Dynamic polarization compensation method and system based on quantum key distribution network

Abstract

The embodiment of the application provides a kind of dynamic polarization compensation method and system based on quantum key distribution (QKD) network, belong to quantum communication technical field.The dynamic polarization compensation method includes: the angle value of the rotation paddle of electric polarization controller in each QKD network node is initialized;The polarization degree of each network node is calculated according to the angle value;Each angle value is adjusted so that the polarization degree of each network node reaches maximum;Global polarization degree is calculated according to the polarization degree of each network node;Whether the global polarization degree is greater than global polarization threshold is judged;In the case where the global polarization degree is greater than the global polarization threshold, it is determined that the network at this time is in the best state.The dynamic polarization compensation method and system can network in higher polarization degree.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantum communication, in particular to a dynamic polarization compensation method and system based on a quantum key distribution network. BACKGROUND

[0002] Quantum Key Distribution (QKD) provides unconditional security, which promotes the development of quantum communication networks. However, as these networks develop, there is an increasing need to reduce complexity and overhead. Due to the scalability of the network and the lack of trusted nodes, polarization-based entanglement distribution technology is a promising approach. However, they are only feasible when the birefringence of all the optical distribution fibers in the network is compensated to maintain polarization-based quantum states. Even for a medium-sized network, a brute-force approach requires several hundred fiber polarization controllers, making it difficult to engineer quantum communication applications.

[0003] Quantum Key Distribution provides provable security for protocols used to exchange encryption keys and encrypted messages between multiple users. Generally, most implementations focus on a single QKD link consisting of two users. In particular, for short QKD approaches, polarization encoding is a common method. Compared with time-bin encoding, using the polarization state of photons in QKD simplifies the end-user hardware, as this encoding method does not require an interferometer. However, any polarization encoding scheme will be affected by the birefringence of the optical fibers used, and will not work without some form of polarization compensation. As quantum communication gradually moves towards real-world applications, it is crucial to design and implement a simple and effective polarization compensation scheme. In addition, since manual polarization controllers are limited by human factors and are slow to meet polarization requirements, electric polarization controllers have emerged. Electric controllers can take advantage of the stress birefringence generated inside the optical fiber to control the rotation paddle inside it to make the incident light output polarization state. Therefore, how to effectively complete polarization compensation in the QKD network using electric polarization controllers to ensure that the network has a high degree of polarization is still a problem that needs to be solved. SUMMARY

[0004] The purpose of the embodiments of the present application is to provide a dynamic polarization compensation method and system based on a quantum key distribution network, which can ensure that the network has a high degree of polarization.

[0005] To achieve the above-mentioned purpose, the embodiments of the present application provide a dynamic polarization compensation method based on a quantum key distribution network, comprising:

[0006] initializing the angle value of the electric polarization controller rotation paddle in each QKD network node;

[0007] calculating the degree of polarization of each network node according to the angle value.

[0008] adjusting each of the angle values so that the polarization degree of each network node reaches a maximum value;

[0009] calculating a global polarization degree according to the polarization degree of each of the network nodes;

[0010] judging whether the global polarization degree is greater than a global polarization threshold value;

[0011] in a case where it is judged that the global polarization degree is greater than the global polarization threshold value, determining that the network at this time is in an optimal state.

[0012] Optionally, in a case where it is judged that the global polarization degree is less than or equal to the global polarization threshold value, adjusting the incident polarized light angle of the network, and returning to the step of initializing the angle value of the electric polarization controller rotating paddle in each QKD network node again.

[0013] Optionally, calculating the polarization degree of each network node according to the angle values comprises:

[0014] calculating the polarization degree according to formula (1),

[0015]

[0016] wherein P i is the polarization degree of the i th network node, I max is the light intensity of the most dominant vibration direction, and I min is the light intensity of the least dominant vibration direction.

[0017] Optionally, adjusting each of the angle values so that the polarization degree of each network node reaches a maximum value comprises:

[0018] controlling the electric polarization controller rotating paddle of the network node to rotate to adjust the angle value.

[0019] Optionally, calculating a global polarization degree according to the polarization degree of each of the network nodes comprises:

[0020] calculating the global polarization degree according to formula (2),

[0021] P ave =∑ N P imax / N, (2)

[0022] wherein P ave is the global polarization degree, and P imax is the maximum value of the polarization degree of the i th network node.

[0023] In another aspect, the present application also provides a dynamic polarization compensation system based on a quantum key distribution network, the dynamic polarization compensation system comprising a controller configured to:

[0024] initialize an angle value of a rotating paddle of an electric polarization controller in each QKD network node;

[0025] calculate a polarization degree of each network node according to the angle value;

[0026] adjust each of the angle values so that the polarization degree of each network node reaches a maximum value;

[0027] calculate a global polarization degree according to the polarization degree of each network node;

[0028] determine whether the global polarization degree is greater than a global polarization threshold value;

[0029] in a case where it is determined that the global polarization degree is greater than the global polarization threshold value, determine that the network at this time is in an optimal state.

[0030] Optionally, in a case where it is determined that the global polarization degree is less than or equal to the global polarization threshold value, adjust an incident polarization light angle of the network, and return to the step of initializing the angle value of the rotating paddle of the electric polarization controller in each QKD network node again.

[0031] Optionally, the calculation of the polarization degree of each network node according to the angle value comprises:

[0032] the polarization degree is calculated according to formula (1),

[0033]

[0034] wherein P i is the polarization degree of the i-th network node, I max is an optical intensity of a most advantageous vibration direction, and I min is an optical intensity of a most disadvantageous vibration direction.

[0035] Optionally, the adjustment of each of the angle values so that the polarization degree of each network node reaches the maximum value comprises:

[0036] the network node electric polarization controller rotating paddle is controlled to rotate to adjust the angle value.

[0037] Optionally, the calculation of the global polarization degree according to the polarization degree of each network node comprises:

[0038] the global polarization degree is calculated according to formula (2),

[0039] P ave =∑ N P imaxN, (2)

[0040] wherein P ave is the global polarization degree, P imax is the maximum value of the polarization degree of the i-th network node.

[0041] By the above technical solution, the dynamic polarization compensation method and system based on a quantum key distribution network provided by the application adjusts the angle value of each network node to adjust the polarization degree. When adjusting the polarization degree, the dynamic polarization compensation method and system determines whether the current network node is in a higher polarization degree as a whole in combination with the evaluation of the global polarization degree, so that the network node can always be in a higher polarization degree state. The dynamic polarization compensation method fully utilizes the advantages of the electric polarization controller and does not need downtime to dynamically adjust the rotation paddle amplitude of the electric polarization controller in the active state of the network, thereby realizing the maximum global polarization degree of the quantum communication network.

[0042] Other features and advantages of the embodiments of the application will be described in detail in the following specific implementation part. BRIEF DESCRIPTION OF DRAWINGS

[0043] The accompanying drawings are included to provide a further understanding of the embodiments of the application, and constitute a part of the specification, and are used together with the following specific implementation to explain the embodiments of the application, but do not constitute a limitation on the embodiments of the application. In the drawings:

[0044] Figure 1 is a flowchart of a dynamic polarization compensation method based on a quantum key distribution network according to an embodiment of the application;

[0045] Figure 2 is a schematic diagram of a network node according to an embodiment of the application;

[0046] Figure 3 is a schematic diagram of a network node connection relationship according to an embodiment of the application. DETAILED DESCRIPTION

[0047] The specific implementation of the embodiments of the application will be described in detail below in combination with the drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiments of the application, and is not used to limit the embodiments of the application.

[0048] As shown in Figure 1 is a flowchart of a dynamic polarization compensation method based on a quantum key distribution network according to an embodiment of the application. In this Figure 1 , the dynamic polarization compensation method can include:

[0049] In step S10, the angle value of the rotating paddle of the electric polarization controller in each QKD network node is initialized. In this embodiment, the structure of each network node can be as shown in Figure 2 . The connection relationship between the network nodes can be as shown in Figure 3 . In this Figure 2 embodiment, the network node can include a polarization entangled photon source, an electric fiber polarization controller, a polarization analysis module, a dense optical wave multiplexer, and a QKD device group. In this Figure 3 embodiment, each network node can be connected to each other to form a full-mesh QKD network, each pair of users is a transmitter and a receiver of a high-dimensional two-particle entangled state and shares a single two-particle entangled state. Each user is in an unknown state with respect to the particle entangled state between other users.

[0050] In step S11, the polarization degree of each network node is calculated according to the angle value. Specifically, the polarization degree can be calculated according to formula (1),

[0051]

[0052] where P i is the polarization degree of the i-th network node, I max is the light intensity of the most dominant vibration direction, and I min is the light intensity of the most inferior vibration direction.

[0053] In step S12, each angle value is adjusted so that the polarization degree of each network node reaches a maximum value. Specifically, the way to adjust the angle value can be to control the rotation of the rotating paddle of the electric polarization controller of the network node to adjust the angle value. The electric polarization controller is powered by a USB, which can be connected to a computer. The staff can control the electric polarization controller through the computer using software, thereby realizing the homing, micro-motion, and positioning of the rotating paddle of the electric polarization controller.

[0054] In step S13, the global polarization degree is calculated according to the polarization degree of each network node. Specifically, the way to calculate the global polarization degree can be to calculate according to formula (2),

[0055] P ave =∑ N P imax / N, (2)

[0056] where P ave is the global polarization degree, and P imax is the maximum value of the polarization degree of the i-th network node.

[0057] In step S14, it is determined whether the global polarization degree is greater than a global polarization threshold value;

[0058] In step S15, if the global polarization degree is greater than the global polarization threshold, the network is determined to be in the optimal state.

[0059] In step S16, if it is determined that the global polarization degree is less than or equal to the global polarization threshold, the incident polarization angle of the network is adjusted (in one example of the present invention, step S16 may be adjusting the incident polarization angle of the network node that is lower than the global polarization threshold), and the process returns to the step of initializing the angle value of the electric polarization controller rotary propeller in each QKD network node, that is, returning to the execution of step S10.

[0060] On the other hand, the present invention also provides a dynamic polarization compensation system based on a quantum key distribution network. This dynamic polarization compensation system may include a controller, which can be used to perform actions such as... Figure 1 The method shown in the diagram. Figure 1 In this context, the controller can be used for:

[0061] In step S10, the angle value of the propeller of the electric polarization controller in each QKD network node is initialized. In this embodiment, the structure of each network node can be as follows: Figure 2 As shown. The connection relationships between network nodes can be as follows: Figure 3 As shown. In this Figure 2 In this network, the node may comprise a polarization-entangled photon source, an electrically powered fiber polarization controller, a polarization analysis module, a dense optical multiplexer, and a QKD device. Figure 3 In this system, each network node can be interconnected to form a fully meshed QKD network. Each pair of users acts as the transmitter and receiver of a high-dimensional two-particle entangled state and shares a single two-particle entangled state. The particle entanglement states between each user and other users are unknown to each user.

[0062] In step S11, the degree of polarization of each network node is calculated based on the angle value. Specifically, this degree of polarization can be calculated according to formula (1).

[0063]

[0064] Among them, P i Let I be the polarization degree of the i-th network node. max The light intensity in the direction of the most dominant vibration, I min The light intensity is in the direction of the least dominant vibration.

[0065] In step S12, each angle value is adjusted so that the polarization degree of each network node reaches its maximum value. Specifically, the angle value can be adjusted by controlling the rotation of the motorized polarization controller's paddle at the network node to adjust the angle value. The motorized polarization controller is powered by a USB cable, which can be connected to a computer. Operators can use software on the computer to control the motorized polarization controller, thereby achieving the return, fine-tuning, and positioning of the motorized polarization controller's paddle.

[0066] In step S13, the global polarization degree is calculated based on the polarization degree of each network node. Specifically, the global polarization degree can be calculated using formula (2).

[0067] P ave =∑ N P imax / N, (2)

[0068] Among them, P ave For global polarization degree, P imax It represents the maximum polarization degree of the i-th network node.

[0069] In step S14, it is determined whether the global polarization degree is greater than the global polarization threshold;

[0070] In step S15, if the global polarization degree is greater than the global polarization threshold, the network is determined to be in the optimal state.

[0071] In step S16, if the global polarization degree is less than or equal to the global polarization threshold, the incident polarization angle of the network is adjusted, and the process returns to the step of initializing the angle value of the electric polarization controller rotating propeller in each QKD network node, that is, returning to step S10.

[0072] Through the above technical solution, the dynamic polarization compensation method and system based on quantum key distribution networks provided by this invention adjusts the degree of polarization by adjusting the angle value of each network node. When adjusting the degree of polarization, this dynamic polarization compensation method and system combines a global polarization degree assessment to determine whether the current network node is in a high polarization degree overall, thus ensuring that the network node remains in a high polarization degree state. This dynamic polarization compensation method fully utilizes the advantages of the electric polarization controller, dynamically adjusting the rotation amplitude of the electric polarization controller's propellers while the network is active, without requiring downtime, thereby maximizing the global polarization degree of the quantum communication network.

[0073] Those skilled in the art will appreciate that embodiments of the application can be readily used as software, hardware, or a combination of software and hardware. In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0074] The present application is described in reference to the flowchart illustrations and / or block diagrams according to the embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processing system, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 Figure 1

[0075] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the flowchart illustrations and / or block diagrams. Figure 1 Figure 1

[0076] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the flowchart illustrations and / or block diagrams. Figure 1 Figure 1

[0077] In one typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0078] The memory can include non-persistent memory and / or volatile memory, such as a random access memory (RAM) including a cache area for the temporary storage of data. The memory can also include non-volatile memory, such as a read only memory (ROM), EPROM, EEPROM, flash memory, or other non-volatile memory storage. The memory can be another type of computer-readable media, a magnetic-based computer-readable media, an optical-based computer-readable media, or any other medium from which a computer can read. ​​​​​​

[0079] Computer-readable media includes permanent and non-permanent, movable and non-movable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer-readable media does not include transitory media such as modulated data signals and carriers.

[0080] It should also be noted that the terms "comprising", "containing", or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article or apparatus that includes a list of elements does not only include those elements, but also includes other elements not explicitly listed, or further includes elements inherent in such a process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0081] The above only is an embodiment of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A dynamic polarization compensation method based on a quantum key distribution (QKD) network, characterized in that, The dynamic polarization compensation method comprises: initializing an angle value of a rotating paddle of an electric polarization controller in each QKD network node; calculating a polarization degree of each network node according to the angle value; adjusting each of the angle values so that the polarization degree of each network node reaches a maximum value; calculating a global polarization degree according to the polarization degrees of each of the network nodes, comprising: calculating the global polarization degree according to formula (2), P ave =∑ N P imax / N, (2) where P ave is the global polarization, P imax is the maximum value of the polarization of the i-th network node; judging whether the global polarization degree is greater than a global polarization threshold value; in a case where it is judged that the global polarization degree is greater than the global polarization threshold value, determining that the network at this time is in an optimal state; in a case where it is judged that the global polarization degree is less than or equal to the global polarization threshold value, adjusting an incident polarization light angle of the network node below the global polarization threshold value, and returning to the step of initializing the angle value of the rotating paddle of the electric polarization controller in each QKD network node again.

2. The dynamic polarization compensation method of claim 1, wherein, calculating the polarization degree of each network node according to the angle value comprises: calculating the polarization degree according to formula (1), where P i is the polarization degree of the i-th network node, I max is the light intensity of the most dominant vibration direction, I min is the light intensity of the most inferior vibration direction.

3. The dynamic polarization compensation method of claim 1, wherein, adjusting each of the angle values so that the polarization degree of each network node reaches a maximum value comprises: controlling the rotating paddle of the electric polarization controller of the network node to rotate to adjust the angle value.

4. A dynamic polarization compensation system based on a quantum key distribution network, characterized in that, The dynamic polarization compensation system comprises a controller, which is configured to: initialize an angle value of a rotating paddle of an electric polarization controller in each QKD network node; calculate a polarization degree of each network node according to the angle value; adjust each of the angle values so that the polarization degree of each network node reaches a maximum value; calculate a global polarization degree according to the polarization degrees of each of the network nodes, comprising: calculate the global polarization degree according to formula (2), P ave =∑ N P imax / N, (2) where P ave is the global polarization, P imax is the maximum value of the polarization of the i-th network node; judge whether the global polarization degree is greater than a global polarization threshold value; in a case where it is judged that the global polarization degree is greater than the global polarization threshold value, determine that the network at this time is in an optimal state; in a case where it is judged that the global polarization degree is less than or equal to the global polarization threshold value, adjust an incident polarization light angle of the network, and return to the step of initializing the angle value of the rotating paddle of the electric polarization controller in each QKD network node again.

5. The dynamic polarization compensation system of claim 4, wherein, calculating the polarization degree of each network node according to the angle value comprises: calculating the polarization degree according to formula (1), where P i is the polarization degree of the i-th network node, I max is the light intensity of the most dominant vibration direction, I min is the light intensity of the most inferior vibration direction.

6. The dynamic polarization compensation system of claim 4, wherein, adjusting each of the angle values so that the polarization degree of each network node reaches a maximum value comprises: controlling the rotating paddle of the electric polarization controller of the network node to rotate to adjust the angle value.

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