Quantum Communication Methods

Abstract

The present disclosure provides a quantum communication method that can be applied to the field of quantum network communication. The method includes: in response to a data transmission request from a transmitting end, generating session data to obtain m data qubits and W initial entanglement connection information required to be transmitted by the transmitting end in the tth time slot, where the entanglement connection information has a first fidelity; using the transmitting end to generate a resource reservation request based on the m data qubits, and notifying the receiving end of the resource reservation request along a target path, wherein the resource reservation request includes the number of initial entanglement connection information, the expected fidelity, the fidelity threshold, and the purification method; starting from the receiving end and the multiple repeaters in the target path, sending resource confirmation information to the transmitting end in a reverse transmission manner; and connecting the transmitting end, the target path, and the receiving end based on the resource confirmation information to transmit the m data qubits to the receiving end.

Description

Technical Field

[0001] The present disclosure relates to the field of quantum network communication, and more particularly to a quantum communication method. Background Art

[0002] With the rapid development of information technology, the design and development of quantum data networks and related protocols have attracted more and more people. Many physical layer-related technologies, link layer and network layer-related protocols have been proposed for discussion, but the transport layer has been blank for a long time. Technicians in related fields have proposed a distributed transport layer protocol suitable for quantum data networks. Although it improves the throughput, it ignores the impact of environmental noise on entangled connections, resulting in an imbalance between transmission rate and entanglement fidelity, and ultimately it is difficult to achieve the expected results. Summary of the Invention

[0003] In view of the above problems, the present disclosure provides a quantum communication method.

[0004] According to a first aspect of the present disclosure, a quantum communication method is provided, which can be applied to a quantum communication system, comprising:

[0005] In response to a data transmission request from a transmitting end, session data is generated to obtain m data qubits and W initial entanglement connection information that the transmitting end needs to transmit in a t-th time slot, wherein the entanglement connection information represents the transmission of the data qubits between the transmitting end and the receiving end, and the entanglement connection information has a first fidelity;

[0006] Generate a resource reservation request using the transmitter based on the m data qubits, and notify the receiver of the resource reservation request along a target path, wherein the resource reservation request includes the amount of the initial entangled connection information, the expected fidelity, the fidelity threshold, and a purification method, wherein the purification method is used to improve the fidelity of the entangled connection information, and the target path includes a plurality of repeaters connected in sequence;

[0007] sending resource confirmation information from the receiving end and the plurality of repeaters in the target path to the sending end in a reverse transmission manner, wherein the resource confirmation information includes the amount of target entangled connection information obtained by simulated purification of the entangled connection information using the purification method, a second fidelity, the purification method, and a Boolean variable representing whether the size of the sending window of the session data has changed;

[0008] The transmitting end, the target path and the receiving end are connected based on the resource confirmation information to transmit the m data qubits to the receiving end.

[0009] According to an embodiment of the present disclosure, the quantum communication method further includes:

[0010] Before transmitting n data quantum bits in the t+1th time slot, the quantity and first fidelity of the entangled connection information of the above-mentioned sending end are updated to obtain the updated quantity and updated first fidelity, so as to transmit the n data quantum bits to the above-mentioned receiving end using the above-mentioned updated quantity and updated first fidelity in the t+1th time slot.

[0011] According to an embodiment of the present disclosure, the quantity and first fidelity of the entanglement connection information of the transmitting end are updated to obtain an updated quantity and an updated first fidelity, including:

[0012] At the t+1th time slot, performing initial assignment processing on the quantity and first fidelity of the entangled connection information to obtain the assigned quantity and assigned fidelity;

[0013] When the Boolean variable in the resource confirmation information of the t+1th time slot received by the transmitting end is a preset value, the assigned quantity and the assigned fidelity are updated to obtain the updated quantity and the updated first fidelity.

[0014] According to an embodiment of the present disclosure, updating the assigned quantity and the assigned fidelity to obtain the updated quantity and the updated first fidelity includes:

[0015] The updated number and the updated first fidelity are generated based on the number of data quantum bits transmitted to the receiving end.

[0016] According to an embodiment of the present disclosure, generating a resource reservation request based on the m data qubits by the transmitting end and notifying the receiving end of the resource reservation request along the target path includes:

[0017] The above-mentioned sending end generates the above-mentioned purification method according to the preset packet length, purification threshold, purification step size and fidelity requirement value;

[0018] generating the resource reservation request according to the amount of the initial entangled connection information, the expected fidelity, the purification method, and the fidelity threshold;

[0019] The resource reservation request is forwarded to the receiving end through the plurality of relays in the target path.

[0020] According to an embodiment of the present disclosure, sending resource confirmation information from the receiving end and the plurality of repeaters in the target path to the sending end in a reverse transmission manner includes:

[0021] In the case where there are multiple pieces of session data, generating a Boolean variable corresponding to each piece of session data using the receiving end and processing resources of the receiving end;

[0022] For each of the Boolean variables, generating resource confirmation information corresponding to the receiving end according to the Boolean variable and the resource reservation request;

[0023] The resource confirmation information of the receiving end is transmitted to the target path in a reverse propagation manner until the sending end receives the resource confirmation information sent by the repeater closest to the sending end.

[0024] According to an embodiment of the present disclosure, the target path includes i repeaters, where i=1, 2, 3, ..., N, the Nth repeater is connected to the receiving end, and the first repeater is connected to the transmitting end;

[0025] The i-th repeater sends the resource confirmation information in the following manner:

[0026] Obtaining multiple resource confirmation information sent by the receiving end or the (i+1)th repeater, wherein one resource confirmation information corresponds to one session data, and the resource confirmation information includes the Boolean variable and the expected fidelity;

[0027] When the quantum resources of the i-th repeater satisfy all the session data, multiple resource confirmation messages sent by the receiving end or the i+1-th repeater are sent to the i-1-th repeater;

[0028] In a case where the quantum resources of the i-th repeater do not satisfy all the session data, if the multiple Boolean variables all have the first value, adjusting the largest sending window among the multiple resource confirmation information to obtain a target sending window and a target Boolean variable with the second value, wherein the sending window represents the amount of the entangled connection information;

[0029] The resource confirmation information is modified using the target sending window and the target Boolean variable of the second value to obtain new resource confirmation information, so as to iteratively determine whether the quantum resource of the i-th repeater satisfies all new session data, wherein all new session data respectively correspond to the new resource confirmation information and a plurality of unadjusted resource confirmation information, thereby iteratively adjusting the sending window;

[0030] If all new resource confirmation information has the second value, then selecting the resource confirmation information corresponding to the largest first fidelity from the session data whose first fidelity is greater than the fidelity threshold as the intermediate confirmation information;

[0031] Modifying the desired fidelity and purification method in the intermediate confirmation information to obtain the second fidelity and new purification method, wherein the target confirmation information includes the second fidelity and the new purification method;

[0032] The target confirmation information is used as new resource confirmation information to iteratively determine whether the quantum resources of the i-th repeater satisfy all new session data, thereby sending multiple new resource confirmation information to the i-1-th repeater when the quantum resources of the i-th repeater satisfy all session data.

[0033] According to an embodiment of the present disclosure, the quantum communication method further includes:

[0034] For any repeater, determining the connection fidelity of the entanglement connection established by the repeater;

[0035] For each entangled connection, based on the first purification formula, a first purified fidelity is generated according to the connection fidelity and the fidelity of the calibration photon pair;

[0036] Based on the second purification formula, a second purification fidelity is generated according to the two first purification fidelities of the two adjacent entangled connections, wherein the second purification fidelity represents the fidelity of the target entangled connection obtained after the two adjacent entangled connections perform the quantum swap operation;

[0037] When the second purified fidelity is less than the required fidelity value, iteratively generating a new second purified fidelity based on the second purified fidelity and the fidelity of the new calibration photon pair based on the first purification formula;

[0038] When the new second purified fidelity is greater than or equal to the fidelity requirement value, the number of the verification photon pairs is determined.

[0039] According to an embodiment of the present disclosure, the first purification formula is shown in formula (1), and the second purification formula is shown in formula (2):

[0040]

[0041]

[0042] Among them, F1′ is the first purification fidelity, F s To verify the fidelity of the photon pair, F is the connection fidelity, F2′ is the second purified fidelity, and F1 and F2 are both the two first purified fidelities of the two entangled connections generated based on formula (1).

[0043] According to a quantum communication method provided by the present disclosure, session data is generated to obtain m data quantum bits and W initial entanglement connection information that the sending end needs to transmit in the tth time slot, a resource reservation request is generated according to the m data quantum bits that the sending end needs to transmit, and the resource reservation request is notified to the receiving end along the target path, wherein the resource reservation request includes the number of initial entanglement connection information, the expected fidelity, the fidelity threshold and the purification method, and the purification method is used to improve the fidelity of the entanglement connection information. The target path includes multiple repeaters connected in sequence. Using the multiple repeaters in the receiving end and the target path, resource confirmation information is started to be sent to the sending end in a reverse propagation manner. The sending end, the target path and the receiving end are connected based on the resource confirmation information, and the m data quantum bits are transmitted to the receiving end, thereby overcoming the influence of environmental noise on the entanglement connection, achieving a dynamic balance between the transmission rate and the entanglement fidelity, and improving the utilization of network resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The above contents and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0045] Figure 1 The flowchart of the quantum communication method according to the embodiment of the present disclosure is schematically shown;

[0046] Figure 2 The following schematically shows a flow chart of a purification method according to an embodiment of the present disclosure;

[0047] Figure 3 The diagram schematically shows a timing diagram corresponding to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0048] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0049] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0050] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0051] When expressions such as "at least one of A, B and C, etc." are used, they should generally be interpreted in accordance with the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0052] With the rapid development of information technology, the design and development of quantum data networks and related protocols have attracted more and more people. Many physical layer-related technologies, link layer and network layer-related protocols have been proposed for discussion, but the transport layer has been blank for a long time. Later, although technicians in related fields proposed a distributed transport layer protocol suitable for quantum data networks, the inventors found that although this method improved the throughput, it ignored the impact of environmental noise on entangled connections, resulting in an imbalance between throughput and entanglement fidelity, and ultimately it was difficult to achieve the desired effect.

[0053] In view of this, an embodiment of the present disclosure provides a quantum communication method, which includes: in response to a data transmission request from a transmitter, generating session data to obtain m data quantum bits and W initial entanglement connection information that the transmitter needs to transmit in the tth time slot; using the transmitter to generate a resource reservation request based on the m data quantum bits, and informing the receiver of the resource reservation request along the target path, wherein the resource reservation request includes the number of initial entanglement connection information, the expected fidelity, the fidelity threshold and the purification method, the purification method is used to improve the fidelity of the entanglement connection information, and the target path includes multiple repeaters connected in sequence; starting from the receiver and the multiple repeaters in the target path, resource confirmation information is sent to the transmitter in a reverse transmission manner, wherein the resource confirmation information includes the number of target entanglement connection information obtained by simulating the purification of the entanglement connection information using the purification method, the second fidelity, the purification method and a Boolean variable, the Boolean variable representing whether the size of the sending window of the session data has changed; based on the resource confirmation information, the transmitter, the target path and the receiver are connected to transmit the m data quantum bits to the receiver.

[0054] In the technical solution of the present invention, the user information involved (including but not limited to user personal information, user image information, user device information, such as location information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) are all information and data authorized by the user or fully authorized by all parties, and the collection, storage, use, processing, transmission, provision, disclosure and application of relevant data comply with the relevant laws, regulations and standards of relevant countries and regions, take necessary confidentiality measures, do not violate public order and good morals, and provide corresponding operation entrances for users to choose to authorize or refuse.

[0055] It should be noted that the quantum communication method provided in the present disclosure can be used in the field of quantum network communication, and can also be used in any field other than the field of quantum network communication. The present disclosure does not limit the application field of the provided quantum communication method.

[0056] The following will be passed Figures 1 to 3 The quantum communication method of the disclosed embodiment is described in detail.

[0057] Figure 1 The flowchart of the quantum communication method according to the embodiment of the present disclosure is schematically shown.

[0058] like Figure 1 As shown, the quantum communication method of this embodiment includes operations S110 to S140, and the quantum communication method can be performed by an electronic device.

[0059] In operation S210, in response to the data transmission request of the sending end, session data is generated to obtain m data quantum bits and W initial entanglement connection information that the sending end needs to transmit in the tth time slot, wherein the entanglement connection information represents the transmission of data quantum bits between the sending end and the receiving end, and the entanglement connection information has a first fidelity.

[0060] In operation S220, the transmitting end generates a resource reservation request based on the m data quantum bits, and notifies the receiving end of the resource reservation request along the target path, wherein the resource reservation request includes the amount of initial entangled connection information, the expected fidelity, the fidelity threshold and the purification method, the purification method is used to improve the fidelity of the entangled connection information, and the target path includes multiple repeaters connected in sequence.

[0061] In operation S230, resource confirmation information is sent to the sending end in a reverse transmission manner starting from the receiving end and multiple repeaters in the target path, wherein the resource confirmation information includes the number of target entangled connection information obtained by simulating the purification of the entangled connection information using the purification method, the second fidelity, the purification method and a Boolean variable, and the Boolean variable represents whether the size of the sending window of the session data has changed.

[0062] In operation S240 , the transmitting end, the target path, and the receiving end are connected based on the resource confirmation information to transmit the m data qubits to the receiving end.

[0063] According to an embodiment of the present disclosure, after responding to the data transmission request of the transmitter, a session data needs to be generated to obtain the m data quantum bits and W initial entanglement connection information that need to be transmitted in the tth time slot.

[0064] According to embodiments of the present disclosure, session data (Session) may refer to the process of communication between an end user and an interactive system. Embodiments of the present disclosure do not limit the method for generating session data, such as from entering an account and password to logging out of an operating system. However, this is not a limitation; any method for generating session data that meets relevant regulatory requirements may be sufficient.

[0065] According to embodiments of the present disclosure, the tth time slot may refer to a relatively short period of time in a quantum data network, such as one second. Embodiments of the present disclosure do not limit the value of the time slot t. Those skilled in the art may select a value based on actual needs.

[0066] According to embodiments of the present disclosure, data qubits can be photons that carry user information in a quantum data network. Entangled link information represents the transmission of data qubits between a transmitter and a receiver using quantum teleportation technology. This entangled link information has a first fidelity, f. Fidelity is measured as the degree to which a data qubit is affected by noise. The fidelity after purification is calculated; a larger value indicates a higher degree of purification.

[0067] According to an embodiment of the present disclosure, the transmitting end may generate a resource reservation request based on the m data qubits to be acquired, and inform the receiving end of the resource reservation request along the target path, wherein the resource reservation request includes the number W of initial entangled connection information, the first fidelity f, the purification method The purification method is to use another pair of data qubits to detect whether the original data qubit pair is in an ideal state. If not, both pairs of data qubits are discarded, and two new pairs of data qubits are generated, and the above steps are repeated. If so, the tested data qubit pair is retained. The purification method improves the fidelity of the entangled connection information.

[0068] According to the embodiments of the present disclosure, a repeater is a network connection device operating at the physical layer. The embodiments of the present disclosure do not limit the number of repeaters, and those skilled in the art may select one according to actual needs.

[0069] According to an embodiment of the present disclosure, resource confirmation information includes the amount of target entangled connection information obtained by simulating the purification of entangled connection information using a purification method, a second fidelity, the purification method, and a Boolean variable. The Boolean variable indicates whether the size of the send window for session data has changed. When the Boolean variable is true, it indicates that the size of the send window for the corresponding session data has changed. Conversely, when the Boolean variable is false, it indicates that the size of the send window for the corresponding session data has not changed.

[0070] According to an embodiment of the present disclosure, after the resource confirmation information is transmitted from the receiving end to multiple repeaters and then to the sending end, m data quantum bits can be transmitted from the sending end to the receiving end.

[0071] According to an embodiment of the present disclosure, in the tth time slot of the quantum data network, the sending end requests to transmit m data quantum bits and W initial entanglement connection information to the receiving end. After the resource reservation request is generated, it is transmitted to the receiving end along the target path. When the receiving end receives the resource reservation request information, it can start to send resource confirmation information to the sending end in a reverse transmission manner. When the resource confirmation information is transmitted to the sending end, if the required fidelity is achieved, a connection from the sending end to the output end can be established according to the resource confirmation information, so that the sending end finally transmits m data quantum bits and W initial entanglement connection information to the receiving end.

[0072] According to an embodiment of the present disclosure, session data is generated to obtain m data qu bits and W initial entanglement connection information that the transmitter needs to transmit in the tth time slot, a resource reservation request is generated according to the m data qu bits that the transmitter needs to transmit, and the resource reservation request is notified to the receiver along the target path, wherein the resource reservation request includes the number of initial entanglement connection information, the expected fidelity F, the fidelity threshold and the purification method, the purification method is used to improve the fidelity of the entanglement connection information, the target path includes multiple repeaters connected in sequence, and the multiple repeaters in the receiver and the target path are used to start sending resource confirmation information to the transmitter in a reverse propagation manner, and the transmitter, the target path and the receiver are connected based on the resource confirmation information, and the m data qu bits are transmitted to the receiver, thereby overcoming the influence of environmental noise on the entanglement connection and achieving a dynamic balance between network throughput and entanglement fidelity.

[0073] According to an embodiment of the present disclosure, the quantum communication method also includes: before transmitting n data quantum bits in the t+1th time slot, updating the quantity and first fidelity of the entanglement connection information of the sending end to obtain an updated quantity and an updated first fidelity, so as to transmit the n data quantum bits to the receiving end using the updated quantity and the updated first fidelity in the t+1th time slot.

[0074] According to an embodiment of the present disclosure, before n data qubits are transmitted in the t+1th time slot, the number of entangled connection information and the first fidelity of the transmitting end in the tth time slot can be updated, and the n data qubits can be transmitted to the receiving end in the t+1th time slot using the updated number and the updated first fidelity.

[0075] According to an embodiment of the present disclosure, updating the quantity and first fidelity of the entanglement connection information of the transmitting end to obtain the updated quantity and the updated first fidelity includes:

[0076] At the t+1th time slot, the quantity of entangled connection information and the first fidelity are initially assigned to obtain the assigned quantity and the assigned fidelity;

[0077] When the Boolean variable in the resource confirmation information of the t+1th time slot received by the transmitting end is a preset value, the assignment quantity and the assignment fidelity are updated to obtain an updated quantity and an updated first fidelity.

[0078] According to an embodiment of the present disclosure, the transmitting end can be updated based on the resource reservation information to obtain the updated number of entanglement connection information and the updated first fidelity f. First, the number of entanglement connection information and the first fidelity f can be initially assigned in the t+1 time slot, for example, W=1, f=0.8, but this is not limited to this. The embodiment of the present disclosure does not limit the value of the number of entanglement connection information and the first fidelity. After obtaining the assigned number and the assigned fidelity, in the resource confirmation information of the t+1 time slot received by the transmitting end, when the Boolean variable is a preset value, the assigned number and the assigned fidelity are updated to obtain the updated number and the updated first fidelity.

[0079] According to an embodiment of the present disclosure, updating the assigned quantity and the assigned fidelity to obtain an updated quantity and an updated first fidelity includes:

[0080] An updated quantity and an updated first fidelity are generated according to the number of data quantum bits transmitted to the receiving end.

[0081] According to an embodiment of the present disclosure, if the resource reservation request can satisfy all session data, an updated quantity and an updated first fidelity can be generated based on the number of data quantum bits transmitted to the receiving end, so that resource confirmation information can be sent to the sending end in a reverse transmission manner.

[0082] According to an embodiment of the present disclosure, when the session data is in the startup state, for every W data quantum bits transmitted, the updated number of quantum data bits W1 can be expressed as W1=W*2, and the updated first fidelity f1 can be expressed as f1=f+0.25*(1-f), where f represents the initial amplitude of the first fidelity during initialization. If the session data is in a congested state, for every W data quantum bits transmitted, the updated number W2 can be expressed as W2=W+1, and the first fidelity can be expressed as f2=f+0.1*(1-f), but is not limited to this. The embodiment of the present disclosure does not limit the updated number of entangled connection information and the updated first fidelity.

[0083] According to an embodiment of the present disclosure, when the number of session data in the network is small, the fidelity of the entanglement connection information established by each session data will be improved. When the amount of session data is large, the flow of resources can be achieved by reducing the fidelity of the session data, thereby achieving a dynamic balance between the data transmission rate and the fidelity of the entanglement connection information, thereby improving network resource utilization.

[0084] According to an embodiment of the present disclosure, a transmitting end generates a resource reservation request based on m data qubits and notifies a receiving end of the resource reservation request along a target path, including:

[0085] The sending end generates a purification method according to the preset packet length, purification threshold, purification step and fidelity requirement value;

[0086] Generate a resource reservation request based on the amount of initial entangled connection information, the expected fidelity, the purification method, and the fidelity threshold;

[0087] The resource reservation request is forwarded to the receiving end through multiple relays in the target path.

[0088] According to the embodiments of the present disclosure, the purification method It may include a quaternary group, which includes: a preset group length L, a purification threshold t, a purification step s, and a fidelity requirement value F′, but is not limited thereto. The embodiments of the present disclosure do not limit the specific variables included in the quaternary group.

[0089] According to an embodiment of the present disclosure, the resource reservation request may include the number of initial entangled connection information W, the expected fidelity F, the purification method and fidelity threshold However, this is not limited to this, and the embodiments of the present disclosure do not limit the variables specifically included in the resource reservation request.

[0090] According to an embodiment of the present disclosure, the resource reservation request is forwarded to the receiving end through multiple repeaters in the target path, and the required resources are calculated, which is beneficial to subsequent transmission between nodes and improves network utilization.

[0091] Figure 2 Schematically shows a flowchart of a purification method according to an embodiment of the present disclosure.

[0092] As Figure 2 shown, the purification method of this embodiment includes operation S210 to operation S2100.

[0093] In operation S210, confirm the packet length L, purification threshold t, purification step s, and fidelity requirement value F'.

[0094] In operation S220, establish entanglement connection information between adjacent nodes.

[0095] In operation S230, determine whether the entanglement connection fidelity f is f < t. If so, perform operations on each entanglement connection with insufficient fidelity and execute operation S240; if not, execute operation S260.

[0096] In operation S240, purify this connection.

[0097] In operation S250, determine whether f ≥ F'. If so, execute operation S260; if not, execute operation S240.

[0098] In operation S260, determine whether it is the required end-to-end (i.e., from the sending end to the receiving end) connection. If so, execute operation S280; if not, execute operation S270.

[0099] In operation S270, perform a quantum swapping operation. Starting from the source node (i.e., the receiving end), every L connections are spliced together. If there are less than L connections, they also need to be spliced, and then execute operation S230.

[0100] In operation S280, determine whether the fidelity is If so, execute operation S2100; if not, execute operation S290.

[0101] In operation S290, purify the end-to-end connection.

[0102] In operation S2100, end.

[0103] According to an embodiment of the present disclosure, starting from the receiving end and multiple repeaters in the target path, resource confirmation information is sent to the sending end in a reverse transmission manner, including:

[0104] In the case of multiple session data, a Boolean variable corresponding to each session data is generated using the processing resources received by the receiving end;

[0105] For each Boolean variable, generating resource confirmation information corresponding to the receiving end according to the Boolean variable and the resource reservation request;

[0106] The resource confirmation information of the receiving end is transmitted to the target path in a reverse propagation manner until the sending end receives the resource confirmation information sent by the repeater closest to the sending end.

[0107] According to the embodiments of the present disclosure, after a resource reservation request is forwarded to the final receiving end, resource confirmation information can be propagated backwards from the receiving end. Each node (including the sending end, relays, and receiving end) can handle resource conflicts based on the collected resource reservation requests. During resource conflict resolution, resource confirmation information can be transmitted to other nodes by adjusting the size and fidelity of session data.

[0108] According to an embodiment of the present disclosure, when resource confirmation information is transmitted in the reverse direction, processing resources received from the receiving end can be used to generate a Boolean variable corresponding to each session data. The Boolean variable can be true (i.e., 1) or false (i.e., 0). When the Boolean variable is true, the send window size representing the session data has changed. Conversely, when the Boolean variable is false, the send window size representing the session data has not changed.

[0109] According to an embodiment of the present disclosure, the target path includes i repeaters, where i=1, 2, 3, ..., N, the Nth repeater is connected to the receiving end, and the 1st repeater is connected to the transmitting end;

[0110] The i-th repeater sends the resource confirmation information in the following manner:

[0111] Acquire multiple resource confirmation information sent by the receiving end or the (i+1)th repeater, wherein one resource confirmation information corresponds to one session data, and the resource confirmation information includes a Boolean variable and an expected fidelity;

[0112] When the quantum resources of the i-th repeater satisfy all the session data, multiple resource confirmation information sent by the receiving end or the i+1-th repeater is sent to the i-1-th repeater;

[0113] In the case where the quantum resources of the i-th repeater do not satisfy all the session data, if the multiple Boolean variables all have the first value, adjusting the largest sending window among the multiple resource confirmation information to obtain a target sending window and a target Boolean variable with the second value, wherein the sending window represents the amount of entangled connection information;

[0114] The resource confirmation information is modified using the target sending window and the target Boolean variable of the second value to obtain new resource confirmation information, so as to iteratively determine whether the quantum resource of the i-th repeater satisfies all new session data, wherein all new session data respectively correspond to the new resource confirmation information and a plurality of unadjusted resource confirmation information, thereby iteratively performing an adjustment operation on the sending window;

[0115] If all new resource confirmation information has the second value, selecting the resource confirmation information corresponding to the largest first fidelity from the session data whose first fidelity is greater than the fidelity threshold as the intermediate confirmation information;

[0116] Modifying the desired fidelity and purification method in the intermediate confirmation information to obtain a second fidelity and a new purification method, wherein the target confirmation information includes the second fidelity and the new purification method;

[0117] The target confirmation information is used as new resource confirmation information to iteratively determine whether the quantum resources of the i-th repeater meet all new session data, so that when the quantum resources of the i-th repeater meet all session data, multiple new resource confirmation information is sent to the i-1-th repeater.

[0118] According to an embodiment of the present disclosure, the target path may include not only a receiving end and a transmitting end, but also multiple repeaters. The embodiment of the present disclosure does not limit the number of repeaters, and those skilled in the art may select according to actual needs.

[0119] According to an embodiment of the present disclosure, the i-th repeater can receive multiple resource confirmation messages sent by the receiving end or the (i+1)-th repeater. Each resource confirmation message corresponds to one session data. The resource confirmation message can include, but is not limited to, a Boolean variable and a first fidelity value. The embodiments of the present disclosure do not limit the variables included in the resource confirmation message.

[0120] According to an embodiment of the present disclosure, when the quantum resources of the i-th repeater satisfy all the session data, multiple resource confirmation messages sent by the receiving end or the i+1-th repeater may be sent to the i-1-th repeater. However, when the quantum resources of the i-th repeater do not satisfy all the session data, the largest sending window in the resource confirmation message may be selected from the session data when all Boolean variables are false (i.e., the Boolean variables are the first value) for adjustment. For example, the window size may be halved, which can be expressed as shown in formula (1):

[0121]

[0122] The embodiment of the present disclosure does not limit the size of the adjustment window. After the window is adjusted, the target sending window and the target Boolean variable of the second value can be obtained (ie, when the sending window changes, the target Boolean variable becomes true).

[0123] According to an embodiment of the present disclosure, resource confirmation information is modified using a target sending window and a target Boolean variable of a second value to obtain new resource confirmation information, and it is possible to determine whether its quantum resources can satisfy all session data. All new session data respectively corresponds to the new resource confirmation information and multiple unadjusted resource confirmation information, thereby enabling iterative adjustment of the sending window.

[0124] According to an embodiment of the present disclosure, when the Boolean variable values ​​in all new resource confirmation information are the second value (ie, the Boolean variable is 1), the first fidelity f is greater than the fidelity threshold value. In the session data, the resource confirmation information corresponding to the largest first fidelity is selected as the intermediate confirmation information, and the purification scheme and resource requirements of the session data are recalculated.

[0125] According to the embodiment of the present disclosure, after the window size is adjusted, the desired fidelity F and the purification mode in the new resource confirmation information (ie, the intermediate confirmation information) can be used. Modify and obtain target confirmation information, including second fidelity and new purification method The target confirmation information can be used as new resource confirmation information to iteratively determine whether the quantum resources of the i-th repeater can meet all new session data. Iteration means determining one by one whether all new session data are met between each node, so that when the quantum resources of the i-th repeater meet all session data, multiple new resource confirmation information is sent to the i-1-th repeater.

[0126] According to an embodiment of the present disclosure, when the number of requests in a quantum communication network is small, idle resources can be used to improve the fidelity of entanglement connections. When the number of requests is large, the fidelity requirements can be appropriately lowered to process more requests, thereby improving network resource utilization.

[0127] According to an embodiment of the present disclosure, the quantum communication method further includes:

[0128] For any repeater, determining the connection fidelity of the entanglement connection established by the repeater;

[0129] For each entangled connection, based on the first purification formula, a first purified fidelity is generated according to the connection fidelity and the fidelity of the calibration photon pair;

[0130] Based on the second purification formula, a second purification fidelity is generated according to the two first purification fidelities of the two adjacent entangled connections, wherein the second purification fidelity represents the fidelity of the target entangled connection obtained after the two adjacent entangled connections perform the quantum swap operation;

[0131] When the second purified fidelity is less than the fidelity requirement value, iteratively generating a new second purified fidelity based on the first purification formula according to the second purified fidelity and the fidelity of the new calibration photon pair;

[0132] When the new second purified fidelity is greater than or equal to the required fidelity value, the number of calibration photon pairs is determined.

[0133] According to embodiments of the present disclosure, the connection fidelity of an entangled connection established by any repeater can be determined. For each entangled connection, a first purified fidelity can be calculated based on the connection fidelity and the fidelity of the calibration photon pair, based on a first purification formula. A second purified fidelity can be calculated and generated based on the two first purified fidelities of two adjacent entangled connections using a second purification method. The second purified fidelity represents the fidelity of the target entangled connection obtained after the two adjacent entangled connections perform a quantum swap operation.

[0134] According to embodiments of the present disclosure, when the calculated second purified fidelity is less than the required fidelity value, the first purification formula can be used to calculate a new second purified fidelity based on the second purified fidelity and the fidelity of the new calibration photon pair. Once the new second purified fidelity is obtained, it can be determined again whether the new second purified fidelity is greater than or equal to the required fidelity value. If it is less than the required fidelity value, the first purification formula can be used again to calculate until it is greater than or equal to the required fidelity value. If the calculated new second purified fidelity is greater than or equal to the required fidelity value, the number of calibration photon pairs can be determined.

[0135] According to an embodiment of the present disclosure, the first purification formula is shown in formula (2), and the second purification formula is shown in formula (3):

[0136]

[0137]

[0138] Among them, F1′ is the first purification fidelity, F s To verify the fidelity of the photon pair, F is the connection fidelity, F2′ is the second purified fidelity, and F1 and F2 are both the two first purified fidelities of the two entangled connections generated based on formula (2).

[0139] According to an embodiment of the present disclosure, the target path is: transmitter-repeater 1-repeater 2-repeater 3-receiver. Taking this path as an example, this is a 4-hop path. The group length L is set to 2. The initial fidelity of the entangled connection information established by the adjacent nodes is 0.7, 0.8, 0.7, and 0.8, respectively. The purification threshold is 0.75, the purification requirement is 0.9, and the purification step is 0.05. Taking the entangled connection information established by the path transmitter-repeater 1 as an example, its fidelity of 0.7 is lower than the purification threshold of 0.75, so it needs to be purified. According to formula (2), the successive purification processes will increase its fidelity to 0.84. It can be seen that the improvement is greater than 0.05, so another set of purification resources will be allocated. According to formula (2), it can be calculated that its fidelity will continue to increase to 0.92. The improved fidelity of 0.92 is greater than the purification requirement, and purification can be stopped. Then, the purification of this link requires 2 sets of purification resources. The simulation process of the remaining links is similar. After that, an entangled connection information exchange operation is required. After the entangled connections with fidelities of F1 and F2 are spliced ​​together, the fidelity calculation formula of the new entangled connection information is shown in formula (3). After repeater 1 performs the quantum exchange operation, an entangled connection is established between the transmitter and repeater 2. Its fidelity is calculated according to formula (3) to be 0.74. This value is lower than the purification threshold. According to the above purification idea, two sets of purification resources are required. It is also known that before the quantum exchange operation, two sets of purification resources are required between the transmitter and repeater 1, and no purification resources are required between repeater 1 and repeater 2. Therefore, 2*(2+1)=6 sets of purification resources are required between the transmitter and repeater 1, and 2*(0+1)=2 sets of purification resources are required between repeater 1 and repeater 2. The rest of the calculation ideas are similar.

[0140] Figure 3 The diagram schematically shows a timing diagram corresponding to an embodiment of the present disclosure.

[0141] like Figure 3 As shown, the timing diagram of this embodiment includes operations S310 to S330.

[0142] In operation S310 , the forward propagation phase begins.

[0143] In operation S320, the back propagation phase begins.

[0144] In operation S330, establishing a connection (ie, entangling connection information) is performed to purify the output data.

[0145] According to an embodiment of the present disclosure, the forward propagation stage may include: in response to a data transmission request from the transmitter, generating session data to obtain m data quantum bits and W initial entanglement connection information that the transmitter needs to transmit in the tth time slot; using the transmitter to generate a resource reservation request based on the m data quantum bits, and informing the receiver of the resource reservation request along the target path.

[0146] According to an embodiment of the present disclosure, the reverse propagation stage may include: starting from the receiving end and multiple repeaters in the target path to the sending end in a reverse transmission manner, wherein the resource confirmation information includes the number of target entangled connection information obtained by simulating the purification of the entangled connection information using a purification method, the second fidelity, the purification method and the Boolean variable.

[0147] According to an embodiment of the present disclosure, establishing a connection (i.e., entangled connection information) to perform purified output data can connect the sending end, the target path and the receiving end based on the resource confirmation information to transmit m data quantum bits to the receiving end.

[0148] Those skilled in the art will appreciate that the features described in the various embodiments and / or claims of this disclosure may be combined and / or coupled in various ways, even if such combinations and / or couplings are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure may be combined and / or coupled in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or couplings are intended to fall within the scope of this disclosure.

[0149] The embodiments of the present disclosure are described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be used in combination to advantage. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A quantum communication method, applied to a quantum communication system, comprising: In response to a data transmission request from a transmitting end, session data is generated to obtain m data qubits and W initial entanglement connection information that the transmitting end needs to transmit in a t-th time slot, wherein the entanglement connection information represents the transmission of data qubits between the transmitting end and the receiving end, and the entanglement connection information has a first fidelity; Generate a resource reservation request using the transmitting end according to the m data qubits, and notify the receiving end of the resource reservation request along a target path, wherein the resource reservation request includes the amount of the initial entangled connection information, the expected fidelity, the fidelity threshold, and a purification method, the purification method being used to improve the fidelity of the entangled connection information, and the target path includes a plurality of repeaters connected in sequence; Sending resource confirmation information to the sending end in a reverse transmission manner from the receiving end and the plurality of repeaters in the target path, wherein the resource confirmation information includes the amount of target entangled connection information obtained by simulating purification of the entangled connection information using the purification method, a second fidelity, the purification method, and a Boolean variable, wherein the Boolean variable represents whether the size of the sending window of the session data has changed; The transmitting end, the target path, and the receiving end are connected based on the resource confirmation information to transmit the m data qubits to the receiving end.

2. The method according to claim 1, further comprising: Before transmitting n data quantum bits in the t+1th time slot, the quantity and first fidelity of the entanglement connection information of the sending end are updated to obtain an updated quantity and an updated first fidelity, so as to transmit the n data quantum bits to the receiving end using the updated quantity and the updated first fidelity in the t+1th time slot.

3. The method according to claim 2, wherein: Updating the quantity and first fidelity of the entanglement connection information of the transmitting end to obtain an updated quantity and an updated first fidelity includes: In the t+1th time slot, performing initial assignment processing on the quantity and the first fidelity of the entangled connection information to obtain the assigned quantity and the assigned fidelity; When the Boolean variable in the resource confirmation information of the t+1th time slot received by the transmitting end is a preset value, the assigned quantity and the assigned fidelity are updated to obtain the updated quantity and the updated first fidelity.

4. The method according to claim 3, wherein: Updating the assigned quantity and the assigned fidelity to obtain the updated quantity and the updated first fidelity includes: The updated quantity and the updated first fidelity are generated according to the quantity of data quantum bits transmitted to the receiving end.

5. The method according to claim 1, wherein Generating a resource reservation request according to the m data qubits by the transmitting end, and notifying the receiving end of the resource reservation request along a target path, comprising: Using the sending end to generate the purification method according to a preset packet length, a purification threshold, a purification step length, and a fidelity requirement value; generating the resource reservation request according to the amount of the initial entangled connection information, the expected fidelity, the purification method, and the fidelity threshold; The resource reservation request is forwarded to the receiving end through the plurality of relays in the target path.

6. The method according to claim 1, wherein The method includes sending resource confirmation information from the receiving end and the plurality of repeaters in the target path to the sending end in a reverse transmission manner, comprising: In the case where there are multiple pieces of session data, generating a Boolean variable corresponding to each piece of session data using the receiving end and processing resources of the receiving end; For each of the Boolean variables, generating resource confirmation information corresponding to the receiving end according to the Boolean variable and the resource reservation request; The resource confirmation information of the receiving end is transmitted to the target path in a reverse propagation manner until the sending end receives the resource confirmation information sent by the repeater closest to the sending end.

7. The method according to claim 1 or 6, wherein: The target path includes i repeaters, where i=1, 2, 3, ..., N, the Nth repeater is connected to the receiving end, and the first repeater is connected to the sending end; The i-th repeater sends the resource confirmation information in the following manner: Acquire multiple resource confirmation information sent by the receiving end or the (i+1)th repeater, wherein one resource confirmation information corresponds to one session data, and the resource confirmation information includes the Boolean variable and the expected fidelity; When the quantum resources of the i-th repeater satisfy all the session data, sending a plurality of resource confirmation information sent by the receiving end or the i+1-th repeater to the i-1-th repeater; In a case where the quantum resources of the i-th repeater do not satisfy all the session data, if the multiple Boolean variables all have the first value, adjusting the largest sending window among the multiple resource confirmation information to obtain a target sending window and a target Boolean variable with a second value, wherein the sending window represents the amount of the entanglement connection information; The resource confirmation information is modified using the target sending window and a target Boolean variable having a second value to obtain new resource confirmation information, so as to iteratively determine whether the quantum resources of the i-th repeater satisfy all new session data, wherein all new session data respectively correspond to the new resource confirmation information and a plurality of unadjusted resource confirmation information, thereby iteratively performing a sending window adjustment operation; If all new resource confirmation information has the second value, selecting the resource confirmation information corresponding to the largest first fidelity from the session data whose first fidelity is greater than the fidelity threshold as the intermediate confirmation information; Modifying the desired fidelity and purification method in the intermediate confirmation information to obtain the second fidelity and the new purification method, wherein the target confirmation information includes the second fidelity and the new purification method; The target confirmation information is used as new resource confirmation information to iteratively determine whether the quantum resources of the i-th repeater meet all new session data, so that when the quantum resources of the i-th repeater meet all session data, multiple new resource confirmation information is sent to the i-1-th repeater.

8. The method according to claim 7, further comprising: For any repeater, determining the connection fidelity of the entanglement connection established by the repeater; For each entangled connection, generating a first purified fidelity based on the first purification formula according to the connection fidelity and the fidelity of the calibration photon pair; Based on the second purification formula, generating a second purification fidelity according to the two first purification fidelities of the two adjacent entangled connections, wherein the second purification fidelity represents the fidelity of the target entangled connection obtained after the two adjacent entangled connections perform the quantum swap operation; When the second purified fidelity is less than the required fidelity value, iteratively generating a new second purified fidelity based on the first purification formula and the second purified fidelity and the fidelity of the new calibration photon pair; When the new second purified fidelity is greater than or equal to the required fidelity value, the number of the calibration photon pairs is determined.

9. The method according to claim 8, wherein The first purification formula is shown in formula (1), and the second purification formula is shown in formula (2): Among them, F1 ′ is the fidelity of the first purification, F s To verify the fidelity of the photon pair, F is the connection fidelity, F2 ′ is the second purified fidelity, and F1 and F2 are both the two first purified fidelities of the two entangled connections generated based on formula (1).

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