteristics of easiness in implementation, high compensation precision, convenience in popularization and the like by skillfully combining various phase compensation technologies, and is a key technology for independent continuous variable quantum key distribution of measuring equipment.
Drawings
FIG. 1 is a schematic diagram of a system for independent quantum key distribution of a continuous variable measurement device according to the present invention;
fig. 2 is a structure of respective data packets of a sending end Alice and a sending end Bob in the phase compensation method of the independent quantum key distribution system of the continuous variable measurement device according to the present invention;
FIG. 3 is a result of Gaussian fitting and probability statistics of slow-drift phase estimation values within a single data block in the phase compensation method of the independent quantum key distribution system of the continuous variable measurement device of the present invention;
fig. 4 is a phase locking result in the phase compensation method of the independent quantum key distribution system of the continuous variable measurement device during the bell state measurement of the continuous variable;
FIG. 5 is a diagram of the correlation between the quadrature amplitude components of the transmitting end Alice and the transmitting end Bob;
fig. 6 is a correlation diagram of quadrature phase components of a transmitting end Alice and a transmitting end Bob.
Detailed Description
The technical solution of the present invention will be further described in more detail with reference to the following embodiments. It is to be understood that the described embodiments are only some, and not all, embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, a system for distributing independent quantum keys of continuous variable measurement devices includes a sending end Alice, a sending end Bob, and a receiving end Charlie;
the sending end Alice comprises a first laser, a first beam splitter, an acousto-optic modulator, a pulse chopping module, a second beam splitter, a first signal light modulation module, a first delay line, a first attenuator, a second attenuator and a first polarization beam combiner, wherein the pulse chopping module comprises a first amplitude modulator and a second amplitude modulator which are connected in series, and the first signal light modulation module comprises a third amplitude modulator and a first phase modulator which are sequentially arranged;
the first laser provides continuous single-frequency light, the continuous single-frequency light is divided into two parts of 90% and 10% by the first beam splitter, 10% of the continuous single-frequency light is shifted upwards by the acousto-optic modulator at a frequency of 80MHz, 90% of the divided continuous single-frequency light is chopped into high-extinction-ratio pulse light with a repetition rate of 500kHz, a pulse width of 50ns and an extinction ratio of 80dB by the pulse chopping module, the high-extinction-ratio pulse light is divided into 1% signal pulse light and 99% phase reference pulse light by the second beam splitter, the 1% signal pulse light sequentially passes through the first signal light modulation module, the first delay line and the first attenuator and enters the first polarization beam combiner, and the phase reference pulse light passes through the second attenuator and enters the first polarization beam combiner;
the 1% signal pulse realizes a Gaussian modulation coherent state protocol through the first signal light modulation module. Delaying the signal pulse by 300ns by using a first delay line to realize time division multiplexing with a phase reference pulse, and further attenuating the intensity of the signal pulse to a single photon level by using a first attenuator;
the intensity of the 99% phase reference pulse light is attenuated to 10 per pulse by the second attenuator5Individual photon number level.
The transmitting end Bob comprises a second laser, a third beam splitter, a fourth beam splitter, a photoelectric detector, a frequency locking module, a second pulse chopping module, a fifth beam splitter, a second signal light modulation module, a second delay line, a third attenuator and a second polarization beam combiner, the second pulse chopping module comprises two cascaded fourth amplitude modulators and fifth amplitude modulators, and the second signal light modulation module comprises a sixth amplitude modulator and a second phase modulator which are sequentially arranged;
the third beam splitter receives continuous single-frequency light from the acousto-optic modulator, the third beam splitter is an 50/50 beam splitter, the second laser provides continuous single-frequency light, the continuous single-frequency light is divided into 10% and 90% by the fourth beam splitter, the 10% continuous single-frequency light is transmitted to the third beam splitter and interferes with the continuous single-frequency light from the acousto-optic modulator, the photoelectric detector detects an optical beat signal, the frequency locking module extracts an error signal from an electrical signal converted from the optical beat signal and feeds the error signal back to the second laser for frequency locking, so that the frequency difference between two beams of light used for frequency locking by the sending end Alice and the sending end Bob is stabilized at 80MHz, and at the moment, the two beams of light used for quantum key distribution by the sending end Alice and the sending end Bob have the same frequency. The transmitting end Bob then operates the same as Alice on its light source for continuous variable quantum key distribution, except that it generates the signal and LO pulses, and the transmitting end Alice generates the signal and phase reference pulses. The LO pulse is much stronger than the phase reference pulse and therefore its strength does not need to be attenuated. The 90% continuous single-frequency light is chopped into high-extinction-ratio pulse light by the second pulse chopping module, the high-extinction-ratio pulse light is divided into 1% signal pulse light and 99% LO pulse light by the fifth beam splitter, the 1% signal pulse light sequentially passes through the second signal light modulation module, the second delay line and the third attenuator and enters the second polarization beam combiner, and the 99% LO pulse light enters the second polarization beam combiner.
The receiving end Charlie comprises a first polarization demultiplexing module, a second polarization demultiplexing module, a sixth beam splitter, a clock recovery module, a third delay line, a fourth delay line, a seventh beam splitter, an optical mixer module and a continuous variable Bell state measurement module, wherein the first polarization demultiplexing module comprises a first polarization controller, a first optical fiber collimator, a first polarization beam splitter and a second optical fiber collimator, the second polarization demultiplexing module comprises a second polarization controller, a third optical fiber collimator, a second polarization beam splitter and a fourth optical fiber collimator, the optical mixer module comprises a 90-degree optical mixer, a first balanced homodyne detector and a second balanced homodyne detector, and the continuous variable Bell state measurement module comprises an eighth beam splitter, a third phase modulator, a fifth optical fiber collimator, a sixth optical fiber collimator, a first beam splitter, a second beam splitter, a clock recovery module, a third delay line, a fourth delay line, a seventh optical fiber collimator, a continuous variable Bell state measurement module, The third beam splitting slice, the third balanced homodyne detector and the fourth balanced homodyne detector;
the first polarization controller is used for adjusting the polarization directions of the signal pulse light and the phase reference pulse light of the transmitting end Alice, the first optical fiber collimator is used for coupling the signal pulse light and the phase reference pulse light of the transmitting end Alice to a free space, the first polarization beam splitter is used for polarization demultiplexing of the signal pulse light and the phase reference pulse light, the signal pulse light enters the continuous variable Bell state measuring module, and the phase reference pulse light is coupled to the optical fiber again through the second optical fiber collimator and enters the optical mixer module through the fourth delay line;
the second polarization controller is used for adjusting the polarization directions of signal pulse light and LO pulse light of a sending end Bob, the third optical fiber collimator couples the signal pulse light and the LO pulse light of the sending end Bob to a free space, the second polarization beam splitter polarizes and demultiplexes the signal pulse light and the LO pulse light, the signal pulse light enters the continuous variable Bell state measuring module, the LO pulse light is coupled to an optical fiber again through a fourth optical fiber collimator and enters a sixth beam splitter, the LO pulse light is divided into two parts of 90% and 10% by the sixth beam splitter, one part of 10% enters the clock recovery module, the other part of 90% enters a seventh beam splitter through a third delay line, the other part of 90% is divided into two parts by the seventh beam splitter, one part of 10% enters the optical mixer module, and the other part of 90% enters the continuous variable Bell state measuring module; by using delay lines, the demultiplexed LO pulses, phase reference pulses and signal pulses will be precisely aligned in the time domain.
In the optical mixer module, the phase reference pulse light from the fourth delay line enters a 90-degree optical mixer, the LO pulse light from the seventh beam splitter enters a 90-degree optical mixer, the first balanced homodyne detector and the second balanced homodyne detector are respectively connected with the 90-degree optical mixer, and the orthogonal amplitude component X of the phase reference pulse is respectively measuredRAnd quadrature phase component PR；
In the continuous variable Bell state measurement module, LO pulse light from a seventh beam splitter is divided into 50% and 50% parts by an eighth beam splitter, one 50% part enters a third balanced homodyne detector through a fifth optical fiber collimator and a second beam splitter, and the other 50% part enters a fourth balanced homodyne detector through a third phase modulator, a sixth optical fiber collimator and a third beam splitter; the signal pulse light from the second polarization beam splitter is divided into two parts by the first beam splitter, one part enters the third balanced homodyne detector through the second beam splitter, and the other part enters the fourth balanced homodyne detector through the third beam splitterA machine; the first beam splitting piece of the signal pulse light from the first polarization beam splitter is divided into two parts, one part enters the third balanced homodyne detector through the second beam splitting piece, and the other part enters the fourth balanced homodyne detector through the third beam splitting piece; the third balanced homodyne detector and the fourth balanced homodyne detector respectively measure orthogonal amplitude components X of the signal light fieldCAnd quadrature phase component PC。
The first beam splitting sheet, the second beam splitting sheet and the third beam splitting sheet are all free spaces 50: 50 bundling pieces.
The continuous variable Bell state measuring module further comprises 4 high-reflection mirrors used for adjusting a light path to enable light to be completely incident to the third balanced homodyne detector and the fourth balanced homodyne detector.
A phase compensation method of a continuous variable measurement device independent quantum key distribution system comprises the following steps:
(1) according to the environment of the system, a sending end Alice and a sending end Bob firstly determine the length of a single data block: the duration of a single data block is at least 1 order of magnitude smaller than the phase drift rate of the system, slow drift phase values are at least ensured to be kept unchanged in the durations of the front data block and the rear data block, each data block is divided into a plurality of data packets, and 1 phase calibration frame is inserted into each data packet;
the slow drift speed of the phase caused by the change of the external environment is in the Hz magnitude. In this embodiment, the system repetition rate is 500kHz, with Alice and Bob treating 5000 pulses that are consecutive within 10ms as a block of data. Every 100 pulses in a single data block are used as a data packet, the data structure of each data packet is completely the same, and the data packet sequentially comprises a phase calibration frame, a shot noise calibration frame and a key frame;
(2) and the sending end Alice and the sending end Bob determine the optimal phase calibration frame length.
The length of the optimal phase calibration frame is combined with the length of the data block to balance the phase estimation precision and the system overhead;
FIG. 2 shows the structure of respective packets of Alice and Bob, Bob having the first 24 optical pulses in each packet as their own phase alignment framesThe optical pulse generating device consists of three types of optical pulses with different phases, and the number of each type of optical pulse is determined to be 8. The phase calibration frame of the sending end Bob is respectively modulated into 0,
Figure BDA0003452901490000151
Figure BDA0003452901490000152
The number of each type of optical pulse is determined according to the length of the optimal phase calibration frame determined by the actual situation, and the amplitudes of the 24 corresponding optical pulses in the sending end Alice data packet are modulated to be 0; the sending end Alice takes the next 40 optical pulses as its own phase alignment frame, and the phase alignment frame of the sending end Alice is modulated into a phase alignment frame of 0,
Figure BDA0003452901490000153
The number of each type of optical pulse is determined according to the length of the optimal phase calibration frame determined in actual conditions, and the amplitude of the corresponding optical pulse in the data packet of the sending end Bob is modulated to 0 (extinction).
(3) The frequency of the second laser and the frequency of the first laser are locked through the frequency locking module, and the relative phase of the phase reference pulse and the LO pulse is kept unchanged within the duration time of a single optical pulse;
(4) the receiving end Charlie respectively records the peak sampling voltages of the electric pulses output by the first balanced homodyne detector and the second balanced homodyne detector as XR、PRAnd calculating the fast-varying phase difference between each phase reference pulse and LO pulse in real time
Figure BDA0003452901490000154
(5) The receiving end Charlie samples output signals of the third balanced homodyne detector and the fourth balanced homodyne detector, extracts measurement voltage values corresponding to all phase calibration frames in the current data block, and calculates slow-drifting phase corresponding to the current data block of the system according to the measurement voltage values and the fast-changing phase difference delta theta corresponding to the phase calibration frames obtained in the step (4)
Figure BDA0003452901490000155
Calculating slow drift phase corresponding to current data block of system
Figure BDA0003452901490000156
The method comprises the following specific steps:
Figure BDA0003452901490000157
respectively indicating the relative phase drift of the Alice signal pulse and the LO pulse light at the third balanced homodyne detector and the fourth balanced homodyne detector, which are introduced due to the fluctuation of the system optical path length, and respectively modulating the Alice phase to 0 and the LO phase at the third balanced homodyne detector and the fourth balanced homodyne detector
Figure BDA0003452901490000158
The sampling voltage values corresponding to the two types of phase calibration pulses are respectively marked as
Figure BDA0003452901490000161
Obtaining a current slow-drift phase
Figure BDA0003452901490000162
Estimated value of (a):
Figure BDA0003452901490000163
Figure BDA0003452901490000164
wherein, Delta theta1、Δθ2The fast-changing phase measured by a 90-degree optical mixer is used for obtaining a plurality of slow-drifting phase estimation values in each data block, then probability statistics and Gaussian fitting are carried out on all the estimation values, and a phase value corresponding to the maximum probability distribution is extracted and used as a slow-drifting phase
Figure BDA0003452901490000165
Is estimated. Fig. 3 shows the probability statistics and gaussian fitting results of the slow-drifting phase estimation values in a single data block, wherein the black points are the probability statistical distribution of the slow-drifting phase estimation values in the single data block obtained in the experiment, and the black curves are the results of gaussian fitting on the experimental data points.
Figure BDA0003452901490000166
Respectively showing the relative phase drift of Bob signal light and LO pulse light at the transmitting end, which is introduced by the fluctuation of the system optical path length, at the third and fourth balanced homodyne detectors, respectively modulating the phase at the third and fourth balanced homodyne detectors to 0,
Figure BDA0003452901490000167
The three types of phase calibration pulses can respectively obtain 400 sampling voltages, and the corresponding voltage average values are respectively recorded as
Figure BDA0003452901490000168
Obtaining the current slow-drifting phase by using the three groups of voltage values
Figure BDA0003452901490000169
Estimated value of (a):
Figure BDA00034529014900001610
(6) receiving end Charlie through slow drifting phase
Figure BDA00034529014900001611
Calculating a corresponding compensation voltage value, wherein the formula is as follows:
Figure BDA00034529014900001612
wherein VπIs the half-wave voltage of the third phase modulator,
Figure BDA00034529014900001613
indicating the phase of the compensation.
Controlling the third phase modulator to compensate the compensation voltage value to the next data block, and simultaneously measuring orthogonal components X 'perpendicular to each other by the third balanced zero-beat detector and the fourth balanced zero-beat detector'C、P′C；
(7) Repeating the steps (4) to (6) to ensure that each data block except the first data block can compensate the compensation voltage value corresponding to the current slow drift phase in real time, and the third balanced zero-beat detector and the fourth balanced zero-beat detector always measure orthogonal components X 'which are perpendicular to each other'C、P′CFIG. 4 shows the phase locking result of the Bell state measurement with the continuous variable in 100 s. The mean and variance of (a) in fig. 4 are 89.99 ° and 0.41 °, respectively, and the mean and variance of (b) in fig. 4 are 89.88 ° and 0.59 °, respectively;
(8) after the data transmission is finished, the receiving end Charlie transmits the fast variable phase delta theta and the slow drifting phase through the classical channel
Figure BDA0003452901490000171
Sending to sending end Alice, slowly drifting phase
Figure BDA0003452901490000172
Sending the data to a sending end Bob;
(9) the sending end Alice and the sending end Bob respectively carry out comparison on respective original data (X)A,PA)、(XB,PB) Orthogonal component remapping is performed to obtain phase-rotated data (X'A,P′A)、(X′B,P′B)；
The formula is as follows:
Figure BDA0003452901490000173
at this time, the orthogonal components after the rotation of the sending end Alice and the sending end Bob are completely matched with the result of the measurement of the Charlie continuous variable bell state at the receiving end, that is:
Figure BDA0003452901490000174
(10) after the phase correction is completed, the sending end Alice and the sending end Bob perform data displacement operation on their respective data to generate correlation to obtain a bare code, fig. 5 is a correlation diagram of orthogonal amplitude components of the sending end Alice and the sending end Bob, fig. 6 is a correlation diagram of orthogonal phase components of the sending end Alice and the sending end Bob, and then the sending end Alice and the sending end Bob perform parameter estimation, data coordination and privacy amplification to generate a final secret key.
The above is only one embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures or equivalent flow transformations made by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (10)

1. A continuous variable measurement equipment independent quantum key distribution system is characterized by comprising a sending end Alice, a sending end Bob and a receiving end Charlie;
the sending end Alice comprises a first laser, a first beam splitter, an acousto-optic modulator, a pulse chopping module, a second beam splitter, a first signal light modulation module, a first delay line, a first attenuator, a second attenuator and a first polarization beam combiner, wherein the pulse chopping module comprises a first amplitude modulator and a second amplitude modulator which are connected in series, and the first signal light modulation module comprises a third amplitude modulator and a first phase modulator which are sequentially arranged;
the first laser provides continuous single-frequency light, the continuous single-frequency light is divided into two parts by the first beam splitter, one part of the continuous single-frequency light is subjected to frequency shifting by the acousto-optic modulator, the other part of the continuous single-frequency light is chopped into pulse light with a high extinction ratio by the pulse chopping module, the pulse light with the high extinction ratio is divided into signal pulse light and phase reference pulse light by the second beam splitter, the signal pulse light sequentially passes through the first signal light modulation module, the first delay line and the first attenuator and enters the first polarization beam combiner, and the phase reference pulse light enters the first polarization beam combiner through the second attenuator;
the transmitting end Bob comprises a second laser, a third beam splitter, a fourth beam splitter, a photoelectric detector, a frequency locking module, a second pulse chopping module, a fifth beam splitter, a second signal light modulation module, a second delay line, a third attenuator and a second polarization beam combiner, the second pulse chopping module comprises two cascaded fourth amplitude modulators and fifth amplitude modulators, and the second signal light modulation module comprises a sixth amplitude modulator and a second phase modulator which are sequentially arranged;
the third beam splitter receives continuous single-frequency light from the acousto-optic modulator, the second laser provides continuous single-frequency light, the continuous single-frequency light is divided into two parts through the fourth beam splitter, one part of the continuous single-frequency light is transmitted to the third beam splitter to interfere with the continuous single-frequency light from the acousto-optic modulator, the photoelectric detector detects a light beat signal, and the frequency locking module extracts an error signal from an electric signal converted from the light beat signal and feeds the error signal back to the second laser for frequency locking; the other part of continuous single-frequency light is chopped into high-extinction-ratio pulse light by the second pulse chopping module, the high-extinction-ratio pulse light is divided into signal pulse light and LO pulse light by the fifth beam splitter, the signal pulse light sequentially passes through the second signal light modulation module, the second delay line and the third attenuator and enters the second polarization beam combiner, and the LO pulse light enters the second polarization beam combiner;
the receiving end Charlie comprises a first polarization demultiplexing module, a second polarization demultiplexing module, a sixth beam splitter, a clock recovery module, a third delay line, a fourth delay line, a seventh beam splitter, an optical mixer module and a continuous variable Bell state measurement module, wherein the first polarization multiplexing module comprises a first polarization controller, a first optical fiber collimator, a first polarization beam splitter and a second optical fiber collimator, the second polarization demultiplexing module comprises a second polarization controller, a third optical fiber collimator, a second polarization beam splitter and a fourth optical fiber collimator, the optical mixer module comprises a 90-degree optical mixer, a first balanced homodyne detector and a second balanced homodyne detector, and the continuous variable Bell state measurement module comprises an eighth beam splitter, a third phase modulator, a fifth optical fiber collimator, a sixth optical fiber collimator, a first beam splitter, a second beam splitter, a clock recovery module, a third delay line, a fourth delay line, a seventh optical fiber collimator, a continuous variable Bell state measurement module, The third beam splitting slice, the third balanced homodyne detector and the fourth balanced homodyne detector;
the first polarization controller is used for adjusting the polarization directions of the signal pulse light and the phase reference pulse light of the transmitting end Alice, the first optical fiber collimator is used for coupling the signal pulse light and the phase reference pulse light of the transmitting end Alice to a free space, the first polarization beam splitter is used for polarization demultiplexing of the signal pulse light and the phase reference pulse light, the signal pulse light enters the continuous variable Bell state measuring module, and the phase reference pulse light is coupled to the optical fiber again through the second optical fiber collimator and enters the optical mixer module through the fourth delay line;
the second polarization controller is used for adjusting the polarization directions of signal pulse light and LO pulse light of a sending end Bob, the third optical fiber collimator couples the signal pulse light and the LO pulse light of the sending end Bob to a free space, the second polarization beam splitter polarizes and demultiplexes the signal pulse light and the LO pulse light, the signal pulse light enters the continuous variable Bell state measuring module, the LO pulse light is coupled to an optical fiber again through a fourth optical fiber collimator and enters a sixth beam splitter, the LO pulse light is divided into two parts by the sixth beam splitter, one part enters the clock recovery module, the other part enters a seventh beam splitter through a third delay line, the LO pulse light is divided into two parts by the seventh beam splitter, one part enters the optical mixer module, and the other part enters the continuous variable Bell state measuring module;
in the optical mixer module, the phase reference pulse light from the fourth delay line enters a 90-degree optical mixer, the LO pulse light from the seventh beam splitter enters a 90-degree optical mixer, the first balanced homodyne detector and the second balanced homodyne detector are respectively connected with the 90-degree optical mixer, and the orthogonal amplitude component X of the phase reference pulse is respectively measuredRAnd quadrature phase component PR；
In the continuous variable bell state measurement module,the LO pulse light from the seventh beam splitter is divided into two parts by the eighth beam splitter, one part enters the third balanced homodyne detector through the fifth optical fiber collimator and the second beam splitter, and the other part enters the fourth balanced homodyne detector through the third phase modulator, the sixth optical fiber collimator and the third beam splitter; the signal pulse light from the second polarization beam splitter is divided into two parts by the first beam splitter, one part enters the third balanced homodyne detector through the second beam splitter, and the other part enters the fourth balanced homodyne detector through the third beam splitter; the first beam splitting piece of the signal pulse light from the first polarization beam splitter is divided into two parts, one part enters the third balanced homodyne detector through the second beam splitting piece, and the other part enters the fourth balanced homodyne detector through the third beam splitting piece; the third balanced homodyne detector and the fourth balanced homodyne detector respectively measure orthogonal amplitude components X of the signal light fieldCAnd quadrature phase component PC。
2. The system according to claim 1, wherein the first beam splitter splits the continuous single-frequency light into two parts, i.e., 90% and 10%, wherein 10% of the continuous single-frequency light is shifted up by 80MHz through the acousto-optic modulator, and 90% of the continuous single-frequency light is chopped into high-extinction-ratio pulsed light with a repetition rate of 500kHz, a pulse width of 50ns, and an extinction ratio of 80dB by the pulse chopping module;
the second beam splitter divides the high extinction ratio pulsed light of the transmitting end Alice into 1% signal pulsed light and 99% phase reference pulsed light;
the third beam splitter is an 50/50 beam splitter;
the fourth beam splitter divides the continuous single-frequency light provided by the second laser into two parts, namely 10% and 90%, the 10% continuous single-frequency light is transmitted to the third beam splitter and interferes with the continuous single-frequency light from the acousto-optic modulator, and the 90% continuous single-frequency light is chopped into pulsed light with a high extinction ratio by the second pulse chopping module;
the fifth beam splitter divides the high extinction ratio pulsed light of the transmitting end Bob into 1% signal pulsed light and 99% LO pulsed light;
the sixth beam splitter divides the LO pulse light from the fourth optical fiber collimator into two parts, namely 90% and 10%, the 10% LO pulse light enters the clock recovery module, and the 90% LO pulse light enters the seventh beam splitter through the third delay line;
the seventh beam splitter divides the LO pulse light into 10% and 90% parts, the 10% LO pulse light enters the light mixer module, and the 90% LO pulse light enters the continuous variable Bell state measuring module;
the eighth beam splitter divides the LO pulse light entering the continuous variable Bell state measurement module into two parts, namely 50% and 50%.
3. The continuous variable measurement device-independent quantum key distribution system of claim 2, wherein the first beam splitting slice, the second beam splitting slice, and the third beam splitting slice are all free space 50: 50 bundling pieces.
4. The system according to claim 3, wherein the continuous variable Bell state measurement module further comprises a plurality of high-reflection mirrors for adjusting the optical path such that the light is incident on the third and fourth balanced homodyne detectors completely.
5. The phase compensation method for the continuous variable measurement device-independent quantum key distribution system of claim 4, comprising the steps of:
(1) according to the environment of a system, a sending end Alice and a sending end Bob firstly determine the length of a single data block, then divide each data block into a plurality of data packets, and insert 1 phase calibration frame into each data packet;
(2) and the sending end Alice and the sending end Bob determine the optimal phase calibration frame length.
(3) The frequency of the second laser and the frequency of the first laser are locked through the frequency locking module, and the relative phase of the phase reference pulse and the LO pulse is kept unchanged within the duration time of a single optical pulse;
(4) the receiving end Charlie outputs electric pulse to the first balanced zero-beat detector and the second balanced zero-beat detectorThe peak impact value sampling voltages are respectively marked as XR、PRAnd calculating the fast-varying phase difference between each phase reference pulse and LO pulse in real time
Figure FDA0003452901480000051
(5) The receiving end Charlie samples output signals of the third balanced homodyne detector and the fourth balanced homodyne detector, extracts measurement voltage values corresponding to all phase calibration frames in the current data block, and calculates slow-drifting phase corresponding to the current data block of the system according to the measurement voltage values and the fast-changing phase difference delta theta corresponding to the phase calibration frames obtained in the step (4)
Figure FDA0003452901480000052
(6) Receiving end Charlie through slow drifting phase
Figure FDA0003452901480000053
Calculating corresponding compensation voltage value, loading the compensation voltage value to a data block which controls a third phase modulator to compensate the compensation voltage value to the next data block, and enabling a third balanced zero-beat detector and a fourth balanced zero-beat detector to simultaneously measure orthogonal components X 'which are perpendicular to each other'C、P′C；
(7) Repeating the steps (4) to (6) to ensure that each data block except the first data block can compensate the compensation voltage value corresponding to the current slow drift phase in real time, and the third balanced zero-beat detector and the fourth balanced zero-beat detector always measure orthogonal components X 'which are perpendicular to each other'C、P′C；
(8) After the data transmission is finished, the receiving end Charlie transmits the fast variable phase delta theta and the slow drifting phase through the classical channel
Figure FDA0003452901480000054
Sending to sending end Alice, slowly drifting phase
Figure FDA0003452901480000055
Is sent toA sending end Bob;
(9) the sending end Alice and the sending end Bob respectively carry out comparison on respective original data (X)A,PA)、(XB,PB) Orthogonal component remapping is performed to obtain phase-rotated data (X'A,P′A)、(X′B,P′B)；
(10) After the phase correction is completed, the sending end Alice and the sending end Bob perform data displacement operation on the respective data to generate correlation to obtain a bare code, and then perform parameter estimation, data coordination and privacy amplification to generate a final secret key.
6. The phase compensation method for the continuous variable measurement equipment-independent quantum key distribution system according to claim 5, wherein the specific step of determining the length of the single data block in the step (1) is as follows: the duration of a single data block is at least 1 order of magnitude less than the phase drift rate of the system, at least to ensure that the slow drift phase value remains constant for the duration of two preceding and following data blocks.
7. The phase compensation method for the continuous variable measurement equipment-independent quantum key distribution system according to claim 5, wherein the optimal phase calibration frame length in step (2) is balanced between the phase estimation accuracy and the system overhead in combination with the data block length;
the phase calibration frame of the sending end Bob is respectively modulated into 0,
Figure FDA0003452901480000061
The number of each type of optical pulse is determined according to the length of the optimal phase calibration frame determined by the actual situation, and the amplitude of the corresponding optical pulse in the sending end Alice data packet is modulated to be 0; the phase calibration frame of the sending end Alice is respectively modulated into 0,
Figure FDA0003452901480000062
Of each type of light pulseThe number is determined according to the length of the optimal phase calibration frame determined by the actual situation, and the amplitude of the optical pulse corresponding to the optical pulse in the data packet of the sending end Bob is modulated to be 0.
8. The phase compensation method for the continuous variable measurement equipment-independent quantum key distribution system according to claim 5, wherein the slow drift phase corresponding to the current data block of the system is calculated in the step (5)
Figure FDA0003452901480000063
The method comprises the following specific steps:
Figure FDA0003452901480000064
respectively indicating the relative phase drift of the Alice signal pulse and the LO pulse light at the third balanced homodyne detector and the fourth balanced homodyne detector, which are introduced due to the fluctuation of the system optical path length, and respectively modulating the Alice phase to 0 and the LO phase at the third balanced homodyne detector and the fourth balanced homodyne detector
Figure FDA0003452901480000065
The sampling voltage values corresponding to the two types of phase calibration pulses are respectively marked as
Figure FDA0003452901480000066
Obtaining a current slow-drift phase
Figure FDA0003452901480000067
Estimated value of (a):
Figure FDA0003452901480000068
Figure FDA0003452901480000069
wherein, Delta theta1、Δθ2The fast-changing phase measured by a 90-degree optical mixer is used for obtaining a plurality of slow-drifting phase estimation values in each data block, then probability statistics and Gaussian fitting are carried out on all the estimation values, and a phase value corresponding to the maximum probability distribution is extracted and used as a slow-drifting phase
Figure FDA0003452901480000071
The final estimate of (d);
Figure FDA0003452901480000072
respectively showing the relative phase drift of Bob signal light and LO pulse light at the transmitting end, which is introduced by the fluctuation of the system optical path length, at the third and fourth balanced homodyne detectors, respectively modulating the phase to 0,
Figure FDA0003452901480000073
The average voltage values corresponding to the three types of phase calibration pulses are respectively recorded as
Figure FDA0003452901480000074
Obtaining the current slow-drifting phase by using the three groups of voltage values
Figure FDA0003452901480000075
Estimated value of (a):
Figure FDA0003452901480000076
9. the phase compensation method of the continuous variable measurement equipment-independent quantum key distribution system according to claim 5, wherein in the step (6), the receiving end Charlie passes through slow drift phase
Figure FDA0003452901480000077
Figure FDA0003452901480000078
Calculating a corresponding compensation voltage value, wherein the formula is as follows:
Figure FDA0003452901480000079
wherein VπIs the half-wave voltage of the third phase modulator,
Figure FDA00034529014800000710
indicating the phase of the compensation.
10. The phase compensation method for the continuous variable measurement equipment-independent quantum key distribution system according to claim 5, wherein the formula of the orthogonal component remapping in the step (9) is as follows:
Figure FDA00034529014800000711
at this time, the orthogonal components after the rotation of the sending end Alice and the sending end Bob are completely matched with the result of the measurement of the Charlie continuous variable bell state at the receiving end, that is:
Figure FDA0003452901480000081
CN202111670733.2A 2021-12-31 2021-12-31 Continuous variable measurement device independent quantum key distribution system and phase compensation method Active CN114337847B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111670733.2A CN114337847B (en) 2021-12-31 2021-12-31 Continuous variable measurement device independent quantum key distribution system and phase compensation method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111670733.2A CN114337847B (en) 2021-12-31 2021-12-31 Continuous variable measurement device independent quantum key distribution system and phase compensation method

Publications (2)

Publication Number Publication Date
CN114337847A true CN114337847A (en) 2022-04-12
CN114337847B CN114337847B (en) 2023-07-18

Family

ID=81020791

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111670733.2A Active CN114337847B (en) 2021-12-31 2021-12-31 Continuous variable measurement device independent quantum key distribution system and phase compensation method

Country Status (1)

Country Link
CN (1) CN114337847B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115242314A (en) * 2022-08-02 2022-10-25 北京中科国光量子科技有限公司 Coherent receiving device based on bidirectional multiplexing 90-degree frequency mixer
CN116527251A (en) * 2023-05-06 2023-08-01 山西大学 Device and method for distributing sideband interferometry measurement equipment independent double-field quantum key
CN116723054A (en) * 2023-08-08 2023-09-08 合肥量芯科技有限公司 Method for resisting detection efficiency mismatch loopholes introduced in calibration process
CN117914411A (en) * 2024-03-19 2024-04-19 济南量子技术研究院 Phase feedback method for TF-QKD system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108696352A (en) * 2018-05-25 2018-10-23 中南大学 The unrelated quantum key distribution system of continuous variable measuring apparatus and its implementation
CN108989035A (en) * 2018-09-07 2018-12-11 上海循态信息科技有限公司 Based on the unrelated continuous variable quantum key delivering method of measuring device and system
CN109379188A (en) * 2018-12-10 2019-02-22 山西大学 A kind of unrelated phase matched quantum key distribution device of measuring device
CN109586911A (en) * 2019-02-01 2019-04-05 上海循态信息科技有限公司 Continuous variable quantum key delivering method based on coherent optical communication system
CN111404681A (en) * 2020-03-13 2020-07-10 上海循态信息科技有限公司 Method, system and medium for distributing independent quantum key of continuous variable measurement equipment

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108696352A (en) * 2018-05-25 2018-10-23 中南大学 The unrelated quantum key distribution system of continuous variable measuring apparatus and its implementation
CN108989035A (en) * 2018-09-07 2018-12-11 上海循态信息科技有限公司 Based on the unrelated continuous variable quantum key delivering method of measuring device and system
CN109379188A (en) * 2018-12-10 2019-02-22 山西大学 A kind of unrelated phase matched quantum key distribution device of measuring device
CN109586911A (en) * 2019-02-01 2019-04-05 上海循态信息科技有限公司 Continuous variable quantum key delivering method based on coherent optical communication system
CN111404681A (en) * 2020-03-13 2020-07-10 上海循态信息科技有限公司 Method, system and medium for distributing independent quantum key of continuous variable measurement equipment

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
李蔚: "高速测量设备无关量子密钥分发系统的集成化研究", 中国科学技术大学, vol. 2021, no. 01 *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115242314A (en) * 2022-08-02 2022-10-25 北京中科国光量子科技有限公司 Coherent receiving device based on bidirectional multiplexing 90-degree frequency mixer
CN115242314B (en) * 2022-08-02 2023-03-24 北京中科国光量子科技有限公司 Coherent receiving device based on bidirectional multiplexing 90-degree frequency mixer
CN116527251A (en) * 2023-05-06 2023-08-01 山西大学 Device and method for distributing sideband interferometry measurement equipment independent double-field quantum key
CN116527251B (en) * 2023-05-06 2023-11-03 山西大学 Device and method for distributing sideband interferometry measurement equipment independent double-field quantum key
CN116723054A (en) * 2023-08-08 2023-09-08 合肥量芯科技有限公司 Method for resisting detection efficiency mismatch loopholes introduced in calibration process
CN116723054B (en) * 2023-08-08 2023-10-27 合肥量芯科技有限公司 Method for resisting detection efficiency mismatch loopholes introduced in calibration process
CN117914411A (en) * 2024-03-19 2024-04-19 济南量子技术研究院 Phase feedback method for TF-QKD system
CN117914411B (en) * 2024-03-19 2024-06-04 济南量子技术研究院 Phase feedback method for TF-QKD system

Also Published As

Publication number Publication date
CN114337847B (en) 2023-07-18

Similar Documents

Publication Publication Date Title
CN109586907B (en) Fusion network system and method for quantum communication and quantum time-frequency transmission
CN114337847B (en) Continuous variable measurement device independent quantum key distribution system and phase compensation method
Ferreira da Silva et al. Proof-of-principle demonstration of measurement-device-independent quantum key distribution using polarization qubits
US11411723B2 (en) Apparatus and method for quantum enhanced physical layer security
US7403623B2 (en) High-rate quantum key distribution scheme relying on continuously phase and amplitude-modulated coherent light pulses
US11258594B2 (en) Quantum key distribution using a thermal source
Qi et al. Experimental study on the Gaussian-modulated coherent-state quantum key distribution over standard telecommunication fibers
US7929700B2 (en) Continuous variable quantum encryption key distribution system
US8374350B2 (en) Quantum communication system
US10972187B1 (en) Light source for quantum communication system, and encoding device
CN113676323B (en) Irrelevant quantum key distribution system of polarization encoding measuring equipment
CN102868524B (en) DPS QKD (differential phase shift quantum key distribution) encryption system suitable for GPON (gigabit passive optical network) system
CN113162767B (en) Heterodyne measurement-based four-state quantum key distribution method and system
Kleis et al. Improving the secret key rate of coherent quantum key distribution with Bayesian inference
Hosseinidehaj et al. CV-MDI quantum key distribution via satellite
CN112929163B (en) Measuring device-independent continuous variable quantum key distribution method and system
US20080198437A1 (en) Converting optical information encoding
Zhang et al. Continuous-variable quantum key distribution system: A review and perspective
KR102168674B1 (en) Polarization robust plug-and-play CV QKD system
US20220085895A1 (en) Generation of optical pulses with controlled distributions of quadrature values
KR20230130220A (en) Quantum key distribution system and operation method thereof
CN113992323A (en) Chip-based measuring equipment independent quantum key distribution system and method
da Silva et al. Proof-of-principle demonstration of measurement device independent QKD using polarization qubits
CN113632414A (en) Light injection locking in quantum key distribution
RU2789538C1 (en) Quantum key distribution method

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant