Apparatus, system and duplex communication method for duplex quantum direct communication

Abstract

The application relates to a device, a system and a duplex communication method for duplex quantum direct communication, the device comprising a quantum system sending device, a quantum system receiving device and a circulator, wherein the quantum system sending device is used for sending a first quantum state signal out on a first optical fiber via the circulator; and the quantum system receiving device is used for receiving a second quantum state signal transmitted on the first optical fiber via the circulator. Through the scheme, the optical fiber link resource consumption in the deployment process of the duplex quantum direct communication terminal is effectively reduced, the deployment cost is reduced, meanwhile, the quantum signal and the classical signal are separated and transmitted, the interference problem of the classical signal on the quantum signal in the common fiber transmission process is solved, and the communication performance of the terminal is prevented from being reduced. Therefore, the optical fiber link resource and cost are reduced, and meanwhile, the performance of the system is maintained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantum communication, and in particular to a device and system for duplex quantum direct communication and a duplex communication method. BACKGROUND

[0002] Quantum communication uses quantum mechanics to provide secure transmission of information, and its security is based on physical principles, unlike traditional secure communication based on computational security. Quantum secure direct communication is a type of quantum communication, which can also be referred to as quantum direct communication (QSDC). Quantum direct communication encodes information in quantum states and transmits them directly in a quantum channel, achieving both security and reliability of information transmission.

[0003] With the development of quantum computing, the security of classical cryptographic systems based on mathematical complex problems is facing great challenges. Quantum communication has received widespread attention and rapid development, and has become a mature direction in the field of quantum information, and will play an important role in the next generation of secure communication. Quantum communication technology mainly includes four branches: quantum key distribution (QKD), quantum direct communication, quantum secret sharing, and quantum teleportation.

[0004] Quantum direct communication was proposed in 2000 and has a history of more than 20 years. Its development has gone through four stages. (1) 2000-2004, the basic concepts and theories were established. In this stage, typical quantum direct communication protocols such as high-efficiency protocols based on entanglement, two-step protocols based on entanglement, and DL04 protocols based on single photons were proposed. (2) 2005-2015, development of protocols and application exploration stage. A large number of theoretical protocols were proposed, and the possible uses of quantum direct communication were widely explored. (3) 2016-2019, principle experiment verification and prototype development stage. In this stage, quantum direct communication protocols based on entanglement and single-photon quantum direct communication schemes were verified in experiments. In particular, researchers proposed high-loss channel coding, quantum storage substitution, and security quantitative analysis techniques to solve multiple problems in the practical application of quantum direct communication, and developed a quantum direct communication prototype with an information transmission rate of 50bps at a communication distance of 1.5km optical fiber. (4) Since 2020, product development and practical application promotion. The typical performance of the communication prototype in this stage is 10km@4kbps, which can realize real-time secure transmission of text, pictures, and voice files, and can achieve 100km quantum direct communication using low-loss optical fiber.

[0005] The existing single set of quantum direct communication system consists of a transmitting terminal Tx and a receiving terminal Rx. Information is transmitted from the Tx terminal to the Rx terminal, which belongs to simplex communication. In order to realize duplex communication between the two parties, another set of quantum direct communication equipment is needed to realize it. In addition, the existing quantum direct communication system between the terminals needs a classical channel (for example, Ethernet) to support the exchange of protocol information and a synchronization channel (for example, SFP (Small Form Pluggable) optical module) for clock synchronization in addition to the quantum channel (QC), and the channel has a direct connection requirement, so it occupies a lot of link resources in deployment. Figure 1 is a schematic diagram of the connection between quantum direct communication terminals. In Figure 1 , the QC channel is unidirectional transmission, and the signal is sent from Tx to Rx, transmitting quantum state signals. The SFP and Ethernet channels are bidirectional transmission, transmitting classical signals. The QC channel needs 1 optical fiber on the actual link, and the SFP and Ethernet channels each need 2 optical fibers.

[0006] As shown in Figure 2 , the duplex quantum direct communication terminals are connected, and the communication parties are denoted as A and B, and each party sets up 1 transmitting terminal Tx and 1 receiving terminal Rx. Each transmitting terminal Tx is equipped with a quantum system sending device and a classical transmission device (Ethernet and SFP), and each receiving terminal Rx is equipped with a quantum system receiving device and a classical transmission device (Ethernet and SFP). A set of Tx to Rx system, a total of 5 optical fibers are needed. In the duplex communication case, a set of Tx to Rx system needs to be added, so a total of 10 optical fibers are needed. In this way, a total of 10 optical fibers are needed for connection between A and B, of which optical fibers 1-5 are used for A to B communication, and optical fibers 6-10 are used for B to A communication. SUMMARY

[0007] For the scheme shown in Figure 2 , the occupation of optical fiber link resources is large, and the link wiring is also complex in actual deployment. The inventors realize that a solution is to use wavelength division multiplexing technology for each set of terminals to fuse optical fibers 1-5 and 6-10 into one optical fiber for transmission. This solution compresses the transmission link between A and B to 2, but this scheme still has certain deficiencies. The signals transmitted between A and B have quantum signals and classical signals. Quantum signals are weak optical quantum pulses, and classical signals are classical optical communication signals, which are very strong. In Figure 2In the figure, link 1 and 10 are quantum state transmission links, and 2-9 are classical optical signal transmission links. Directly merging optical fibers 1-5 (or 6-10) into one optical fiber will cause strong optical signals of 2-5 (or 6-10) links to affect quantum state transmission of 1 (or 10) link, resulting in a certain degree of performance decline of quantum direct communication terminals.

[0008] To solve the above problems, according to a first aspect of the present application, a device for duplex quantum direct communication is provided, characterized in that it comprises a quantum system sending device, a quantum system receiving device and a circulator, wherein:

[0009] The quantum system sending device is configured to send a first quantum state signal out on a first optical fiber via the circulator.

[0010] The quantum system receiving device is configured to receive a second quantum state signal transmitted on the first optical fiber via the circulator.

[0011] According to some embodiments, the number of quantum system sending devices and quantum system receiving devices is multiple, and the device further comprises a first wavelength division multiplexing device and a second wavelength division multiplexing device, wherein:

[0012] The first wavelength division multiplexing device is configured to multiplex multiple first quantum state signals from multiple quantum system sending devices and send the multiplexed first quantum state signals out on the first optical fiber via the circulator; and

[0013] The second wavelength division multiplexing device is configured to demultiplex multiple second quantum state signals transmitted on the first optical fiber and send the demultiplexed second quantum state signals to multiple quantum system receiving devices.

[0014] According to some embodiments, the device for duplex quantum direct communication further comprises multiple first classical transmission devices, multiple second classical transmission devices, a third wavelength division multiplexing device, a fourth wavelength division multiplexing device and a second circulator, wherein:

[0015] The multiple first classical transmission devices and the multiple second classical transmission devices are configured to send multiple first classical transmission signals to the third wavelength division multiplexing device.

[0016] The third wavelength division multiplexing device is configured to multiplex the multiple first classical transmission signals and send the multiplexed first classical transmission signals out on a second optical fiber via the second circulator; and

[0017] The fourth wavelength division multiplexing device is configured to demultiplex a second classical transmission signal transmitted on the second optical fiber and send the demultiplexed second classical transmission signal to the plurality of first classical transmission devices and the plurality of second classical transmission devices.

[0018] According to a second aspect of the present application, a system for duplex quantum direct communication is provided, comprising a first device and a second device, wherein the first device comprises a first quantum system transmitting device, a first quantum system receiving device and a first circulator; the second device comprises a second quantum system transmitting device, a second quantum system receiving device and a second circulator; wherein:

[0019] The first quantum system transmitting device is configured to transmit a first quantum state signal to the second device via the first circulator on a first optical fiber;

[0020] The second quantum system receiving device is configured to receive the first quantum state signal transmitted on the first optical fiber via the second circulator;

[0021] The second quantum system transmitting device is configured to transmit a second quantum state signal to the first device via the second circulator on the first optical fiber; and

[0022] The first quantum system receiving device is configured to receive the second quantum state signal transmitted on the first optical fiber via the first circulator.

[0023] According to some embodiments, the number of the first quantum system transmitting device, the first quantum system receiving device, the second quantum system transmitting device and the second quantum system receiving device is multiple, the first device further comprises a first wavelength division multiplexing device and a second wavelength division multiplexing device, and the second device further comprises a third wavelength division multiplexing device and a fourth wavelength division multiplexing device, wherein:

[0024] The first wavelength division multiplexing device is configured to multiplex a plurality of first quantum state signals from a plurality of the first quantum system transmitting devices and transmit the multiplexed first quantum state signals to the second device via the first circulator on the first optical fiber;

[0025] The third wavelength division multiplexing device is configured to receive the multiplexed first quantum state signals via the second circulator, demultiplex the multiplexed first quantum state signals, and send the demultiplexed first quantum state signals to a plurality of the second quantum system receiving devices;

[0026] The fourth wavelength division multiplexing device is used to multiplex multiple second quantum state signals from multiple second quantum system transmitting devices, and transmit the multiplexed second quantum state signals to the first device via the second circulator and on the first optical fiber; and

[0027] The second wavelength division multiplexing device is used to receive the multiplexed second quantum state signal via the first circulator, demultiplex the multiplexed second quantum state signal, and send the demultiplexed second quantum state signal to multiple first quantum system receiving devices.

[0028] According to some embodiments, the first device further includes a plurality of first classical transmission devices, a plurality of second classical transmission devices, a fifth wavelength division multiplexing device, a sixth wavelength division multiplexing device, and a third circulator; the second device further includes a plurality of third classical transmission devices, a plurality of fourth classical transmission devices, a seventh wavelength division multiplexing device, an eighth wavelength division multiplexing device, and a fourth circulator, wherein:

[0029] The plurality of first classical transmission devices and the plurality of second classical transmission devices are used to transmit the plurality of first classical transmission signals to the fifth wavelength division multiplexing device;

[0030] The fifth wavelength division multiplexing device is used to multiplex the plurality of first classical transmission signals, and transmit the multiplexed first classical transmission signals to the second device via the third circulator and on the second optical fiber;

[0031] The seventh wavelength division multiplexing device is used to demultiplex the multiplexed first classical transmission signal transmitted on the second optical fiber, and send the demultiplexed first classical transmission signal to the plurality of third classical transmission devices and the plurality of fourth classical transmission devices.

[0032] The plurality of third classical transmission devices and the plurality of fourth classical transmission devices are used to transmit the plurality of second classical transmission signals to the eighth wavelength division multiplexing device;

[0033] The eighth wavelength division multiplexing device is used to multiplex the plurality of second classical transmission signals, and transmit the multiplexed second classical transmission signals to the first device via the fourth circulator on the second optical fiber; and

[0034] The sixth wavelength division multiplexing device is used to demultiplex the multiplexed second classical transmission signal transmitted on the second optical fiber, and send the demultiplexed second classical transmission signal to the plurality of first classical transmission devices and the plurality of second classical transmission devices.

[0035] According to some embodiments, the first wavelength division multiplexing device and the fourth wavelength division multiplexing device use corresponding wavelengths to multiplex multiple first quantum state signals and multiple second quantum state signals, respectively; the second wavelength division multiplexing device and the third wavelength division multiplexing device use corresponding wavelengths to demultiplex the multiplexed second quantum state signals and the multiplexed first quantum state signals, respectively; the fifth wavelength division multiplexing device and the eighth wavelength division multiplexing device use corresponding wavelengths to multiplex the multiple first classical transmission signals and the multiple second classical transmission signals, respectively; and the sixth wavelength division multiplexing device and the seventh wavelength division multiplexing device use corresponding wavelengths to demultiplex the multiplexed second classical transmission signals and the multiplexed first classical transmission signals, respectively.

[0036] According to a third aspect of this application, a duplex communication method based on a duplex quantum direct communication system is provided, characterized in that the duplex quantum direct communication system includes a first device and a second device, wherein the first device includes a first quantum system transmitting device, a first quantum system receiving device, and a first circulator, and the second device includes a second quantum system transmitting device, a second quantum system receiving device, and a second circulator, and the method includes:

[0037] The first quantum state signal is transmitted to the second device via the first circulator and the first optical fiber through the first quantum system transmitting device;

[0038] The first quantum state signal transmitted on the first optical fiber is received by the second quantum system receiving device via the second circulator;

[0039] The second quantum state signal is transmitted to the first device via the second circulator and the first optical fiber through the second quantum system transmitting device; and

[0040] The second quantum state signal transmitted on the first optical fiber is received by the first quantum system receiving device via the first circulator.

[0041] According to some embodiments, the number of the first quantum system transmitting device, the first quantum system receiving device, the second quantum system transmitting device, and the second quantum system receiving device are all multiple. The first device further includes a first wavelength division multiplexing device and a second wavelength division multiplexing device, and the second device further includes a third wavelength division multiplexing device and a fourth wavelength division multiplexing device.

[0042] The step of transmitting the first quantum state signal to the second device via the first circulator and the first optical fiber through the first quantum system transmitting device includes:

[0043] The first wavelength division multiplexing device multiplexes multiple first quantum state signals from multiple first quantum system transmitting devices, and transmits the multiplexed first quantum state signals to the second device via the first circulator and on the first optical fiber;

[0044] The receiving of the first quantum state signal transmitted on the first optical fiber via the second quantum system receiving device through the second circulator includes:

[0045] The third wavelength division multiplexing device receives the multiplexed first quantum state signal via the second circulator, demultiplexes the multiplexed first quantum state signal, and sends the demultiplexed first quantum state signal to multiple second quantum system receiving devices.

[0046] The step of transmitting the second quantum state signal via the second circulator to the first device through the second quantum system transmitting device includes:

[0047] The fourth wavelength division multiplexing device multiplexes multiple second quantum state signals from multiple second quantum system transmitting devices, and then transmits the multiplexed second quantum state signals to the first device via the second circulator on the first optical fiber;

[0048] The receiving of the second quantum state signal transmitted on the first optical fiber via the first circulator through the first quantum system receiving device includes:

[0049] The second wavelength division multiplexing device receives the multiplexed second quantum state signal via the first circulator, demultiplexes the multiplexed second quantum state signal, and sends the demultiplexed second quantum state signal to multiple first quantum system receiving devices.

[0050] According to some embodiments, the first device further includes a plurality of first classical transmission devices, a plurality of second classical transmission devices, a fifth wavelength division multiplexing device, a sixth wavelength division multiplexing device, and a third circulator; the second device further includes a plurality of third classical transmission devices, a plurality of fourth classical transmission devices, a seventh wavelength division multiplexing device, an eighth wavelength division multiplexing device, and a fourth circulator; the method further includes:

[0051] Multiple first classical transmission signals are transmitted to the fifth wavelength division multiplexing device through the multiple first classical transmission devices and the multiple second classical transmission devices;

[0052] The fifth wavelength division multiplexing device multiplexes the plurality of first classical transmission signals, and then transmits the multiplexed first classical transmission signals to the second device via the third circulator and on the second optical fiber.

[0053] The seventh wavelength division multiplexing device demultiplexes the multiplexed first classical transmission signal transmitted on the second optical fiber, and sends the demultiplexed first classical transmission signal to the plurality of third classical transmission devices and the plurality of fourth classical transmission devices.

[0054] Multiple second classical transmission signals are transmitted to the eighth wavelength division multiplexing device through the multiple third classical transmission devices and the multiple fourth classical transmission devices;

[0055] The plurality of second classical transmission signals are multiplexed by the eighth wavelength division multiplexing device, and the multiplexed second classical transmission signals are transmitted to the first device via the fourth circulator on the second optical fiber; and

[0056] The sixth wavelength division multiplexing device demultiplexes the multiplexed second classical transmission signal transmitted on the second optical fiber, and sends the demultiplexed second classical transmission signal to the plurality of first classical transmission devices and the plurality of second classical transmission devices.

[0057] According to the device, system, and method for full-duplex quantum direct communication provided in this application, by introducing a circulator, quantum state signals can be transmitted and received in the same optical fiber, reducing the optical fiber link resources required for transmitting and receiving quantum state signals during full-duplex quantum direct communication. Furthermore, by using a wavelength division multiplexing (WDM) device, multiple quantum state signals in the full-duplex quantum direct communication process are multiplexed into the same optical fiber, further reducing the required optical fiber link resources. Even further, by using a WDM device, multiple classical transmission signals are multiplexed into the same optical fiber, further reducing the required optical fiber link resources. Still further, by introducing a circulator, multiple classical transmission signals in the full-duplex quantum direct communication process can be transmitted and received in the same optical fiber, reducing the optical fiber link resources required for transmitting and receiving classical transmission signals during full-duplex quantum direct communication. Ultimately, the optical fiber link resources required for full-duplex quantum direct communication can be reduced to two optical fibers. The solution of this application effectively reduces the optical fiber link resource consumption during the deployment of full-duplex quantum direct communication terminals, lowers deployment costs, and simultaneously separates the transmission of quantum and classical signals, solving the problem of classical signals interfering with quantum signals during co-fiber transmission and preventing a decrease in terminal communication performance. Thus, while reducing fiber optic link resources and costs, the system's performance was maintained. Attached Figure Description

[0058] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings, without exceeding the scope of protection claimed by this application.

[0059] Figure 1 This is a schematic diagram of the inter-device connection for quantum direct communication.

[0060] Figure 2 This is a schematic diagram of the terminal link setup for full-duplex quantum direct communication.

[0061] Figure 3 This is a schematic diagram of a system for duplex quantum direct communication according to an embodiment of this application.

[0062] Figure 4 This is a schematic diagram of the principle of a circulator.

[0063] Figure 5 This is a schematic diagram of a system for duplex quantum direct communication according to another embodiment of this application.

[0064] Figure 6 This is a schematic diagram of a system for duplex quantum direct communication according to yet another embodiment of this application.

[0065] Figure 7 This is a schematic diagram of a system for duplex quantum direct communication according to another embodiment of this application.

[0066] Figure 8 This is a flowchart of a duplex communication method based on a duplex quantum direct communication system according to an embodiment of this application.

[0067] Figure 9 This is a flowchart of a duplex communication method based on a duplex quantum direct communication system according to another embodiment of this application. Detailed Implementation

[0068] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0069] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0070] Figure 3 This is a schematic diagram of a system for duplex quantum direct communication according to an embodiment of this application. Figure 3 As shown, the system includes a first device and a second device, wherein the first device includes a first quantum system transmitting device, a first quantum system receiving device and a first circulator (CIR), and the second device includes a second quantum system transmitting device, a second quantum system receiving device and a second circulator.

[0071] Figure 4 This is a schematic diagram of the principle of a circulator. (For example...) Figure 4 As shown, light incident through port 1 will only exit through port 2; light incident through port 3 will only exit through port 1. The specific relationship follows the direction of the circular arrows.

[0072] exist Figure 3 In this process, the first device and the second device send quantum state signals to each other, wherein the first device sends a first quantum state signal to the second device, and the second device sends a second quantum state signal to the first device.

[0073] according to Figure 3 In the embodiment shown, the first quantum system transmitting device transmits a first quantum state signal to the second device via a first circulator and on a first optical fiber; the second quantum system receiving device receives the first quantum state signal transmitted on the first optical fiber via a second circulator; the second quantum system transmitting device transmits a second quantum state signal to the first device via a second circulator and on the first optical fiber; and the first quantum system receiving device receives the second quantum state signal transmitted on the first optical fiber via a first circulator.

[0074] exist Figure 3 In the illustrated embodiment, the introduction of a circulator enables the transmission and reception of quantum state signals within the same optical fiber, thereby reducing the optical fiber link resources required for transmitting and receiving quantum state signals during duplex quantum direct communication compared to existing technologies.

[0075] exist Figure 3In the illustrated embodiments, both the first and second devices contain only one set of quantum system transmitting and receiving devices. In cases where the first and second devices contain multiple sets of quantum system transmitting and receiving devices, this invention employs wavelength division multiplexing (WDM) to further reduce the fiber optic link resources required for transmitting and receiving quantum state signals during duplex quantum direct communication.

[0076] Figure 5 This is a schematic diagram of a system for duplex quantum direct communication according to another embodiment of this application. Figure 5 As shown, there are multiple first quantum system transmitting devices, multiple first quantum system receiving devices, multiple second quantum system transmitting devices, and multiple second quantum system receiving devices. The first device also includes a first wavelength division multiplexing device and a second wavelength division multiplexing device, and the second device also includes a third wavelength division multiplexing device and a fourth wavelength division multiplexing device.

[0077] exist Figure 5 In the illustrated embodiment, a first wavelength division multiplexing (WDM) device multiplexes multiple first quantum state signals from multiple first quantum system transmitting devices and transmits the multiplexed first quantum state signals to a second device via a first circulator and a first optical fiber; a third WDM device receives the multiplexed first quantum state signals via a second circulator, demultiplexes the multiplexed first quantum state signals, and transmits the demultiplexed first quantum state signals to multiple second quantum system receiving devices; a fourth WDM device multiplexes multiple second quantum state signals from multiple second quantum system transmitting devices and transmits the multiplexed second quantum state signals to a first device via a second circulator and a first optical fiber; a second WDM device receives the multiplexed second quantum state signals via a first circulator, demultiplexes the multiplexed second quantum state signals, and transmits the demultiplexed second quantum state signals to multiple first quantum system receiving devices.

[0078] Figure 3 and Figure 5 The illustrated embodiments demonstrate a scheme for reducing the fiber optic link resources required for transmitting and receiving quantum state signals during full-duplex quantum direct communication. Existing quantum direct communication systems require both quantum channels (QC) and classical channels for communication between end units. These classical channels may include those supporting protocol information exchange (e.g., Ethernet) and clock synchronization channels (e.g., SFP optical modules). This application can also reduce the fiber optic link resources required for transmitting and receiving classical signals during full-duplex quantum direct communication, particularly for classical signal transmission within classical channels.

[0079] Figure 6This is a schematic diagram of a system for duplex quantum direct communication according to yet another embodiment of this application. Figure 6 As shown, the first device and the second device, in addition to including Figure 3 or Figure 5 The quantum system transmitting device, quantum system receiving device, circulator and / or multiplexer shown also include devices related to classical signal transmission.

[0080] exist Figure 6 In the illustrated embodiment, the first device further includes a plurality of first classical transmission devices, a plurality of second classical transmission devices, a fifth wavelength division multiplexing device, a sixth wavelength division multiplexing device, and a third circulator; the second device further includes a plurality of third classical transmission devices, a plurality of fourth classical transmission devices, a seventh wavelength division multiplexing device, an eighth wavelength division multiplexing device, and a fourth circulator.

[0081] exist Figure 6 In this process, the first device and the second device send classical transmission signals to each other, wherein the classical transmission device of the first device sends a first classical transmission signal to the second device, and the classical transmission device of the second device sends a second classical transmission signal to the first device.

[0082] Multiple first classical transmission devices and multiple second classical transmission devices transmit multiple first classical transmission signals to a fifth wavelength division multiplexing (WDM) device; the fifth WDM multiplexing device multiplexes the multiple first classical transmission signals and transmits the multiplexed first classical transmission signals to a second device via a third circulator on a second optical fiber; a seventh WDM multiplexing device demultiplexes the multiplexed first classical transmission signals transmitted on the second optical fiber and transmits the demultiplexed first classical transmission signals to multiple third classical transmission devices and multiple fourth classical transmission devices; multiple third classical transmission devices and multiple fourth classical transmission devices transmit multiple second classical transmission signals to an eighth WDM multiplexing device; the eighth WDM multiplexing device multiplexes the multiple second classical transmission signals and transmits the multiplexed second classical transmission signals to a first device via a fourth circulator on a second optical fiber; a sixth WDM multiplexing device demultiplexes the multiplexed second classical transmission signals transmitted on the second optical fiber and transmits the demultiplexed second classical transmission signals to multiple first classical transmission devices and multiple second classical transmission devices.

[0083] exist Figure 6 In the illustrated embodiment, the first classical transmission device, the second classical transmission device, the third classical transmission device, and the fourth classical transmission device can be any classical transmission device that transmits and receives classical transmission signals, such as an Ethernet module, an SFP optical module, etc.

[0084] Regarding wavelength selection between the first and second devices: Assume a total of m wavelengths are needed between the first and second devices, where j wavelengths (λ1, ..., λ2) are used. j Let Tx be the quantum state signal from the transmitter Tx of the first device to the receiver Rx of the second device, with kj-1 wavelengths (λ). (j+1) ,…,λ (k-1) ) represents the quantum state signal from the second device transmitter Tx to the first device receiver Rx, with l-k+1 wavelengths (λ). k ,…,λ l ( ) represents the classical signal from transmitter Tx to receiver Rx, with ml wavelengths (λ) (l+1) ,…,λ m The signal from receiver Rx to transmitter Tx is a classic signal, such as... Figure 6 As shown, although there are many wavelengths, only two transmission links are needed between the first and second devices.

[0085] exist Figure 6 In the illustrated embodiment, the first and fourth wavelength division multiplexing devices use corresponding wavelengths to multiplex multiple first quantum state signals and multiple second quantum state signals, respectively. The second and third wavelength division multiplexing devices use corresponding wavelengths to demultiplex the multiplexed second quantum state signals and multiplexed first quantum state signals, respectively. The fifth and eighth wavelength division multiplexing devices use corresponding wavelengths to multiplex multiple first classical transmission signals and multiple second classical transmission signals, respectively. The sixth and seventh wavelength division multiplexing devices use corresponding wavelengths to demultiplex the multiplexed second classical transmission signals and multiplexed first classical transmission signals, respectively.

[0086] Figure 7 This is a schematic diagram of a system for duplex quantum direct communication according to another embodiment of this application. Figure 7 In the illustrated embodiment, the number of the first quantum system transmitting device, the first quantum system receiving device, the second quantum system transmitting device, and the second quantum system receiving device is one each. Figure 7 In the embodiment shown, Figure 6 The first, second, third, and fourth classic transmission devices are Ethernet modules or SFP optical modules. Multiple first, second, third, and fourth classic transmission devices respectively include combinations of Ethernet modules and SFP optical modules.

[0087] exist Figure 7In this configuration, quantum state signals are connected via a first circulator, forming Link 1, enabling bidirectional transmission of quantum state signals using a 1550nm wavelength. Both the SFP and Ethernet interfaces are bidirectional, with each interface having one input and one output. On the first device side, the SFP output signal from the first device transmitter Tx is 1530nm, and the Ethernet output signal is 1590nm. The SFP output signal from the first device receiver Rx is 1510nm, and the Ethernet output signal is 1570nm. These four wavelengths are fed into a wavelength division multiplexing (WDM) device, combined, and transmitted to the circulator on the first device side. Subsequently, they are transmitted via Link 2 to the circulator on the second device side. The circulator sends the combined signal to the WDM device on the second device side, where it is then split, and the four wavelengths are sent to the SFP interface input and Ethernet interface input of the second device receiver Rx, respectively. The transmission from the second device receiver RX to the first device transmitter Tx is similar.

[0088] Specifically, the wavelength allocation is as follows: From the first device to the second device, the signal is transmitted from the transmitter (Tx) of the first device to the receiver (Rx) of the second device. Quantum state signals are transmitted unidirectionally from the quantum system transmitter interface of the transmitter (Tx) of the first device to the quantum system receiver interface of the receiver (Rx) of the second device, using a wavelength of 1550nm. SFP classical signals represent bidirectional communication between the SFP interfaces of the transmitter (Tx) and receiver (Rx) of the first device; the transmitter (Tx) uses a wavelength of 1530nm, and the receiver (Rx) uses a wavelength of 1510nm. Ethernet classical signals represent bidirectional communication between the Ethernet interfaces of the transmitter (Tx) and receiver (Rx) of the first device; the transmitter (Tx) uses a wavelength of 1590nm, and the receiver (Rx) uses a wavelength of 1570nm.

[0089] The signal transmission from the second device to the first device is from the transmitter (Tx) of the second device to the receiver (Rx) of the first device. Quantum state signals are unidirectional transmissions from the quantum system transmitter interface of the second device (Tx) to the quantum system receiver interface of the first device (Rx), using a wavelength of 1550nm. SFP classical signals represent bidirectional communication between the SFP interfaces of the second device (Tx) and the first device (Rx), with the transmitter (Tx) using a wavelength of 1530nm and the receiver (Rx) using a wavelength of 1510nm. Ethernet classical signals represent bidirectional communication between the Ethernet interfaces of the second device (Tx) and the first device (Rx), with the transmitter (Tx) using a wavelength of 1590nm and the receiver (Rx) using a wavelength of 1570nm.

[0090] It should be noted that the wavelengths of quantum state signals and classical transmission signals are not limited to the values ​​given in the above embodiments, and can be set according to actual needs, all of which fall within the scope of this application.

[0091] Based on the aforementioned system for duplex quantum direct communication, this application provides a device for duplex quantum direct communication. According to one specific embodiment, the device for duplex quantum direct communication may be… Figures 3 to 6 The first or second device in the system shown.

[0092] According to some embodiments, the device for duplex quantum direct communication includes a quantum system transmitting device, a quantum system receiving device, and a circulator, wherein: the quantum system transmitting device transmits a first quantum state signal via the circulator on a first optical fiber; and the quantum system receiving device receives a second quantum state signal transmitted on the first optical fiber via the circulator.

[0093] According to some embodiments, when there are multiple first quantum system transmitting devices and multiple first quantum system receiving devices, the device for duplex quantum direct communication further includes a first wavelength division multiplexing device and a second wavelength division multiplexing device, wherein: the first wavelength division multiplexing device multiplexes multiple first quantum state signals from multiple quantum system transmitting devices and transmits the multiplexed first quantum state signals via a circulator on a first optical fiber; the second wavelength division multiplexing device demultiplexes multiple second quantum state signals transmitted on the first optical fiber and transmits the demultiplexed second quantum state signals to multiple quantum system receiving devices.

[0094] According to some embodiments, the device for duplex quantum direct communication further includes multiple first classical transmission devices, multiple second classical transmission devices, a third wavelength division multiplexing device, a fourth wavelength division multiplexing device, and a second circulator, wherein: the multiple first classical transmission devices and the multiple second classical transmission devices transmit multiple first classical transmission signals to the third wavelength division multiplexing device; the third wavelength division multiplexing device multiplexes the multiple first classical transmission signals and transmits the multiplexed first classical transmission signals via the second circulator on a second optical fiber; the fourth wavelength division multiplexing device demultiplexes the second classical transmission signals transmitted on the second optical fiber and transmits the demultiplexed second classical transmission signals to the multiple first classical transmission devices and the multiple second classical transmission devices.

[0095] Based on the aforementioned system for duplex quantum direct communication, according to one aspect of this application, a duplex communication method based on a duplex quantum direct communication system is provided. The duplex quantum direct communication system includes a first device and a second device, wherein the first device includes a first quantum system transmitting device, a first quantum system receiving device, and a first circulator, and the second device includes a second quantum system transmitting device, a second quantum system receiving device, and a second circulator. Figure 8 As shown, the method includes the following steps.

[0096] Step S801: The first quantum state signal is transmitted to the second device via the first circulator and the first optical fiber through the first quantum system transmitting device;

[0097] Step S802: The first quantum state signal transmitted on the first optical fiber is received by the second quantum system receiving device via the second circulator;

[0098] Step S803: The second quantum state signal is transmitted to the first device via the second circulator and the first optical fiber through the second quantum system transmitting device; and

[0099] Step S804: The second quantum state signal transmitted on the first optical fiber is received by the first quantum system receiving device via the first circulator.

[0100] According to some embodiments, when there are multiple first quantum system transmitting devices, first quantum system receiving devices, second quantum system transmitting devices, and second quantum system receiving devices, the first device further includes a first wavelength division multiplexing device and a second wavelength division multiplexing device, and the second device further includes a third wavelength division multiplexing device and a fourth wavelength division multiplexing device.

[0101] Step S801 may include:

[0102] The first wavelength division multiplexing device multiplexes multiple first quantum state signals from multiple first quantum system transmitting devices, and then transmits the multiplexed first quantum state signals to the second device via the first circulator and the first optical fiber.

[0103] Step S802 may include:

[0104] The first quantum state signal is received by the third wavelength division multiplexing device via the second circulator, the multiplexed first quantum state signal is demultiplexed, and the demultiplexed first quantum state signal is sent to multiple second quantum system receiving devices.

[0105] Step S803 may include:

[0106] The fourth wavelength division multiplexing device multiplexes multiple second quantum state signals from multiple second quantum system transmitting devices, and then transmits the multiplexed second quantum state signals to the first device via the second circulator and the first optical fiber.

[0107] Step S804 may include:

[0108] The second wave division multiplexing device receives the multiplexed second quantum state signal via the first circulator, demultiplexes the multiplexed second quantum state signal, and sends the demultiplexed second quantum state signal to multiple first quantum system receiving devices.

[0109] For existing quantum direct communication systems to communicate between end devices, in addition to quantum channels (QC), classical channels are also required, such as classical channels that support protocol information exchange (e.g., Ethernet) and clock synchronization channels (e.g., SFP optical modules).

[0110] According to another aspect of this application, a duplex communication method based on a duplex quantum direct communication system is provided. The first and second devices in the system for duplex quantum direct communication include, in addition to a quantum system transmitting device, a quantum system receiving device, a circulator, and / or a multiplexer, devices related to classical signal transmission. According to some embodiments, the first device further includes multiple first classical transmission devices, multiple second classical transmission devices, a fifth wavelength division multiplexing device, a sixth wavelength division multiplexing device, and a third circulator; the second device further includes multiple third classical transmission devices, multiple fourth classical transmission devices, a seventh wavelength division multiplexing device, an eighth wavelength division multiplexing device, and a fourth circulator. Figure 8 compared to, Figure 9 Steps S901 to S904 and Figure 8 Steps S801 to S804 are the same, except that... Figure 9 The method shown also includes the following steps.

[0111] Step S905: Multiple first classical transmission signals are sent to the fifth wavelength division multiplexing device through multiple first classical transmission devices and multiple second classical transmission devices;

[0112] Step S906: Multiple first classical transmission signals are multiplexed by the fifth wavelength division multiplexing device, and the multiplexed first classical transmission signals are transmitted to the second device via the third circulator and the second optical fiber.

[0113] Step S907: The multiplexed first classical transmission signal transmitted on the second optical fiber is demultiplexed by the seventh wavelength division multiplexing device, and the demultiplexed first classical transmission signal is sent to multiple third classical transmission devices and multiple fourth classical transmission devices.

[0114] Step S908: Multiple second classical transmission signals are sent to the eighth wavelength division multiplexing device through multiple third classical transmission devices and multiple fourth classical transmission devices;

[0115] Step S909: Multiple second classical transmission signals are multiplexed using the eighth wavelength division multiplexing device, and the multiplexed second classical transmission signals are transmitted to the first device via the fourth circulator and on the second optical fiber; and

[0116] Step S910: The multiplexed second classical transmission signal transmitted on the second optical fiber is demultiplexed by the sixth wavelength division multiplexing device, and the demultiplexed second classical transmission signal is sent to multiple first classical transmission devices and multiple second classical transmission devices.

[0117] According to the device, system, and method for full-duplex quantum direct communication provided in this application, by introducing a circulator, quantum state signals can be transmitted and received in the same optical fiber, reducing the optical fiber link resources required for transmitting and receiving quantum state signals during full-duplex quantum direct communication. Furthermore, by using a wavelength division multiplexing (WDM) device, multiple quantum state signals in the full-duplex quantum direct communication process are multiplexed into the same optical fiber, further reducing the required optical fiber link resources. Even further, by using a WDM device, multiple classical transmission signals are multiplexed into the same optical fiber, further reducing the required optical fiber link resources. Still further, by introducing a circulator, multiple classical transmission signals in the full-duplex quantum direct communication process can be transmitted and received in the same optical fiber, reducing the optical fiber link resources required for transmitting and receiving classical transmission signals during full-duplex quantum direct communication. Ultimately, the optical fiber link resources required for full-duplex quantum direct communication can be reduced to two optical fibers. The solution of this application effectively reduces the optical fiber link resource consumption during the deployment of full-duplex quantum direct communication terminals, lowers deployment costs, and simultaneously separates the transmission of quantum and classical signals, solving the problem of classical signals interfering with quantum signals during co-fiber transmission and preventing a decrease in terminal communication performance. Thus, while reducing fiber optic link resources and costs, the system's performance was maintained.

[0118] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. Furthermore, any changes or modifications made by those skilled in the art based on the ideas of this application, and on the specific implementation methods and application scope of this application, are all within the scope of protection of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A device for duplex quantum direct communication, characterized in that, It includes a quantum system transmitting device, a quantum system receiving device, and a circulator, wherein: The quantum system transmitting device is used to transmit the first quantum state signal via the circulator and on the first optical fiber; The quantum system receiving device is used to receive a second quantum state signal transmitted on the first optical fiber via the circulator; The device comprises multiple quantum system transmitting devices and multiple quantum system receiving devices, and further includes a first wavelength division multiplexing device and a second wavelength division multiplexing device, wherein: The first wavelength division multiplexing device is used to multiplex multiple first quantum state signals from multiple quantum system transmitting devices, and transmit the multiplexed first quantum state signals via the circulator on the first optical fiber; and The second wavelength division multiplexing device is used to demultiplex multiple second quantum state signals transmitted on the first optical fiber, and send the demultiplexed second quantum state signals to multiple quantum system receiving devices.

2. The device as described in claim 1, characterized in that, It also includes multiple first classical transmission devices, multiple second classical transmission devices, a third wavelength division multiplexing device, a fourth wavelength division multiplexing device, and a second circulator, wherein: The plurality of first classical transmission devices and the plurality of second classical transmission devices are used to transmit the plurality of first classical transmission signals to the third wavelength division multiplexing device; The third wavelength division multiplexing device is used to multiplex the plurality of first classical transmission signals, and transmit the multiplexed first classical transmission signals via the second circulator and on the second optical fiber; and The fourth wavelength division multiplexing device is used to demultiplex the second classical transmission signal transmitted on the second optical fiber, and send the demultiplexed second classical transmission signal to the plurality of first classical transmission devices and the plurality of second classical transmission devices.

3. A system for duplex quantum direct communication, characterized in that, The device includes a first device and a second device, wherein the first device includes a first quantum system transmitting device, a first quantum system receiving device, and a first circulator; the second device includes a second quantum system transmitting device, a second quantum system receiving device, and a second circulator; wherein: The first quantum system transmitting device is used to transmit the first quantum state signal to the second device via the first circulator and on the first optical fiber; The second quantum system receiving device is used to receive the first quantum state signal transmitted on the first optical fiber via the second circulator; The second quantum system transmitting device is used to transmit the second quantum state signal to the first device via the second circulator and on the first optical fiber; and The first quantum system receiving device is used to receive the second quantum state signal transmitted on the first optical fiber via the first circulator; The device comprises multiple first quantum system transmitting devices, multiple first quantum system receiving devices, multiple second quantum system transmitting devices, and multiple second quantum system receiving devices. The first device further includes a first wavelength division multiplexing (WDM) device and a second WDM device, and the second device further includes a third WDM device and a fourth WDM device. The first wavelength division multiplexing device is used to multiplex multiple first quantum state signals from multiple first quantum system transmitting devices, and transmit the multiplexed first quantum state signals to the second device via the first circulator and on the first optical fiber; The third wavelength division multiplexing device is used to receive the multiplexed first quantum state signal via the second circulator, demultiplex the multiplexed first quantum state signal, and send the demultiplexed first quantum state signal to multiple second quantum system receiving devices; The fourth wavelength division multiplexing device is used to multiplex multiple second quantum state signals from multiple second quantum system transmitting devices, and transmit the multiplexed second quantum state signals to the first device via the second circulator and on the first optical fiber; and The second wavelength division multiplexing device is used to receive the multiplexed second quantum state signal via the first circulator, demultiplex the multiplexed second quantum state signal, and send the demultiplexed second quantum state signal to multiple first quantum system receiving devices.

4. The system as described in claim 3, characterized in that, The first device further includes multiple first classical transmission devices, multiple second classical transmission devices, a fifth wavelength division multiplexing device, a sixth wavelength division multiplexing device, and a third circulator; the second device further includes multiple third classical transmission devices, multiple fourth classical transmission devices, a seventh wavelength division multiplexing device, an eighth wavelength division multiplexing device, and a fourth circulator, wherein: The plurality of first classical transmission devices and the plurality of second classical transmission devices are used to transmit the plurality of first classical transmission signals to the fifth wavelength division multiplexing device; The fifth wavelength division multiplexing device is used to multiplex the plurality of first classical transmission signals, and transmit the multiplexed first classical transmission signals to the second device via the third circulator and on the second optical fiber; The seventh wavelength division multiplexing device is used to demultiplex the multiplexed first classical transmission signal transmitted on the second optical fiber, and send the demultiplexed first classical transmission signal to the plurality of third classical transmission devices and the plurality of fourth classical transmission devices. The plurality of third classical transmission devices and the plurality of fourth classical transmission devices are used to transmit the plurality of second classical transmission signals to the eighth wavelength division multiplexing device; The eighth wavelength division multiplexing device is used to multiplex the plurality of second classical transmission signals, and transmit the multiplexed second classical transmission signals to the first device via the fourth circulator on the second optical fiber; and The sixth wavelength division multiplexing device is used to demultiplex the multiplexed second classical transmission signal transmitted on the second optical fiber, and send the demultiplexed second classical transmission signal to the plurality of first classical transmission devices and the plurality of second classical transmission devices.

5. The system as described in claim 4, characterized in that, The first and fourth wavelength division multiplexing devices use corresponding wavelengths to multiplex multiple first quantum state signals and multiple second quantum state signals, respectively. The second and third wavelength division multiplexing devices use corresponding wavelengths to demultiplex the multiplexed second quantum state signals and the multiplexed first quantum state signals, respectively. The fifth and eighth wavelength division multiplexing devices use corresponding wavelengths to multiplex the multiple first classical transmission signals and the multiple second classical transmission signals, respectively. The sixth and seventh wavelength division multiplexing devices use corresponding wavelengths to demultiplex the multiplexed second classical transmission signals and the multiplexed first classical transmission signals, respectively.

6. A duplex communication method based on a duplex quantum direct communication system, characterized in that, The duplex quantum direct communication system includes a first device and a second device, wherein the first device includes a first quantum system transmitting device, a first quantum system receiving device, and a first circulator, and the second device includes a second quantum system transmitting device, a second quantum system receiving device, and a second circulator; the method includes: The first quantum state signal is transmitted to the second device via the first circulator and the first optical fiber through the first quantum system transmitting device; The first quantum state signal transmitted on the first optical fiber is received by the second quantum system receiving device via the second circulator; The second quantum state signal is transmitted to the first device via the second circulator and the first optical fiber through the second quantum system transmitting device; and The second quantum state signal transmitted on the first optical fiber is received by the first quantum system receiving device via the first circulator; The device comprises multiple first quantum system transmitting devices, first quantum system receiving devices, second quantum system transmitting devices, and second quantum system receiving devices. The first device further includes a first wavelength division multiplexing (WDM) device and a second WDM device, and the second device further includes a third WDM device and a fourth WDM device. The step of transmitting the first quantum state signal to the second device via the first circulator and the first optical fiber through the first quantum system transmitting device includes: The first wavelength division multiplexing device multiplexes multiple first quantum state signals from multiple first quantum system transmitting devices, and transmits the multiplexed first quantum state signals to the second device via the first circulator and on the first optical fiber; The receiving of the first quantum state signal transmitted on the first optical fiber via the second quantum system receiving device through the second circulator includes: The third wavelength division multiplexing device receives the multiplexed first quantum state signal via the second circulator, demultiplexes the multiplexed first quantum state signal, and sends the demultiplexed first quantum state signal to multiple second quantum system receiving devices. The step of transmitting the second quantum state signal via the second circulator to the first device through the second quantum system transmitting device includes: The fourth wavelength division multiplexing device multiplexes multiple second quantum state signals from multiple second quantum system transmitting devices, and then transmits the multiplexed second quantum state signals to the first device via the second circulator on the first optical fiber; The receiving of the second quantum state signal transmitted on the first optical fiber via the first circulator through the first quantum system receiving device includes: The second wavelength division multiplexing device receives the multiplexed second quantum state signal via the first circulator, demultiplexes the multiplexed second quantum state signal, and sends the demultiplexed second quantum state signal to multiple first quantum system receiving devices.

7. The method as described in claim 6, characterized in that, The first device further includes multiple first classical transmission devices, multiple second classical transmission devices, a fifth wavelength division multiplexing device, a sixth wavelength division multiplexing device, and a third circulator; the second device further includes multiple third classical transmission devices, multiple fourth classical transmission devices, a seventh wavelength division multiplexing device, an eighth wavelength division multiplexing device, and a fourth circulator; the method further includes: Multiple first classical transmission signals are transmitted to the fifth wavelength division multiplexing device through the multiple first classical transmission devices and the multiple second classical transmission devices; The fifth wavelength division multiplexing device multiplexes the plurality of first classical transmission signals, and then transmits the multiplexed first classical transmission signals to the second device via the third circulator and on the second optical fiber. The seventh wavelength division multiplexing device demultiplexes the multiplexed first classical transmission signal transmitted on the second optical fiber, and sends the demultiplexed first classical transmission signal to the plurality of third classical transmission devices and the plurality of fourth classical transmission devices. Multiple second classical transmission signals are transmitted to the eighth wavelength division multiplexing device through the multiple third classical transmission devices and the multiple fourth classical transmission devices; The plurality of second classical transmission signals are multiplexed by the eighth wavelength division multiplexing device, and the multiplexed second classical transmission signals are transmitted to the first device via the fourth circulator on the second optical fiber; and The sixth wavelength division multiplexing device demultiplexes the multiplexed second classical transmission signal transmitted on the second optical fiber, and sends the demultiplexed second classical transmission signal to the plurality of first classical transmission devices and the plurality of second classical transmission devices.

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