CN114465716B - MRR-QKD-based trusted relay quantum key distribution system - Google Patents
MRR-QKD-based trusted relay quantum key distribution system Download PDFInfo
- Publication number
- CN114465716B CN114465716B CN202111665832.1A CN202111665832A CN114465716B CN 114465716 B CN114465716 B CN 114465716B CN 202111665832 A CN202111665832 A CN 202111665832A CN 114465716 B CN114465716 B CN 114465716B
- Authority
- CN
- China
- Prior art keywords
- signal
- modulation
- polarization
- interrogation
- intensity modulator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 230000010287 polarization Effects 0.000 claims abstract description 65
- 238000004891 communication Methods 0.000 claims abstract description 22
- 238000005259 measurement Methods 0.000 claims abstract description 12
- 230000005540 biological transmission Effects 0.000 claims description 12
- 230000001427 coherent effect Effects 0.000 claims description 6
- 239000013598 vector Substances 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 3
- 238000000691 measurement method Methods 0.000 claims description 2
- 238000012544 monitoring process Methods 0.000 claims 4
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims 3
- 241000282326 Felis catus Species 0.000 claims 2
- 230000008054 signal transmission Effects 0.000 claims 1
- 230000011664 signaling Effects 0.000 claims 1
- 230000003287 optical effect Effects 0.000 abstract description 20
- 230000006870 function Effects 0.000 abstract description 5
- 238000010295 mobile communication Methods 0.000 abstract 1
- 238000005516 engineering process Methods 0.000 description 13
- 238000010586 diagram Methods 0.000 description 6
- 230000004044 response Effects 0.000 description 5
- 238000010276 construction Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012805 post-processing Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 230000006855 networking Effects 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000005610 quantum mechanics Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Images
Classifications
-
- 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
- H04L9/0855—Quantum cryptography involving additional nodes, e.g. quantum relays, repeaters, intermediate nodes or remote nodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Theoretical Computer Science (AREA)
- Computer Security & Cryptography (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
Abstract
The invention provides a reverse modulation free space QKD system based on a B92 protocol, which comprises an inquiry end and a reverse modulation end: the inquiring end comprises a signal generating module and a signal measuring module; the reverse modulation end comprises a signal modulation module. The signal generating module at the inquiring end mainly has the function of generating right-hand circular polarized classical optical signals. The signal measurement module of the interrogation terminal mainly has the function of measuring the polarization state of the quantum signal. The signal modulation module of the reverse modulation end mainly has the functions of modulating the polarization state of the signal generated by the inquiry end, outputting the non-orthogonal quantum signal required by the B92 protocol and reversely reflecting the quantum signal back to the inquiry end. The invention realizes the polarization state modulation of the signal by an intensity modulation mode based on the principle of vertical polarization state superposition. The system has the advantages of simple structure, few devices and low cost, and is suitable for mobile communication platforms with strict limits on load and cost, thereby realizing quantum secret communication.
Description
Technical Field
The invention relates to the field of quantum key distribution and free space optical communication, in particular to a reverse modulation quantum key distribution technology based on intensity-polarization modulation, and particularly relates to a free space quantum key distribution technology based on trusted relay.
Background
Quantum cryptography is a new information transmission technology, the security of which is guaranteed by the laws of physics. One important and currently most practical branch of technology is quantum key distribution. Quantum Key Distribution (QKD) allows two remote users to send photons over a communication channel (typically optical fiber or free space) to create a common secret bit string that is not known to an eavesdropper Eve.
The fiber channel can only realize the quantum key distribution of hundreds of kilometers at present due to the limitation of channel loss. Quantum repeaters and satellite-based free space are alternative solutions to achieve longer-range quantum key distribution. However, mature quantum repeaters still cannot be implemented due to the difficulty in building a reliably operating quantum memory. Thus, satellites are currently commonly used as relays to achieve remote quantum key distribution through low loss free space.
The university of science and technology of China utilizes the 'ink number' quantum science experiment satellite as a trusted relay, achieves intercontinental quantum key distribution with a distance of 7600 km between China and Austria for the first time, and achieves encrypted data transmission and video communication by utilizing a shared key. Future global quantum communication needs to be achieved through a quantum constellation. The quantum satellite with the ink mark has larger volume and higher cost. The miniaturization of quantum satellites is realized, and networking by using a plurality of satellites becomes an important task.
Quantum Key Distribution (QKD) ensures the security of key distribution based on the hessian-burg inaccuracy principle of quantum mechanics and the quantum unclonable theorem. Different from the classical key, the security of the encryption information is ensured through the calculation complexity of the mathematical problem, the security of the quantum key distribution is based on a physical basis, the possibility of the key being cracked is fundamentally solved, and the method is an encryption communication mode which is absolute and safe in theory.
The free space optical communication technology based on the reverse modulation technology has the advantages of small volume and low cost. And high-precision ATP (Acquisition, tracking and Pointing) equipment is not needed, so that the technical difficulty is reduced. The technology is combined with a free space QKD technology, so that the cost of a quantum satellite can be reduced, and the construction of a globalization quantum network is promoted.
The patent designs a trusted relay quantum key distribution system based on MRR-QKD. The system is based on the principle of reverse modulation quantum key distribution technology. Quantum satellites, which are trusted relays, can implement quantum key distribution with two terrestrial communication users simultaneously using pixelated spatial light modulators. And then the two ground communication users obtain a string of the same encryption keys through AND or logic operation. The invention can reduce the construction cost of the trusted relay quantum satellite and realize real-time quantum encryption communication between two remote ground users.
Disclosure of Invention
The invention aims to optimize the defects of the prior art and provides a trusted relay quantum key distribution system based on MRR-QKD. The system is based on a reverse modulation quantum key distribution technology, and reverse modulation equipment with a direction resolution function is carried on an aircraft to be used as a trusted relay, such as a satellite, an airplane and the like, so that real-time quantum secret communication between two remote ground terminals is realized.
A trusted relay quantum key distribution system based on MRR-QKD comprises a query end 1, a query end 2 and a reverse modulation end. The query end is responsible for preparation and transmission of query signals and receiving and measuring of quantum signals, and the reverse modulation end is responsible for receiving and modulating the query signals into weak coherent quantum signals meeting the B92 protocol, reverse reflection of the quantum signals and key distribution of trusted relay.
The interrogation terminal 1 and the interrogation terminal 2 prepare classical pulse signals in circular polarization state: the laser generates a series of classical pulse signals in vertical linear polarization states, and the signals are converted into right-hand circular polarization state signals through a quarter wave plate; the fast axis of the quarter wave plate is 45 deg. from the vertical linear polarization state.
The right-hand circularly polarized signal passes through 10: the 90 beam splitter splits the beam and the transmitted signal is transmitted as an interrogation signal to the reverse modulation end via the optical antenna. The transmitted signal has an intensity of 10% of the incident signal and the polarization state is the same.
The interrogation signal 1 produced by the interrogation terminal 1 and the interrogation signal 2 produced by the interrogation terminal 2 are respectively received by the optical antennas of the reverse modulation terminal. The two interrogation signals are first split by a beam splitter. The beam splitter is 90:10 beam splitter. The intensity of the reflected signal is 10% of the incident signal and the intensity of the transmitted signal is 90% of the incident signal.
The reflected signal is converged on a spatial light detector through a positive lens, and the spatial light detector is positioned on the focal plane of the positive lens. As known from the principle of light transmission, parallel light rays with different incident directions are focused at different positions on the focal plane of the lens by the lens. Thus, the interrogation signal 1 and the interrogation signal 2 will be focused at different locations of the spatial light detector. The interrogation terminal records the incident intensity, direction and time information of the two beams of interrogation signals respectively according to the measurement result, and the reverse modulation module does not work at the moment. The reverse modulation side informs the inquiring side 1 and the inquiring side 2 respectively by classical communication. The interrogation end 1 and the interrogation end 2 adjust the intensity and the time delay of the light signals emitted by the lasers, so that the time and the intensity of the two interrogation signals when the two interrogation signals are incident on the reverse modulation end are the same. The reverse modulation module starts to work.
The transmitted signal passes through an intensity modulator and then is split by a polarizing beam splitter. The horizontally polarized component of the incident signal is transmitted and the vertically polarized component is reflected. The horizontally polarized component and the vertically polarized component are converged on the intensity modulator and the mirror via positive lenses, respectively. The intensity modulator and the mirror are located at the focal plane of the positive lens. The two positive lenses, the intensity modulator and the mirror are identical. Since the interrogation signals 1 and 2 come from different interrogation terminals, the two signals have different directions of incidence and they converge at different locations of the intensity modulator. The intensity modulator is a modulation unit pixelated multiple quantum well modulator, and is an electrically modulated light absorption type intensity modulator, as shown in fig. 6. According to the information to be loaded, the two signals are subjected to independent intensity modulation by performing time synchronization and mutually independent control on the pixels. The two signals are modulated by a positive lens and an intensity modulator and reversely reflected by a reflecting mirror, and are reversely combined by a polarization beam splitter, and the polarization state of the combined signals is related to the intensity of the two signals which are reversely incident. When the phase difference is 2npi, the combined signal is in a linear polarization state and is expressed by Jones vector:
wherein C is a constant, tables 1 and 2 below represent interrogation signal 1 and interrogation signal 2, respectively; θ 1 E [0,2 pi) represents the polarization direction of the signal; e represents the light field amplitude.
The combined signal reversely passes through the intensity modulator, and the output signal is a quantum signal in a weak coherent state. According to the decoy state protocol, the modulation output signal is selected to be in a signal state or a decoy state by adjusting the modulation efficiency of the intensity modulator. Quantum signal passes through 90: the 10 beam splitter splits the beam. The quantum signal has 90% probability transmission, and the transmission signal is reversely transmitted back to the corresponding interrogation terminal through the optical antenna.
The quantum signals are received by the optical antennas of the respective interrogation terminals via 10: the 90 beam splitter splits the beam. The quantum signal has 90% probability reflection and enters the quantum signal measuring module. The quantum signal can be subjected to polarization compensation through a half-wave plate with a rotatable optical axis, and the variation of a reference system caused by transmission is compensated, so that the quantum signal after compensation is a diagonal base signal or a right angle base signal. The polarization-compensated signal passes through 50: the 50 beam splitter is passively selected. The quantum signal has 50% probability of transmitting into the right angle base measurement unit and 50% probability of reflecting into the right angle base measurement unit. And recording corresponding key information according to the B92 protocol according to the response result of the detector.
The challenge end 1 and the challenge end 2 perform post-processing with the reverse modulation end through classical communication to extract the security key. The final inquiring end 1 and the reverse modulation end obtain a string of the same key string KA, and the inquiring end 2 and the reverse modulation end obtain a string of the same key string K B . Reverse modulation end-to-key string K A And key string K B And or operation to obtain a series of sequences
And sends the sequence to the interrogating end 2 via classical communication. Inquiry terminal 2 is according to the sequence->
Secret key string K mastered by self B The key string K is obtained through calculation A . Finally, challenge 1 and challenge 2 share the key string K A 。
The invention has the beneficial effects that:
the invention provides a trusted relay quantum key distribution system based on MRR-QKD, which can realize point-to-many quantum key distribution, and trusted relay can only realize point-to-point quantum key distribution. The system uses the weak coherent state to load the key information, the realization is simple, the technology is mature, and in the entanglement-based relay-free scheme, the practical entanglement source is difficult to prepare; based on the preparation-measurement, entanglement source and other sub-key distribution systems, the preparation and measurement of signals are the most critical and complex tasks, the system resources can be greatly occupied, the energy consumption, the cost, the volume and the like are high, the system adopts a reverse modulation technology, and most of operation tasks are skillfully arranged on one party (an inquiry end) of communication, and the work task of the other party (a reverse modulation end) of communication is lightened, so that the system is suitable for being applied to application scenes such as satellite-ground or air-ground.
Drawings
FIG. 1 is a schematic diagram of quantum key distribution for a trusted relay-based reverse modulation free space QKD system provided by the present invention;
fig. 2 is a schematic diagram of a reverse modulation end and an inquiry end performing classical communication matching key in a reverse modulation free space QKD system based on trusted relay provided by the present invention;
FIG. 3 is a schematic diagram of the workflow of a reverse-modulated free-space QKD system based on trusted relay provided by the present invention;
FIG. 4 is a diagram of a device for quantum key distribution between a reverse modulation end and an interrogation end in a reverse modulation free space QKD system based on trusted relay provided by the present invention;
FIG. 5 is a schematic diagram of the invention in which interrogation signals of different angles of incidence are focused onto an intensity modulator by a positive lens;
FIG. 6 is a schematic diagram of a spot of an interrogation signal focused on an intensity modulator by a positive lens in accordance with the present invention;
description of the reference numerals
1-interrogation side 1, 2-interrogation side 2, 3-reverse modulation side, 4-free space channel 1, 5-free space channel 2;
01-pulse laser, 02-quarter wave plate, 03-beam splitter 1, 04-half wave plate 1, 05-beam splitter 2, 06-half wave plate 2, 07-polarization beam splitter 1, 08-polarization beam splitter 2, 09-single photon detector 1, 10-single photon detector 2, 11-single photon detector 3, 12-single photon detector 4, 13-optical antenna 1;
14-optical antenna 2, 15-beam splitter 3, 16-positive lens 1, 17-spatial light detector, 18-intensity modulator 1, 19-polarizing beam splitter 3, 20-positive lens 2, 21-positive lens 3, 22-intensity modulator 2, 23-intensity modulator 3, 24-mirror 1, 25-mirror 2.
Detailed Description
Step 1: the interrogation terminal 1 (1) and the interrogation terminal 2 (2) respectively send a beam of right-handed circularly polarized strong pulse optical signals to the reverse modulation terminal (3) through the free space channel 1 (4) and the free space channel 2 (5). The pulse frequency and wavelength of the two signals are the same.
Step 2: the reverse modulation end (3) monitors the incident signal. When the two signals reach the reverse modulation end (3) and are detected, the reverse modulation end (3) records the time, the intensity and the direction of the two signals.
Step 3: the reverse modulation end (3) informs the interrogation end 1 (1) and the interrogation end 2 (2) which transmit the signals respectively by classical communication of the time, the intensity and the direction of the two signals respectively.
Step 4: the information fed back by the query terminal 1 (1) and the query terminal 2 (2) through the reverse modulation terminal (3) ensures that the time and the intensity of two beams of signals when reaching the reverse modulation terminal (3) are the same by adjusting the internal time delay and the signal intensity.
Step 5: the inverse modulation end (3) performs quantum key distribution with the inquiry end 1 (1) and the inquiry end 2 (2) at the same time. The reverse modulation end (3) realizes simultaneous and independent signal modulation of an incident signal of an incident angle through the spatial resolution capability and the pixelation modulation capability of the intensity modulator. The two beams of signals are respectively polarized and modulated by a reverse modulation end (3) and attenuated into weak coherent signals, and then are reversely reflected back to the inquiring end 1 (1) and the inquiring end 2 (2). The modulated polarization state satisfies the B92 protocol, i.e. two non-orthogonal polarization states. They are θ and θ+45°, respectively, typically θ is chosen to be 22.5 °. The interrogation terminal 1 (1) and the interrogation terminal 2 (2) respectively receive the reflected signals to measure the polarization states.
Step 6: the reverse modulation end (3) and the inquiry end 1 (1) and the inquiry end 2 (2) carry out post-processing through classical communication to extract the security key. The measurement method and the obtained secret key meet the B92 protocol. At this time, the inquiry terminal 1 (1) and the reverse modulation terminal (3) The same key K is obtained A The same key K is obtained between the challenge terminal 2 (2) and the reverse modulation terminal 3 B 。
Step 7: the reverse modulation end (3) is used for transmitting the data by classical communication
The result is sent to the interrogating end 2 (2).
Step 8: the inquiry terminal 2 (2) passes through
And K obtained by quantum key distribution B Calculating to obtain K A . At this time, the challenge side 1 (1) and the challenge side 2 (2) realize the key K A Is shared by the plurality of users.
The quantum key distribution process between the challenge and reverse modulation ends is as follows:
the pulse laser (01) generates a series of pulse signals. The signal is a classical optical signal of vertical linear polarization. The signal is changed into a right-hand circularly polarized signal through a quarter wave plate (02). The fast axis of the quarter wave plate (02) forms an angle of 45 degrees with the polarization direction of the incident signal. Expressed by Jones vector and Jones matrix
Wherein,,
is a Jones matrix of a quarter wave plate (02) having an optical axis direction of 45 degrees.
Is the jones vector for the vertical linear polarization state. E' is the output signal of the vertical linear polarization signal after passing through the quarter wave plate with the optical axis direction of 45 degrees.
The signal is split into two signals by the beam splitter 1 (03), one being a transmitted signal and one being a reflected signal. The beam splitter 1 (03) is 10: a 90 beam splitter. The transmitted signal intensity is 10% of the incident signal intensity and the reflected signal intensity is 90% of the incident signal intensity. The reflected signal is rejected. The transmission signal is transmitted as an interrogation signal via the optical antenna 1 (13) via the free-space channel 1 (4) to the inverse modulation terminal (3).
The reverse modulation side (3) receives the interrogation signal transmitted by the interrogation side via the optical antenna (2) (14). The interrogation signal is split by a beam splitter 3 (15). The beam splitter 3 (15) is 10: the interrogation signal passes through beam splitter 3 (15), 10% of the energy being reflected and 90% of the energy being transmitted.
The signal reflected by the beam splitter 3 (15) is converged by the positive lens 1 (16) onto the spatial light detector (17). The spatial light detector (17) is located at the focal plane of the positive lens 1 (16). Incoming signals in different directions are focused at different spatial locations by the positive lens. The spatial light detector (17) obtains the direction, time and intensity information of the incident signal according to the intensity, position and time of the convergence of the incident signal obtained by measurement.
The signal transmitted through the beam splitter 3 (15) is first intensity modulated by the intensity modulator 1 (18). The output signal strength is M times the input signal strength. M is the modulation efficiency of the intensity modulator 1 (18), the value of which is less than 1.
The intensity modulator 1 (18) is a multiple quantum well modulator, and the multiple quantum well modulator is an electrically modulated absorption type light intensity modulator. Output signals of different intensities can be achieved by varying the control electrical signal of the multiple quantum well modulator.
The signal is then incident on the polarizing beam splitter 3 (19). The incident signal is a right-hand circularly polarized signal, and after passing through the polarization beam splitter 3 (19). The transmitted signal is a horizontally linearly polarized signal and the signal strength is half of the incident signal. The reflected signal is a vertically polarized signal and the signal strength is half that of the incident signal.
The signal transmitted through the polarizing beam splitter 3 (19) is converged onto the intensity modulator and the mirror through the positive lens. The mirror closely conforms to the back of the intensity modulator and can be approximated as if the intensity modulator and mirror were in the same plane, and that plane coincides with the focal plane of the positive lens.
Horizontal polarization transmitted through polarization beam splitter 3 (19)The vibration signal is focused on the intensity modulator 2 (22) through the positive lens 2 (20) to be subjected to intensity modulation, and the emergent beam is reflected by the reflecting mirror 1 (24). The beam then passes through the intensity modulator 2 (22) in a second reverse direction for intensity modulation and finally passes out through the positive lens 2 (20) in the reverse direction. The polarization state of the signal reversely output from the positive lens 2 (20) is the same as the signal positively input from the positive lens, and the transmission directions are parallel and opposite. The signal intensity outputted from the positive lens 2 (20) in the reverse direction is M1 of the signal intensity inputted from the positive lens 2 (20) in the forward direction 2 Multiple times. The intensity modulator 2 (22) is a multiple quantum well modulator. M1 is the modulation efficiency of the intensity modulator 2 (22), and its value is less than 1.
The vertical linear polarization signal reflected by the polarization beam splitter 3 (19) is focused by the positive lens 3 (21) onto the intensity modulator 3 (23) for intensity modulation, and the outgoing beam is reflected by the mirror 2 (25). The light beam then passes through the intensity modulator 3 (23) in a second reversal of the direction, is intensity modulated, and is finally output in the opposite direction through the positive lens 3 (21). The polarization state of the signal finally output reversely from the positive lens 3 (21) is the same as the signal input positively from the positive lens 3 (21), and the transmission directions are parallel and opposite. The signal intensity reversely output from the positive lens 3 (21) is M2 of the signal intensity positively input from the positive lens 3 (21) 2 Multiple times. The intensity modulator 3 (23) is a multiple quantum well modulator identical to the intensity modulator 2 (22). M2 is the modulation efficiency of the intensity modulator 3 (23), which is less than 1.
The location at which the incident signal is converged on the intensity modulator through the positive lens is determined by the direction of the incident signal, and the incident signals in different directions are converged at different locations of the intensity modulator, as shown in fig. 4. The interrogating end 1 (1) and interrogating end 2 (2) are spatially located at different positions and the interrogating signals they emit converge on different pixels of the intensity modulator, as shown in figure 5. By controlling the pixels independently of each other, different signal modulations can be realized for incident signals in different directions. The size of the incident signal converging light spot is affected by the transfer function of the positive lens, typically converging on one or several pixels of the intensity modulator.
The direction of incidence of the incident signal is monitored by a spatial light detector (17) to control the pixels illuminated by the light beam to be in a "modulated" state. At this time, the modulated pixels of the intensity modulators 2 (22) and 3 (23) can realize modulation of signals by changing the modulation efficiency of the pixels according to the key information to be loaded.
The reflected and transmitted signals are combined in opposite directions through the polarizing beam splitter 3 (19), respectively. The intensity ratio of the two signals is M1 2 ：M2 2 . The phase difference of the two beams of signals is an integral multiple of 2 pi, and the output signal after beam combination is a linear polarization signal.
The optical axis ψ of the linear polarization satisfies ψ=arctan (M 2 /M 1 ). By controlling M 2 /M 1 To output linear polarizations of ψ=22.5° and 67.5 °.
The signal after being combined by the polarizing beam splitter 3 (19) is subjected to intensity modulation reversely by the intensity modulator 1 (18). The polarization state of the output signal is the same as that of the input signal, and the intensity of the output signal is M times of that of the input signal. The signal is modulated twice by the intensity modulator 1 (18). The selection of the signal between the signal state, the spoofing state or the vacuum state is achieved by controlling the modulation efficiency M.
The final output signal from the intensity modulator 1 (18) is a 22.5 ° or 67.5 ° linearly polarized quantum signal. The signal will pass through the beam splitter 3 (15) again, and the signal will be reflected with 10% probability, and the reflected signal cannot be transmitted back to the interrogation end, and is an invalid signal; there is a 90% probability that the signal will be transmitted. The transmitted signal is transmitted back through the optical antenna 2 (14) via the free space channel back to the interrogating end, as reflected signal shown in fig. 4. The signal is received by the optical antenna 1 (13) at the interrogation end. Since free space hardly changes the polarization state of the signal, the reflected signal is still in a linear polarization state. But because the relative spatial positions and attitudes of the interrogating and retro-modulating ends are not fixed. The reflected signal received by the interrogation end is not necessarily 22.5 ° or 67.5 ° linear polarized, but is θ or θ+45° linear polarized (where θ is [0, 360 °), and the relative spatial positions of θ and the interrogation and counter-modulation ends are related to the pose).
The reflected signal is transmitted to the beam splitter 1 (03). The reflected signal has 10% probability of transmitting through the beam splitter 1 (03), and the transmitted signal is an invalid signal which is selectively discarded; there is a 90% probability of being reflected by the beam splitter 1 (03) for subsequent polarization measurements.
The signal reflected by the beam splitter 1 (03) first passes through the half-wave plate 1 (04). The optical axis of the half-wave plate 1 (04) may be rotatable by a connected rotating electric machine. By adjusting the direction of the optical axis of the half-wave plate 1 (04), it is possible to convert the incident signals of θ and θ+45° linear polarization into output signals of 45 ° and 0 ° linear polarization, respectively.
The beam splitter 2 (05) is 50:50 beam splitters. The output signal has 50% probability transmission and 50% probability reflection when it is incident on the beam splitter 2 (05).
When the signal input to the beam splitter 2 (05) is reflected, it passes through the half-wave plate 2 (06) first. The included angle between the optical axis of the half-wave plate 2 (06) and the horizontal polarization state is 22.5 degrees. The right-angle base signal becomes a diagonal base signal through the half-wave plate 2 (06), and the diagonal base signal becomes a right-angle base signal through the half-wave plate 2 (06).
The signal output from the half-wave plate 2 (06) is input to the polarizing beam splitter 1 (07). The horizontally polarized component of the input signal is transmitted from the polarizing beam splitter 1 (07) and is incident on the single photon detector 1 (09) to cause a response. The vertically polarized component of the input signal is reflected from the polarizing beam splitter 1 (07) and incident on the single photon detector 2 (10) to cause a response.
When a signal incident on the beam splitter 2 (05) is transmitted, it passes through the polarizing beam splitter 2 (08). The horizontal polarization component of the signal input to the polarization beam splitter 2 (08) is transmitted from the polarization beam splitter 2 (08), and is incident on the single photon detector 4 (12) to cause a response. The vertically polarized component of the input signal is reflected from the polarizing beam splitter 2 (08) and incident on the single photon detector 3 (11) to cause a response.
Variations and modifications to the above would be obvious to persons skilled in the art to which the invention pertains from the foregoing description and teachings. Therefore, the invention is not limited to the specific embodiments disclosed and described above, but some modifications and changes of the invention should be also included in the scope of the claims of the invention. In addition, although specific terms are used in the present specification, these terms are for convenience of description only and do not limit the present invention in any way.
Claims (4)
1. A trusted relay quantum key distribution system based on MRR-QKD, characterized by: two communication parties including the carrying of an interrogation device, called interrogation terminals; the method also comprises a trusted relay carrying reverse modulation equipment, which is called a reverse modulation end; the reverse modulation end respectively and simultaneously distributes quantum keys with the two inquiry ends through free space channels to obtain two strings of encryption keys; the encryption key is subjected to AND or calculation, the calculation result is informed to an inquiring end in a classical communication mode, and the inquiring end which obtains the calculation result can calculate and obtain the key held by the other inquiring end according to the string of keys obtained before the inquiring end which obtains the calculation result;
the interrogation device comprises an interrogation signal generation module and a quantum signal measurement module; the reverse modulation equipment comprises an interrogation signal monitoring module and a reverse modulation module;
the interrogation signal generation module comprises a laser and a quarter wave plate; the quantum signal measurement module comprises a half-wave plate 1, a beam splitter 1, a half-wave plate 2, a polarization beam splitter 1, a polarization beam splitter 2, a single photon detector 1, a single photon detector 2, a single photon detector 3 and a single photon detector 4;
the interrogation signal monitoring module is used for monitoring the incidence direction, the intensity and the time of interrogation signals sent to the reverse modulation end by the two interrogation ends; the interrogation signal monitoring module comprises a positive lens 1 and a spatial light detector;
the reverse modulation module comprises an intensity modulator 1, a polarization beam splitter 3, a positive lens 2, a positive lens 3, an intensity modulator 2, an intensity modulator 3, a reflecting mirror 1 and a reflecting mirror 2;
a laser in the interrogation signal generation module generates classical pulsed light of vertical linear polarization; the fast axis of the quarter wave plate forms an angle of 45 degrees with the polarization direction of the incident signal, and the vertical linearly polarized light generated by the laser is converted into a right-handed circular polarization state through the quarter wave plate;
the quantum signal measurement module is used for measuring the polarization state of an incident signal, and the measurement method is in accordance with the B92 protocol: passive basis vector selection is achieved by the beam splitter 2; the signal reflection pair diagonal basis measurement comprises a half wave plate 2, a polarization beam splitter 1, a single photon detector 1 and a single photon detector 2; the signal transmission is measured on a right angle basis and comprises a polarization beam splitter 2, a single photon detector 3 and a single photon detector 4;
the reverse modulation module is used for modulating the interrogation signal, loading different polarization states according to the key information and attenuating the different polarization states into a weak coherent state signal, and reversely reflecting the weak coherent state signal back to the interrogation terminal; the modulation principle is superposition of two light waves with the same frequency and mutually perpendicular polarization directions, and the polarization state of the signal is modulated by changing the intensity of horizontal and vertical components of the signal and controlling the phase difference to be 2npi;
the reverse modulation module comprises an information modulation function and a reverse reflection function; the information modulation function carries out polarization modulation on an incident interrogation signal, and modulates the signal into two corresponding polarization states of non-orthogonal polarization states, namely linear polarization with the polarization directions of theta and theta+45 degrees according to key information to be loaded and a B92 protocol; modulating an interrogation signal into a signal state or an tempting state through intensity attenuation according to an tempting state protocol; the retroreflective function transmits the incident and modulated interrogation signal back to the interrogation end in a parallel but opposite transmission direction.
2. The MRR-QKD-based trusted relay quantum key distribution system of claim 1, wherein: the modulation principle is represented by jones vectors as follows:
right-handed circular polarization state input, linear polarization state output with the polarization direction of theta; wherein E is 0 For the light field amplitude, C is a constant.
3. The MRR-QKD-based trusted relay quantum key distribution system of claim 1, wherein:
the reverse modulation module can realize mutually independent modulation and reverse reflection of signals in different incidence directions; the function of the information modulation is realized by an intensity modulator 1, a polarization beam splitter 3, a positive lens 2, a positive lens 3, an intensity modulator 2, an intensity modulator 3, a reflecting mirror 1 and a reflecting mirror 2; the intensity modulator 1 is used for modulating the signal state, and the selection between the signal state and the tempting state is realized by controlling the modulation efficiency of the intensity modulator 1; the polarization beam splitter 3 is used for separating a horizontal component and a vertical component of the signal, and outputting a target polarization state after combining the modulated signals of the horizontal component and the vertical component; the positive lens 2 and the intensity modulator 2 constitute a horizontal component intensity modulation device having a signal incident direction resolution capability; the positive lens 3 and the intensity modulator 3 constitute a vertical component intensity modulation device having a signal incident direction resolution capability; the positive lens 2 and the reflector 1 form a cat eye retroreflector with the signal incidence direction resolution capability, and for a plurality of parallel light beams which are incident in different directions, the retroreflection of each beam of signals can be realized simultaneously and the signals are not interfered with each other; the positive lens 3 and the reflector 2 form a cat eye retroreflector with the signal incidence direction resolution capability, and for multiple parallel light beams incidence in different directions, the retroreflection of each beam of signals can be realized simultaneously without mutual interference.
4. The MRR-QKD-based trusted relay quantum key distribution system of claim 3, wherein: the intensity modulator 2 and the intensity modulator 3 are modulators with pixelated modulation units and have spatial resolution capability; the intensity modulator 2 is placed in the focal plane of the positive lens 2 and the intensity modulator 3 is placed in the focal plane of the positive lens 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111665832.1A CN114465716B (en) | 2021-12-31 | 2021-12-31 | MRR-QKD-based trusted relay quantum key distribution system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111665832.1A CN114465716B (en) | 2021-12-31 | 2021-12-31 | MRR-QKD-based trusted relay quantum key distribution system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114465716A CN114465716A (en) | 2022-05-10 |
| CN114465716B true CN114465716B (en) | 2023-06-30 |
Family
ID=81408141
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111665832.1A Active CN114465716B (en) | 2021-12-31 | 2021-12-31 | MRR-QKD-based trusted relay quantum key distribution system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114465716B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116170081B (en) * | 2023-04-26 | 2023-08-04 | 中国人民解放军军事科学院系统工程研究院 | Quantum communication protocol automatic switching method based on link perception |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107947860A (en) * | 2017-12-12 | 2018-04-20 | 长春理工大学 | The energy of full-duplex communication and information combined Transmission system are realized based on fiber-optic vibration |
| CN108306680A (en) * | 2017-12-19 | 2018-07-20 | 中国人民解放军战略支援部队航天工程大学 | A kind of reverse modulation laser netting communication system based on chatoyancy |
| CN112688777A (en) * | 2020-12-29 | 2021-04-20 | 华南师范大学 | Space-optical fiber coupling array reverse modulation free space QKD system |
-
2021
- 2021-12-31 CN CN202111665832.1A patent/CN114465716B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107947860A (en) * | 2017-12-12 | 2018-04-20 | 长春理工大学 | The energy of full-duplex communication and information combined Transmission system are realized based on fiber-optic vibration |
| CN108306680A (en) * | 2017-12-19 | 2018-07-20 | 中国人民解放军战略支援部队航天工程大学 | A kind of reverse modulation laser netting communication system based on chatoyancy |
| CN112688777A (en) * | 2020-12-29 | 2021-04-20 | 华南师范大学 | Space-optical fiber coupling array reverse modulation free space QKD system |
Non-Patent Citations (1)
| Title |
|---|
| 基于声光调制的逆向调制光通信系统研究;徐山河;肖沙里;王珊;彭帝永;;激光技术(第05期);全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114465716A (en) | 2022-05-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Liao et al. | Satellite-to-ground quantum key distribution | |
| Liao et al. | Satellite-relayed intercontinental quantum network | |
| CN110620652B (en) | Quantum key distribution system and communication method thereof | |
| CN106161009B (en) | Quantum key distribution system based on time-phase encoding | |
| CN111162903B (en) | Free space quantum key distribution system and method for aircraft | |
| EP2885886B1 (en) | Quantum communications system with integrated photonic devices | |
| CN111130779B (en) | OAM entanglement modulation key distribution network system and method for real-time tracking compensation | |
| Nordholt et al. | Present and future free-space quantum key distribution | |
| CN112688777B (en) | Space-optical fiber coupling array reverse modulation free space QKD system | |
| US20100166187A1 (en) | Qkd using high-altitude paltforms | |
| CN211406034U (en) | Free space quantum key distribution system for aircraft | |
| Toyoshima et al. | Polarization‐Basis Tracking Scheme in Satellite Quantum Key Distribution | |
| CN104993925A (en) | Quantum key distribution system of aircraft | |
| CN114465716B (en) | MRR-QKD-based trusted relay quantum key distribution system | |
| US7221812B2 (en) | Compact optics assembly for a QKD station | |
| CN214626985U (en) | Space-optical fiber coupling array reverse modulation free space QKD system | |
| CN115361118A (en) | Loss tolerant reference frame and measuring device independent quantum key distribution method | |
| CN217363101U (en) | Inverse modulation free space QKD system based on B92 protocol | |
| CN114531231B (en) | Reverse modulation free space QKD system based on B92 protocol | |
| US11139897B2 (en) | Receiver for receiving information transmitted using very weak light pulses, a system for transmitting information comprising such a receiver and a method for transmitting information using very weak light pulses | |
| CN114448617B (en) | Reverse modulation free space QKD system and key distribution method | |
| Berra et al. | High-speed source for satellite quantum key distribution | |
| KR102709494B1 (en) | Method and device for correcting polarization distortion of faraday rotation mirror for quantum key distribution in communication system | |
| Zhang et al. | Real time basis-deviation measurement system based on BB84 module | |
| Jimenez-Girela et al. | Inflight demonstrator of quantum key distribution between CubeSats of Q-ANSER program |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20240104 Address after: 510663 room A105, first floor, ladder a, No. 11, panglv Road, Science City, Guangzhou high tech Industrial Development Zone, Guangdong Province Patentee after: Guangdong Yukopod Technology Development Co.,Ltd. Address before: School of information and optoelectronics, South China Normal University, 378 Waihuan West Road, Panyu District, Guangzhou, Guangdong 510000 Patentee before: SOUTH CHINA NORMAL University |