CN113259090A - Encoder of polarization encoding quantum key distribution system - Google Patents
Encoder of polarization encoding quantum key distribution system Download PDFInfo
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- CN113259090A CN113259090A CN202110248995.3A CN202110248995A CN113259090A CN 113259090 A CN113259090 A CN 113259090A CN 202110248995 A CN202110248995 A CN 202110248995A CN 113259090 A CN113259090 A CN 113259090A
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- 230000010287 polarization Effects 0.000 title claims abstract description 48
- 230000003287 optical effect Effects 0.000 claims abstract description 42
- 239000004065 semiconductor Substances 0.000 claims description 4
- 230000001960 triggered effect Effects 0.000 abstract description 6
- 230000002238 attenuated effect Effects 0.000 abstract description 4
- 230000005540 biological transmission Effects 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0852—Quantum cryptography
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/503—Laser transmitters
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/61—Coherent receivers
- H04B10/614—Coherent receivers comprising one or more polarization beam splitters, e.g. polarization multiplexed [PolMux] X-PSK coherent receivers, polarization diversity heterodyne coherent receivers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/70—Photonic quantum communication
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/80—Optical aspects relating to the use of optical transmission for specific applications, not provided for in groups H04B10/03 - H04B10/70, e.g. optical power feeding or optical transmission through water
- H04B10/801—Optical aspects relating to the use of optical transmission for specific applications, not provided for in groups H04B10/03 - H04B10/70, e.g. optical power feeding or optical transmission through water using optical interconnects, e.g. light coupled isolators, circuit board interconnections
- H04B10/802—Optical aspects relating to the use of optical transmission for specific applications, not provided for in groups H04B10/03 - H04B10/70, e.g. optical power feeding or optical transmission through water using optical interconnects, e.g. light coupled isolators, circuit board interconnections for isolation, e.g. using optocouplers
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Electromagnetism (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optics & Photonics (AREA)
- Theoretical Computer Science (AREA)
- Computer Security & Cryptography (AREA)
- Optical Communication System (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
The invention discloses a polarization coding quantum key distribution system encoder main laser which emits a 45-degree linearly polarized light pulse laser signal, the signal is divided into horizontal and vertical linearly polarized light by a beam splitter and a polarization beam splitter and respectively injected into a laser 1, a laser 2, a laser 3 and a laser 4, when the laser 1, the laser 2, the laser 3 and the laser 4 are respectively triggered, an optical signal with the same wavelength as the main laser is obtained, emergent polarized light and injected polarized light of different lasers are the same, and finally single photon transmission is attenuated by beam combination. The encoder can realize the transmitting end of the polarization encoding quantum key transmitting system, and can realize the frequency domain consistency among the multiple lasers under the condition of adopting the multiple lasers, thereby not only ensuring the feasibility of engineering realization, but also ensuring the system safety.
Description
Technical Field
The invention relates to the technical field of quantum cryptography, in particular to a quantum key distribution system adopting a polarization coding scheme.
Background
Quantum key distribution systems have attracted much attention for many years because they can provide theoretically secure symmetric keys for both parties. The BB84 protocol is the first quantum key distribution protocol and is currently the most applied to engineering, and its theoretical security has been proven. The polarization encoding quantum key distribution system usually adopts a multi-laser device to randomly encode four polarization quantum states, and particularly in a free space system, when the modulation rate is high, no practical high-speed polarization modulation device exists at present. Because of the difference between the lasers, the consistency of the multiple lasers in the frequency domain dimension cannot be ensured, so that the actually emergent polarization states can be distinguished in the frequency domain dimension, and potential safety hazards exist.
Disclosure of Invention
The invention aims to solve the technical problem of realizing a polarization coding quantum key distribution system encoder, which can realize consistency in a frequency domain and ensure that emergent polarization states cannot be distinguished in the dimension of the frequency domain, thereby ensuring the feasibility of engineering realization and ensuring the safety of the system.
In order to achieve the purpose, the invention adopts the technical scheme that: a polarization coding quantum key distribution system encoder, the main laser sends out optical signal to the beam splitter 1 and divides into two optical signals to output, wherein, one path of optical signal is transmitted to a beam splitter 2, the other path of optical signal is transmitted to a beam splitter 3, the beam splitter 2 outputs optical signals to a laser 1 only receiving horizontal polarized light and a laser 2 only receiving vertical polarized light respectively, the laser 1 and the laser 2 emit the same optical signal as the injected optical signal and send the optical signal to the attenuator through the beam splitter 2 and the beam splitter 4, the beam splitter 3 outputs optical signals to a laser 3 receiving only horizontally polarized light and a laser 4 receiving only vertically polarized light, the laser 3 and the laser 4 emit the same optical signal as the injected optical signal, and the optical signal is transmitted to the attenuator through the beam splitter 3, the half-wave plate and the beam splitter 4, and the attenuator attenuates the received optical signals emitted by the four lasers into single photon pulses and outputs the single photon pulses.
The laser 1 and the laser 3 are lasers of a horizontal polarizing plate, and the laser 2 and the laser 4 are lasers of a vertical polarizing plate.
The beam splitter 2 divides 45-degree linearly polarized light into horizontal polarized light and vertical polarized light through the polarization beam splitter 1 and respectively sends the horizontal polarized light and the vertical polarized light to the laser 1 and the laser 2, and the beam splitter 3 divides 45-degree linearly polarized light into horizontal polarized light and vertical polarized light through the polarization beam splitter 2 and respectively sends the horizontal polarized light and the vertical polarized light to the laser 3 and the laser 4.
An isolator 1 which only allows the optical signal to be sent from the beam splitter 1 to the beam splitter 2 is arranged on an optical path between the beam splitter 1 and the beam splitter 2, and an isolator 2 which only allows the optical signal to be sent from the beam splitter 1 to the beam splitter 3 is arranged on an optical path between the beam splitter 1 and the beam splitter 3.
The main laser, the laser 1, the laser 2, the laser 3 and the laser 4 are all semiconductor lasers, and the main laser emits 45-degree linearly polarized light which is an optical signal with a set wavelength.
The half-wave plate is used for rotating linearly polarized light by 45 degrees.
The polarization beam splitter is used for splitting or combining and transmitting horizontally linear polarized light and vertically linear polarized light.
The beam splitter 1, the beam splitter 2, the beam splitter 3 and the beam splitter 4 are polarization-independent beam splitters, the splitting ratio is 50:50, the beam splitters are used for equally splitting incident light energy into two parts on a horizontal path and a vertical path, and the beam splitters are also used for combining beams and transmitting the combined beams on the horizontal path and the vertical path.
The encoder can realize the transmitting end of the polarization encoding quantum key transmitting system, and can realize the frequency domain consistency among the multiple lasers under the condition of adopting the multiple lasers, thereby not only ensuring the feasibility of engineering realization, but also ensuring the system safety.
Drawings
The following is a brief description of the contents of each figure in the description of the present invention:
FIG. 1 is a schematic diagram of an encoder of a polarization encoded quantum key distribution system;
fig. 2 is a schematic diagram of another embodiment of an encoder of a polarization-encoded quantum key distribution system.
Detailed Description
The following description of the embodiments with reference to the drawings is provided to describe the embodiments of the present invention, and the embodiments of the present invention, such as the shapes and configurations of the components, the mutual positions and connection relationships of the components, the functions and working principles of the components, the manufacturing processes and the operation and use methods, etc., will be further described in detail to help those skilled in the art to more completely, accurately and deeply understand the inventive concept and technical solutions of the present invention.
The polarization encoding quantum key distribution system encoder comprises the following components:
the main laser, preferably a semiconductor laser, can be linearly polarized light with 45 degrees; providing an optical pulse signal with a specific wavelength;
a laser, preferably a semiconductor laser, for emitting an optical pulse signal of a specific wavelength and polarization state from the injected optical pulse signal;
a beam splitter, preferably a polarization independent beam splitter, with a splitting ratio of 50:50, equally dividing incident light energy into two parts on horizontal and vertical paths; meanwhile, the beam combining function is also provided, and the beams on the horizontal and vertical paths are combined and transmitted;
an isolator, preferably a polarization independent optical isolator, allowing light to pass only in the forward direction and cut off in the reverse direction;
the polarization beam splitter is used for splitting or combining and transmitting the horizontal line polarized light and the vertical line polarized light;
the half-wave plate rotates the linearly polarized light by 45 degrees;
and the attenuator is used for attenuating the emergent light pulse into a single photon pulse.
As shown in fig. 1, the main laser emits 45-degree linearly polarized light, which is divided into two light signals with equal energy by the beam splitter 1, one light signal reaches the beam splitter 2 by the isolator 1, the beam splitter 2 divides one light signal to reach the polarization beam splitter 1, and the polarization beam splitter 1 divides the 45-degree linearly polarized light into horizontal polarized light and vertical polarized light, which respectively reach the laser 1 and the laser 2. Under the injected horizontal polarized light and vertical polarized light, the laser 1 and the laser 2 will generate optical signals with the same wavelength as the injected optical signals, when the laser 1 is triggered, the horizontal polarized light with the same wavelength as the main laser is generated, and when the laser 2 is triggered, the vertical polarized light with the same wavelength as the main laser is generated. The two are polarized and combined by a polarization beam splitter, and are split by a beam splitter 2 to reach a beam splitter 4, and are attenuated into single photon pulses by an attenuator;
similarly, one beam reaches the beam splitter 3 through the isolator 2, the beam splitter 3 splits the other beam to reach the polarization beam splitter 2, and the polarization beam splitter 2 splits the 45-degree linearly polarized light into horizontal polarized light and vertical polarized light which respectively reach the laser 3 and the laser 4. The laser 3 and the laser 4 will generate an optical signal with the same wavelength as the injected optical signal under the injected horizontally polarized light and vertically polarized light, and generate horizontally polarized light with the same wavelength as the main laser when the laser 3 is triggered and generate vertically polarized light with the same wavelength as the main laser when the laser 4 is triggered. The two are polarized and combined through a polarization beam splitter, the beams are split through the beam splitter 3 and reach a half-wave plate, the half-wave plate rotates the horizontal polarized light and the vertical polarized light for 45 degrees to obtain 45-degree linearly polarized light and 135-degree linearly polarized light, and finally the single-photon pulses are attenuated through an attenuator.
Thus, when the main laser continuously works, the randomly selected trigger laser 1/2/3/4 can obtain four polarization encoding quantum states with consistent wavelengths, and the requirements of a quantum key distribution system are met.
Fig. 2 shows another embodiment of an encoder for a polarization-encoded quantum key distribution system, which differs from fig. 1 in that the polarization beam splitter is omitted, but the corresponding laser 1/2/3/4 needs to have a corresponding polarizer, for example: lasers 1 and 3 contain horizontal polarizers and lasers 2 and 4 contain vertical polarizers. In this way, four polarization encoded quantum states with consistent wavelengths can be obtained, but the laser needs to integrate a horizontal/vertical polarizer and can also meet the requirements of a quantum key distribution system.
The working principle of the encoder of the polarization coding quantum key distribution system is that a main laser emits a 45-degree linearly polarized light pulse laser signal, the laser signal is divided into horizontal linearly polarized light and vertical linearly polarized light through a beam splitter and a polarization beam splitter and is respectively injected into a laser 1, a laser 2, a laser 3 and a laser 4, when the laser 1, the laser 2, the laser 3 and the laser 4 are respectively triggered, an optical signal with the same wavelength as that of the main laser is obtained, emergent polarized light and injected polarized light of different lasers are the same, single photon transmission is attenuated through beam combination, wherein the laser 1 and the laser 2 generate horizontal line polarized light and vertical linearly polarized light, the horizontal polarized light and vertical polarized light generated by the laser 3 and the laser 4 rotate for 45 degrees through a half-wave plate, 45-degree linearly polarized light and 135-degree linearly polarized light are obtained, and random coding of four polarization states can be realized, the requirements of a quantum key distribution system are met, the practical feasibility of engineering is guaranteed, and the system safety is improved.
The invention has been described above with reference to the accompanying drawings, it is obvious that the invention is not limited to the specific implementation in the above-described manner, and it is within the scope of the invention to apply the inventive concept and solution to other applications without substantial modification.
Claims (8)
1. A polarization encoded quantum key distribution system encoder, comprising: the main laser emits light signals to the beam splitter 1 and is divided into two paths of light signals to be output, wherein one path of light signals is transmitted to the beam splitter 2, the other path of light signals is transmitted to the beam splitter 3, the beam splitter 2 outputs optical signals to a laser 1 receiving only horizontally polarized light and a laser 2 receiving only vertically polarized light, the laser 1 and the laser 2 emit the same optical signal as the injected optical signal and send the optical signal to the attenuator through the beam splitter 2 and the beam splitter 4, the beam splitter 3 outputs optical signals to a laser 3 receiving only horizontally polarized light and a laser 4 receiving only vertically polarized light, the laser 3 and the laser 4 emit the same optical signal as the injected optical signal, and the optical signal is transmitted to the attenuator through the beam splitter 3, the half-wave plate and the beam splitter 4, and the attenuator attenuates the received optical signals emitted by the four lasers into single photon pulses and outputs the single photon pulses.
2. The polarization encoded quantum key distribution system encoder of claim 1, wherein: the laser 1 and the laser 3 are lasers of a horizontal polarizing plate, and the laser 2 and the laser 4 are lasers of a vertical polarizing plate.
3. The polarization encoded quantum key distribution system encoder of claim 1, wherein: the beam splitter 2 divides 45-degree linearly polarized light into horizontal polarized light and vertical polarized light through the polarization beam splitter 1 and respectively sends the horizontal polarized light and the vertical polarized light to the laser 1 and the laser 2, and the beam splitter 3 divides 45-degree linearly polarized light into horizontal polarized light and vertical polarized light through the polarization beam splitter 2 and respectively sends the horizontal polarized light and the vertical polarized light to the laser 3 and the laser 4.
4. The polarization encoded quantum key distribution system encoder of claim 2, wherein: the polarization beam splitter is used for splitting or combining and transmitting horizontally linear polarized light and vertically linear polarized light.
5. The polarization encoded quantum key distribution system encoder of claim 1, 2, 3 or 4, wherein: an isolator 1 which only allows the optical signal to be sent from the beam splitter 1 to the beam splitter 2 is arranged on an optical path between the beam splitter 1 and the beam splitter 2, and an isolator 2 which only allows the optical signal to be sent from the beam splitter 1 to the beam splitter 3 is arranged on an optical path between the beam splitter 1 and the beam splitter 3.
6. The polarization encoded quantum key distribution system encoder of claim 5, wherein: the main laser, the laser 1, the laser 2, the laser 3 and the laser 4 are all semiconductor lasers, and the main laser emits 45-degree linearly polarized light which is an optical signal with a set wavelength.
7. The polarization encoded quantum key distribution system encoder of claim 1 or 6, wherein: the half-wave plate is used for rotating linearly polarized light by 45 degrees.
8. The polarization encoded quantum key distribution system encoder of claim 7, wherein: the beam splitter 1, the beam splitter 2, the beam splitter 3 and the beam splitter 4 are polarization-independent beam splitters, the splitting ratio is 50:50, the beam splitters are used for equally splitting incident light energy into two parts on a horizontal path and a vertical path, and the beam splitters are also used for combining beams and transmitting the combined beams on the horizontal path and the vertical path.
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| CN202110248995.3A CN113259090A (en) | 2021-03-08 | 2021-03-08 | Encoder of polarization encoding quantum key distribution system |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080037998A1 (en) * | 2004-02-02 | 2008-02-14 | University Of Science And Technology Of China | Polarization-Controlled Encoding Method, Encoder, And Quantum Key Distribution System |
| CN106254065A (en) * | 2016-08-01 | 2016-12-21 | 中国科学技术大学 | Quantum key distribution light source based on injection locking technique |
| CN110048841A (en) * | 2019-05-24 | 2019-07-23 | 浙江九州量子信息技术股份有限公司 | A kind of simple polarization encoder quantum key distribution system and method |
| CN111740823A (en) * | 2020-07-09 | 2020-10-02 | 国开启科量子技术(北京)有限公司 | Time-phase quantum key coding device, system and method |
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2021
- 2021-03-08 CN CN202110248995.3A patent/CN113259090A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080037998A1 (en) * | 2004-02-02 | 2008-02-14 | University Of Science And Technology Of China | Polarization-Controlled Encoding Method, Encoder, And Quantum Key Distribution System |
| CN106254065A (en) * | 2016-08-01 | 2016-12-21 | 中国科学技术大学 | Quantum key distribution light source based on injection locking technique |
| CN110048841A (en) * | 2019-05-24 | 2019-07-23 | 浙江九州量子信息技术股份有限公司 | A kind of simple polarization encoder quantum key distribution system and method |
| CN111740823A (en) * | 2020-07-09 | 2020-10-02 | 国开启科量子技术(北京)有限公司 | Time-phase quantum key coding device, system and method |
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Application publication date: 20210813 |