CN114465717A - Quantum key distribution system and method capable of controlling pulse delay - Google Patents
Quantum key distribution system and method capable of controlling pulse delay Download PDFInfo
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Abstract
The invention discloses a quantum key distribution system with controllable pulse delay and a method thereof, comprising n sending party ALICE and n receiving party BOB, wherein the sending party ALICE is connected with a first DWDM, the receiving party BOB is connected with a second DWDM, and a quantum channel and a classical channel in each sending party ALICE and receiving party BOB are coupled to an optical fiber for transmission through the DWDM; in the sender, a pulse laser, a phase modulator, an intensity modulator and a receiver are sequentially connected through optical fibers and are used for transmitting quantum signals; in the receiving party, the circulator, the 2x2 coupler and the pulse delay unit are sequentially connected through the optical fiber, so that accurate pulse delay is realized. The system adopts a Sagnac ring network structure, has better stability, can compensate phase jitter brought by a light path, ensures that two pulses successfully generate stable interference of a coupler after passing through the same light path, greatly reduces the requirement of the whole system on the number of signals, and improves the finished code rate of the system.
Description
Technical Field
The invention belongs to the technical field of quantum information and optical communication, and particularly relates to a quantum key distribution system capable of controlling pulse delay and a method thereof.
Background
Since the Quantum Key Distribution (QKD) technology was proposed in 1984, the technology becomes the basis of Quantum secret communication and is widely applied to the technical field of Quantum communication because of the characteristic that the Quantum Key Distribution (QKD) technology can generate theoretically unconditional security keys. The quantum communication technology is an important means for guaranteeing information security in the future and is an industry which is mainly supported and developed by the nation. The construction period of fourteen five is provided, the innovative application of key digital technology is enhanced, the advanced technologies such as quantum communication and quantum computation are quickened, a complete all-in-one-heaven wide-area quantum communication network technology system is constructed in China, and the quantum communication technology is promoted to be widely applied in the fields of finance, government affairs, energy and the like.
In the technical field of optical communication, it is often necessary to delay each optical pulse in a pulse sequence by a different period T to ensure that two different optical pulses reach a coupler to interfere with each other. Particularly, in a commonly used mach-zehnder interferometer, when a pulse is divided into two pulses by a first beam splitter and then reaches a second beam splitter through different optical paths, it is difficult to ensure that the two optical pulses reach the second beam splitter through different optical paths to realize stable interference. At this time, a pulse delay unit can be connected into the Sagnac loop, two light pulses respectively pass through the same optical path clockwise and anticlockwise, and one light pulse is subjected to proper period delay, so that the two light pulses simultaneously reach the coupler to realize stable interference.
The prior art patents are as follows: (CN101866091B) proposes a one-way periodic programmable optical pulse delayer and an electrical pulse delayer. The time delay of different periods is realized by designing the optical pulse delayers with different optical fiber lengths. The phase of the pulse is changed by adjusting the voltage value, and the integral multiple of period delay is realized. However, such a delay device can only realize unidirectional transmission of optical pulses, does not consider bidirectional transmission of optical pulses, is greatly limited in practical application, and cannot be applied to a large-scale network.
The prior art patents are as follows: (CN108123803A) provides a quantum key distribution system and method. The method can reduce the requirement of the whole system on the number of signals, improve the coding rate of the system, and improve the transmission distance of the quantum key and the key generation rate. However, when different pulses in the same pulse sequence at the BOB end reach the second beam splitter through different optical paths to interfere with each other, factors such as different channel noise and link loss are not considered, and the actual time for the two pulses to reach the second beam splitter is not always the same, so that the two pulses cannot interfere with each other, the pulse resources are wasted, and the final result is that the resultant code rate is reduced.
Disclosure of Invention
The invention aims to provide a quantum key distribution system and a method capable of controlling pulse delay, wherein a new pulse delay technology is applied, and a pulse delay unit in the technology adopts a Sagnac ring network structure to ensure that optical pulses needing to be delayed and optical pulses not needing to be delayed are output to a coupler through the same optical path to generate interference; in quantum key distribution, only a small amount of pulses are used to generate the required original key, so that the requirement of the whole system on the number of signals is reduced to a greater extent, and the code rate of the system is improved.
The calculation scheme adopted for realizing the purpose of the invention is as follows: a quantum key distribution system capable of controlling pulse delay comprises n sending ends and n receiving ends, wherein n is an integer larger than 2;
the n sending terminals are respectively a first sending terminal ALICE1, a second sending terminal ALICE2, … … and an nth sending terminal ALICEn; the n receiving ends are respectively a first receiving end BOB1, a second receiving end BOB2, a second receiving end … … and an nth receiving end BOBn;
the first sending end ALICE1, the second sending end ALICE2, … … and the nth sending end ALICEn are respectively connected with the first DWDM; the first receiving terminal BOB1, the second receiving terminals BOB2, … … and the nth receiving terminal BOBn are respectively connected with the second DWDM;
the first DWDM and the second DWDM are connected with each other through an optical fiber and used for optical pulse signal transmission;
quantum channels for transmitting quantum signals and classical channels for transmitting classical signals are arranged between the n transmitting ends and the n receiving ends;
in the first sending end ALICE1, comprising: the system comprises a pulse laser, a first phase modulator, an intensity modulator, a first quantum random number generator, a second quantum random number generator, a first quantum key manager and a first classical signal transceiving end; the pulse laser is connected with a first input end of a first phase modulator, and an output end of the first phase modulator is connected with a first input end of an intensity modulator; the first quantum random number generator is respectively connected with the second input end of the first phase modulator and the first input end of the first quantum key manager, the second quantum random number generator is respectively connected with the second input end of the intensity modulator, the second input end of the first quantum key manager and the first input end of the first classical signal receiving and transmitting end, and the second output end of the first classical signal receiving and transmitting end is mutually connected with the third input end of the first quantum key manager;
in the first receiving end BOB1, the method includes: the device comprises a circulator, a first 2x2 coupler, a pulse delay unit, a third quantum random number generator, a first detector, a second quantum key manager and a second classical signal transceiving end; the circulator comprises a first port, a second port and a third port, the first port is connected with the intensity modulator through quantum channels through wavelength division multiplexing, the second port is connected with the first 2x2 coupler, and the third port is connected with the second detector; the pulse delay unit is respectively connected with two output ends of the first 2x2 coupler and the third quantum random number generator to form a Sagnac loop, and the first 2x2 coupler is also connected with the first detector; the output end of the first detector and the output end of the second detector are respectively connected with a second quantum key manager, and the second quantum key manager is connected with a second classical signal transceiving end;
the output end of the intensity modulator is connected with the first port of the circulator through a quantum channel by wavelength division multiplexing;
the first output end of the first classical signal transceiving end is connected with the second classical signal transceiving end through classical channel by wavelength division multiplexing;
the structures and the connections of the second sending end ALICE2, … … and the nth sending end ALICEn are consistent with the first sending end ALICE 1; the structures and connections of the second receiving terminals BOB2, … … and the nth receiving terminal BOB are consistent with the first receiving terminal BOB 1.
Preferably, in the Sagnac loop, two output terminals of the four ports of the first 2 × 2 coupler are respectively connected to two ends of the pulse delay unit to form a loop, the third quantum random number generator is connected to a third end of the pulse delay unit, and the delay period of the pulse delay unit is controlled by the third quantum random number generator.
Preferably, the pulse delay unit performs periodic delay control on the arriving optical pulse; the pulse delay unit comprises a second phase modulator, a second 2x2 coupler, a 2x1 coupler and an optical switch; four ports of the second 2x2 coupler, wherein two output ends are respectively connected to two ends of the second phase modulator to form a loop, and the other two ports are respectively connected with the optical switch and one input end of the 2x1 coupler; the other input end of the 2x1 coupler is connected with one output end of the first 2x2 coupler; the optical switch is a 2-to-1 optical switch, and two selection ports of the 2-to-1 optical switch are respectively connected with the output end of the 2x1 coupler and the other output end of the first 2x2 coupler; the port of the second 2x2 coupler connected to the optical switch can be selectively connected to the output terminal of the 2x1 coupler or to the other output terminal of the first 2x2 coupler by the 2-in-1 operation of the optical switch, and the input and output of the optical pulse are controlled by the switching selection of the two selected ports of the optical switch.
Preferably, the third quantum random number generator is connected to the second phase modulator, and the input of the voltage of the second phase modulator is adjusted through the random binary number generated by the third quantum random number generator, so as to change the phase of the optical pulse sequence passing through the second phase modulator, and control the time delay of the optical pulse.
Preferably, the first 2x2 coupler comprises a first input terminal, a second input terminal, a first output terminal and a second output terminal, the first input terminal of the first 2x2 coupler is connected with the second port of the circulator and is used for receiving the optical pulse signal; the first 2x2 coupler is coupled at a 50: the input optical pulse signal is divided into two paths according to the proportion of 50, and the two paths are respectively input into the clockwise optical fiber link and the counterclockwise optical fiber link through the first output end and the second output end; the optical pulse signals in the optical fiber links in the clockwise direction or the anticlockwise direction are respectively connected to the pulse delay units and then return to the first 2x2 coupler again, and interference occurs at the first 2x2 coupler; the second input of the first 2x2 coupler is connected to the first detector, which measures the interference occurring at the first 2x2 coupler through the second input of the first 2x2 coupler.
Preferably, the first detector and the second detector are single photon detectors, and one of the two detectors is set to code 1 when detecting a photon, and the other is set to code 0 when detecting a photon.
Preferably, the n sending ends transmit quantum signals and classical signals to a receiving end in a long distance by multiplexing to one optical fiber through a first DWDM, and the n receiving ends receive the signals through a second DWDM and demultiplex the signals to the corresponding receiving ends.
The other scheme adopted for achieving the aim of the invention is as follows: a quantum key distribution method according to the above quantum key distribution system, comprising the steps of:
a, preparing M quantum states consisting of L pulses by a pulse laser at a sending end, preparing a random binary number for each pulse of each quantum state by a first quantum random number generator, and sending the random binary number to a first phase modulator to perform phase modulation on the pulses, wherein M and L are both natural numbers;
b, the intensity modulator adjusts the signal state and the decoy state of each quantum state after phase modulation according to the random binary number generated by the second quantum random number generator;
step C1, the first quantum random number generator and the second quantum random number generator send the random binary numbers generated by the first quantum random number generator to the first quantum key manager for recording and storing;
step C2, the second quantum random number generator also sends the generated random binary number to the first classical signal receiving and transmitting end, and sends the random binary number to the second classical signal receiving and transmitting end and the second quantum key manager of the receiving end through the classical channel via the first classical signal receiving and transmitting end;
d1, the sending end sends the encoded signal state and the decoy state to the receiving end through the quantum channel;
d2, the receiving end receives the signal state and the decoy state and sends the signal state and the decoy state into a Sagnac loop through a circulator, and a third quantum random number generator generates a random binary number and sends the random binary number to a second phase modulator to carry out periodic time delay on a pulse sequence which enters a pulse time delay unit clockwise or anticlockwise;
step D3, returning the pulse sequence transmitted clockwise and anticlockwise in the Sagnac loop to the first 2x2 coupler again for interference, and measuring interference results by the first 2x2 coupler and the circulator respectively through the interference of the first detector and the second detector;
step D4, the second quantum key manager receives and records the measurement result, and the position (x, y) of the pulse in the pulse sequence when the first detector and the second detector respond, and sends the result to the second classical signal transceiver, and then the second classical signal transceiver sends the result to the sending terminal through the classical channel;
step D5, the first classical signal transceiver end of the sending end receives the measuring result and the position (x, y) information and sends the measuring result and the position (x, y) information to the first quantum key manager;
and E, communication double-sending, namely comparing and evaluating a channel parameter and an original key by a first quantum key manager at a sending end and a second quantum key manager at a receiving end according to the decoy state information, and if the error rate of the channel parameter is less than a threshold value, carrying out security enhancement and error correction on the obtained original quantum key by the first quantum key manager and the second quantum key manager to obtain a final quantum key.
Preferably, the optical pulse train input from the circulator enters the first 2x2 coupler through the output port of the circulator, and the optical pulse train is split into two beams from the first 2x2 coupler, which are the first optical pulse train component and the second optical pulse train component respectively; when the first optical pulse sequence component reaches the second phase modulator, if the random binary number generated by the third quantum random number generator is 1, the pulse of the first optical pulse sequence component is delayed, and if the random binary number generated by the third quantum random number generator is 0, the pulse of the first optical pulse sequence component is not delayed; when the second optical pulse sequence component reaches the phase modulator, if the random binary number generated by the third quantum random number generator is 0, the second optical pulse sequence component is not delayed and is not operated, and if the random binary number generated by the third quantum random number generator is 1, the pulse of the second optical pulse sequence component is delayed; the second optical pulse sequence component is not delayed and directly passes through the phase modulator and returns to the first 2x2 coupler; the two light pulse components interfere after arriving at the first 2x2 coupler again.
Preferably, in step E, if the error rate of the channel parameter is greater than the threshold, the process returns to step a to start over.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention adopts a network structure based on the Sagnac ring, has better stability, can compensate phase jitter brought by a light path, and ensures that two pulses simultaneously reach a coupler to generate stable interference after passing through the same light path. In a quantum key distribution protocol in the prior art, two beams of pulses reach a coupler to interfere through a Sagnac ring at the same time by carrying out precise periodic delay on the pulses to be interfered; the invention can generate the needed original key only by using a small amount of pulse number, thereby greatly reducing the requirement of the whole system on the pulse number and further improving the code rate of the system.
(2) The pulse delay unit is a reversible unit device, allows pulses to pass through in two directions, and can be applied to a Sagnac loop. And is widely applied to large-scale networks in practical application.
(3) The method meets the wavelength division multiplexing, can be accessed to a plurality of transmitting ends and a plurality of receiving ends, and maximally supports the requirement of multiple users.
Drawings
Fig. 1 is a block diagram of the overall structure of a quantum key distribution system of the present invention;
FIG. 2 is a block diagram of a transmitting end of the quantum key distribution system of the present invention;
FIG. 3 is a block diagram of a receiving end structure of the quantum key distribution system of the present invention;
FIG. 4 is a block diagram of a specific structure of the quantum key distribution system of the present invention;
FIG. 5 is a diagram of a pulse delay unit of the quantum key distribution system of the present invention;
FIG. 6 is a flow chart illustrating a quantum key distribution method according to the present invention;
Detailed Description
The technical solutions in the embodiments of the present invention will be described in detail and clearly with reference to the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.
As shown in fig. 1, the quantum key distribution system capable of controlling pulse delay of this embodiment includes n transmitting ends and n receiving ends, where n is an integer greater than 2; the n sending terminals are respectively a first sending terminal ALICE1, a second sending terminal ALICE2, a third sending terminal ALICE3 … … and an nth sending terminal ALICEn; the n receiving terminals are respectively a first receiving terminal BOB1, a second receiving terminal BOB2, a third receiving terminal BOB3, … … and an nth receiving terminal BOBn.
The first sending end ALICE1, the second sending end ALICE2, … … and the nth sending end ALICEn are respectively connected with the first DWDM; the first receiving terminal BOB1, the second receiving terminals BOB2, … … and the nth receiving terminal BOBn are respectively connected with the second DWDM; the first DWDM and the second DWDM are connected with each other through an optical fiber and used for optical pulse signal transmission; and a quantum channel 03 for transmitting quantum signals and a classical channel 04 for transmitting classical signals are arranged between the n transmitting ends and the n receiving ends.
The structures and the connections of the second sending end ALICE2, … … and the nth sending end ALICEn are consistent with the first sending end ALICE 1; the structures and connections of the second receiving terminals BOB2, … … and the nth receiving terminal BOB are consistent with the first receiving terminal BOB 1. The n sending ends transmit quantum signals and classical signals to a receiving end in a long distance through first DWDM multiplexing to an optical fiber, and the n receiving ends receive the signals through second DWDM and demultiplex the signals to the corresponding receiving ends.
As shown in fig. 2 and fig. 4, taking the structure of first sender ALICE1 of sender 01 as an example:
in the first sending end ALICE1, comprising: a pulse laser 11, a first phase modulator 12, an intensity modulator 13, a first quantum random number generator 14, a second quantum random number generator 15, a first quantum key manager 16, and a first classical signal transceiving terminal 17.
The pulsed laser 11 is connected to a first input of a first phase modulator 12, and the output of the first phase modulator 12 is connected to a first input of an intensity modulator 13.
The first quantum random number generator 14 is connected to the second input terminal of the first phase modulator 12 and the first input terminal of the first quantum key manager 16, respectively, the second quantum random number generator 15 is connected to the second input terminal of the intensity modulator 13, the second input terminal of the first quantum key manager 16 and the first input terminal of the first classical signal transceiver 17, respectively, and the second output terminal of the first classical signal transceiver 17 is connected to the third input terminal of the first quantum key manager 16.
As shown in fig. 3 and fig. 4, taking the structure of the first receiving end BOB1 of the receiving end 02 as an example:
in the first receiving end BOB1, the method includes: a circulator 21, a first 2x2 coupler 22, a pulse delay unit 23, a third quantum random number generator 24, a first detector (D1)25, a second detector (D2)26, a second quantum key manager 27, and a second classical signal transceiving terminal 28.
The circulator 21 includes a first port 1, a second port 2, and a third port 3, the first port 1 is connected to the intensity modulator 13 through quantum channels via wavelength division multiplexing, the second port 2 is connected to the first 2x2 coupler 22, and the third port 3 is connected to the second detector 26. The output of the intensity modulator 13 is connected to the first port 1 of the circulator 21 via wavelength division multiplexing via the quantum channel 03.
The pulse delay unit 23 is connected to two output ends of the first 2x2 coupler 22 and the third quantum random number generator 24 respectively to form a Sagnac loop.
As shown in fig. 3 and fig. 5, in the Sagnac loop, four ports of the first 2x2 coupler 22, two output ends of which are respectively connected to two ends of the pulse delay unit 23, that is, one end in the clockwise CW direction is < 11 >, and the other end in the counterclockwise CCW direction is < 22 >, form a loop, the third quantum random number generator 24 is connected to the third end of the pulse delay unit 23, and the delay period of the pulse delay unit 23 is controlled by the third quantum random number generator 24.
As shown in fig. 5, the pulse delay unit 23 has the following structure: the pulse delay unit 23 includes a second Phase Modulator (PM)44, a second 2x2 coupler 33, a 2x1 coupler, and an optical switch.
And four ports e, d, f and g of the second 2x2 coupler 33, wherein two output ports f and g are respectively connected to two ends of the second phase modulator 44 to form a loop, namely a clockwise loop CW and a counterclockwise loop CCW, and two other ports, wherein the port e is connected to the input port b of the 2x1 coupler, and the port d is connected to the port 122 of the 1-out-of-2 optical switch.
The other input terminal a of the 2x1 coupler is connected to an output terminal of the first 2x2 coupler 22; the two selection ports 121, 132 of the 1-out-of-2 optical switch are connected to the output c of the 2x1 coupler and the other output of the first 2x2 coupler 22, respectively. In use, the port 122 connected to the optical switch connected to the second 2x2 coupler may select the port 121 connected to the output c of the 2x1 coupler to conduct, by a 2-out-of-1 operation of the optical switch, or the port 132 connected to the other output of the first 2x2 coupler to conduct, by a switched selection of the two selected ports of the optical switch, to control the input and output of optical pulses.
The third quantum random number generator 24 is connected to the second phase modulator 44, and the input of the voltage of the second phase modulator 44 is adjusted by the random binary number generated by the third quantum random number generator 24, so as to change the phase of the optical pulse sequence passing through the second phase modulator, and control the time delay of the optical pulse.
The first 2x2 coupler 22 comprises a first input terminal, a second input terminal, a first output terminal and a second output terminal, the first input terminal of the first 2x2 coupler 22 is connected with the second port 2 of the circulator and is used for receiving the optical pulse signal; the first 2x2 coupler 22 is coupled at a 50: the ratio of 50 divides the input optical pulse signal into two paths respectively entering the clockwise CW optical fiber link and the counterclockwise CCW optical fiber link. The optical pulse signals in the optical fiber links in the clockwise direction or the counterclockwise direction are respectively connected to the pulse delay unit 23, and then return to the first 2x2 coupler 22 again, so that interference occurs at the first 2x2 coupler 22; a second input of the first 2x2 coupler 22 is connected to the first detector 25, and the first detector 25 measures the interference occurring at the first 2x2 coupler through the second input of the first 2x2 coupler. The second detector 26 then measures the interference occurring at the first 2x2 coupler through the circulator 21 and the first input of the first 2x2 coupler 22.
In the above system, the pulse laser 11 at the transmitting end generates M pulse trains at time intervals T and transmits the generated pulse trains to the first phase modulator 12. In which one pulse train is composed of L pulses, and thus one pulse train can be regarded as one quantum state.
The values of M and L may be chosen appropriately according to the number of keys that need to be prepared. In this embodiment, when the receiving end interferes two pulses in the same input pulse sequence, the two pulses input into the Sagnac loop can be successfully interfered by controlling the optical switch of the pulse delay unit and the input of the voltage, so that the number of the input pulses is greatly saved. And because each pulse sequence is used as a quantum state, different M can be set according to the number of keys required to be prepared in the actual preparation process, and the value of L can be set to be smaller.
In addition, the first quantum random number generator generates M random binary sequences. For example, a number of 0 or 1 is taken as a value, and the generated random binary numbers are sent to the first phase modulator, the first quantum key manager and the first classical signal transceiver, and the number of the random binary numbers generated by the first quantum random number generator is equal to the number M of the pulse sequences generated by the pulse laser.
The first phase modulator modulates each pulse in the pulse sequence generated by the pulsed laser in accordance with a random binary sequence generated by the first quantum random number generator.
For example, if the L (L ≦ L) random binary number in the M (M ≦ M) th random binary sequence generated by the first quantum random number generator is 1, the phase of the L pulse in the M-th pulse sequence generated by the pulse laser is modulated to be shifted by 0 with respect to the total phase of the pulse sequence (i.e., the phase of the L pulse is shifted by 0), and if the 1(1 ≦ L) random binary number in the M (M ≦ M) th random binary sequence generated by the first quantum random number generator is 0, the phase of the L pulse in the M-th signal state or decoy state generated by the pulse laser is modulated to be shifted by pi with respect to the total phase of the pulse sequence (i.e., the phase of the L pulse is shifted by pi), or vice versa. Alternatively, other modulation schemes are possible.
The first phase modulator sends the modulated pulse sequences to the intensity modulator, and the intensity modulator can modulate the intensity of each pulse sequence generated by the first phase modulator according to the random numbers generated by the second quantum random number generator, wherein one pulse sequence is in a signal state, and the other pulse sequences are in a decoy state. So that an attacker cannot distinguish the signal state from the decoy state to prevent the PNS attack. Wherein the total light intensity of the pulses in the signal state is greater than that in the decoy state.
The second quantum random number generator may generate M random numbers, and then the second quantum random number generator may transmit the generated random numbers to the intensity modulator and the first quantum key manager. Thus, the number of random numbers generated by the second quantum random number generator is equal to the number of pulse trains generated by the pulsed laser.
By this intensity modulation, the intensity modulation for each optical pulse train can be completed. And encoded into a signal state and a spoof state. PNS attacks can be prevented. Here, the sending side ALICE and the receiving side BOB may define the coding scheme in advance. For example, it is predetermined that a pulse having a phase shift of 0 is regarded as a code of 0, and a pulse having a phase shift of pi is regarded as a code of 1; and vice versa. Alternatively, other modulation schemes are possible.
The signal state or the spoofing state modulated by the intensity modulator is sent to the circulator. In a circulator, light can only be transmitted in the direction of the designated arrow.
The first port interface of the circulator sends the received signal state or the spoofing state to a first 2x2 coupler through a second port, the signal state or the spoofing state passing through the coupler is divided into two beams, the pulse passes through a pulse delay unit respectively in the clockwise direction or the anticlockwise direction, then, the two beams simultaneously reach the coupler again, interference occurs at the coupler, and finally, measurement is carried out through a first detector D1 and a second detector D2. Wherein, the pulse delay unit is used for: with proper cycle delay of the arriving pulses, the first 2x2 coupler splits and combines the arriving pulses for transmission.
The random binary number generated by the third quantum random number generator modulates the input (for example, half-wave voltage) of the voltage of the pulse delay unit PM, and modulates the phase of the optical pulse, so that the pulse is delayed. For example, when the random binary number generated by the third quantum random number generator is 0, the voltage of the pulse delay unit PM is not modulated, and the pulse is not delayed. When the random binary number generated by the third quantum random number generator is 1, the voltage of the pulse delay unit PM is modulated, and the pulse is delayed, or vice versa.
The specific delay transmission of the pulse sequence into the Sagnac loop through the circulator is as follows:
firstly, the method comprises the following steps: as shown in fig. four, the pulse train output by the first 2 × 2 coupler 22 in the first receiving terminal BOB1 is divided into two beams, which are transmitted along the clockwise and counterclockwise optical paths in the Sagnac loop, respectively. The pulse sequence is transmitted along a CW link in a clockwise direction in a Sagnac loop and enters a pulse delay unit.
At this time, as shown in fig. five, in the specific structure diagram of the pulse delay unit 23, the pulse sequence transmitted along the clockwise CW link enters the pulse delay unit from the < 11 > port, and is input through the a port and output through the c port of the 2x1 coupler. At this time, the optical switch switches on the links 121 to 122, the pulse train is transmitted to the second 2x2 coupler through the d port via the link connected to the optical switch, and one pulse train passing through the second 2x2 coupler 33 is divided into two identical optical pulse trains, namely an optical pulse train 1 and an optical pulse train 2. Where optical pulse train 1 is output by the f-port, the CW link in the clockwise direction is returned to the g-port of the second 2x2 coupler 33 through the phase modulator 44. The optical pulse train 2 is input from the g-port and the CCW link in the counterclockwise direction is returned to the f-port of the second 2x2 coupler 33 through the phase modulator 44.
When the optical pulse sequence 1 reaches the second phase modulator, if the random binary number generated by the third quantum random number generator is 1, the optical pulse sequence 1 is delayed, and when the optical pulse sequence 2 reaches the phase modulator, if the random binary number generated by the third quantum random number generator is 0, no operation is performed on the optical pulse sequence component 2, and the optical pulse sequence component 2 directly passes through the phase modulator and returns to the f port of the second 2x2 coupler 33. Since the optical pulse train 1 and the optical pulse train 2 travel the same path, there is no time difference between the optical pulse train 1 and the optical pulse train 2 in their own pulse laser transmissions. By delaying the pulse sequence, it can be realized that different pulses in the same pulse sequence interfere at the second 2 × 2 coupler. When the delayed optical pulse train 1 amount 1 and the undelayed optical pulse train 2 reach the second 2x2 coupler again, the phase difference between the pulse of the optical pulse train component 1 and the pulse of the optical pulse train component 2 after returning to the second 2x2 coupler for interference is pi, and at this time, the synthesized pulse after interference is output from the first port e. The delayed pulse arrives at the b port of the 2x1 coupler, is output from the c port of the 2x1 coupler, and again arrives at the d port of the second 2x2 coupler. And repeating the steps, and continuing to delay the pulse sequence when the third quantum random number generator generates the random binary number 1. When the third quantum random number generator generates a random binary number 0, the pulse sequence is not delayed any more. The third quantum random number generator does not modulate the input of the voltage of the phase modulator, the second phase modulator does not perform any operation on the optical pulses 1 and 2 passing clockwise and anticlockwise, after the optical pulse sequences 1 and 2 reach the second 2x2 coupler again and are combined through interference, the phase difference is 0, and the optical pulse sequences are output from a d port of the second 2x2 coupler. The optical switch turns on the 122-132 link, and the optical pulse output through the second port d is output from the < 22 > port through the link connected by the 122 and 132.
Secondly, the method comprises the following steps: as shown in fig. four, the pulse sequence output by the first 2x2 coupler 22 in the first receiving terminal BOB1 is divided into two beams, which are transmitted along clockwise and counterclockwise optical paths in the Sagnac loop, respectively. The pulse train travels in a CCW link in a counterclockwise direction in the Sagnac loop into the pulse delay unit.
At this time, as shown in fig. five, in the specific structure diagram of the pulse delay unit, the pulse train transmitted along the CCW link in the counterclockwise direction enters the pulse delay unit from the < 22 > port, the optical switch is turned on 132 and 122, the pulse train is transmitted to the second 2x2 coupler through the d port via the link communicated by the optical switch, and the pulse train is divided into two identical optical pulse trains, namely, optical pulse train 1 and optical pulse train 2, via the second 2x2 coupler 33. Where optical pulse train 1 is output by the f-port, the CW link in the clockwise direction is returned to the g-port of the second 2x2 coupler 33 through the phase modulator 44. The optical pulse train 2 is input from the g-port and the CCW link in the counterclockwise direction is returned to the f-port of the second 2x2 coupler 33 through the second phase modulator 44.
When the optical pulse sequence 1 reaches the second phase modulator, if the random binary number generated by the third quantum random number generator is 1, the optical pulse sequence 1 is delayed, and when the optical pulse sequence 2 reaches the second phase modulator, if the random binary number generated by the third quantum random number generator is 0, no operation is performed on the optical pulse sequence 2, and the optical pulse sequence 2 directly passes through the second phase modulator and returns to the f port of the second 2x2 coupler 33. Because the optical pulse train 1 and the optical pulse train 2 travel the same path, there is no time difference between the optical pulse train 1 and the optical pulse train 2 in their own pulse laser transmissions. By delaying the pulse sequence, it can be realized that different pulses in the same pulse sequence interfere at the 2 × 2 coupler. The phase difference between the pulse of the optical pulse train 1 and the pulse of the optical pulse train 2 after returning to the second 2 × 2 coupler and after the interference is pi, the pulse train synthesized after the interference at this time is output from the first port e. The delayed pulse train reaches the b port of the 2x1 coupler, and is output from the c port of the 2x1 coupler, the optical switch is adjusted, the 121-122 link is switched on, and the pulse train reaches the d port of the second 2x2 coupler again. And repeating the steps, and continuing to delay the pulse sequence when the third quantum random number generator generates the random binary number 1. When the third quantum random number generator generates a random binary number 0, the pulse sequence is not delayed any more. The third quantum random number generator does not modulate the input of the voltage of the phase modulator, the second phase modulator does not operate the optical pulse sequence components passing clockwise and anticlockwise, the optical pulse sequence components respectively reach the second 2x2 coupler again, after interference combination, the phase difference is 0, the optical pulse sequence is output from the d port of the second 2x2 coupler, and the pulse sequence is output from the port less than 11.
Therefore, the input of the voltage of the phase modulator is adjusted through the random binary number generated by the third quantum random number generator, the phase of one beam of clockwise or anticlockwise optical pulse sequence or two beams of anticlockwise and clockwise optical pulse sequences is changed, accurate pulse delay can be realized, the number of input pulses at a sending end is reduced, and the required original key can be generated only by using a small number of pulses. The requirement of the whole system for the number of pulses is greatly reduced, and the code rate of the system is further improved. The length of the optical fiber used by the pulse delay unit is reasonably selected according to requirements, and the delay of different periods t (the period of the pulse in the pulse sequence emitted by the pulse laser is t) of the pulse sequence is realized through the random binary number generated by the third quantum random number generator. The pulse delay unit is arranged in the Sagnac ring, bidirectional pulse delay can be realized according to needs, and two ports of the pulse delay unit can be used as an input port and an output port. The optical switch is flexibly adjusted to realize the input and output of the pulse.
In this embodiment, it may be preset such that when the phase difference between the pulses interfering in the coupler is 0, the first detector D1 responds, i.e. detects a photon, and the code corresponding to the successful detection event is 0. When the phase difference between the two pulses interfering at the coupler is pi, the second detector D2 responds, i.e., detects a photon, and the code for the successful detection event is 1. And vice versa.
When a photon is detected by the first detector D1 or the second detector D2 (i.e., a successful detection event), the measurement and the position (x, y) of the two pulses in the pulse sequence are recorded and sent to the quantum key manager 2.
The second quantum key manager may send the position (x, y) of the two pulses in the pulse sequence to the second classical signaling terminal, which sends the received position (x, y) to the first classical signaling terminal via classical channel 04. The first typical signal transceiving end sends the received position (x, y) to the first quantum key manager, and the random binary sequence generated by the second quantum random number generator is sent to the first quantum key manager.
And (3) data post-processing stage: the first classical signal transceiving end can also send the random binary number generated by the second quantum random number generator to the second classical signal transceiving end through a classical channel 04. And the second classical signal transceiving end sends the received random binary number generated by the second quantum random number generator to the second quantum key manager.
At this time, both the first quantum key manager and the second quantum key manager can obtain the random number sequence generated by the second quantum random number generator, measure the positions (x, y) of the two pulses corresponding to the measurement result, and obtain the original quantum key according to the measurement result. And then, the first quantum key manager and the second quantum key manager perform security enhancement and error correction on the obtained original quantum key to obtain a final quantum key.
The structures and the connections of the second sending terminal ALICE2, the third sending terminals ALICE3, … … and the nth sending terminal ALICEn are all consistent with the first sending terminal ALICE1, the n sending terminals are connected through the first DWDM, and the n sending terminals ALICE are multiplexed to one optical fiber through the first DWDM, so that distance selection transmission is realized, and optical fiber resources are effectively saved. And the quantum signal is positioned in a lower waveband, the classical signal is positioned in a higher waveband, and the interference of the classical signal to the quantum signal is reduced as much as possible. The structures and connections of the second receiving terminal BOB2, the third receiving terminals BOB3, … …, and the nth receiving terminal BOB are consistent with the first receiving terminal BOB 1. And the n receiving terminals are connected through a second DWDM and respectively demultiplex the signals to the corresponding receiving terminals.
In this embodiment, a quantum key distribution method according to the quantum key distribution system includes the following steps:
a, preparing M quantum states consisting of L pulses by a pulse laser at a sending end, preparing a random binary number for each pulse of each quantum state by a first quantum random number generator, and sending the random binary number to a first phase modulator to perform phase modulation on the pulses, wherein M and L are both natural numbers;
b, the intensity modulator adjusts the signal state and the decoy state of each quantum state after phase modulation according to the random binary number generated by the second quantum random number generator;
step C1, the first quantum random number generator and the second quantum random number generator send the random binary numbers generated by the first quantum random number generator to the first quantum key manager for recording and storing;
step C2, the second quantum random number generator also sends the generated random binary number to the first classical signal receiving and transmitting end, and sends the random binary number to the second classical signal receiving and transmitting end and the second quantum key manager of the receiving end through the classical channel via the first classical signal receiving and transmitting end;
d1, the sending end sends the encoded signal state and the decoy state to the receiving end through the quantum channel;
d2, the receiving end receives the signal state and the decoy state and sends the signal state and the decoy state into a Sagnac loop through a circulator, and a third quantum random number generator generates a random binary number and sends the random binary number to a second phase modulator to carry out periodic time delay on a pulse sequence which enters a pulse time delay unit clockwise or anticlockwise;
step D3, returning the pulse sequence transmitted clockwise and anticlockwise in the Sagnac loop to the first 2x2 coupler again for interference, and measuring interference results by the first 2x2 coupler and the circulator respectively through the interference of the first detector and the second detector;
step D4, the second quantum key manager receives and records the measurement result, and the position (x, y) of the pulse in the pulse sequence when the first detector and the second detector respond, and sends the result to the second classical signal transceiver, and then the second classical signal transceiver sends the result to the sending terminal through the classical channel;
step D5, the first classical signal transceiver end of the sending end receives the measuring result and the position (x, y) information and sends the measuring result and the position (x, y) information to the first quantum key manager;
and E, communication double-sending, namely comparing and evaluating a channel parameter and an original key by a first quantum key manager at a sending end and a second quantum key manager at a receiving end according to the decoy state information, and if the error rate of the channel parameter is less than a threshold value, carrying out security enhancement and error correction on the obtained original quantum key by the first quantum key manager and the second quantum key manager to obtain a final quantum key.
In step E, if the error rate of the channel parameter is larger than the threshold value, returning to the step A to restart.
The optical pulse sequence input from the circulator enters a first 2x2 coupler through an output port of the circulator, and the optical pulse sequence is divided into two beams from the first 2x2 coupler, wherein the two beams are a first optical pulse sequence component and a second optical pulse sequence component respectively; when the first optical pulse sequence component reaches the second phase modulator, if the random binary number generated by the third quantum random number generator is 1, the pulse of the first optical pulse sequence component is delayed, and if the random binary number generated by the third quantum random number generator is 0, the pulse of the first optical pulse sequence component is not delayed; when the second optical pulse sequence component reaches the phase modulator, if the random binary number generated by the third quantum random number generator is 0, the second optical pulse sequence component is not delayed and is not operated, and if the random binary number generated by the third quantum random number generator is 1, the pulse of the second optical pulse sequence component is delayed; the second optical pulse sequence component is not delayed and directly passes through the phase modulator and returns to the first 2x2 coupler; the two light pulse components interfere after arriving at the first 2x2 coupler again.
Compared with the prior art, the beneficial effect of this embodiment has:
(1) in the embodiment, a network structure based on the Sagnac loop is adopted for 2 times, so that the stability is good, the phase jitter caused by the optical path can be compensated, and the two pulses can reach the coupler to generate stable interference after passing through the same optical path. In a quantum key distribution protocol in the prior art, two beams of pulses reach a coupler to interfere through a Sagnac ring at the same time by carrying out precise periodic delay on the pulses to be interfered; the invention can generate the needed original key only by using a small amount of pulse number, thereby greatly reducing the requirement of the whole system on the pulse number and further improving the code rate of the system.
(2) The pulse delay unit is a reversible unit device, allows pulses to pass through in two directions, and can be applied to a Sagnac loop. And is widely applied to large-scale networks in practical application.
(3) The method meets the wavelength division multiplexing, can be accessed to a plurality of transmitting ends and a plurality of receiving ends, and maximally supports the requirement of multiple users.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A quantum key distribution system capable of controlling pulse delay comprises n sending ends and n receiving ends, wherein n is an integer larger than 2;
the n sending terminals are respectively a first sending terminal ALICE1, a second sending terminal ALICE2, … … and an nth sending terminal ALICEn; the n receiving ends are respectively a first receiving end BOB1, a second receiving end BOB2, a second receiving end … … and an nth receiving end BOBn;
the first sending end ALICE1, the second sending end ALICE2, … … and the nth sending end ALICEn are respectively connected with the first DWDM; the first receiving terminal BOB1, the second receiving terminals BOB2, … … and the nth receiving terminal BOBn are respectively connected with the second DWDM;
the first DWDM and the second DWDM are connected with each other through an optical fiber and used for optical pulse signal transmission; the method is characterized in that:
quantum channels for transmitting quantum signals and classical channels for transmitting classical signals are arranged between the n transmitting ends and the n receiving ends;
in the first sending end, ALICE1, including: the system comprises a pulse laser, a first phase modulator, an intensity modulator, a first quantum random number generator, a second quantum random number generator, a first quantum key manager and a first classical signal transceiving end; the pulse laser is connected with a first input end of a first phase modulator, and an output end of the first phase modulator is connected with a first input end of an intensity modulator; the first quantum random number generator is respectively connected with the second input end of the first phase modulator and the first input end of the first quantum key manager, the second quantum random number generator is respectively connected with the second input end of the intensity modulator, the second input end of the first quantum key manager and the first input end of the first classical signal receiving and transmitting end, and the second output end of the first classical signal receiving and transmitting end is mutually connected with the third input end of the first quantum key manager;
in the first receiving end BOB1, the method includes: the device comprises a circulator, a first 2x2 coupler, a pulse delay unit, a third quantum random number generator, a first detector, a second quantum key manager and a second classical signal transceiving end; the circulator comprises a first port, a second port and a third port, the first port is connected with the intensity modulator through quantum channels through wavelength division multiplexing, the second port is connected with the first 2x2 coupler, and the third port is connected with the second detector; the pulse delay unit is respectively connected with two output ends of the first 2x2 coupler and the third quantum random number generator to form a Sagnac loop, and the first 2x2 coupler is also connected with the first detector; the output end of the first detector and the output end of the second detector are respectively connected with a second quantum key manager, and the second quantum key manager is connected with a second classical signal transceiving end;
the output end of the intensity modulator is connected with the first port of the circulator through a quantum channel by wavelength division multiplexing;
the first output end of the first classical signal transceiving end is connected with the second classical signal transceiving end through classical channel by wavelength division multiplexing;
the structures and the connections of the second sending end ALICE2, … … and the nth sending end ALICEn are consistent with the first sending end ALICE 1; the structures and connections of the second receiving terminals BOB2, … … and the nth receiving terminal BOB are consistent with the first receiving terminal BOB 1.
2. The quantum key distribution system of claim 1, wherein: in the Sagnac loop, two output ends of four ports of a first 2x2 coupler are respectively connected to two ends of a pulse delay unit to form a loop, a third quantum random number generator is connected to a third end of the pulse delay unit, and a delay period of the pulse delay unit is controlled by the third quantum random number generator.
3. A quantum key distribution system according to claim 1 or 2, wherein: the pulse delay unit performs periodic delay control on the arrived light pulse; the pulse delay unit comprises a second phase modulator, a second 2x2 coupler, a 2x1 coupler and an optical switch; four ports of the second 2x2 coupler, wherein two output ends are respectively connected to two ends of the second phase modulator to form a loop, and the other two ports are respectively connected with the optical switch and one input end of the 2x1 coupler; the other input end of the 2x1 coupler is connected with one output end of the first 2x2 coupler; the optical switch is a 2-to-1 optical switch, and two selection ports of the 2-to-1 optical switch are respectively connected with the output end of the 2x1 coupler and the other output end of the first 2x2 coupler; the port of the second 2x2 coupler connected to the optical switch can be selectively connected to the output terminal of the 2x1 coupler or to the other output terminal of the first 2x2 coupler by the 2-in-1 operation of the optical switch, and the input and output of the optical pulse are controlled by the switching selection of the two selected ports of the optical switch.
4. A quantum key distribution system according to claim 3, wherein: the third quantum random number generator is connected to the second phase modulator, the input of the voltage of the second phase modulator is adjusted through random binary numbers generated by the third quantum random number generator, and the phase of the optical pulse sequence passing through the second phase modulator is changed so as to control the time delay of the optical pulse.
5. The quantum key distribution system of claim 1, wherein: the first 2x2 coupler comprises a first input end, a second input end, a first output end and a second output end, the first input end of the first 2x2 coupler is connected with the second port of the circulator and used for receiving optical pulse signals; the first 2x2 coupler divides the input optical pulse signal into two paths according to the proportion of 50: 50, and the two paths are respectively input into a clockwise optical fiber link and a counterclockwise optical fiber link through a first output end and a second output end; the optical pulse signals in the optical fiber links in the clockwise direction or the anticlockwise direction are respectively connected to the pulse delay units and then return to the first 2x2 coupler again, and interference occurs at the first 2x2 coupler; the second input of the first 2x2 coupler is connected to the first detector, which measures the interference occurring at the first 2x2 coupler through the second input of the first 2x2 coupler.
6. The quantum key distribution system of claim 1, wherein: the first detector and the second detector are single-photon detectors, one of the two detectors is set to be 1 when detecting photons, and the other detector is set to be 0 when detecting photons.
7. The quantum key distribution system of claim 1, wherein: the n sending ends transmit quantum signals and classical signals to a receiving end in a long distance through an optical fiber by multiplexing through a first DWDM, and the n receiving ends receive the signals through a second DWDM and demultiplex the signals to the corresponding receiving ends.
8. A quantum key distribution method of the quantum key distribution system according to any one of claims 1 to 7, comprising the steps of:
a, preparing M quantum states consisting of L pulses by a pulse laser at a sending end, preparing a random binary number for each pulse of each quantum state by a first quantum random number generator, and sending the random binary number to a first phase modulator to perform phase modulation on the pulses, wherein M and L are both natural numbers;
b, the intensity modulator adjusts the signal state and the decoy state of each quantum state after phase modulation according to the random binary number generated by the second quantum random number generator;
step C1, the first quantum random number generator and the second quantum random number generator send the random binary numbers generated by the first quantum random number generator to the first quantum key manager for recording and storing;
step C2, the second quantum random number generator also sends the generated random binary number to the first classical signal receiving and transmitting end, and sends the random binary number to the second classical signal receiving and transmitting end and the second quantum key manager of the receiving end through the classical channel via the first classical signal receiving and transmitting end;
d1, the sending end sends the encoded signal state and the decoy state to the receiving end through the quantum channel;
d2, the receiving end receives the signal state and the decoy state and sends the signal state and the decoy state into a Sagnac loop through a circulator, and a third quantum random number generator generates a random binary number and sends the random binary number to a second phase modulator to carry out periodic time delay on a pulse sequence which enters a pulse time delay unit clockwise or anticlockwise;
step D3, returning the pulse sequence transmitted clockwise and anticlockwise in the Sagnac loop to the first 2x2 coupler again for interference, and measuring interference results by the first 2x2 coupler and the circulator respectively through the interference of the first detector and the second detector;
step D4, the second quantum key manager receives and records the measurement result, and the position (x, y) of the pulse in the pulse sequence when the first detector and the second detector respond, and sends the result to the second classical signal transceiver, and then the second classical signal transceiver sends the result to the sending terminal through the classical channel;
step D5, the first classical signal transceiver end of the sending end receives the measuring result and the position (x, y) information and sends the measuring result and the position (x, y) information to the first quantum key manager;
and E, communication double-sending, namely comparing and evaluating a channel parameter and an original key by a first quantum key manager at a sending end and a second quantum key manager at a receiving end according to the decoy state information, and if the error rate of the channel parameter is less than a threshold value, carrying out security enhancement and error correction on the obtained original quantum key by the first quantum key manager and the second quantum key manager to obtain a final quantum key.
9. The quantum key distribution method of claim 8, wherein: the optical pulse sequence input from the circulator enters a first 2x2 coupler through an output port of the circulator, and the optical pulse sequence is divided into two beams from the first 2x2 coupler, wherein the two beams are a first optical pulse sequence component and a second optical pulse sequence component respectively; when the first optical pulse sequence component reaches the second phase modulator, if the random binary number generated by the third quantum random number generator is 1, the pulse of the first optical pulse sequence component is delayed, and if the random binary number generated by the third quantum random number generator is 0, the pulse of the first optical pulse sequence component is not delayed; when the second optical pulse sequence component reaches the phase modulator, if the random binary number generated by the third quantum random number generator is 0, the second optical pulse sequence component is not delayed and is not operated, and if the random binary number generated by the third quantum random number generator is 1, the pulse of the second optical pulse sequence component is delayed; the second optical pulse sequence component is not delayed and directly passes through the phase modulator and returns to the first 2x2 coupler; the two light pulse components interfere after arriving at the first 2x2 coupler again.
10. The quantum key distribution method of claim 8, wherein: in step E, if the error rate of the channel parameter is larger than the threshold value, returning to the step A to restart.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203590241U (en) * | 2013-12-13 | 2014-05-07 | 上海朗研光电科技有限公司 | Decoy state quantum light source generating device of high-speed polarization encoding |
| CN207896974U (en) * | 2018-02-14 | 2018-09-21 | 清华大学 | A kind of quantum key distribution system |
| CN110752884A (en) * | 2019-08-19 | 2020-02-04 | 中国电子科技集团公司第三十研究所 | Reciprocal Gaussian modulation quantum optical signal generation device and method |
| CN112929157A (en) * | 2019-12-06 | 2021-06-08 | 北京中创为南京量子通信技术有限公司 | Quantum key distribution device, method and system |
-
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- 2021-12-31 CN CN202111683474.7A patent/CN114465717B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203590241U (en) * | 2013-12-13 | 2014-05-07 | 上海朗研光电科技有限公司 | Decoy state quantum light source generating device of high-speed polarization encoding |
| CN207896974U (en) * | 2018-02-14 | 2018-09-21 | 清华大学 | A kind of quantum key distribution system |
| CN110752884A (en) * | 2019-08-19 | 2020-02-04 | 中国电子科技集团公司第三十研究所 | Reciprocal Gaussian modulation quantum optical signal generation device and method |
| CN112929157A (en) * | 2019-12-06 | 2021-06-08 | 北京中创为南京量子通信技术有限公司 | Quantum key distribution device, method and system |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116170077A (en) * | 2023-04-24 | 2023-05-26 | 中国科学技术大学 | Quantum and classical laser communication multiplexing receiving device and system |
| CN116170077B (en) * | 2023-04-24 | 2023-08-29 | 中国科学技术大学 | Quantum and classical laser communication multiplexing receiving device and system |
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