Quantum communication method

Abstract

The invention provides a quantum communication method which can be applied to the field of quantum network communication. The method comprises the following steps: in response to a data transmission request of a sending end, generating session data to obtain m data quantum bits and W initial entanglement connection information needing to be transmitted by the sending end in a t-th time slot, the entanglement connection information having a first fidelity; a sending end generates a resource reservation request according to the m data quantum bits and informs a receiving end of the resource reservation request along a target path, the resource reservation request comprises the number of initial entangled connection information, expected fidelity, a fidelity threshold and a purification mode, and the target path comprises a plurality of repeaters connected in sequence; sending resource confirmation information to the sending end in a reverse transmission mode from the receiving end and the plurality of repeaters in the target path; and connecting the sending end, the target path and the receiving end based on the resource confirmation information, so as to transmit the m data quantum bits to the receiving end.

Description

Technical Field

[0001] The present disclosure relates to the field of quantum network communication, and more specifically 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 entanglement connections, resulting in an imbalance between transmission rate and entanglement fidelity, and ultimately it is difficult to achieve the desired effect. 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 the tth 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;

[0006] Using the transmitting end to generate a resource reservation request according to the m data qubits, and notifying the receiving end of the resource reservation request along the target path, wherein the resource reservation request includes the amount of the 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 a plurality of repeaters connected in sequence;

[0007] 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, the 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;

[0008] The transmitting end, the target path and the receiving end are connected based on the resource confirmation information to transmit the m data quantum bits 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 the first fidelity of the entangled connection information of the above-mentioned sending end are updated to obtain the updated quantity and the updated first fidelity, so as to transmit the n data quantum bits to the above-mentioned receiving end in the t+1th time slot using the updated quantity and the updated first fidelity.

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

[0012] At the t+1th time slot, the quantity and the first fidelity of the entangled connection information are initially assigned to obtain the assigned quantity and the 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 assignment quantity and the assignment fidelity are updated to obtain the updated quantity and the updated first fidelity.

[0014] According to an embodiment of the present disclosure, the assignment quantity and the assignment fidelity are updated to obtain the updated quantity and the updated first fidelity, including:

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

[0016] According to an embodiment of the present disclosure, the transmitting end generates a resource reservation request according to the m data qubits, and notifies the receiving end of the resource reservation request along the target path, including:

[0017] Using the above-mentioned sending end to generate the above-mentioned purification method according to the preset packet length, purification threshold, purification step length 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 repeaters in the target path.

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

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

[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 1st repeater is connected to the transmitting end;

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

[0026] 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;

[0027] In the case where the quantum resources of the i-th repeater satisfy all the session data, a plurality of resource confirmation information sent by the receiving end or the i+1-th repeater is sent to the i-1-th repeater;

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

[0029] The resource confirmation information is modified by 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 resources of the i-th repeater meet 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;

[0030] If all new resource confirmation information are 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;

[0031] Modifying the expected 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, so that when the quantum resources of the i-th repeater satisfy all session data, multiple new resource confirmation information is sent to the i-1-th repeater.

[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 verification photon pair;

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

[0037] In the case where the second purified fidelity is less than the fidelity requirement value, based on the first purification formula, iteratively generating a new second purified fidelity according to the second purified fidelity and the fidelity of the new calibration photon pair;

[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 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).

[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 sender needs to transmit in the tth time slot, a resource reservation request is generated according to the m data quantum bits that the sender 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, 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 receiving end and the multiple repeaters in the target path are used to start sending resource confirmation information to the sender in a reverse propagation manner, the sender, 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 rate 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 flowchart of the purification method according to the embodiment of the present disclosure is schematically shown;

[0047] Figure 3 The timing diagram corresponding to the embodiment of the present disclosure is schematically shown. 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 exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, 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 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 existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0050] All terms (including technical and scientific terms) used herein 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 using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to 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 the entanglement connection, 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 receiving end 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 a plurality of repeaters connected in sequence; starting from the receiving end and the plurality of repeaters in the target path, sending resource confirmation information 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 the Boolean variable, and the Boolean variable represents 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 receiving end are connected to transmit the m data quantum bits to the receiving end.

[0054] In the technical solution of the present invention, the user information (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.) involved 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 except 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 Figure 1 to Figure 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 executed by an electronic device.

[0059] In operation S210, in response to a data transmission request from the transmitter, session data is generated to obtain m data quantum bits and W initial entanglement connection information that the transmitter needs to transmit in the tth time slot, wherein the entanglement connection information represents the transmission of data quantum bits between the transmitter and the receiver, 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 informs 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 sender, 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 the embodiments of the present disclosure, session data (Session) may refer to the process of communication between a terminal user and an interactive system. The embodiments of the present disclosure do not limit the generation method of session data, such as from entering an account and password to exiting the operating system. However, it is not limited to this, as long as the session data is generated under the conditions that meet the requirements of relevant regulations.

[0065] According to the embodiment of the present disclosure, the tth time slot may refer to a time period in the quantum data network, which is relatively short, for example, within 1 second. The embodiment of the present disclosure does not limit the value of the time slot t. Those skilled in the art may select it according to actual needs.

[0066] According to an embodiment of the present disclosure, a data qubit may be a photon that carries information transmitted by a user in a quantum data network. The entangled connection information represents the transmission of data qubits between a transmitter and a receiver by quantum teleportation technology, wherein the entangled connection information has a first fidelity f. The fidelity represents the degree to which a data qubit is affected by noise, and the fidelity after purification is calculated. The larger the value, the better the 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 used to obtain, 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 working on 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, 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 the Boolean variable. Among them, the Boolean variable represents whether the size of the sending window of the session data has changed. When the Boolean variable is true, it indicates that the size of the sending window of the corresponding session data has changed. On the contrary, when the Boolean variable is false, it indicates that the size of the sending window of 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 transmitter requests to transmit m data quantum bits and W initial entanglement connection information to the receiver. After the resource reservation request is generated, it is transmitted to the receiver along the target path. When the receiver receives the resource reservation request information, it can start to send resource confirmation information to the transmitter in a reverse transmission manner. When the resource confirmation information is transmitted to the transmitter, when the required fidelity is achieved, a connection from the transmitter to the output end can be established based on the resource confirmation information, so that the transmitter finally transmits m data quantum bits and W initial entanglement connection information to the receiver.

[0072] According to an embodiment of the present disclosure, session data is generated to obtain m data qubits and W initial entanglement connection information that the sender needs to transmit in the tth time slot, a resource reservation request is generated according to the m data qubits that the sender 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 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 receiving end and the multiple repeaters in the target path are used to start sending resource confirmation information to the sender in a reverse propagation manner, the sender, the target path and the receiving end are connected based on the resource confirmation information, and the m data qubits are transmitted to the receiving end, 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 the first fidelity of the entangled 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 transmitting n data qubits in the t+1th time slot, the amount 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 amount and the updated first fidelity.

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

[0076] In 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 may be updated based on the resource reservation information to obtain the updated number of entangled connection information and the updated first fidelity f. First, the number of entangled connection information and the first fidelity f may be initially assigned values ​​at the t+1 time slot, for example, W=1, f=0.8, but not limited to this. The embodiment of the present disclosure does not limit the value of the number of entangled 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 assignment quantity and the assignment fidelity to obtain an updated quantity and an updated first fidelity includes:

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

[0081] According to an embodiment of the present disclosure, if the resource reservation request can satisfy all session data, an updated number 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 a startup state, for every W data qubits 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 blocked state, for every W data qubits 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 embodiments of the present disclosure do 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 amount 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 according to 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 a preset packet length, a purification threshold, a purification step length and a fidelity requirement value;

[0086] Generate a resource reservation request according to 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 entanglement 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, a resource reservation request is forwarded to a receiving end through multiple repeaters in a 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 a 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 where there are 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 embodiment of the present disclosure, after the resource reservation request is forwarded to the last receiving end, the resource confirmation information can be reversely propagated from the receiving end, and each node (including the sending end, the repeater and the receiving end) can handle the resource conflict based on the collected resource reservation request. In the process of handling the resource conflict, the resource confirmation information can be transmitted to other nodes by adjusting the size of the session data and the value of the fidelity.

[0108] According to an embodiment of the present disclosure, when the resource confirmation information is transmitted in reverse, the 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 sending window size representing the session data changes. Conversely, when the Boolean variable is false, the sending window size representing the session data does not change.

[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 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 are all the first value, the largest sending window in the multiple resource confirmation information is adjusted to obtain a target sending window and a target Boolean variable of 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 resources of the i-th repeater meet 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 are 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 expected 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 the embodiments of the present disclosure, the target path may include a plurality of repeaters in addition to a receiving end and a transmitting end. The embodiments of the present disclosure do 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 may receive multiple resource confirmation messages sent by the receiving end or the i+1-th repeater. One resource confirmation message corresponds to one session data, and the resource confirmation message may include a Boolean variable and a first fidelity value, but is not limited thereto. The embodiment of the present disclosure does 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 information 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 information may be selected for adjustment in the session data when all Boolean variables are false (i.e., the Boolean variable is the first value). For example, the window size may be halved, which may 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, so that new resource confirmation information can be obtained, and it can be determined whether its quantum resources can satisfy all session data, wherein all new session data correspond to the new resource confirmation information and a plurality of unadjusted resource confirmation information, respectively, so that the sending window can be adjusted iteratively.

[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 method in the new resource confirmation information (i.e., the intermediate confirmation information) can be used. Modifications are made to obtain target confirmation information, including second fidelity and new purification methods 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 satisfy all new session data, wherein iteration refers to determining one by one whether all new session data can be satisfied between each node and each node, so that when the quantum resources of the i-th repeater satisfy 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, and 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 verification photon pair;

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

[0131] When the second purified fidelity is less than the fidelity requirement value, based on the first purification formula, iteratively generates a new second purified fidelity 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 fidelity requirement value, the number of calibration photon pairs is determined.

[0133] According to an embodiment of the present disclosure, the connection fidelity of the entangled connection established by the repeater can be determined for any repeater, and for each entangled connection, the first purification fidelity can be calculated based on the connection fidelity and the fidelity of the verification photon pair based on the first purification formula. The second purification fidelity can be calculated and generated based on the two first purification fidelities of two adjacent entangled connections using a second purification method, wherein the second purification fidelity characterizes the fidelity of the target entangled connection obtained after the two adjacent entangled connections perform a quantum exchange operation.

[0134] According to an embodiment of the present disclosure, when the calculated second purification fidelity is less than the fidelity requirement value, the first purification formula can be used to calculate and generate a new second purification fidelity based on the second purification fidelity and the fidelity of the new verification photon pair. When the new second purification fidelity is obtained, it can be determined again whether the new second purification fidelity is greater than or equal to the fidelity requirement value. If it is less than the fidelity requirement value, the first purification formula can be used again to calculate until it is greater than or equal to the fidelity requirement value. If the calculated new second purification fidelity is greater than or equal to the fidelity requirement value, the number of verification 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 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 (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 packet 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, 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 degree of improvement is greater than 0.05, so a group of purification resources will be allocated again. According to formula (2), it can be calculated that its fidelity will continue to be improved 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 groups of purification resources, and 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 calculation formula for the fidelity 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, and 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, 2 sets of purification resources are required. It is also known that before the quantum exchange operation, 2 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 timing diagram corresponding to the embodiment of the present disclosure is schematically shown.

[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.

[0143] In operation S320, a back propagation phase is performed.

[0144] In operation S330, establishing a connection (ie, entangling connection information) performs purification of 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 send resource confirmation information 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, a second fidelity, a purification method and a Boolean variable.

[0147] According to an embodiment of the present disclosure, establishing a connection (ie, entanglement connection information) to perform purification output data may connect the sending end, the target path, and the receiving end based on resource confirmation information to transmit m data qubits to the receiving end.

[0148] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations and / or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0149] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of 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 the tth 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; Using the transmitting end to generate a resource reservation request according to the m data qubits, and notifying the receiving end of the resource reservation request along the target path, wherein the resource reservation request includes the amount of the 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 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 a plurality of the 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 changes; 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 the first fidelity of the entangled 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 in the t+1th time slot using the updated quantity and the updated first fidelity.

3. The method according to claim 2, wherein: The number and the first fidelity of the entanglement connection information of the sending end are updated to obtain an updated number and an updated first fidelity, including: 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 assignment quantity and the assignment 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: The assignment quantity and the assignment fidelity are updated to obtain the updated quantity and the updated first fidelity, including: The updated number and the updated first fidelity are generated according to the number of data quantum bits transmitted to the receiving end.

5. The method according to claim 1, wherein: Using the transmitting end to generate a resource reservation request according to the m data qubits, 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 a plurality of the 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 a plurality of the repeaters in the target path to the sending end in a reverse transmission manner, comprising: In the case where there are multiple session data, using the receiving end to generate a Boolean variable corresponding to each session data according to the 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 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 the case where the quantum resources of the i-th repeater do not satisfy all the session data, if the multiple Boolean variables are all the first value, adjusting the largest sending window in the multiple resource confirmation information to obtain a target sending window and a target Boolean variable of the second value, wherein the sending window represents the amount of the entanglement connection information; The resource confirmation information is modified by 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; If all new resource confirmation information are 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 expected 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, based on a first purification formula, generating a first purified fidelity according to the connection fidelity and the fidelity of the verification photon pair; Based on the second purification formula, a second purification fidelity is generated according to two first purification fidelities of two adjacent entangled connections, wherein the second purification fidelity represents the fidelity of a target entangled connection obtained after the two adjacent entangled connections perform a quantum exchange operation; When the second purification fidelity is less than the fidelity requirement value, based on the first purification formula, iteratively generating a new second purification fidelity according to the second purification fidelity and the fidelity of the new calibration photon pair; 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.

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 two first purified fidelities of two entangled connections generated based on formula (1).

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