Routing method for quantum communication network

Abstract

The application discloses a routing method of a quantum communication network, which comprises the following steps: firstly, establishing a quantum relay node availability evaluation mechanism based on a queuing model, and adopting the time required by a system to complete a remaining task to represent the congestion degree of a node; and secondly, establishing a multi-path routing mechanism of entanglement distribution based on node attributes and link attributes; wherein the node attributes comprise the availability of a quantum relay node and a quantum bit capacity attribute; and the link attributes comprise the entanglement link fidelity between quantum relay nodes and a classical communication time delay attribute. The above method integrates the relay node queuing model into the network modeling process, so as to enhance the perception of each node to the resource use state in the network environment and balance the task load of each relay node; meanwhile, the multi-path discovery method is integrated into the routing transmission mechanism, so as to cope with the high competition of quantum bit resources and reduce the risk of single request delivery failure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantum communication, and in particular to a routing method of a quantum communication network. BACKGROUND

[0002] As a research direction with great application value in quantum information science, quantum communication technology can provide a physically unconditionally secure communication method from the physical layer, greatly improving the security of existing information systems. In addition, because of the superposition and entanglement of quantum states, quantum communication is more efficient in data transmission than classical communication. Quantum communication embeds quantum channels into classical networks to form quantum networks, thereby transmitting and manipulating quantum bits between remote nodes, and ultimately running applications that cannot be implemented on the Internet, such as clock synchronization, quantum key distribution, distributed quantum computing, etc. The long-term development goal of quantum communication is to realize metropolitan quantum communication networks through optical fibers, connections between two adjacent cities through repeaters, and connections between remote areas through satellite platforms, and ultimately to build a global wide-area quantum communication network system.

[0003] When a quantum communication network runs the promising services such as secure communication and high-precision clock synchronization described above, in addition to the connections of classical communication, quantum communication connections provided by quantum entangled pairs need to be shared in advance between nodes. At the same time, the transmission of quantum bit data in the quantum communication network will be accompanied by the consumption process of quantum entangled resources. Therefore, the establishment and distribution of entangled pairs between any nodes in the network are crucial for quantum communication networks. The effective entanglement distribution between distant nodes faces many severe challenges: unlike binary classical bits in traditional communication, quantum bits created by photons are very fragile, and under the influence of channel transmission loss in optical fibers, the probability of successfully establishing entanglement between quantum bits decreases exponentially with distance. Quantum bits are essentially non-reproducible, making it impossible to use signal amplification or retransmission methods to eliminate the effects of transmission loss in long-distance communication scenarios. Currently, the scheme of establishing entangled pairs between nodes close to each other, and then performing entanglement swapping through quantum relay nodes to realize long-distance entanglement distribution is considered to be a relatively reliable solution.

[0004] However, quantum storage devices are the core constraint of building quantum communication networks in this way. The current maximum quantum register with a storage time of minutes has a capacity of only 10 quantum bits. In a classical network, each terminal node can manipulate billions of bits, while a quantum network node can only establish a limited number of entanglement links with other nodes for a long time, which may lead to a situation where multiple relay nodes have no remaining quantum bits for subsequent requests in a multi-request environment. Therefore, due to the limited capacity of quantum bits stored by each relay node, it is difficult to meet the demand in a complex scenario where multiple entangled pairs are required for each request. SUMMARY

[0005] The purpose of the present application is to provide a routing method for a quantum communication network, which integrates a relay node queuing model into the network modeling process to enhance the perception of each node to the resource usage state in the network environment and balance the task load of each relay node; and integrates a multi-path discovery method into the routing transmission mechanism to cope with the high competition for quantum bit resources and reduce the risk of single request delivery failure.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] A routing method for a quantum communication network, the method comprising:

[0008] Step 1, establishing a quantum relay node availability evaluation mechanism based on a queuing model, using the time required for the system to complete the remaining tasks to represent the congestion degree of the node;

[0009] Step 2, establishing a multi-path routing mechanism for entanglement distribution based on node attributes and link attributes; wherein the node attributes include the availability of quantum relay nodes and quantum bit capacity attributes; the link attributes include the entanglement link fidelity between quantum relay nodes and classical communication delay attributes.

[0010] As can be seen from the above technical solutions provided by the present application, the above method integrates a relay node queuing model into the network modeling process to enhance the perception of each node to the resource usage state in the network environment and balance the task load of each relay node; and integrates a multi-path discovery method into the routing transmission mechanism to cope with the high competition for quantum bit resources and reduce the risk of single request delivery failure. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0012] Figure 1 A flow chart of a routing method of a quantum communication network according to an embodiment of the present application is shown in FIG. 1;

[0013] Figure 2 A schematic diagram of a quantum communication network according to an embodiment of the present application is shown in FIG. 2;

[0014] Figure 3 A schematic diagram of a relay node availability evaluation according to an embodiment of the present application is shown in FIG. 3;

[0015] Figure 4 A schematic diagram of attribute information of each node and link according to an embodiment of the present application is shown in FIG. 4. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application, which do not constitute a limitation on the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0017] As shown in FIG. 1, a flow chart of a routing method of a quantum communication network according to an embodiment of the present application is shown in FIG. 1, the method comprising: Figure 1

[0018] Step 1, establishing a quantum relay node availability evaluation mechanism based on a queuing model, using the time required for the system to complete the remaining tasks to represent the congestion degree of the node;

[0019] In this step, N=(V, E, C) is used to represent the quantum communication network, where V represents the nodes of the network N; E represents that the nodes at both ends of the edge have a quantum channel and can establish single-hop entanglement; C represents the number of quantum storage bits available to the node, as shown in FIG. 2. Figure 2 A schematic diagram of a quantum communication network according to an embodiment of the present application is shown in FIG. 2;

[0020] The request set in the system is R, and each request r i ∈R is represented by a triple (s i , d i , w i ), respectively representing the node initiating the request, the target node of the node desiring to establish entanglement, and the number of entangled pairs (bandwidth) required by the request;

[0021] ​Queuing theory applies mathematical methods from probability theory and statistics to study the properties and behavior of queuing systems, optimizing system performance from the perspectives of reducing average waiting time, improving service efficiency, and increasing system capacity. Therefore, using queuing theory to model the service process of relay nodes in quantum communication networks can more clearly characterize the qubit usage of each node and create differentiation among busy nodes. More importantly, subsequent requests can utilize this information during the route discovery phase to avoid the most congested nodes, achieving a more time-sensitive entanglement distribution process under limited resource constraints. In this application, considering a scenario where entanglement requests are initiated independently by each node, transformed into multiple independent tasks reaching the relevant relay nodes after routing and resource allocation processes, and each relay node continuously provides services for different requests, a service model for quantum relay nodes is first established, including:

[0022] Each node is considered as a G / G / C queuing system with a number of service stations equal to the number of quantum storage bits, where G represents the arrival time of customers and the service time of the system following a general distribution; C represents the number of quantum storage bits available to the node, indicating that each storage bit corresponds to a service station in the queuing system, and the operations on these storage bits are performed in parallel.

[0023] With quantum repeater node v i For example, each quantum relay node maintains an ordered list of tasks according to a first-come, first-served rule. Each task's information is represented by a quadruple r = (c r F r v f v l The symbols represent, in order, the number of entangled pairs to be established in the task, the fidelity requirement for establishing entangled pairs, the previous hop node, and the next hop node of the task.

[0024] Taking task r as an example, the service process of each task in the queuing system is broken down into the following four stages, and the service time is examined for each stage:

[0025] 1) Task initialization

[0026] To obtain entanglement with the required fidelity, task r requests n vectors from the quantum relay node. r =2c r +n f +n l Each quantum bit (service desk) provides service to itself, where n f and n l These represent the links in the previous hop, v, respectively. f →v i and next-hop link v i →v lThe number of extra quantum bits reserved for subsequent entanglement purification, the time consumed by the initialization process is negligible;

[0027] 2) Establish entanglement link

[0028] Through the classical channel with the previous hop node V f After confirming the storage bits matching the task r, the link layer protocol is responsible for c r +n f Quantum bits to establish single-hop heralded entanglement with the previous hop node V f ; The average time required for this process is t fe , which depends on the distance between the two nodes and includes the time for classical communication; At the same time, the remaining c r +n l Quantum bits establish single-hop entanglement with the next hop node V l in t le Time, so the total time consumed in this stage is max{t fe , t le};

[0029] 3) Entanglement purification

[0030] The present application adopts the first generation repeater model, so the universal entanglement purification scheme based on the CNOT (Controlled-Non) gate is used. As known from the initialization stage, in the purification process with the previous hop node V f , c r +n f Single-hop entanglement links are divided into c r Groups, that is, each single-hop entanglement meeting the fidelity requirement F r requires an additional consumption of Single-hop entanglement; In view of the simplicity of scheduling, efficiency of purification and fidelity improvement effect, a symmetric entanglement scheduling scheme is adopted, which divides each group of purification into Rounds, and the purification within the round is performed in parallel; In the entanglement purification process with the previous hop node V f , the average time required for single-round entanglement purification is represented by t fp (Similarly, it includes the time for classical communication with other nodes), so the total time consumed in this stage is s fp ·t fp ; Similarly, the total time consumed in the purification with the next hop node V l is s lp ·t lp , so the total time consumed in the entanglement purification stage of the task r is max{s fp ·t fp , s lp ·t lp};

[0031] 4) entanglement swapping

[0032] Task r will perform Bell state joint measurement on those entangled pairs after entanglement purification: after passing two qubits through a CNOT gate, make X basis measurement on the control qubit and Z basis measurement on the target qubit respectively; finally, send the measurement results to the previous hop node v f and the next hop node v l respectively. The average time required for this process is t s (also including the time for classical communication between two nodes);

[0033] Considering the time spent in the above four stages, the total service time of task r at the quantum relay node is:

[0034] t r = max{t fe , t le} + max{s fp · t fp , s lp · t lp} + t s

[0035] This shows that task r will occupy n r quantum bits in the relay node for a period of t r ; To estimate the queuing time of a newly arrived task u at the node when the ordered task list at the node is R = {1,..., r,..., u-1}, since the number of service stations and service time required by different tasks may not be the same, and there is a possibility that different tasks are executed in parallel in the G / G / C queuing system formed at the node, which means that neither the queue length u-1 nor the sum of the service times of all tasks in the queue characterize the queuing time of task u at the node, the time required for the system to complete the remaining tasks is used to represent the congestion degree of the node, which is:

[0036] Let the time when task r leaves the queuing system be y r , then the time required for the system to complete the remaining tasks is also the latest completion time of all tasks in R = {1,..., r,..., u-1}, so the availability property of the quantum relay node v i is:

[0037]

[0038] A recursive algorithm is used to determine the time when all tasks leave the queuing system: by reviewing the list of tasks being served by the system, the estimated service time is used to estimate the departure time of these tasks in turn, the next task to be completed and the number of qubits released by it are determined; according to the first-come-first-served rule, the time when the next task to be served can enter the system is determined; the same method is used to estimate the departure time of the request, and the time when the next task to be served can enter the system is further inferred; this process is repeated until the completion time of all tasks R={1,...,r,...,u-1} is obtained.

[0039] Step 2, a multi-path routing mechanism for entanglement distribution is established based on node attributes and link attributes; wherein the node attributes include the availability of quantum relay nodes, quantum bit capacity attributes; the link attributes include the entanglement link fidelity between quantum relay nodes, classical communication delay attributes.

[0040] In this step, for the routing metric of entanglement distribution, given by k m +1 nodes formed k m -hop path is expressed as:

[0041]

[0042] Wherein represents the i-hop link between nodes and nodes on the path; meanwhile, the following node attributes and link attributes are considered:

[0043] 1) Node availability attribute, the availability attribute T m of path o m is expanded from the node availability attribute, and is expressed as the availability of the bottleneck node:

[0044]

[0045] Wherein is the node availability attribute of node obtained by step 1;

[0046] 2) Node quantum bit capacity attribute, i.e. the number of stored quantum bits in the node, the capacity attribute C m of path o m is expanded from the node capacity attribute, and is expressed as the quantum bit capacity of the bottleneck node:

[0047]

[0048] Wherein is the number of stored quantum bits in node ;

[0049] 3) the quantum fidelity property of the link, path o m F m is compounded by the fidelity properties of all single-hop links on the path, which is taken as the sum of the negative logarithm of the quantum fidelity property of each hop link:

[0050]

[0051] where is the expected fidelity of producing an entangled pair on the i-th hop link ;

[0052] 4) the classical communication latency property of the link, path o m D m is represented as the sum of the communication latency of each hop link on the path:

[0053]

[0054] where is the average latency of classical communication on the i-th hop link ;

[0055] where properties 1 and 2 comprehensively represent the availability of quantum bit resources on the path; properties 3 and 4 comprehensively represent the quality of entanglement distribution on the path;

[0056] A composite routing metric K m is defined as:

[0057]

[0058] where k1, k2, k3 are weight coefficients, used to flexibly adjust the routing strategy according to the actual scene needs; for example, in the usual case, the availability of quantum bit resources on the path and the quality of entanglement distribution can be considered equally important, then k1, k2, k3 are taken as values that make the order of magnitude of each addend in K m be comparable; when the nodes in the quantum communication network are busy, the value of k1 can be appropriately increased so that the routing algorithm considers the node properties as a priority factor; when the fidelity requirement of the service is higher, the value of k2 can be increased on the basis of the normal strategy so that the routing algorithm pays more attention to the fidelity property of the link;

[0059] K m is taken as the quality property of each path, and an extended Dijkstra algorithm is used to minimize the composite routing metric K m , so as to find the current optimal path;

[0060] In the implementation scheme of the multi-path, in order to avoid the resource contention of different paths of the same request on the link and form a bottleneck, a multi-path algorithm with link disjoint is adopted:

[0061] After the current optimal path is found, the edges associated with each hop on the optimal path are deleted, and then a path disjoint with the next path is searched, and the process is repeated until a sufficient number of paths are found, and the upper limit of the number of paths selected for each request is set to the number of entangled pairs required by the request.

[0062] Therefore, the introduction of the multi-path method in the entanglement distribution routing process can reduce the requirement for the available storage capacity of a single relay node, more fully utilize the resources of different nodes to cope with the possible probabilistic failure on part of the path, and improve the overall robustness of the entanglement distribution process.

[0063] The following will take the quantum communication network shown in the accompanying Figure 2 as an example to describe the method in detail.

[0064] 1) Quantum relay node availability evaluation mechanism based on queuing model

[0065] In the quantum communication network, each node will maintain its availability attribute according to its request list for the entire network node. Taking the evaluation process of the quantum relay node E as an example, as shown in Figure 3 The ordered request queue of the relay node in the example of the present application includes r1, r2, r3, and r4, and according to the service process of the relay node and the basic time parameter of the node E described in step 1, the number of quantum bits occupied by the request r1 is calculated as:

[0066] n r1 =2·c r1 +n f1 +n l1 =2

[0067] The expected service time is:

[0068] t r1 =max{t Ce ,t Ge}+max{s Cp ·0,S Gp ·0}+t s =60ms

[0069] Similarly, the number of quantum bits occupied by r2, r3, and r4 is 2, 4, and 4 respectively, and the expected service time is 60ms, 80ms, and 60ms respectively.

[0070] At the current time T, the requests r1 and r2 can be served in the CE Node E with 4 qubits is served in parallel, while r3 and r4 need to wait for node E to have 4 free qubits before they can receive service. Therefore, their departure time is first estimated based on the expected service time of r1 and r2, which is T+60ms. At T+60ms, node E has no qubits occupied, so it requests r3 to enter the system, receives 80ms of service, and leaves the system at T+140ms. Finally, it requests r4 to enter the system and leaves at T+200ms.

[0071] Therefore, the availability attribute of quantum repeater node E is:

[0072] T E =max{y1, y2, y3, y4}=max{60ms, 60ms, 140ms, 200ms}=200ms.

[0073] 2) Multi-path discovery methods that take into account both node attributes and link attributes

[0074] like Figure 4 The diagram shows the attribute information of each node and link in the example of the present invention. Taking the multipath discovery process between node A and node G as an example, the parameters of the composite routing metric K are set to k1=1, k2=500, and k3=0.5.

[0075] First, an optimal path is found using the weighted Dijkstra's algorithm, with the following steps:

[0076] 1. Following step 2 of the method described in this embodiment of the invention, calculate K starting from source node A. A→B K A→C The initial values ​​are respectively and Therefore, node B is added to the visited set, and its previous node is denoted as A;

[0077] 2. Starting from node B, expand the temporary K values ​​of all adjacent nodes C, D, and F in the unvisited set, and find them to be 170, 157.5, and 157.5 respectively; therefore, only update the K values ​​of nodes D and F and add node C to the visited set, and denote the previous hop node as A.

[0078] 3. After executing one round of Dijkstra's algorithm in the same way, the routing information is as follows: Figure 3 As shown in the table, the first optimal path can be determined as A→B→F→G.

[0079] After finding the current optimal path, the edges AB, BF and FG are deleted in the original network topology graph, and the Dijkstra algorithm is executed again to obtain another path A→C→E→G. In the remaining topology graph, the edges related to the another path are further deleted, and it is found that the nodes A and G are not connected, and more feasible paths cannot be found. At this time, the multi-path discovery process ends, and the two feasible paths are output as:

[0080] A→B→F→G and A→C→E→G.

[0081] It is worth noting that the contents not described in detail in the embodiments of the present application belong to the prior art known to those skilled in the art.

[0082] In summary, the method described in the embodiments of the present application is based on queuing theory, considers the service model of the first generation of quantum relay establishment nodes by considering the physical processes of the relay nodes performing heralded entanglement, CNOT gate entanglement purification and entanglement exchange, and constructs the whole network quantum resource perception mechanism through the relay node availability evaluation means. In addition, the relay node availability and link fidelity unique to quantum communication networks are introduced into the routing metric, and the link disjoint multi-path routing method is combined, which is conducive to avoiding the failure caused by the uncertainty mechanism of quantum operation, reducing the requirement for the available storage capacity of the relay node, and having an advantage in dealing with the high competition of quantum bit resources.

[0083] In addition, those skilled in the art can understand that all or part of the steps in the above-mentioned embodiment methods can be completed by programs instructing related hardware, and the corresponding programs can be stored in a computer readable storage medium. The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk.

[0084] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements easily thought of by those skilled in the art within the technical range disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims. The information disclosed in the background section of this document is only intended to deepen the understanding of the overall background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A routing method for a quantum communication network, characterized in that, The method includes: Step 1: Establish a quantum repeater node availability assessment mechanism based on a queuing model, using the time required for the system to complete the remaining tasks to characterize the congestion level of the nodes; where the time it takes for task r to leave the queuing system is denoted as . So, the time still needed for the system to complete the remaining tasks is... The latest completion time of all tasks in the quantum relay node, therefore the quantum relay node The availability attribute is: ； Then, a recursive algorithm is used to determine the departure time of all tasks from the queuing system: by reviewing the list of tasks currently being served by the system, the departure time of these tasks is estimated sequentially using the estimated service time, thus determining the next task to be completed and the number of qubits it releases; based on the first-come, first-served rule, the time when the next task to be served can enter the system is determined; the departure time of this request is estimated in the same way, further deducing the time when the next task to be served can enter the system; this process is repeated until all tasks are obtained. Completion time; Step 2: Establish a multi-path routing mechanism for entanglement distribution based on node attributes and link attributes; wherein, the node attributes include the availability of quantum relay nodes and the capacity of quantum bits; the link attributes include the entanglement link fidelity between quantum relay nodes and the classical communication delay attribute; Among them, As a quality attribute for each path, use the extended... Algorithm minimizes composite routing metric In order to find the current optimal path; In the implementation of multi-path solutions, a multi-path algorithm with non-intersecting links is adopted: After finding the current optimal path, delete the edges associated with each hop on the optimal path; then find the next path that does not intersect with the current path; repeat this process until a sufficient number of paths are found, and set the upper limit of the number of paths selected for each request to be a quantity related to the number of entangled pairs required by the request.

2. The routing method for a quantum communication network according to claim 1, characterized in that, The process of step 1 is as follows: use Let V represent a quantum communication network; E represents a node in network N; E represents a quantum channel between nodes at both ends of an edge, enabling single-hop entanglement; and C represents the number of quantum storage bits available to a node. The system has a set of requests, R, and each request... By triplet The representations are the node that initiated the request, the target node to which the node wants to establish entanglement, and the number of entanglement pairs required for the request, respectively. First, establish the service model for quantum relay nodes, including: Each node is considered as a server with a number of quantum storage bits. A queuing system, where G represents the arrival time of customers and the service time of the system following a general distribution; C represents the number of quantum storage bits available at the nodes, indicating that each storage bit corresponds to a service station in the queuing system, and operations on these storage bits are performed in parallel; With quantum repeater nodes For example, each quantum relay node maintains an ordered list of tasks according to a first-come, first-served rule, and each task information is represented by a quadruple. The symbols represent, in order, the number of entangled pairs to be established in the task, the fidelity requirement for establishing entangled pairs, and the previous and next hop nodes of the task. Taking task r as an example, the service process of each task in the queuing system is broken down into the following four stages, and the service time is examined for each stage: 1) Task initialization To obtain entanglement with the required fidelity, task r requests vectors to the quantum relay node. Each quantum bit provides services for itself, among which and These represent the links in the previous hop. and next-hop link The above represents the additional number of qubits reserved for subsequent entanglement purification; the time consumed by this initialization process is negligible. 2) Establish entangled links Through the classic channel and the previous hop node After confirming the storage bits that match task r, the link layer protocol is responsible for... Each qubit is generated in parallel with the previous hop node. A single jump between them indicates entanglement; the average time required for this process is It depends on the distance between the two nodes, including the time required for classic communication; meanwhile, the rest... One quantum bit in Within the time limit, follow the same method to the next hop node. Establishing single-hop entanglement, therefore the total time consumed in this phase is ; 3) Entanglement Purification As can be seen from the initialization phase, in relation to the previous hop node During the purification process, The single-hop entangled link is divided into A group, meaning each item that meets the fidelity requirements. Single-jump entanglement requires additional resources. Single-hop entanglement; employing a symmetric entanglement scheduling scheme, each purification group is divided into... The process is carried out in rounds, and the purification within each round is performed in parallel; at the previous hop node In the entanglement purification process, the average time required for a single round of entanglement purification is... This means that the total time consumed in this stage is... Similarly, the next hop node The total time consumed for purification is Then, the total time consumed by task r in the entanglement purification phase is ; 4) Entanglement Exchange Task r will perform Bell state joint measurements on the entangled pairs after entanglement purification: after passing two bits through a CNOT gate, X-basis measurements and Z-basis measurements will be performed on the control bit and the target bit, respectively; finally, the measurements will be performed on the next hop node. and the next hop node Transmitting information and measurement results regarding the success or failure of entanglement swapping; the average time required for this process is... ; Taking into account the time spent in the above four stages, the total service time of task r at the quantum relay node is: ； This indicates that task r will be of length The time period occupied by the relay node 1 qubit; to estimate the ordered task list of a newly arrived task u in the node. Queuing time is used to characterize the congestion level of a node by taking the time required for the system to complete the remaining tasks.

3. The routing method for a quantum communication network according to claim 1, characterized in that, In step 2, for the routing metric of entanglement distribution, given by Nodes Formed The jump path is represented as: ； in Represents nodes on the path and nodes Between the first hop link; Consider the following node and link attributes: 1) Node availability attributes, path Availability attributes Extended from node availability attributes, it represents the availability of bottleneck nodes: ； in It is a node The node availability attribute obtained in step 1; 2) The qubit capacity attribute of a node, i.e., the number of stored qubits within the node and the path... capacity attribute Extended from the capacity attribute of nodes, it represents the qubit capacity of bottleneck nodes: ； in It is a node The number of internal storage qubits; 3) Quantum fidelity properties of the link, path quantum fidelity properties It is derived from the composite of the fidelity properties of all single-hop links on the path, and is taken as the negative logarithm sum of the quantum fidelity properties of each hop link: ； in It is in the hop link The expected fidelity of generating entangled pairs; 4) Classic communication delay properties of links, path Classical communication delay properties This is expressed as the sum of the communication delays of each hop link along the path: ； in It is in the hop link The average latency for classical communication; Among them, attributes 1 and 2 comprehensively characterize the availability of qubit resources on the path; attributes 3 and 4 comprehensively characterize the quality of entanglement distribution on the path. Define a composite routing metric by combining four attributes. for: ； in It is a weighting coefficient, used to flexibly adjust the routing strategy according to the needs of the actual scenario.

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