CN116800422B - Quantum key distribution transmitting end of integrated quantum random number generator - Google Patents
Quantum key distribution transmitting end of integrated quantum random number generator Download PDFInfo
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- 101100139907 Arabidopsis thaliana RAR1 gene Proteins 0.000 claims description 14
- 101100028790 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) PBS2 gene Proteins 0.000 claims description 14
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- 239000013307 optical fiber Substances 0.000 claims description 4
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- 239000004973 liquid crystal related substance Substances 0.000 description 16
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0852—Quantum cryptography
- H04L9/0858—Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/503—Laser transmitters
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/508—Pulse generation, e.g. generation of solitons
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/516—Details of coding or modulation
- H04B10/54—Intensity modulation
- H04B10/541—Digital intensity or amplitude modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0861—Generation of secret information including derivation or calculation of cryptographic keys or passwords
- H04L9/0869—Generation of secret information including derivation or calculation of cryptographic keys or passwords involving random numbers or seeds
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L2209/00—Additional information or applications relating to cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
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Abstract
The invention belongs to the technical field of secret communication, and discloses a quantum key distribution transmitting end of an integrated quantum random number generator, which comprises a laser LD, a beam splitting module, a light intensity modulation module, an unequal arm interferometer formed by a first beam splitter BS1 and a second beam splitter BS2, a first phase modulator PM1, an adjustable optical attenuator VOA, a photoelectric detector and a main control module. Compared with the prior art, the quantum key distribution transmitting end of the integrated quantum random number generator is provided, and the quantum random number and the quantum key distribution can be simultaneously carried out by multiplexing the laser and the interferometer and integrating the random number signal acquisition processing module with the QKD main control module, so that the complexity and the cost of the system are reduced. In addition, the photoelectric detector can be used for realizing high-speed quantum random number generation, and the requirements of quantum key distribution decoy state modulation and quantum state coding can be met.
Description
Technical Field
The invention relates to the technical field of secret communication, in particular to a quantum key distribution transmitting end of an integrated quantum random number generator.
Background
Quantum key distribution (quantum key distribution, QKD) can provide unconditionally secure key distribution for both parties in remote communications, with information theory security guaranteed by the basic principles of quantum mechanics. At present, the BB84 protocol quantum key distribution system is mature and becomes practical. The sender of existing QKD systems typically employs an independent random number generator to generate random numbers for decoy-state, quantum-state selection. One type is commonly used with various sources of physical random numbers, which are relatively high in rate, but are poorly secure. If a higher security high-speed quantum random number generator (quantum random number generator, QRNG) is employed, additional lasers, interferometers or other optical devices, and separate data acquisition and processing modules are required, greatly increasing the complexity and cost of the QKD system.
In order to solve the above problems, patent CN112994877B provides a scheme for switching quantum random number generation and quantum key distribution processes based on an optical switch, however, two processes cannot be performed simultaneously in the scheme, and only a laser is multiplexed to perform quantum random number generation, and in addition, a quantum random number generation scheme of photon arrival time is adopted, a time-to-digital converter and a single photon avalanche diode are required, and the scheme has the disadvantages of low speed, high complexity and the like. The QRNG based on vacuum fluctuation is integrated at the QKD transmitting end in the patents CN113037468B and CN112968768B, however, the solution needs a homodyne detector reaching the shot noise limit, and it is difficult to meet the high-speed requirement.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a quantum key distribution transmitting end of an integrated quantum random number generator.
The technical scheme of the invention is realized as follows:
the quantum key distribution transmitting end of the integrated quantum random number generator comprises a laser LD, a beam splitting module, a light intensity modulation module, an unequal arm interferometer formed by a first beam splitter BS1 and a second beam splitter BS2, a first phase modulator PM1, an adjustable optical attenuator VOA, a photoelectric detector and a main control module;
the laser LD is used for generating optical pulses with random phases with period T;
the beam splitting module is used for splitting the light pulse into a first component and a second component;
the light intensity modulation module is used for modulating the first component into a signal state or a decoy state and enabling the period of the first component to be changed into 2T;
the long and short arm delay difference of the unequal arm interferometer is T, and the long and short arm delay difference is used for enabling a first component incident from one input port of the first beam splitter BS1 to generate two time modes which are emergent from one output port of the second beam splitter BS2 and have a time interval of T; and for causing the front and rear pulses of the second component incident from the other output port of the second beam splitter BS2 to interfere, producing a random light intensity signal exiting from the other input port of the first beam splitter BS 1;
the first phase modulator PM1 is used to modulate the phase difference between the two time patterns in the first component to achieve phase encoding;
the variable optical attenuator VOA is used for attenuating the first component subjected to phase encoding to a single photon magnitude to generate a quantum state;
the photoelectric detector is used for converting the random light intensity signal into a random electric signal;
the main control module is used for triggering the laser LD; the method comprises the steps of generating an initial random bit, and obtaining a quantum random number through a post-processing algorithm; and for providing a driving voltage to the light intensity modulation module and the first phase modulator PM1 based on the generated quantum random numbers
Preferably, the beam splitting module is a third beam splitter BS3.
Preferably, the beam splitting module is a first polarization beam splitter PBS1, and an angle between a polarization maintaining fiber slow axis of an input port of the first polarization beam splitter PBS1 and a horizontal polarization direction is 45 °.
Preferably, the light intensity modulation module is an intensity modulator IM.
Preferably, the light intensity modulation module comprises a circulator CIR, a fourth beam splitter BS4 and a second phase modulator PM2, wherein two output ports of the fourth beam splitter BS4 are respectively connected with two ends of the second phase modulator PM2 through polarization maintaining optical fibers with different lengths to form a first annular structure; the first port, the second port and the third port of the circulator CIR are respectively and correspondingly connected with one output port of the beam splitting module, one input port of the fourth beam splitter BS4 and one input port of the first beam splitter BS 1.
Preferably, the light intensity modulation module comprises a second polarization beam splitter PBS2, a third phase modulator PM3 and a polarizer POL, and the slow axes of polarization-maintaining fibers of two input ports of the second polarization beam splitter PBS2 are both inclined at 45 degrees with the horizontal polarization direction; two output ports of the second polarization beam splitter PBS2 are respectively connected with two ends of the third phase modulator PM3 through polarization maintaining fibers with different lengths to form a second shape structure; two input ports of the second polarization beam splitter PBS2 are respectively and correspondingly connected with one output port of the beam splitting module and the input port of the polarizer POL; the output port of the polarizer POL is connected to one input port of the first beam splitter BS 1.
Preferably, the post-processing algorithm is a Toeplitz matrix algorithm based on a fast fourier transform: constructing a Toeplitz matrix, and multiplying the Toeplitz matrix with the original random sequence to obtain the extracted quantum random number.
Preferably, the first phase modulator PM1 is located at one output port of the second beam splitter BS 2.
Preferably, the first phase modulator PM1 is located on the long arm of the unequal arm interferometer.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a quantum key distribution transmitting end of an integrated quantum random number generator, which integrates a random number signal acquisition processing module and a QKD main control module through multiplexing a laser and an interferometer, so that the quantum random number and the quantum key can be distributed simultaneously, and the complexity and the cost of a system are reduced. In addition, the photoelectric detector can be used for realizing high-speed quantum random number generation, and the requirements of quantum key distribution decoy state modulation and quantum state coding can be met.
Drawings
FIG. 1 is a schematic block diagram of a quantum key distribution transmitter of an integrated quantum random number generator of the present invention;
FIG. 2 is a schematic diagram of the evolution of a first component in a quantum key distribution transmitter of an integrated quantum random number generator of the present invention;
FIG. 3 is a schematic diagram of the evolution of a second component in a quantum key distribution transmitter of an integrated quantum random number generator of the present invention;
FIG. 4 is a schematic block diagram of a first embodiment of a quantum key distribution transmitter of an integrated quantum random number generator of the present invention;
FIG. 5 is a schematic block diagram of a second embodiment of a quantum key distribution transmitter of the integrated quantum random number generator of the present invention;
fig. 6 is a schematic block diagram of a third embodiment of a quantum key distribution transmitter of the integrated quantum random number generator of the present invention.
Detailed Description
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown.
As shown in fig. 1, a quantum key distribution transmitting end of an integrated quantum random number generator comprises a laser LD, a beam splitting module, a light intensity modulation module, an unequal arm interferometer formed by a first beam splitter BS1 and a second beam splitter BS2, a first phase modulator PM1, an adjustable optical attenuator VOA, a photoelectric detector and a main control module;
the laser LD is used for generating optical pulses with random phases with period T;
the beam splitting module is used for splitting the light pulse into a first component and a second component;
the light intensity modulation module is used for modulating the first component into a signal state or a decoy state and enabling the period of the first component to be changed into 2T;
the long and short arm delay difference of the unequal arm interferometer is T, and the long and short arm delay difference is used for enabling a first component incident from one input port of the first beam splitter BS1 to generate two time modes which are emergent from one output port of the second beam splitter BS2 and have a time interval of T; and for causing the front and rear pulses of the second component incident from the other output port of the second beam splitter BS2 to interfere, producing a random light intensity signal exiting from the other input port of the first beam splitter BS 1;
the first phase modulator PM1 is used to modulate the phase difference between the two time patterns in the first component to achieve phase encoding;
the variable optical attenuator VOA is used for attenuating the first component subjected to phase encoding to a single photon magnitude to generate a quantum state;
the photoelectric detector is used for converting the random light intensity signal into a random electric signal;
the main control module is used for triggering the laser LD; the method comprises the steps of generating an initial random bit, and obtaining a quantum random number through a post-processing algorithm; and is used for providing the drive voltage for the light intensity modulation module and the first phase modulator PM1 according to the generated quantum random number.
The post-processing algorithm is a Toeplitz matrix algorithm based on fast Fourier transform: constructing a Toeplitz matrix, and multiplying the Toeplitz matrix with the original random sequence to obtain the extracted quantum random number.
First phase modulator PM1 is located at one output port of second beam splitter BS 2.
The specific working principle is as follows:
the main control module triggers the laser LD to generate light pulses with a period of T and random phases, and the light pulses are split into a first component and a second component by the beam splitting module.
As shown in fig. 2, the first component is modulated into a signal state or a decoy state by the light intensity modulation module and the period thereof is changed to 2T, that is, the light intensity modulation module performs intensity modulation on each pulse of the first component, randomly modulates the pulse intensity with the sequence number of odd (or even) into the light intensity required by the signal state or the light intensity required by the decoy state, and modulates the pulse intensity with the sequence number of even (or odd) into 0, so that the pulse period of the output first component is changed to 2T and each pulse is modulated into the signal state or the decoy state.
The first component is then incident from one input port of the first beam splitter BS1 to the unequal arm interferometer, each pulse of which is split into two pulses propagating along the longer arm of the unequal arm interferometer, and two sub-pulses with a time interval T are finally emitted from one output port of the second beam splitter BS2 as the previous time patternAnd the latter time modeThe method comprises the steps of carrying out a first treatment on the surface of the Wherein the latter time mode modulates the phase phi through the first phase modulator PM1, and the coded quantum state is obtained after the phase phi is attenuated to the single photon magnitude through the adjustable optical attenuator VOA
As shown in fig. 3, the second component is incident on the unequal arm interferometer from the other output port of the second beam splitter BS2, wherein the former pulse passes through the long arm of the unequal arm interferometer in the opposite direction, and the latter pulse passes through the short arm of the unequal arm interferometer and reaches the first beam splitter BS1 at the same time to interfere, and since the phase of each optical pulse generated by the laser LD is random, the interference generates a random light intensity signal, and exits from the other input port of the first beam splitter BS 1.
The pulsed laser LD generates an optical pulse signal with a random phase and a horizontal polarization state, the electric field of which can be written as
Wherein, the liquid crystal display device comprises a liquid crystal display device,the amplitude, frequency and phase of the optical pulse signal are respectively.
The random electric signal generated after the direct current component is detected and filtered by the photoelectric detector is
Wherein, the liquid crystal display device comprises a liquid crystal display device,for the detection efficiency of the photodetector, +.>Is the phase difference between the different optical pulse signals.
The random electric signal is converted into a digital signal through an analog-to-digital conversion module, namely, the original random bit is obtained, then the randomness of the random original random bit is extracted according to a post-processing algorithm such as toeplitz matrix multiplication and the like, and finally, the quantum random number with true randomness is output.
The generated quantum random numbers are converted into corresponding driving voltages for the intensity modulator IM to perform signal state or decoy state random modulation, and the first phase modulator PM1 to perform random phase modulation.
As shown in fig. 4, embodiment one:
the beam splitting module is a third beam splitter BS3, the light intensity modulation module is an intensity modulator IM, and the first phase modulator PM1 is located at an output port of the second beam splitter BS 2.
An embodiment of the method comprises the following specific working procedures:
the main control module triggers the laser LD to generate light pulses with a period of T and random phases, and the light pulses are split into a first component and a second component through the third beam splitter BS3.
The first component modulates the light intensity by an intensity modulator IM, intensity-modulates each pulse thereof, randomly modulates the pulse intensity of odd number (or even number) to the light intensity required for the signal state or the light intensity required for the decoy state, and modulates the pulse intensity of even number (or odd number) to 0, so that the pulse period of the output first component becomes 2T, and each pulse is modulated to the signal state or the decoy state.
The first component is then incident from one input port of the first beam splitter BS1 to the unequal arm interferometer, each pulse of which is split into two pulses propagating along the longer arm of the unequal arm interferometer, and two sub-pulses with a time interval T are finally emitted from one output port of the second beam splitter BS2 as the previous time patternAnd the latter time modeThe method comprises the steps of carrying out a first treatment on the surface of the Wherein the latter time mode modulates the phase phi through the first phase modulator PM1, and the coded quantum state is obtained after the phase phi is attenuated to the single photon magnitude through the adjustable optical attenuator VOA
The second component is incident on the unequal arm interferometer from the other output port of the second beam splitter BS2, wherein the former pulse passes through the long arm of the unequal arm interferometer in the opposite direction, and the latter pulse passes through the short arm of the unequal arm interferometer and reaches the first beam splitter BS1 at the same time to interfere, and since the phase of each optical pulse generated by the laser LD is random, the interference generates a random light intensity signal, and the random light intensity signal exits from the other input port of the first beam splitter BS 1.
The pulsed laser LD generates an optical pulse signal with a random phase and a horizontal polarization state, the electric field of which can be written as
Wherein, the liquid crystal display device comprises a liquid crystal display device,the amplitude, frequency and phase of the optical pulse signal are respectively.
The random electric signal generated after the direct current component is detected and filtered by the photoelectric detector is
Wherein, the liquid crystal display device comprises a liquid crystal display device,for the detection efficiency of the photodetector, +.>Is the phase difference between the different optical pulse signals.
The random electric signal is converted into a digital signal through an analog-to-digital conversion module, namely, the original random bit is obtained, then the randomness of the random original random bit is extracted according to a post-processing algorithm such as toeplitz matrix multiplication and the like, and finally, the quantum random number with true randomness is output.
The generated quantum random numbers are converted into corresponding driving voltages for the intensity modulator IM to perform signal state or decoy state random modulation, and the first phase modulator PM1 to perform random phase modulation.
As shown in fig. 5, embodiment two:
the beam splitting module is a first polarization beam splitter PBS1, and the angle between the slow axis of the polarization maintaining fiber of the input port of the first polarization beam splitter PBS1 and the horizontal polarization direction is 45 degrees.
The light intensity modulation module comprises a circulator CIR, a fourth beam splitter BS4 and a second phase modulator PM2, wherein two output ports of the fourth beam splitter BS4 are respectively connected with two ends of the second phase modulator PM2 through polarization maintaining fibers with different lengths to form a first annular structure; the first port and the second port of the circulator CIR are respectively and correspondingly connected with one output port of the beam splitting module, one input port of the fourth beam splitter BS4 and one input port of the first beam splitter BS 1.
First phase modulator PM1 is located at one output port of second beam splitter BS 2.
The second specific working process of the embodiment comprises the following steps:
the main control module triggers the laser LD to generate light pulses with random phases and a period of T, the light pulses enter the first polarization beam splitter PBS1, and the light pulses are rotated to 45 degrees of polarization and split into a first component and a second component by the polarization due to the fact that the included angle between the slow axis of the polarization-preserving fiber of the input port and the horizontal polarization direction is 45 degrees.
The first component is transmitted from the first polarizing beam splitter PBS1, being horizontally polarized, enters the input port of the fourth beam splitter BS4 via the circulator CIR and is then split into two components of equal amplitude and polarization, propagating in the first ring structure clockwise and counter-clockwise, respectively. Since the polarization maintaining fibers at both ends of the second phase modulator PM2 have different lengths, the two components pass through the second phase modulator PM2 at different times, and the two components can be modulated with different phases by the second phase modulator PM 2. Since both experience the same optical path in the first ring structure, except for the different phases modulated by the second phase modulator PM2, the difference between the different phases modulated by the second phase modulator PM2 is the phase difference θ of the two when they simultaneously return to the two output ports of the fourth beam splitter BS4 for interference. Adjusting the different phase differences θ may output a signal state, a spoof state, or 0, respectively, from the fourth beam splitter BS 4. Thus, intensity modulation is performed on each pulse of the first component, the pulse intensity of the odd number (or even number) is randomly modulated to the light intensity required for the signal state or the light intensity required for the spoof state, and the pulse intensity of the even number (or odd number) is modulated to 0, so that the pulse period of the output first component becomes 2T, and each pulse is modulated to the signal state or the spoof state.
The first component is then incident from one input port of the first beam splitter BS1 via the circulator CIR to the unequal arm interferometer, each pulse of which is split into two pulses propagating along the longer arm of the unequal arm interferometer, and two sub-pulses with a time interval T are finally emitted from one output port of the second beam splitter BS2 as the previous time pattern, respectivelyAnd the latter time mode->The method comprises the steps of carrying out a first treatment on the surface of the Wherein the latter time mode modulates the phase phi through the first phase modulator PM1, and the coded quantum state is obtained after the phase phi is attenuated to the single photon magnitude through the adjustable optical attenuator VOA
The second component is reflected from the first polarization beam splitter PBS1, is vertically polarized, and is incident to the unequal arm interferometer from the other output port of the second beam splitter BS2, wherein the former pulse reversely passes through the long arm of the unequal arm interferometer, and the latter pulse passes through the short arm of the unequal arm interferometer and then simultaneously reaches the first beam splitter BS1 to interfere, and since the phase of each optical pulse generated by the laser LD is random, the interference generates a random light intensity signal, and the random light intensity signal exits from the other input port of the first beam splitter BS 1.
The pulsed laser LD generates an optical pulse signal with a random phase and a horizontal polarization state, the electric field of which can be written as
Wherein, the liquid crystal display device comprises a liquid crystal display device,the amplitude, frequency and phase of the optical pulse signal are respectively.
The random electric signal generated after the direct current component is detected and filtered by the photoelectric detector is
Wherein, the liquid crystal display device comprises a liquid crystal display device,for the detection efficiency of the photodetector, +.>Is the phase difference between the different optical pulse signals.
The random electric signal is converted into a digital signal through an analog-to-digital conversion module, namely, the original random bit is obtained, then the randomness of the random original random bit is extracted according to a post-processing algorithm such as toeplitz matrix multiplication and the like, and finally, the quantum random number with true randomness is output.
The generated quantum random numbers are converted into corresponding driving voltages for the light intensity modulation module to perform signal state or decoy state random modulation, and the first phase modulator PM1 performs random phase modulation.
As shown in fig. 6, embodiment three:
the beam splitting module is a first polarization beam splitter PBS1, and the angle between the slow axis of the polarization maintaining fiber of the input port of the first polarization beam splitter PBS1 and the horizontal polarization direction is 45 degrees.
The light intensity modulation module comprises a second polarization beam splitter PBS2, a third phase modulator PM3 and a polarizer POL, wherein the slow axes of polarization-preserving optical fibers of two input ports of the second polarization beam splitter PBS2 are both 45 degrees with the horizontal polarization direction; two output ports of the second polarization beam splitter PBS2 are respectively connected with two ends of the third phase modulator PM3 through polarization maintaining fibers with different lengths to form a second shape structure; two input ports of the second polarization beam splitter PBS2 are respectively and correspondingly connected with one output port of the beam splitting module and the input port of the polarizer POL; the output port of the polarizer POL is in phase with one input port of the first beam splitter BS 1.
The first phase modulator PM1 is located on the long arm of the unequal arm interferometer.
The third specific working procedure of the embodiment comprises the following steps:
the main control module triggers the laser LD to generate light pulses with random phases and a period of T, the light pulses enter the first polarization beam splitter PBS1, and the light pulses are rotated to 45 degrees of polarization and split into a first component and a second component by the polarization due to the fact that the included angle between the slow axis of the polarization-preserving fiber of the input port and the horizontal polarization direction is 45 degrees.
The first component is transmitted from the first polarization beam splitter PBS1, is horizontally polarized, enters the input port of the second polarization beam splitter PBS2, is polarized and split into two mutually perpendicular components with equal amplitude after being rotated by 45 degrees, and propagates in the second annular structure clockwise and anticlockwise respectively. Since the polarization maintaining fibers at both ends of the third phase modulator PM3 have different lengths, the two components pass through the third phase modulator PM3 at different times, and the third phase modulator PM3 can modulate different phases. Since the two optical paths are the same in the second annular structure, except for the different phases modulated by the third phase modulator PM3, when the two optical paths return to the two output ports of the second polarization beam splitter PBS2 at the same time for polarization beam combination, the difference between the different phases modulated by the third phase modulator PM3 is the phase difference θ of the two optical paths. The two polarization beams are rotated 45 degrees after being combined, and the corresponding polarization states are
Then pass only the horizontal polarization state through the polarizer POL, and the corresponding normalized light intensity is that. I.e., adjusting the different phase differences θ, may output a signal state, a decoy state, or 0, respectively, from the polarizer POL. Thus, intensity modulation is performed on each pulse of the first component, the pulse intensity of the odd number (or even number) is randomly modulated to the light intensity required for the signal state or the light intensity required for the spoof state, and the pulse intensity of the even number (or odd number) is modulated to 0, so that the pulse period of the output first component becomes 2T, and each pulse is modulated to the signal state or the spoof state.
The first component is then incident from one input port of the first beam splitter BS1 to the unequal arm interferometer, each pulse of which is split into two pulses propagating along the longer arm of the unequal arm interferometer, and two sub-pulses with a time interval T are finally emitted from one output port of the second beam splitter BS2 as the previous time patternAnd the latter time modeThe method comprises the steps of carrying out a first treatment on the surface of the Wherein the latter time mode modulates the phase phi through the first phase modulator PM1, and the coded quantum state is obtained after the phase phi is attenuated to the single photon magnitude through the adjustable optical attenuator VOA
The second component is reflected from the first polarization beam splitter PBS1, is vertically polarized, and is incident to the unequal arm interferometer from the other output port of the second beam splitter BS2, wherein the former pulse reversely passes through the long arm of the unequal arm interferometer, and the latter pulse passes through the short arm of the unequal arm interferometer and then simultaneously reaches the first beam splitter BS1 to interfere, and since the phase of each optical pulse generated by the laser LD is random, the interference generates a random light intensity signal, and the random light intensity signal exits from the other input port of the first beam splitter BS 1.
The pulsed laser LD generates an optical pulse signal with a random phase and a horizontal polarization state, the electric field of which can be written as
Wherein, the liquid crystal display device comprises a liquid crystal display device,the amplitude, frequency and phase of the optical pulse signal are respectively.
The random electric signal generated after the direct current component is detected and filtered by the photoelectric detector is
Wherein, the liquid crystal display device comprises a liquid crystal display device,for the detection efficiency of the photodetector, +.>Is the phase difference between the different optical pulse signals.
The random electric signal is converted into a digital signal through an analog-to-digital conversion module, namely, the original random bit is obtained, then the randomness of the random original random bit is extracted according to a post-processing algorithm such as toeplitz matrix multiplication and the like, and finally, the quantum random number with true randomness is output.
The generated quantum random numbers are converted into corresponding driving voltages for the light intensity modulation module to perform signal state or decoy state random modulation, and the first phase modulator PM1 performs random phase modulation.
By integrating the embodiments of the invention, the invention provides a quantum key distribution transmitting end of an integrated quantum random number generator, and by multiplexing a laser and an interferometer and integrating a random number signal acquisition processing module with a QKD main control module, the simultaneous performance of quantum random number and quantum key distribution can be realized, and the complexity and cost of a system are reduced. In addition, the photoelectric detector can be used for realizing high-speed quantum random number generation, and the requirements of quantum key distribution decoy state modulation and quantum state coding can be met.
Claims (9)
1. The quantum key distribution transmitting end of the integrated quantum random number generator is characterized by comprising a laser LD, a beam splitting module, a light intensity modulation module, an unequal arm interferometer formed by a first beam splitter BS1 and a second beam splitter BS2, a first phase modulator PM1, an adjustable optical attenuator VOA, a photoelectric detector and a main control module;
the laser LD is used for generating optical pulses with random phases with period T;
the beam splitting module is used for splitting the light pulse into a first component and a second component;
the light intensity modulation module is used for modulating the first component into a signal state or a decoy state and enabling the period of the first component to be changed into 2T;
the long and short arm delay difference of the unequal arm interferometer is T, and the long and short arm delay difference is used for enabling a first component incident from one input port of the first beam splitter BS1 to generate two time modes which are emergent from one output port of the second beam splitter BS2 and have a time interval of T; and for causing the front and rear pulses of the second component incident from the other output port of the second beam splitter BS2 to interfere, producing a random light intensity signal exiting from the other input port of the first beam splitter BS 1;
the first phase modulator PM1 is used to modulate the phase difference between the two time patterns in the first component to achieve phase encoding;
the variable optical attenuator VOA is used for attenuating the first component subjected to phase encoding to a single photon magnitude to generate a quantum state;
the photoelectric detector is used for converting the random light intensity signal into a random electric signal;
the main control module is used for triggering the laser LD; the method comprises the steps of generating an initial random bit, and obtaining a quantum random number through a post-processing algorithm; and is used for providing the drive voltage for the light intensity modulation module and the first phase modulator PM1 according to the generated quantum random number.
2. The quantum key distribution transmitter of the integrated quantum random number generator of claim 1, wherein the beam splitting module is a third beam splitter BS3.
3. The quantum key distribution transmitting end of the integrated quantum random number generator according to claim 1, wherein the beam splitting module is a first polarization beam splitter PBS1, and an angle between a polarization maintaining optical fiber slow axis of an input port of the first polarization beam splitter PBS1 and a horizontal polarization direction is 45 °.
4. A quantum key distribution transmitter for an integrated quantum random number generator according to claim 1, 2 or 3, wherein the light intensity modulation module is an intensity modulator IM.
5. The quantum key distribution transmitting end of the integrated quantum random number generator according to claim 1, 2 or 3, wherein the light intensity modulation module comprises a circulator CIR, a fourth beam splitter BS4 and a second phase modulator PM2, and two output ports of the fourth beam splitter BS4 are respectively connected with two ends of the second phase modulator PM2 through polarization maintaining optical fibers with different lengths to form a first annular structure; the first port, the second port and the third port of the circulator CIR are respectively and correspondingly connected with one output port of the beam splitting module, one input port of the fourth beam splitter BS4 and one input port of the first beam splitter BS 1.
6. The quantum key distribution transmitting end of the integrated quantum random number generator according to claim 1, 2 or 3, wherein the light intensity modulation module comprises a second polarization beam splitter PBS2, a third phase modulator PM3 and a polarizer POL, and the slow axes of polarization-preserving fibers of two input ports of the second polarization beam splitter PBS2 are both inclined at 45 degrees with respect to the horizontal polarization direction; two output ports of the second polarization beam splitter PBS2 are respectively connected with two ends of the third phase modulator PM3 through polarization maintaining fibers with different lengths to form a second annular structure; two input ports of the second polarization beam splitter PBS2 are respectively and correspondingly connected with one output port of the beam splitting module and the input port of the polarizer POL; the output port of the polarizer POL is connected to one input port of the first beam splitter BS 1.
7. The quantum key distribution transmitting end of the integrated quantum random number generator according to claim 1, wherein the post-processing algorithm is a Toeplitz matrix algorithm based on fast fourier transform: and forming a Toeplitz matrix, and multiplying the Toeplitz matrix with the original random sequence to obtain the extracted quantum random number.
8. The quantum key distribution transmitter of the integrated quantum random number generator of claim 1, wherein the first phase modulator PM1 is located at an output port of the second beam splitter BS 2.
9. The quantum key distribution transmitter of the integrated quantum random number generator of claim 1, wherein the first phase modulator PM1 is located on a long arm of the unequal arm interferometer.
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| CN210839600U (en) * | 2019-12-06 | 2020-06-23 | 北京中创为南京量子通信技术有限公司 | Quantum key distribution device and system |
| CN114900245A (en) * | 2022-07-13 | 2022-08-12 | 北京中科国光量子科技有限公司 | Polarization-independent phase decoding integrated chip and quantum key distribution system |
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| CN210839600U (en) * | 2019-12-06 | 2020-06-23 | 北京中创为南京量子通信技术有限公司 | Quantum key distribution device and system |
| CN114900245A (en) * | 2022-07-13 | 2022-08-12 | 北京中科国光量子科技有限公司 | Polarization-independent phase decoding integrated chip and quantum key distribution system |
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