Quantum state encoding device, method and software-defined quantum communication system

Abstract

The present application provides a quantum state encoding device, method, and software-defined quantum communication system. The quantum state encoding device includes: a polarization encoding unit, a first optical coupling unit, an unequal-arm polarization control interferometer, a first transmission optical path, and a second optical coupling unit. The polarization encoding unit is used to generate optical pulses in a polarization-encoded quantum state; the unequal-arm polarization control interferometer is used to convert the optical pulses in the polarization-encoded quantum state into optical pulses in a time-phase-encoded quantum state. By controlling the first and second optical coupling units to output optical pulses in the polarization-encoded quantum state or in the time-phase-encoded quantum state according to quantum communication coding control instructions, the present application enables the same quantum state encoding device to meet the different coding requirements of a quantum communication system.

Description

Technical Field

[0001] The present application relates to the fields of quantum communication and optical quantum coding technology, and in particular to a quantum state coding device, method, and software-defined quantum communication system. Background Art

[0002] Quantum communication technology is a cutting-edge field at the intersection of quantum physics and information science. Current applications primarily include quantum key distribution (QKD) and quantum direct communication (QDC). Based on physical principles such as the Heisenberg uncertainty relation in quantum mechanics and the quantum no-cloning theorem, QKD enables real-time and secure key sharing between communicating parties. Quantum direct communication ensures secure information transmission. Quantum communication can detect potential eavesdropping on communication channels and has applications in defense, government, finance, electricity, and other sectors requiring high-security information transmission.

[0003] The physical implementation of quantum communication systems, such as quantum key distribution and direct quantum communication, requires encoding and decoding quantum states. Currently, commonly used quantum communication encoding methods include polarization encoding and time phase encoding. A quantum communication system typically uses only one of these encoding methods, making it non-universal and inflexible in networking.

[0004] How to realize universal quantum state coding that is compatible with multiple quantum communication system coding methods in an optical quantum coding device is an important issue in quantum communication applications. Summary of the Invention

[0005] The purpose of this application is to provide a quantum state encoding device, method and software-defined quantum communication system to solve the technical problems mentioned in the prior art.

[0006] To achieve the above objectives, in a first aspect, the present application provides a quantum state encoding device, comprising: a polarization encoding unit, a first optical coupling unit, an unequal-arm polarization control interferometer, a first transmission optical path, and a second optical coupling unit. The polarization encoding unit includes at least one input port and an output port, and the polarization encoding unit is used to input an optical pulse through one of the input ports, generate an optical pulse of a polarization-encoded quantum state based on the input optical pulse, and output it through the output port. The first optical coupling unit includes an input port and two output ports, namely a first port, a second port, and a third port, and the first port is connected to the output port of the polarization encoding unit. The second optical coupling unit includes two input ports and one output port, namely a fourth port, a fifth port, and a sixth port. The unequal-arm polarization control interferometer includes an input port and an output port, and is used to perform time-phase encoding conversion on the input optical pulse of the polarization-encoded quantum state and output an optical pulse of the time-phase-encoded quantum state. The third port of the first optical coupling unit is connected to the input port of the unequal-arm polarization control interferometer, and the output port of the unequal-arm polarization control interferometer is connected to the fifth port of the second optical coupling unit, forming a first optical output branch. The second port of the first optical coupling unit is connected to the fourth port of the second optical coupling unit via the first transmission optical path, forming a second optical output branch. The first optical coupling unit is configured to input the polarization-encoded quantum state optical pulse output by the polarization encoding unit into the first optical output branch and / or the second optical output branch in accordance with quantum communication coding control instructions. The quantum communication coding control instructions are determined based on the coding requirements of the quantum communication system. The sixth port of the second optical coupling unit is the output port of the quantum state encoding device and is configured to output the polarization-encoded quantum state optical pulse transmitted by the second optical output branch or the time-phase-encoded quantum state optical pulse transmitted by the first optical output branch in accordance with the quantum communication coding control instructions.

[0007] In a second aspect, the present application provides a quantum state encoding method, which uses the above-mentioned quantum state encoding device to implement quantum state encoding.

[0008] In a third aspect, the present application provides a software-defined quantum communication system, comprising the above-mentioned quantum state encoding device.

[0009] In summary, the quantum state encoding device, method, and software-defined quantum communication system provided by this application have at least the following beneficial effects:

[0010] This application utilizes a polarization encoding unit, a first optical coupling unit, an unequal-arm polarization control interferometer, a first transmission optical path, and a second optical coupling unit to form a quantum state encoding device. The polarization encoding unit is used to generate optical pulses in a polarization-encoded quantum state, and the unequal-arm polarization control interferometer is used to convert the optical pulses in the polarization-encoded quantum state into optical pulses in a time-phase-encoded quantum state. The first and second optical coupling units are controlled to output optical pulses in the polarization-encoded quantum state or in the time-phase-encoded quantum state according to quantum communication coding control instructions, thereby enabling the same quantum state encoding device to meet the different coding requirements of a quantum communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without any creative work.

[0012] Figure 1 A block diagram of a quantum state encoding device provided in an embodiment of the present application;

[0013] Figure 2 A structural block diagram of a polarization coding unit provided in an embodiment of the present application;

[0014] Figure 3 A structural block diagram of a first polarization operation module provided in an embodiment of the present application;

[0015] Figure 4 A structural block diagram of a second polarization operation module provided in an embodiment of the present application;

[0016] Figure 5 A structural block diagram of a third polarization operation module provided in an embodiment of the present application;

[0017] Figure 6 A structural block diagram of a fourth polarization operation module provided in an embodiment of the present application;

[0018] Figure 7 A structural block diagram of a fifth polarization operation module provided in an embodiment of the present application;

[0019] Figure 8 A structural block diagram of a sixth polarization operation module provided in an embodiment of the present application;

[0020] Figure 9 A structural block diagram of a seventh polarization operation module provided in an embodiment of the present application;

[0021] Figure 10 A structural block diagram of an eighth polarization operation module provided in an embodiment of the present application;

[0022] Figure 11 A structural block diagram of a ninth polarization operation module provided in an embodiment of the present application;

[0023] Figure 12 A structural block diagram of a tenth polarization operation module provided in an embodiment of the present application;

[0024] Figure 13 A structural block diagram of an eleventh polarization operation module provided in an embodiment of the present application;

[0025] Figure 14 A structural block diagram of a twelfth polarization operation module provided in an embodiment of the present application;

[0026] Figure 15 A structural block diagram of a thirteenth polarization operation module provided in an embodiment of the present application;

[0027] Figure 16 A structural block diagram of a fourteenth polarization operation module provided in an embodiment of the present application;

[0028] Figure 17 A structural block diagram of a fifteenth polarization operation module provided in an embodiment of the present application;

[0029] Figure 18 A structural block diagram of a sixteenth polarization operation module provided in an embodiment of the present application;

[0030] Figure 19 A structural diagram of a first embodiment of an unequal-arm polarization control interferometer provided in an embodiment of the present application;

[0031] Figure 20 A structural diagram of a second embodiment of an unequal-arm polarization control interferometer provided in an embodiment of the present application;

[0032] Figure 21 A structural diagram of a third embodiment of an unequal-arm polarization control interferometer provided in an embodiment of the present application;

[0033] Figure 22 A structural diagram of a fourth embodiment of an unequal-arm polarization control interferometer provided in an embodiment of the present application;

[0034] Figure 23 A structural diagram of a fifth embodiment of an unequal-arm polarization control interferometer provided in an embodiment of the present application;

[0035] Figure 24 A structural diagram of a sixth embodiment of an unequal-arm polarization control interferometer provided in an embodiment of the present application;

[0036] Figure 25 A schematic structural diagram of another quantum state encoding device provided in an embodiment of the present application;

[0037] Figure 26 Schematic diagram of the software-defined quantum communication system structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present application. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion in the concepts of the present application.

[0039] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments of the present application. These figures are not drawn to scale, and for the purpose of clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0040] In the context of this application, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intervening layer / element between them. Furthermore, if a layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element. To make the technical problems, technical solutions, and beneficial effects to be solved by this application more clearly understood, the application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely intended to explain this application and are not intended to limit this application.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0042] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0043] The quantum state encoding devices in existing quantum communication systems have the following problems:

[0044] 1. Currently, commonly used quantum communication coding methods include polarization coding and time phase coding. A quantum communication system generally chooses one of these coding methods. Therefore, the system is not universal and cannot be flexibly networked, and cannot meet the quantum state coding requirements of different quantum communication systems.

[0045] 2. The preparation of polarization-encoded or time-phase-encoded quantum states is usually achieved using a phase modulator. However, phase modulators are easily affected by the environment, resulting in phase drift, which requires real-time feedback compensation or temperature control measures, making it difficult for quantum communication systems to operate stably and efficiently.

[0046] 3. Currently, the coding rates of quantum communication systems in practical applications are mainly 100 MHz and 1 GHz. However, in order to increase the secure transmission distance of quantum communication and improve the quantum key generation rate or information transmission rate, it is necessary to encode quantum states at a rate of 10 GHz or higher.

[0047] 4. Currently, quantum communication systems generally support encoding of four quantum states with two bases. It is difficult to be compatible with multiple quantum communication protocols such as BB84 and reference frame independence in one quantum communication system. Quantum communication systems need to support encoding of four quantum states with three bases or six quantum states with three bases.

[0048] In order to solve the above problems, this application proposes a quantum state encoding device, such as Figure 1 The figure shows a structural block diagram of a quantum state encoding device provided in an embodiment of the present application, wherein the device includes: a polarization encoding unit 100, a first optical coupling unit 200, an unequal-arm polarization control interferometer 300, a first transmission optical path 400, and a second optical coupling unit 500.

[0049] In some embodiments, the polarization encoding unit 100 includes at least one input port and one output port. The polarization encoding unit 100 is configured to input a light pulse through one of the input ports, generate a light pulse in a polarization-encoded quantum state based on the input light pulse, and output the light pulse through the output port.

[0050] The first optical coupling unit 200 includes an input port and two output ports, namely a first port G, a second port H, and a third port I. The first port G is connected to the output port of the polarization coding unit 100 .

[0051] The second optical coupling unit 500 includes two input ports and one output port, namely a fourth port H′, a fifth port I′ and a sixth port G′.

[0052] The unequal-arm polarization control interferometer 300 includes an input port and an output port, and is used to perform time-phase encoding conversion on the input polarization-encoded quantum state optical pulse and output the time-phase encoded quantum state optical pulse. The input port of the unequal-arm polarization control interferometer 300 is used to receive the polarization-encoded quantum state optical pulse input by the first optical coupling unit, and the output port of the unequal-arm polarization control interferometer 300 is used to output the time-phase encoded quantum state optical pulse after the time-phase encoding conversion performed by the unequal-arm polarization control interferometer 300.

[0053] It should be noted that the time phase encoding described in this application includes phase encoding, that is, the time phase encoding is an encoding composed of any combination of quantum states of the X phase basis, the Y phase basis, and the Z time basis.

[0054] The third port I of the first optical coupling unit 200 is connected to the input port of the unequal-arm polarization control interferometer 300. The output port of the unequal-arm polarization control interferometer 300 is connected to the fifth port I' of the second optical coupling unit 500 to form a first optical output branch.

[0055] The second port H of the first optical coupling unit 200 is connected to the fourth port H′ of the second optical coupling unit 500 through the first transmission optical path 400 to form a second optical output branch.

[0056] The sixth port G' of the second optical coupling unit 500 is the output port of the quantum state encoding device. In the embodiment of the present application, the second optical coupling unit 500 can be used to output the polarization-encoded quantum state optical pulse output by the second optical output branch or the time-phase-encoded quantum state optical pulse output by the first optical output branch according to the quantum communication coding control instruction.

[0057] It should be noted that quantum communication coding control instructions can be issued by programmable control software. For example, when the first optical coupling unit and the second optical coupling unit are both optical switches, according to the coding requirements of the quantum communication system, the control software is run by the host computer (control circuit unit or processor unit) in the quantum communication system to issue quantum communication coding control instructions to configure the gating state of the optical switch, thereby realizing the selective output of polarization-encoded quantum state light pulses or time-phase-encoded quantum state light pulses.

[0058] In the above embodiment, a polarization encoding unit 100, a first optical coupling unit 200, an unequal-arm polarization control interferometer 300, a first transmission optical path 400, and a second optical coupling unit 500 are used to form a quantum state encoding device, wherein the polarization encoding unit 100 can generate a light pulse of a polarization-encoded quantum state, and the unequal-arm polarization control interferometer 300 can convert the light pulse of the polarization-encoded quantum state into a light pulse of a time-phase-encoded quantum state. The first optical coupling unit 200 and the second optical coupling unit 500 can control the output of the light pulse of the polarization-encoded quantum state or the output of the light pulse of the time-phase-encoded quantum state according to the quantum communication coding control instruction. Therefore, the quantum state encoding device described in the embodiment of the present application flexibly implements multiple quantum communication coding methods of polarization-encoded quantum states and time-phase-encoded quantum states, and realizes that the same quantum state encoding device can meet the different coding requirements of the quantum communication system.

[0059] In some embodiments, the first optical coupling unit 200 is an optical coupler, and the second optical coupling unit 500 is an optical switch. The optical coupler can be a free-space crystal coupler or a fiber coupler, configured to split the optical pulses. The optical switch can selectively output the encoded quantum state transmitted by one optical output branch by connecting or disconnecting the optical switch.

[0060] Since the first port G of the first optical coupling unit 200 is connected to the output port of the polarization coding unit 100, the second port H is connected to one end of the first transmission optical path 400, and the third port I is connected to the input port of the unequal-arm polarization control interferometer 300, when the first optical coupling unit 200 is an optical coupler, it can be used to input the polarization-coded quantum state optical pulse output by the polarization coding unit 100 through the first port, and split the polarization-coded quantum state optical pulse into two sub-optical pulses, and input the two sub-optical pulses into the first optical output branch and the second optical output branch respectively through the third port I and the second port H.

[0061] In this embodiment, the second optical coupling unit 500 is configured to selectively output an optical pulse in a polarization-encoded quantum state output by the second optical output branch or an optical pulse in a time-phase-encoded quantum state output by the first optical output branch, based on the quantum communication coded control instruction. In this embodiment, the second optical coupling unit 500 is an optical switch that can flexibly switch the connection between the second optical output branch and the first optical output branch based on the quantum communication coded control instruction, thereby selectively outputting an optical pulse in a polarization-encoded quantum state output by the second optical output branch or an optical pulse in a time-phase-encoded quantum state output by the first optical output branch.

[0062] In the above embodiment, the first optical coupling unit 200 splits the polarization-encoded quantum state optical pulse into two paths, which are respectively fed into the first optical output branch and the second optical output branch. Furthermore, the selection function of the second optical coupling unit 500 enables switching of the connected optical output branch according to the coding requirements of the quantum communication system. In this way, quantum states with different coding schemes can be selectively output, improving the flexibility and adaptability of the quantum communication system. Furthermore, the advantages of both coding schemes can be fully utilized to ensure the adaptability of quantum states to the communication channel during quantum communication, thereby improving the security and reliability of the quantum communication system. Furthermore, it facilitates the integration of new coding schemes, thereby supporting new communication protocols and higher-performance quantum state transmission.

[0063] In some further embodiments, the first optical coupling unit 200 is an optical switch, and the second optical coupling unit 500 is an optical switch.

[0064] Since the first port G of the first optical coupling unit 200 is connected to the output port of the polarization encoding unit 100, the second port H is connected to the input port of the first transmission optical path 400, and the third port I is connected to the input port of the unequal-arm polarization control interferometer 300, when the first optical coupling unit 200 is an optical switch, the optical pulse of the polarization-encoded quantum state can be selectively input to the first optical output branch or the second optical output branch based on the quantum communication coding control instruction.

[0065] In one embodiment of the present application, the first optical coupling unit 200 can select a connection to a corresponding optical output branch based on a quantum communication coding control instruction and input an optical pulse of a polarization-encoded quantum state output by the polarization coding unit 100 into the corresponding optical output branch. Specifically, when the quantum communication coding control instruction is an instruction corresponding to outputting a polarization-encoded quantum state, the first optical coupling unit 200 selects a connection to a second optical output branch and inputs an optical pulse of a polarization-encoded quantum state into the second optical output branch. When the quantum communication coding control instruction is an instruction corresponding to outputting a time-phase-encoded quantum state, the first optical coupling unit 200 selects a connection to a first optical output branch and inputs an optical pulse of a polarization-encoded quantum state into the first optical output branch.

[0066] In this embodiment, the second optical coupling unit 500 is an optical switch, which can connect the first optical output branch or the second optical output branch according to the quantum communication coding control instruction, that is, connect the first optical output branch that outputs the optical pulse of the time phase encoded quantum state, or connect the second optical output branch that outputs the optical pulse of the polarization encoded quantum state.

[0067] It should be noted that, generally, the optical output branch selected for connection by the second optical coupling unit 500 is the same as the optical output branch selected for connection by the first optical coupling unit 200. Specifically, the first optical coupling unit 200 and the second optical coupling unit 500 select the same optical output branch for connection based on the quantum communication coded control instruction. That is, the first optical coupling unit 200 selects connection to the first optical output branch based on the quantum communication coded control instruction, and the second optical coupling unit 500 also selects connection to the first optical output branch based on the quantum communication coded control instruction. When both the first optical coupling unit 200 and the second optical coupling unit 500 are connected to the first transmission optical path, the second optical coupling unit 500 outputs an optical pulse of a time-phase-encoded quantum state transmitted by the first optical output branch.

[0068] Alternatively, the first optical coupling unit 200 selects to connect to the second optical output branch based on the quantum communication coded control instruction, and the second optical coupling unit 500 also selects to connect to the second optical output branch based on the quantum communication coded control instruction. When both the first optical coupling unit 200 and the second optical coupling unit 500 are connected to the second optical output branch, the second optical coupling unit 500 outputs the optical pulse of the polarization-encoded quantum state transmitted by the second optical output branch.

[0069] In the above embodiment, the first optical coupling unit 200 and the second optical coupling unit 500 can be connected to the same optical output branch according to quantum communication coding control instructions. This allows the output of coded quantum states that match the quantum communication protocol, thereby improving the flexibility and adaptability of the quantum communication system. Furthermore, the advantages of both coding methods can be fully utilized to ensure the adaptability of quantum states to the communication channel during quantum communication, thereby improving the security and reliability of the quantum communication system. Furthermore, this facilitates the integration of new coding methods, thereby supporting new communication protocols and higher-performance quantum state transmission.

[0070] In some embodiments, the first optical coupling unit 200 is an optical switch, and the second optical coupling unit 500 is an optical coupler.

[0071] In the embodiment of the present application, the first optical coupling unit 200 includes one input port and two output ports. The first optical coupling unit 200 can freely switch the connection port based on the quantum communication coding control instruction, thereby connecting to the first optical output branch or the second optical output branch.

[0072] The optical coupler corresponding to the second optical coupling unit 500 may include two input ports and one output port, each input port being connected to a corresponding optical output branch. The optical coupler is configured to output an optical pulse in a time-phase-encoded quantum state transmitted by the first optical output branch or an optical pulse in a polarization-encoded quantum state transmitted by the second optical output branch.

[0073] Specifically, when the first optical coupling unit 200 is connected to the first optical output branch through the output port I based on the quantum communication coding control instruction, the first optical coupling unit 200 inputs the polarization-encoded quantum state optical pulse output by the polarization coding unit 100 into the first optical output branch through the output port I. At this time, the first optical output branch inputs the polarization-encoded quantum state optical pulse transmitted by the first optical coupling unit 200 and outputs the time phase-encoded quantum state optical pulse converted by the unequal-arm polarization control interferometer 300. The input and output of the second optical output branch are both empty. The second optical coupling unit 500 couples the outputs of the two optical output branches, and the output coupling amount is the time phase-encoded quantum state optical pulse of the first optical output branch.

[0074] When the first optical coupling unit 200 is connected to the second optical output branch via output port H based on the quantum communication coding control instruction, the first optical coupling unit 200 inputs the polarization-encoded quantum state optical pulse output by the polarization coding unit 100 into the second optical output branch via output port H. At this time, the second optical output branch receives the polarization-encoded quantum state optical pulse input by the first optical coupling unit 200 and outputs it, and the input and output of the first optical output branch are both empty. The second optical coupling unit 500 couples the outputs of the two optical output branches, and the output coupling amount is the polarization-encoded quantum state optical pulse of the second optical output branch.

[0075] In the above embodiment, the first optical coupling unit 200 can output the polarization-encoded quantum state to an optical output branch that matches the encoding requirements of the quantum communication system. The second optical coupling unit 500 can then output the quantum state required by the quantum communication system. This improves the flexibility and adaptability of the quantum communication system. Furthermore, the advantages of both encoding schemes can be fully utilized, ensuring the adaptability of the quantum state to the communication channel during communication, thereby improving the security and reliability of the quantum communication system. Furthermore, it facilitates the integration of new encoding schemes, thereby supporting new communication protocols and higher-performance quantum state transmission.

[0076] Figure 2 The following is a block diagram of a polarization encoding unit provided in an embodiment of the present application. The polarization encoding unit 100 includes at least one polarization operation module 110. The polarization operation module 110 includes a polarization control optical path 111 and at least one phase modulator 112 disposed in the transmission optical path of the polarization control optical path. In other words, a polarization operation module 110 includes a polarization control optical path 111 and one or more phase modulators 112.

[0077] The polarization control optical path 111 includes at least one input port and one output port, wherein the input port of the polarization control optical path 111 serves as the input port of the polarization operation module 110 , and the output port of the polarization control optical path 111 serves as the output port of the polarization operation module 110 .

[0078] The polarization-controlled optical circuit 111 is configured to split an input optical pulse into two sub-optical pulses. The phase modulator 112 is configured to phase-modulate at least one sub-optical pulse based on a modulation signal, thereby generating a specific phase difference between the two optical pulses. The polarization-controlled optical circuit 111 is further configured to combine the two sub-optical pulses with the phase difference and output the resulting polarization-encoded quantum state optical pulse.

[0079] In an embodiment of the present application, the two optical pulses split by the polarization control optical path 111 can be a first optical pulse and a second optical pulse. One or more phase modulators 112 in the polarization operation module 110 can perform phase modulation on the first optical pulse and / or the second optical pulse to generate a specific phase difference between the two optical pulses that meets the requirements of the quantum communication system. After passing through the one or more phase modulators 112, the first optical pulse and the second optical pulse are combined in the polarization control optical path 111 to output a combined optical pulse.

[0080] The two intrinsic polarization states of the polarization control optical path 111 are and The intrinsic polarization state of the polarization control optical path 111 is the intrinsic polarization state of the polarization operation module 110 .

[0081] Figure 3 A structural block diagram of a polarization operation module provided in an embodiment of the present application is shown in FIG. Figure 3 As shown in FIG, the polarization control optical path 111 in the polarization operation module 110 may include a third optical coupling unit 31, a fourth optical coupling unit 32, a second transmission optical path 33, and a third transmission optical path 34. The third optical coupling unit 31 and the fourth optical coupling unit 32 are connected via the second transmission optical path 33 and the third transmission optical path 34.

[0082] In one embodiment of the present application, the third optical coupling unit 31 may include at least three ports, including at least one input port and two output ports. The fourth optical coupling unit 32 may include at least three ports, including two input ports and at least one output port. One output port of the third optical coupling unit 31 is connected to one input port of the fourth optical coupling unit 32 via a second transmission optical path 33, and another output port of the third optical coupling unit 31 is connected to another input port of the fourth optical coupling unit 32 via a third transmission optical path 34.

[0083] In this embodiment, the one or more phase modulators 112 may be both disposed in the second transmission optical path 33 or the third transmission optical path 34 , or may be disposed in the second transmission optical path 33 and the third transmission optical path 34 respectively.

[0084] The third optical coupling unit 31 is used to split an input optical pulse into two optical pulses, namely a first optical pulse and a second optical pulse. The first optical pulse and the second optical pulse are transmitted along the second transmission optical path 33 and the third transmission optical path 34 respectively, and after passing through at least one phase modulator 112, they are combined and output by the fourth optical coupling unit 32.

[0085] In some embodiments, the phase modulator 112 includes a forward input optical port E and a reverse input optical port F. The transmission optical paths (the second transmission optical path 33 or the third transmission optical path 34) connected to the phase modulator 112 are both coupled to the slow axis of the forward input optical port and the slow axis of the reverse input optical port of the phase modulator 112, or are both coupled to the fast axis of the forward input optical port and the fast axis of the reverse input optical port of the phase modulator 112. The phase modulator 112 is configured to phase modulate the input sub-optical pulses based on the modulation signal, thereby generating a phase difference between the two sub-optical pulses.

[0086] In addition, it can be understood that the phase modulator 112 also includes an electrical port for receiving a modulated signal.

[0087] In some embodiments, after applying a low-frequency modulation signal (e.g., a modulation signal with a frequency less than 1 GHz), the phase modulator 112 effectively phase modulates the sub-optical pulses input from the forward input optical port and the reverse input optical port. After applying a high-frequency modulation signal with a frequency greater than a specified threshold (e.g., a modulation signal with a frequency not less than 10 GHz), when the phase modulator 112 operates in a non-reciprocal state, the ratio of the modulation efficiency of the sub-optical pulse input from the forward input optical port to the modulation efficiency of the sub-optical pulse input from the reverse input optical port is greater than a preset threshold, i.e., only the sub-optical pulse input from the forward input optical port is effectively phase modulated, while the sub-optical pulse input from the reverse input optical port is not effectively phase modulated, which can also be considered as no modulation. When applying a high-frequency modulation signal with a frequency greater than the specified threshold, the phase modulator 112 may simultaneously receive multiple sub-optical pulses input from the forward input optical port and multiple sub-optical pulses input from the reverse input optical port.

[0088] In some embodiments, the third optical coupling unit 31 and the fourth optical coupling unit 32 are the same optical coupler. The second transmission optical path 33 and the third transmission optical path 34 are two different transmission optical paths. Figure 4 A schematic diagram of the specific structure of a polarization operation module provided in an embodiment of the present application is shown in FIG. Figure 4 As shown, the polarization control optical path 111 in the polarization operation module 110 may include: an optical coupler 41 (i.e., the third optical coupling unit 31 and the fourth optical coupling unit 32), a second transmission optical path 42 and a third transmission optical path 43, a reflector 44 and a reflector 45. Among them, the reflector 44 and the reflector 45 are used to reflect the input sub-light pulse back to the optical coupler 41. The reflector 44 or the reflector 45 is a quarter-wave plate reflector or a 90° Faraday rotation reflector, so that the polarization state of the reflected sub-light pulse is rotated by 90° relative to the polarization state of the sub-light pulse input to the corresponding reflector, so that the polarization states of the two sub-light pulses are orthogonal to each other when they are reflected back to the optical coupler 41. In this embodiment, the polarization state of the two sub-light pulses reflected back to the optical coupler 41 is the intrinsic polarization state of the polarization control optical path 111. In other words, the polarization state of the two sub-light pulses reflected back to the optical coupler 41 is the intrinsic polarization state of the polarization operation module 110.

[0089] The optical coupler 41 may include at least three ports, including at least one input port and two output ports, namely port A, port B, and port C. Port B and port C are output ports, connected to two reflectors 44 and 45 via a second transmission optical path 42 and a third transmission optical path 43, respectively. Port A serves as an input port for receiving optical pulses output by the input polarization control optical path 111. Specifically, Figure 4 As shown, port B is connected to the reflector 44 through the second transmission light path 42 , and port C is connected to the reflector 45 through the third transmission light path 43 .

[0090] In one embodiment, when the optical coupler 41 includes three ports, the input port can also serve as the output port of the polarization operation module 110 for outputting optical pulses in polarization-encoded quantum states.

[0091] In another embodiment, when the optical coupler 41 includes four ports, Figure 4 As described above, the optical coupler 41 may further include an output port, namely, port D, which serves as the output port of the polarization operation module 110 for outputting optical pulses in polarization-encoded quantum states.

[0092] The one or more phase modulators 112 in the polarization manipulation module 110 can be disposed in the second optical transmission path 42 or the third optical transmission path 43, or respectively disposed in the second optical transmission path 42 and the third optical transmission path 43. The phase modulator 112 is configured to perform phase modulation on the passing optical sub-pulses based on a modulation signal, so as to generate a phase difference between the two optical sub-pulses reflected back to the optical coupler 41. Figure 4 Only the case where one phase modulator is provided in the second transmission optical path 42 is shown.

[0093] In one embodiment of the present application, the optical coupler 41 is used to split a single optical pulse received from the input port into two sub-optical pulses, which are output through port B and port C, respectively, and transmitted along the second transmission optical path 42 and the third transmission optical path 43 to two reflectors, respectively, and then reflected back to the optical coupler 41 by the two reflectors. The sub-optical pulses transmitted along the transmission optical path where the phase modulator 112 is located are phase modulated by the phase modulator 112, thereby generating a phase difference between the two sub-optical pulses reflected back to the optical coupler 41.

[0094] In some embodiments, the third optical coupling unit 31 and the fourth optical coupling unit 32 are the same polarization beam splitter. The second transmission optical path 33 and the third transmission optical path 34 are two different transmission optical paths. Figure 5 and Figure 6 FIG. 1 shows a schematic structural diagram of another polarization operation module provided in an embodiment of the present application. Figure 5 and Figure 6 As shown. The polarization control optical path 111 in the polarization operation module 110 may include a polarization beam splitter 51 (i.e., the third optical coupling unit 31 and the fourth optical coupling unit 32), a second transmission optical path 52 and a third transmission optical path 53, a reflector 54, and a reflector 55. The reflector 54 and the reflector 55 are used to reflect the input sub-light pulse back to the polarization beam splitter 51. Optionally, the reflector 54 and the reflector 55 are polarization state rotation mirrors, for example, the reflector 54 and the reflector 55 may be a quarter-wave plate mirror or a 90° Faraday rotation mirror.

[0095] The polarization beam splitter 51 may include at least three ports, including at least one input port and two output ports, namely port A, port B, and port C, wherein port B and port C are connected to two reflectors via the second transmission optical path 52 and the third transmission optical path 53, respectively. Port A serves as an input port for receiving light pulses input into the polarization control optical path 111. Specifically, Figure 5 As shown, port B is connected to the reflector 54 through the second transmission light path 52 , and port C is connected to the reflector 55 through the third transmission light path 53 .

[0096] In one embodiment, if Figure 5 As shown, when the polarization beam splitter 51 includes three ports, the input port A can also serve as the output port of the polarization operation module 110 for outputting optical pulses in polarization-encoded quantum states.

[0097] In yet another embodiment, Figure 6 As shown, the polarization beam splitter 51 may further include an output port D, serving as an output port of the polarization operation module 110 , for outputting optical pulses in polarization-encoded quantum states.

[0098] It should be noted that, when the reflectors 54 and 55 do not rotate the polarization states of the input sub-light pulses, the polarization beam splitter 51 only outputs the combined light pulse in the polarization-encoded quantum state from port A. When the reflectors 54 and 55 rotate the polarization states of the input sub-light pulses by any angle (other than 0° and 90°), the polarization beam splitter 51 can output the combined light pulse in the polarization-encoded quantum state from both port A and port D. If the polarization states of the sub-light pulses are rotated by 90°, the combined light pulse in the polarization-encoded quantum state can only be output from port D.

[0099] In this embodiment, the intrinsic polarization state of the polarization beam splitter 51 is the intrinsic polarization state of the polarization control optical path 111 .

[0100] One or more phase modulators 112 in the polarization operation module 110 may be all arranged in the second transmission optical path 52 or in the third transmission optical path 53, or respectively arranged in the second transmission optical path 52 and the third transmission optical path 53. It should be noted that, Figure 5 and Figure 6 Only the case where one phase modulator 112 is provided in the second transmission optical path 52 is shown.

[0101] In one embodiment of the present application, the polarization beam splitter 51 is used to polarization-split an optical pulse received from an input port into two sub-optical pulses, which are output through port B and port C, respectively, and transmitted along the second transmission optical path 52 and the third transmission optical path 53 to two reflectors, respectively, and reflected back to the polarization beam splitter 51 by the two reflectors. The sub-optical pulses transmitted along the transmission optical path where the phase modulator 112 is located will be phase-modulated by the phase modulator 112, so that a phase difference is formed between the two sub-optical pulses reflected back to the polarization beam splitter 51.

[0102] It should be noted that the principle of sub-light pulse modulation by the phase modulator 112 in the embodiment of the present application is similar to that described above, and will not be described again for the sake of brevity.

[0103] In one embodiment, the third optical coupling unit 31 may be a polarization beam splitter, and the fourth optical coupling unit 32 may be an optical coupler. Figure 7 A schematic diagram of the specific structure of another polarization operation module provided in an embodiment of the present application is shown as follows: Figure 7 As shown, the polarization control optical path 111 in the polarization operation module 110 may include a polarization beam splitter 71 (ie, the third optical coupling unit 31 ), a second transmission optical path 72 , a third transmission optical path 73 , and an optical coupler 74 (ie, the fourth optical coupling unit 32 ).

[0104] like Figure 7 As shown, the polarization beam splitter 71 is connected to the optical coupler 74 via the second transmission optical path 72 and the third transmission optical path 73. The polarization beam splitter 71 may include three ports, namely, port A, port B, and port C. The optical coupler 74 may include three ports, namely, port A', port B', and port C'. Port B of the polarization beam splitter 71 may be connected to port B' of the optical coupler 74 via the second transmission optical path 72, and port C of the polarization beam splitter 71 may be connected to port C' of the optical coupler 74 via the third transmission optical path 73.

[0105] The one or more phase modulators 112 may be both arranged in the second transmission optical path 72 or both arranged in the third transmission optical path 73 , or respectively arranged in the second transmission optical path 72 and the third transmission optical path 73 . Figure 7 Only one phase modulator 112 is shown disposed in the third transmission optical path 73. The principle of the phase modulator 112 modulating the sub-light pulses in the embodiment of the present application is similar to that described above, and will not be described again for the sake of brevity.

[0106] Polarization beam splitter 71 is used to polarization-split an optical pulse input from port A into two sub-optical pulses: a first optical pulse and a second optical pulse, which are output from ports B and C, respectively. The first optical pulse and the second optical pulse are transmitted along a second transmission optical path 72 and a third transmission optical path 73, respectively. One sub-optical pulse is phase-modulated by at least one phase modulator 112 and input to optical coupler 74 from ports B' and C', respectively. Optical coupler 74 is used to combine the two input sub-optical pulses and output an optical pulse in a polarization-encoded quantum state from port A'.

[0107] It should be noted that, in this embodiment, the intrinsic polarization state of the polarization beam splitter 71 is the intrinsic polarization state of the polarization control optical path 111 .

[0108] In yet another embodiment, the third light coupling unit 31 may be a polarization beam splitter, and the fourth light coupling unit 32 may be a polarization beam splitter. Figure 8 A schematic diagram of the specific structure of another polarization operation module provided in an embodiment of the present application is shown as follows: Figure 8 As shown, the polarization control optical path 111 in the polarization operation module 110 may include a polarization beam splitter 81 (i.e., the third optical coupling unit 31), a second transmission optical path 82, a third transmission optical path 83, and a polarization beam splitter 84 (i.e., the fourth optical coupling unit 32). The intrinsic polarization state of the polarization beam splitter 84 is the intrinsic polarization state of the polarization control optical path 111.

[0109] like Figure 8 As shown, the polarization beam splitter 81 is connected to the polarization beam splitter 84 through the second transmission optical path 82 and the third transmission optical path 83. The polarization beam splitter 81 may include three ports, namely port A, port B and port C. The polarization beam splitter 84 may include three ports, namely port A', port B' and port C'. Port B of the polarization beam splitter 81 can be connected to port B' of the polarization beam splitter 84 through the second transmission optical path 82, and port C of the polarization beam splitter 81 can be connected to port C' of the polarization beam splitter 84 through the third transmission optical path 83. Port A of the polarization beam splitter 81 serves as the input port of the polarization control optical path 111, and port A' of the polarization beam splitter 84 serves as the output port of the polarization control optical path 111.

[0110] The one or more phase modulators 112 may be both arranged in the second transmission optical path 82 or both arranged in the third transmission optical path 83 , or respectively arranged in the second transmission optical path 82 and the third transmission optical path 83 . Figure 8 Only one phase modulator 112 is shown disposed in the third transmission optical path 83. The principle of the phase modulator 112 modulating the sub-light pulses in the embodiment of the present application is similar to that described above, and will not be described again for the sake of brevity.

[0111] Polarization beam splitter 81 is used to polarization-split an optical pulse input from port A into two sub-optical pulses: a first optical pulse and a second optical pulse, which are output from ports B and C, respectively. The first optical pulse and the second optical pulse are transmitted along a second transmission optical path 82 and a third transmission optical path 83, respectively. One of the sub-optical pulses undergoes phase modulation by at least one phase modulator 112. The two sub-optical pulses are input to polarization beam splitter 84 from ports B' and C', respectively. Polarization beam splitter 84 is used to combine the two input sub-optical pulses and output an optical pulse in a polarization-encoded quantum state from port A'.

[0112] In another embodiment, the third optical coupling unit 31 may be an optical coupler, and the fourth optical coupling unit 32 may be an optical coupler. Figure 9 A schematic diagram of the specific structure of another polarization operation module provided in an embodiment of the present application is shown as follows: Figure 9 As shown, the polarization control optical path 111 in the polarization operation module 110 may include an optical coupler 91 (i.e., the third optical coupling unit 31), a second transmission optical path 92, a third transmission optical path 93, and an optical coupler 94 (i.e., the fourth optical coupling unit 32). In this embodiment, the polarization states of the two optical sub-pulses input to the optical coupler 94 are the intrinsic polarization states of the polarization control optical path 111.

[0113] In one embodiment, the polarization manipulation module further includes a 90° polarization state rotator 95, which can be disposed in the second transmission optical path 92 or the third transmission optical path 93 and configured to rotate the polarization state of the passing sub-light pulse by 90°. In some embodiments, the 90° polarization state rotator 95 can be a half-wave plate or a 90° Faraday rotator.

[0114] In another embodiment, the second transmission optical path 92 or the third transmission optical path 93 is a 90° twisted polarization-maintaining optical fiber.

[0115] like Figure 9 As shown in FIG, an optical coupler 91 is connected to an optical coupler 94 via a second transmission optical path 92 and a third transmission optical path 93. The optical coupler 91 may include three ports, namely, port A, port B, and port C. The optical coupler 94 may include three ports, namely, port A', port B', and port C'. Port B of the optical coupler 91 may be connected to port B' of the optical coupler 94 via the second transmission optical path 92, and port C of the optical coupler 91 may be connected to port C' of the optical coupler 94 via the third transmission optical path 93.

[0116] The one or more phase modulators 112 can be all arranged in the second transmission optical path 92 or all arranged in the third transmission optical path 93, or respectively arranged in the second transmission optical path 92 and the third transmission optical path 93. The principle of sub-light pulse modulation by the phase modulator 112 in the embodiment of the present application is similar to the above, and for the sake of brevity, it will not be repeated here. The 90° polarization state rotator 95 is also arranged in the second transmission optical path 92 or the third transmission optical path 93, and is used to rotate the polarization state of the passing sub-light pulse by 90°. The phase modulator 112 and the 90° polarization state rotator 95 can be respectively arranged in different transmission optical paths, or they can be arranged in the same transmission optical path. Figure 9 It is shown that only one phase modulator 112 is arranged in the third transmission optical path 93 and a 90° polarization state rotator 95 is arranged in the second transmission optical path 92 .

[0117] The optical coupler 91 is used to split an optical pulse input from port A into two sub-optical pulses, namely a first optical pulse and a second optical pulse, and output them from port B and port C, respectively. The first optical pulse and the second optical pulse are transmitted along the second transmission optical path 92 and the third transmission optical path 93, respectively. One of the sub-optical pulses passes through at least one phase modulator 112, and the other optical pulse passes through a 90° polarization rotator 95, or one of the sub-optical pulses passes through at least one phase modulator 112 and a 90° polarization rotator 95. The two sub-optical pulses are input to the optical coupler 94 from port B' and port C', respectively. The optical coupler 94 is used to combine the two input sub-optical pulses and output an optical pulse of a polarization-encoded quantum state from port A'.

[0118] In another embodiment, the third optical coupling unit 31 may be an optical coupler, and the fourth optical coupling unit 32 may be a polarization beam splitter. Figure 10 A schematic diagram of the specific structure of another polarization operation module provided in an embodiment of the present application is shown as follows: Figure 10 As shown, the polarization control optical path 111 in the polarization operation module 110 may include an optical coupler 1001, a second transmission optical path 1002, a third transmission optical path 1003, and a polarization beam splitter 1004. In this embodiment, the intrinsic polarization state of the polarization beam splitter 1004 is the intrinsic polarization state of the polarization control optical path 111.

[0119] In one embodiment, the polarization manipulation module further includes a 90° polarization state rotator 1005, which can be disposed in the second transmission optical path 1002 or the third transmission optical path 1003 and configured to rotate the polarization state of the passing sub-light pulse by 90°. In some embodiments, the 90° polarization state rotator 1005 can be a half-wave plate or a 90° Faraday rotator.

[0120] In another embodiment, the second transmission optical path 1002 or the third transmission optical path 1003 is a 90° twisted polarization-maintaining optical fiber.

[0121] like Figure 10 As shown, the optical coupler 1001 is connected to the polarization beam splitter 1004 via the second transmission optical path 1002 and the third transmission optical path 1003. The optical coupler 1001 may include three ports, namely, port A, port B, and port C. The polarization beam splitter 1004 may include three ports, namely, port A', port B', and port C'. Port B of the optical coupler 1001 may be connected to port B' of the polarization beam splitter 1004 via the second transmission optical path 1002, and port C of the optical coupler 1001 may be connected to port C' of the polarization beam splitter 1004 via the third transmission optical path 1003.

[0122] The one or more phase modulators 112 can be all arranged in the second transmission optical path 1002 or all arranged in the third transmission optical path 1003, or respectively arranged in the second transmission optical path 1002 and the third transmission optical path 1003. The principle of sub-light pulse modulation by the phase modulator 112 in the embodiment of the present application is similar to that described above. For the sake of brevity, it will not be repeated here. The 90° polarization state rotator 1005 can also be arranged in the second transmission optical path 1002 or the third transmission optical path 1003 to rotate the polarization state of the passing sub-light pulse by 90°. The phase modulator 112 and the 90° polarization state rotator 1005 can be respectively arranged in different transmission optical paths, or they can be arranged in the same transmission optical path. Figure 10 It is shown that only one phase modulator 112 is arranged in the third transmission optical path 1003 and a 90° polarization state rotator 1005 is arranged in the second transmission optical path 1002 .

[0123] The optical coupler 1001 is used to split an optical pulse input from port A into two sub-optical pulses, namely a first optical pulse and a second optical pulse, and output them from port B and port C, respectively. The first optical pulse and the second optical pulse are transmitted along the second transmission optical path 92 and the third transmission optical path 93, respectively. One of the sub-optical pulses passes through at least one phase modulator 112, and the other optical pulse passes through a 90° polarization rotator 1005, or one of the sub-optical pulses passes through at least one phase modulator 112 and a 90° polarization rotator 1005. The two sub-optical pulses are input to the polarization beam splitter 1004 from port B' and port C', respectively. The polarization beam splitter 1004 is used to combine the two input sub-optical pulses and output an optical pulse of a polarization-encoded quantum state from port A'.

[0124] In some embodiments, to adjust the intensity of the input optical pulse, a pre-interferometer can be provided in the polarization control path to adjust the intensity of the two sub-optical pulses input into the second transmission optical path and the third transmission optical path. The pre-interferometer can have various structures, such as a Mach-Zehnder interferometer and a Sagnac interferometer.

[0125] In one embodiment of the present application, the third optical coupling unit 31 may be an optical coupler, and the fourth optical coupling unit 32 may be an optical coupler. The pre-interferometer may be a first pre-interferometer, i.e., a Sagnac interferometer. The first pre-interferometer includes a fourth transmission optical path, the third optical coupling unit 31, and a pre-phase modulator disposed on the fourth transmission optical path.

[0126] Figure 11 A schematic diagram of the specific structure of another polarization operation module provided in an embodiment of the present application is shown as follows: Figure 11 As shown, the polarization control optical path 111 in the polarization operation module 110 may include an optical coupler 1101 (i.e., the third optical coupling unit 31), a second transmission optical path 1102, a third transmission optical path 1103, a 90° polarization state rotator 1104 disposed on the second transmission optical path 1102 or the third transmission optical path 1103, an optical coupler 1105 (i.e., the fourth optical coupling unit 32), a fourth transmission optical path 1106, a pre-phase modulator 1107, and an intermediate optical coupling unit 1108. The intermediate optical coupling unit 1108 is disposed in the second transmission optical path 1102 or the third transmission optical path 1103. The polarization state of the two optical sub-pulses input to the optical coupler 1105 is the intrinsic polarization state of the polarization control optical path 111.

[0127] compared to Figure 9 , Figure 11 The polarization manipulation module shown is newly equipped with a first pre-interferometer and an intermediate optical coupling unit 1108 , and the optical coupler 1101 includes four ports.

[0128] The first pre-optical interferometer is used to split the input optical pulse into two pre-optical sub-pulses, and generate a phase difference between the two pre-optical sub-pulses through the pre-phase modulator.

[0129] The pre-phase modulator 1107 is used to perform phase modulation on one of the two pre-optical sub-pulses transmitted in the fourth transmission optical path 1106 based on the modulation signal, or to perform different phase modulation on the two pre-optical sub-pulses so that there is a phase difference between the two pre-optical sub-pulses.

[0130] like Figure 11As shown, the optical coupler 1101 may include four ports, namely port A, port B, port C, and port D. The optical coupler 1105 may include three ports, namely port A', port B', and port C'. Port A' of the optical coupler 1105 may serve as the output port of the polarization manipulation module, for outputting the generated polarization-encoded quantum state optical pulse.

[0131] The intermediate optical coupling unit 1108 may include three ports, namely port X, port Y, and port Z.

[0132] The two ports of the intermediate optical coupling unit 1108 are connected to the optical coupler 1101 and the optical coupler 1105 respectively. Specifically, when the intermediate optical coupling unit 1108 is arranged in the third transmission optical path 1103, as shown in FIG. Figure 11 As shown, port Y of the intermediate optical coupling unit 1108 is connected to port B of the optical coupler 1101, and port Z of the intermediate optical coupling unit 1108 is connected to port B' of the optical coupler 1105. When the intermediate optical coupling unit 1108 is arranged in the second transmission optical path 1102, port Y of the intermediate optical coupling unit 1108 is connected to port C of the optical coupler 1101, and port Z of the intermediate optical coupling unit 1108 is connected to port C' of the optical coupler 1105.

[0133] Port X of the intermediate optical coupling unit 1108 is the input port of the polarization operation module 110. The intermediate optical coupling unit 1108 is configured to receive an optical pulse of the input polarization control optical path 111 from port X and input the optical pulse to the first pre-interferometer through port Y.

[0134] Port A and port D of the optical coupler 1101 are connected via a fourth transmission optical path 1106 , and are used to split an optical pulse inputted from the intermediate optical coupling unit 1108 into two preamplifier sub-optical pulses and input them into the fourth transmission optical path 1106 from different ports.

[0135] One or more phase modulators 112 in the polarization operation module 110 can be arranged in the second transmission optical path 1102 or in the third transmission optical path 1103, or respectively in the second transmission optical path 1102 and the third transmission optical path 1103. The principle of sub-light pulse modulation by the phase modulator 112 in the embodiment of the present application is similar to that described above. For the sake of brevity, it will not be repeated here. The 90° polarization state rotator 1104 can also be arranged in the second transmission optical path 1102 or the third transmission optical path 1103 to rotate the polarization state of the passing sub-light pulse by 90°. The phase modulator 112 and the 90° polarization state rotator 1104 can be arranged in different transmission optical paths, or in the same transmission optical path. Figure 11Only one phase modulator 112 is shown disposed in the third transmission optical path 1103, a 90° polarization state rotator 1104 is disposed in the third transmission optical path 1103, and an intermediate optical coupling unit 1108 is disposed in the second transmission optical path 1102. It will be understood that the 90° polarization state rotator 1104 can be replaced by a 90° twisted polarization-maintaining fiber, that is, the second transmission optical path 1102 or the third transmission optical path 1103 can be selected to be a 90° twisted polarization-maintaining fiber.

[0136] Port X of the intermediate optical coupling unit 1108 receives an input optical pulse, which is then output from port Y of the intermediate optical coupling unit 1108 to a port of the optical coupler 1101, which can be port B or port C. Optical coupler 1101 splits the optical pulse into two preamplifier sub-optical pulses. These two preamplifier sub-optical pulses are transmitted in different directions along the fourth transmission optical path 1106, pass through the pre-phase modulator 1107, and enter the optical coupler 1101 from ports A and D of the optical coupler 1101. Optical coupler 1101 reflects and transmits the two preamplifier sub-optical pulses to generate two sub-optical pulses, which are then input into the second transmission optical path 1102 and the third transmission optical path 1103 through ports C and B, respectively. The two optical sub-pulses are transmitted along the second transmission optical path 1102 and the third transmission optical path 1103 respectively, and enter the optical coupler 1105 from different ports of the optical coupler 1105. The optical coupler 1105 combines the two optical sub-pulses and outputs them.

[0137] In another embodiment of the present application, the third optical coupling unit 31 may be an optical coupler, and the fourth optical coupling unit 32 may be a polarization beam splitter. The pre-interferometer may be a first pre-interferometer, i.e., a Sagnac interferometer, wherein the first pre-interferometer includes a fourth transmission optical path, the third optical coupling unit 31, and a pre-phase modulator disposed on the fourth transmission optical path. Figure 12 A schematic diagram of the specific structure of another polarization operation module provided in an embodiment of the present application is shown as follows: Figure 12 As shown, the polarization control optical path in the polarization operation module may include an optical coupler 1201 (i.e., the third optical coupling unit 31), a second transmission optical path 1202, a third transmission optical path 1203, a 90° polarization state rotator 1204 disposed on the second transmission optical path 1202 or the third transmission optical path 1203, a polarization beam splitter 1205 (i.e., the fourth optical coupling unit 32), a fourth transmission optical path 1206, a pre-phase modulator 1207, and an intermediate optical coupling unit 1208. The intermediate optical coupling unit 1208 is disposed on the second transmission optical path 1202 or the third transmission optical path 1203. In this embodiment, the intrinsic polarization state of the polarization beam splitter 1205 is the intrinsic polarization state of the polarization control optical path 111.

[0138] Figure 11 The polarization operation module shown is Figure 12 The difference between the polarization operation modules shown is that the device type of the fourth optical coupling unit 32 is different. Figure 12 The polarization operation module shown is Figure 11 The internal device connection method and light pulse processing method of the polarization operation module shown are similar and will not be repeated here.

[0139] In another embodiment of the present application, the pre-interferometer may be a second pre-optical interferometer, namely a Mach-Zehnder interferometer. The second pre-optical interferometer may include: a pre-optical coupling unit, a first pre-transmission optical path, a second pre-transmission optical path, a pre-phase modulator disposed in the first pre-transmission optical path or the second pre-transmission optical path, and a third optical coupling unit 31.

[0140] The third optical coupling unit 31 may be an optical coupler, and the fourth optical coupling unit 32 may be an optical coupler. Figure 13 A schematic diagram of the specific structure of another polarization operation module provided in an embodiment of the present application is shown as follows: Figure 13 As shown, the polarization control optical path in the polarization operation module may include an optical coupler 1301 (i.e., a third optical coupling unit 31), a second transmission optical path 1302, a third transmission optical path 1303, a 90° polarization state rotator 1304 disposed on the second transmission optical path 1302 or the third transmission optical path 1303, an optical coupler 1305 (i.e., a fourth optical coupling unit 32), a first pre-transmission optical path 1306, a second pre-transmission optical path 1307, and a pre-phase modulator 1308 and a pre-optical coupling unit 1309 disposed in the first pre-transmission optical path 1306 or the second pre-transmission optical path 1307. The polarization states of the two optical sub-pulses input to the optical coupler 1305 are the intrinsic polarization states of the polarization control optical path 111. It can be understood that the 90° polarization state rotator 1304 can be a half-wave plate or a 90° Faraday rotator, and the 90° polarization state rotator 1304 can also be replaced by a 90° twisted polarization-maintaining fiber, that is, the second transmission optical path 1302 or the third transmission optical path 1303 is selected as a 90° twisted polarization-maintaining fiber.

[0141] In some embodiments, the front optical coupling unit 1309 may be an optical coupler.

[0142] The optical coupler 1301 may include four ports, namely, port A, port B, port C, and port D. The optical coupler 1305 includes three ports, namely, port A', port B', and port C'. The pre-optical coupling unit 1309 may include three ports, namely, port X, port Y, and port Z. Port B and port C of the optical coupler 1301 are connected to port B' and port C' of the optical coupler 1305 via the second transmission optical path 1302 and the third transmission optical path 1303, respectively. Port A and port D of the optical coupler 1301 are connected to port Y and port Z of the pre-optical coupling unit 1309 via the second pre-transmission optical path 1307 and the first pre-transmission optical path 1306, respectively. Port X of the pre-optical coupling unit 1309 is the input port of the polarization control optical path. The pre-phase modulator 1308 is used to phase modulate the input sub-optical pulse.

[0143] The front optical coupling unit 1309 is used to receive the input optical pulse and split it into two front sub-optical pulses, which are respectively input into the first front transmission optical path 1306 and the second front transmission optical path 1307. One of the front sub-optical pulses is phase-modulated by the front phase modulator 1308. The two front sub-optical pulses arrive at the optical coupler 1301 at the same time. The optical coupler 1301 is also used to receive the two front sub-optical pulses with a phase difference, generate two sub-optical pulses through reflection and transmission, and input them into the second transmission optical path 1302 and the third transmission optical path 1303 through port B and port C respectively.

[0144] In this embodiment, by providing a second pre-optical interferometer, it is possible to control the intensities of the two sub-light pulses input into the second transmission light path and the third transmission light path.

[0145] Figure 14 A schematic diagram of the specific structure of another polarization operation module provided in an embodiment of the present application is shown. Figure 13 The difference between the structures shown is that the fourth optical coupling unit 32 is a polarization beam splitter, and the working principle of the second front optical interferometer is the same as that in the previous embodiment, which will not be described here. Figure 14 The polarization operation module shown is Figure 13 The internal device connection method and light pulse processing method of the polarization operation module shown are similar and will not be repeated here.

[0146] In some embodiments, the third optical coupling unit 31 and the fourth optical coupling unit 32 are the same optical coupling unit, the second transmission optical path and the third transmission optical path are the same transmission optical path, and the intrinsic polarization state of the optical coupling unit is the intrinsic polarization state of the polarization control optical path 111.

[0147] Figure 15FIG. 1 is a schematic structural diagram of another embodiment of a polarization operation module. In this embodiment, the second transmission optical path and the third transmission optical path are the same transmission optical path, and the same optical coupling unit can be a polarization beam splitter. Figure 15 As shown in , the polarization operation module may include a polarization beam splitter 151, a transmission optical path 152, and at least one phase modulator 112. The phase modulator 112 is provided in the transmission optical path 152 and is used to perform phase modulation on one of the two input sub-light pulses, or to perform different phase modulation on the two sub-light pulses.

[0148] The polarization beam splitter 151 includes three ports: a first port A, a second port B, and a third port C. The first port of the polarization beam splitter 151 serves as the input and output port of the polarization control optical path 111. The second and third ports of the polarization beam splitter 151 are connected via the same transmission optical path 152. In this embodiment, the intrinsic polarization state of the polarization beam splitter 151 is the intrinsic polarization state of the optical coupling unit.

[0149] Figure 16 The figure shows another embodiment of the polarization operation module. In this embodiment, the second transmission optical path and the third transmission optical path are the same transmission optical path. The same optical coupling unit includes four ports, namely port A, port B, port C and port D. The same optical coupling unit may include a polarization beam splitter, a first polarizer and a second polarizer. Figure 16 As shown in , the polarization operation module may include: a polarization beam splitter 161, a first polarizer 162, a second polarizer 163, a transmission optical path 164, and at least one phase modulator 112. The at least one phase modulator 112 may be disposed in the transmission optical path 164 to perform phase modulation on one of the two input optical sub-pulses, or to perform different phase modulation on the two optical sub-pulses.

[0150] The polarization beam splitter 161 includes four ports: a first port, a second port, a third port, and a fourth port. The first port of the polarization beam splitter 161 is port A of the optical coupling unit, which is the input port of the polarization control optical path 111. The fourth port of the polarization beam splitter 161 is port D of the optical coupling unit, wherein the first port or the fourth port is the output port of the polarization control optical path 111. The second port and the third port of the polarization beam splitter 161 are respectively connected to the port on the first side of the first polarizer 162 and the port on the first side of the second polarizer 163. The port on the second side of the first polarizer 162 is port B of the optical coupling unit, and the port on the second side of the second polarizer 163 is port C of the optical coupling unit. The port on the second side of the first polarizer 162 and the port on the second side of the second polarizer 163 are connected via a transmission optical path 164. The angle between the polarization direction of the first polarizer 162 and one intrinsic polarization state of the polarization beam splitter 161 is θ, and the angle between the polarization direction of the second polarizer 163 and another intrinsic polarization state of the polarization beam splitter 161 is δ. Here, θ and δ ≠ n·90°, where n is an integer. In this embodiment, the intrinsic polarization state of the polarization beam splitter 161 is the intrinsic polarization state of the optical coupling unit.

[0151] like Figure 17 FIG2 is a schematic diagram showing another embodiment of the polarization operation module. In this embodiment, the second transmission optical path and the third transmission optical path are the same transmission optical path. The same optical coupling unit includes three ports, namely port A, port B and port C. The same optical coupling unit may include an optical beam splitter, a first polarizer and a second polarizer. Figure 17 As shown in , the polarization operation module may include an optical beam splitter 171, a first polarizer 172 and a second polarizer 173, a transmission optical path 174, and at least one phase modulator 112. The at least one phase modulator 112 may be disposed in the transmission optical path 174 to perform phase modulation on one of the two input light sub-pulses, or to perform different phase modulation on the two light sub-pulses.

[0152] The optical beam splitter 171 includes three ports, namely a first port, a second port and a third port. The first port of the optical beam splitter 171 is the port A of the same optical coupling unit, which is the input port of the polarization control optical path 111. The second port and the third port of the optical beam splitter 171 are respectively connected to the port on the first side of the first polarizer 172 and the port on the first side of the second polarizer 173. The port on the second side of the first polarizer 172 is the port B of the same optical coupling unit, and the port on the second side of the second polarizer 173 is the port C of the same optical coupling unit. The port on the second side of the first polarizer 172 and the port on the second side of the second polarizer 173 are connected through a transmission optical path 174. The polarization direction of the first polarizer 172 is The polarization direction of the second polarizer 173 is The polarization direction of the first polarizer 172 The polarization direction of the second polarizer 173 The polarization direction of the first polarizer 172 is orthogonal to each other. The polarization direction of the second polarizer 173 is the intrinsic polarization state of the optical coupling unit.

[0153] like Figure 18 The figure shows another embodiment of the polarization operation module. In this embodiment, the same optical coupling unit includes four ports, namely port A, port B, port C and port D. The second transmission optical path and the third transmission optical path are the same transmission optical path. The same optical coupling unit may include an optical beam splitter, a first polarizer and a second polarizer. Figure 17 The difference between the illustrated embodiment and the optical beam splitter 171 is that the optical beam splitter 171 further comprises a fourth port, which is the port D of the same optical coupling unit. The fourth port of the optical beam splitter 171 is the output port of the polarization control optical path 111 .

[0154] exist Figures 15 to 18 In the corresponding structure, the two optical pulses polarized and split in a polarization-controlled optical path 111 travel along exactly the same optical path when combined, exhibiting self-compensation for environmental interference and capable of stably generating polarization-encoded quantum states. This allows the generation of temporal phase-encoded quantum states to also have the advantage of high stability against interference. Furthermore, in the corresponding structure, at least one phase modulator 112 is applied with a high-frequency modulation signal having a frequency higher than a specified threshold, such that the phase modulator modulates the phases of the forward and reverse input optical pulses with non-reciprocity. This allows the phase modulator 112 to effectively phase-modulate the optical pulses input from the forward input optical port, but not the reverse input optical port. Consequently, when the optical pulses input from the forward input optical port and the reverse input optical port pass through the high-frequency modulated phase modulator 112, the optical pulse input from the forward input optical port is phase-modulated, while the optical pulse input from the reverse input optical port is not phase-modulated, resulting in a phase difference between the two optical pulses, enabling encoding of temporal phase quantum states at speeds of 10 GHz or higher.

[0155] In some embodiments, the polarization encoding unit comprises N polarization manipulation modules connected in series, where N is a positive integer. By setting the angles between the intrinsic polarization states of the polarization control light paths in the N polarization manipulation modules, and the angles between the intrinsic polarization states of the polarization control light paths and the intrinsic polarization states of the unequal-arm polarization control interferometer, different encoding requirements of quantum communication systems can be met.

[0156] For example, when N is 2, the angle between the eigenpolarization states of the two polarization control light paths can be set to: n·22.5°, where n is an integer, and two or three groups of different polarization states can be prepared.

[0157] In one embodiment, the angle between the eigenpolarization states of the two polarization-controlled light paths can be adjusted by rotating at least one of the two polarization-controlled light paths. In other words, by rotating either polarization-controlled light path, the angle between the eigenpolarization states of the two polarization-controlled light paths can be adjusted.

[0158] In another embodiment, the polarization encoding unit 100 further includes a polarization state rotator, which is disposed between the two polarization control light paths and is used to adjust the angle between the intrinsic polarization states of the two polarization control light paths.

[0159] The polarization state rotator may be a half-wave plate or a Faraday rotator, and the polarization state rotator may rotate at an angle of n·22.5°, where n is an integer.

[0160] In yet another embodiment, the angle between the two polarization-controlled light paths may be adjusted by rotating one of the two polarization-controlled light paths and providing a polarization-normality rotator.

[0161] For another example, when N is 3, the angle between the eigenpolarization state of the first polarization-controlled optical path and the eigenpolarization state of the second polarization-controlled optical path is set to 1·90°, and the angle between the eigenpolarization state of the first polarization-controlled optical path and the eigenpolarization state of the third polarization-controlled optical path is set to 22.5°±m·45°, or 45°±m·90°, where 1 and m are integers, and two groups of four polarization states or three groups of six polarization states can be prepared.

[0162] For another example, when N is 3, the angle between the eigenpolarization state of the first polarization control optical path and the eigenpolarization state of the second polarization control optical path is set to 22.5°±a·45° or 45°±a·90°, and the angle between the eigenpolarization state of the first polarization control optical path and the eigenpolarization state of the third polarization control optical path is set to n·22.5°, where a and n are integers. Similarly, two groups of four polarization states or three groups of six polarization states can be prepared.

[0163] In one embodiment, the angle setting method between the eigenpolarization states of the three polarization-controlled optical paths can be: the angle between the eigenpolarization state of the first polarization-controlled optical path and the eigenpolarization state of the second polarization-controlled optical path is achieved by rotating the second polarization-controlled optical path, and the angle between the eigenpolarization state of the first polarization-controlled optical path and the eigenpolarization state of the third polarization-controlled optical path is achieved by rotating the third polarization-controlled optical path.

[0164] In another embodiment, the polarization encoding unit 100 further includes: a first polarization state rotator and / or a second polarization state rotator.

[0165] The first polarization state rotator is arranged between the first polarization control light path and the second polarization control light path, and the angle between the intrinsic polarization state of the first polarization control light path and the intrinsic polarization state of the second polarization control light path is realized by the first polarization state rotator.

[0166] The second polarization state rotator is arranged between the second polarization control light path and the third polarization control light path, and the angle between the intrinsic polarization state of the first polarization control light path and the intrinsic polarization state of the third polarization control light path is realized by the first polarization state rotator and / or the second polarization state rotator.

[0167] The first polarization state rotator and the second polarization state rotator may be half-wave plates or Faraday rotators.

[0168] In yet another embodiment, the angle between the intrinsic polarization state of the first polarization-controlled optical path and the intrinsic polarization state of the second polarization-controlled optical path can be adjusted by rotating the second polarization-controlled optical path and the first polarization-state rotator. Specifically, the angle between the intrinsic polarization state of the first polarization-controlled optical path and the intrinsic polarization state of the second polarization-controlled optical path can be adjusted by rotating the second polarization-controlled optical path and providing the first polarization-state rotator.

[0169] Furthermore, the angle between the intrinsic polarization state of the first polarization-controlled optical path and the intrinsic polarization state of the second polarization-controlled optical path can be adjusted by rotating the third polarization-controlled optical path and at least one polarization rotator of the first polarization state rotator and the second polarization state rotator.

[0170] In one embodiment, the polarization encoding unit 100 further includes N-1 optical isolation units, where the optical isolation units are optical isolators or optical circulators, and the N-1 optical isolation units are respectively arranged between any two adjacent polarization operation modules.

[0171] It should be noted that, when multiple polarization operation modules are connected in series, the structure of each polarization operation module can be respectively as follows: Figures 15 to 18 The structures of any two polarization operation modules can be the same or different.

[0172] In some embodiments, the polarization state of the light pulse input to the polarization operation module is Alternatively, the polarization state of the optical pulse input to the polarization operation module is Where n is an integer, and where β is the two intrinsic polarization states of the polarization control optical path (the first polarization control optical path for N>1) in the polarization encoding unit, and β is any value between 0 and 2π. For example, the polarization state of the optical pulse input to the polarization manipulation module can be 45° linear polarization, -45° linear polarization, left-hand circular polarization, or right-hand circular polarization.

[0173] In some embodiments, the unequal-arm polarization control interferometer 300 includes a fifth optical coupling unit, a sixth optical coupling unit, a fifth transmission optical path, and a sixth transmission optical path, wherein the fifth optical coupling unit includes at least three ports, one input port and two output ports; the sixth optical coupling unit includes at least three ports, two input ports and one output port, and the two output ports of the fifth optical coupling unit are connected to the two input ports of the sixth optical coupling unit through the fifth transmission optical path and the sixth transmission optical path; the input port of the fifth optical coupling unit is the input port of the unequal-arm polarization control interferometer, and the output port of the sixth optical coupling unit is the output port of the unequal-arm polarization control interferometer. The optical path lengths of the fifth transmission optical path and the sixth transmission optical path are not equal, so that the two sub-light pulses transmitted through the fourth transmission optical path and the fifth transmission optical path generate a time delay when they are combined and output.

[0174] like Figure 19 FIG2 is a schematic structural diagram of an embodiment of an unequal-arm polarization control interferometer 300. In this embodiment, the fifth optical coupling unit is a polarization beam splitter 1901, and the sixth optical coupling unit is a polarization beam combiner 1902. The intrinsic polarization state of the polarization beam splitter 1901 is the intrinsic polarization state of the unequal-arm polarization control interferometer 300. The polarization beam splitter 1901 and the polarization beam combiner 1902 are connected via a fifth transmission optical path 1903 and a sixth transmission optical path 1904, respectively, having unequal optical path lengths.

[0175] like Figure 20FIG2 shows a schematic structural diagram of another embodiment of an unequal-arm polarization control interferometer 300. In this embodiment, the fifth optical coupling unit is a polarization beam splitter 2001, and the sixth optical coupling unit is an optical coupler 2002. The intrinsic polarization state of the polarization beam splitter 2001 is the intrinsic polarization state of the unequal-arm polarization control interferometer 300. The polarization beam splitter 2001 and the optical coupler 2002 are connected respectively via a fifth transmission optical path 2003 and a sixth transmission optical path 2004, both of which have unequal optical path lengths. Optionally, the fifth transmission optical path 2003 or the sixth transmission optical path 2004 is a 90° twisted polarization-maintaining optical fiber, or the unequal-arm polarization control interferometer 300 further includes: a 90° polarization state rotator 2005, which is arranged on the fifth transmission optical path 2003 or the sixth transmission optical path 2004, and is used to rotate the polarization state of the passing sub-light pulse by 90°, and the 90° polarization state rotator 2005 is a half-wave plate or a 90° Faraday rotator.

[0176] like Figure 21 FIG2 shows a schematic structural diagram of another embodiment of an unequal-arm polarization control interferometer 300. In this embodiment, the fifth optical coupling unit is an optical coupler 2101, and the sixth optical coupling unit is a polarization beam combiner 2102. The intrinsic polarization state of the polarization beam combiner 2102 is the intrinsic polarization state of the unequal-arm polarization control interferometer 300. The optical coupler 2101 and the polarization beam combiner 2102 are connected via a fifth transmission optical path 2103 and a sixth transmission optical path 2104, respectively, having unequal optical path lengths.

[0177] like Figure 22FIG2 shows a schematic structural diagram of another embodiment of an unequal-arm polarization control interferometer 300. In this embodiment, the fifth optical coupling unit is an optical coupler 2201, and the sixth optical coupling unit is an optical coupler 2202. The unequal-arm polarization control interferometer further includes two polarizers, namely a polarizer 2203 and a polarizer 2204. The two polarizers 2203 and 2204 are respectively arranged on the fifth transmission optical path 2205 and the sixth transmission optical path 2206. In particular, one output port of the optical coupler 2201 is connected to a port on the first side of the polarizer 2203. The polarizer 2203 is used to polarize a light pulse outputted from the optical coupler 2201. The other output port of the optical coupler 2201 is connected to a port on the first side of the polarizer 2204. The polarizer 2204 is used to polarize a light pulse outputted from the optical coupler 2201. The polarization directions of the two polarizers 2203 and 2204 are orthogonal to each other. The other side port of the polarizer 2203 and the other side port of the polarizer 2204 are connected to the optical coupler 2202 via the fifth transmission optical path 2205 and the sixth transmission optical path 2206, respectively. In this embodiment, the polarization direction of the two polarizers is the intrinsic polarization state direction of the unequal-arm polarization control interferometer. Optionally, the fifth transmission optical path 2205 or the sixth transmission optical path 2206 is a 90° twisted polarization-maintaining fiber, or the unequal-arm polarization control interferometer 300 further includes: a 90° polarization state rotator 2207, which is arranged on the fifth transmission optical path 2205 or the sixth transmission optical path 2206 and is used to rotate the polarization state of the passing sub-light pulse by 90°. The 90° polarization state rotator 2207 is a half-wave plate or a 90° Faraday rotator.

[0178] like Figure 23FIG2 shows a schematic structural diagram of another embodiment of an unequal-arm polarization control interferometer 300. In this embodiment, the fifth optical coupling unit and the sixth optical coupling unit are the same polarization beam splitter 2301, and the intrinsic polarization state of the polarization beam splitter 2301 is the intrinsic polarization state of the unequal-arm polarization control interferometer. The unequal-arm polarization control interferometer 300 also includes two reflectors, namely, reflector 2302 and reflector 2303. The two output ports of the polarization beam splitter 2301 are respectively connected to one end of the fifth transmission optical path 2304 and one end of the sixth transmission optical path 2305. The two reflectors 2302 and 2303 are respectively connected to the other end of the fifth transmission optical path 2304 and the other end of the sixth transmission optical path 2305. The two reflectors 2302 and 2303 are used to reflect the input sub-light pulse back to the polarization beam splitter 2301. Optionally, the two reflectors 2302 and 2303 may be quarter-wave plate reflectors or 90° Faraday rotator reflectors, configured to rotate the polarization state of the input sub-light pulse by 90°. Alternatively, the two reflectors 2302 and 2303 may be polarization rotation reflectors, configured to rotate the polarization state of the input sub-light pulse by 45° or another preset angle.

[0179] It should be noted that the polarization beam splitter 2301 may include three ports or four ports.

[0180] like Figure 24 The figure shows a schematic structural diagram of another embodiment of the unequal-arm polarization control interferometer 300. In this embodiment, the fifth optical coupling unit and the sixth optical coupling unit are the same optical coupler 2401. The unequal-arm polarization control interferometer 300 also includes: two reflectors 2402 and 2403 and two polarizers 2404 and 2405.

[0181] The two output ports of the optical coupler 2401 are respectively connected to one end of the fifth transmission optical path and one end of the sixth transmission optical path, and the two reflectors 2402 and 2403 are respectively connected to the other end of the fifth transmission optical path and the other end of the sixth transmission optical path; the two polarizers 2404 and 2405 are respectively arranged on the fifth transmission optical path and the sixth transmission optical path, and the polarization directions of the two polarizers 2404 and 2405 are orthogonal to each other; the polarization directions of the two polarizers 2404 and 2405 are the intrinsic polarization state directions of the unequal-arm polarization control interferometer.

[0182] In some embodiments, the unequal-arm polarization control interferometer 300 further includes a polarizer, which is disposed at an output port of the unequal-arm polarization control interferometer 300 and is used to polarize the output light pulses.

[0183] In some embodiments, the quantum state encoding device further includes: a quarter-wave plate, disposed between the polarization encoding unit 100 and the first optical coupling unit 200 , or between the first optical coupling unit 200 and the unequal-arm polarization control interferometer 300 .

[0184] In some embodiments, the angle between the intrinsic polarization state of the polarization control optical path and the intrinsic polarization state of the unequal-arm polarization control interferometer 300 may be: n·22.5°, where n is an integer.

[0185] In one embodiment, the angle between the intrinsic polarization state of the polarization control light path and the intrinsic polarization state of the unequal-arm polarization control interferometer 300 can be achieved by rotating at least one of the polarization control light path and the unequal-arm polarization control interferometer 300 .

[0186] Specifically, by rotating the polarization-control optical path, the angle between the intrinsic polarization state of the polarization-control optical path and the intrinsic polarization state of the unequal-arm polarization-control interferometer 300 can be adjusted. Alternatively, by rotating the unequal-arm polarization-control interferometer 300, the angle between the intrinsic polarization state of the polarization-control optical path and the intrinsic polarization state of the unequal-arm polarization-control interferometer 300 can be adjusted. Alternatively, by rotating the polarization-control optical path and the unequal-arm polarization-control interferometer 300, the angle between the intrinsic polarization state of the polarization-control optical path and the intrinsic polarization state of the unequal-arm polarization-control interferometer 300 can be adjusted.

[0187] In another embodiment, the quantum state encoding device further includes a polarization state rotator. The polarization state rotator is disposed between the polarization control optical path and the unequal-arm polarization control interferometer 300. The polarization state rotator can adjust the angle between the intrinsic polarization state of the polarization control optical path and the intrinsic polarization state of the unequal-arm polarization control interferometer 300.

[0188] In another embodiment, the angle between the intrinsic polarization state of the polarization control light path and the intrinsic polarization state of the unequal-arm polarization control interferometer 300 can be adjusted by rotating the polarization control light path and / or the unequal-arm polarization control interferometer 300 and the polarization state rotator.

[0189] In other embodiments, when the polarization coding unit 100 includes N polarization manipulation modules connected in series, the angle between the intrinsic polarization state of the polarization control optical path of the polarization manipulation module connected to the unequal-arm polarization control interferometer 300 and the intrinsic polarization state of the unequal-arm polarization control interferometer 300 can be n·22.5°, where n is an integer.

[0190] In one embodiment, the angle between the intrinsic polarization state of the polarization control light path of the polarization operation module connected to the unequal-arm polarization control interferometer 300 and the intrinsic polarization state of the unequal-arm polarization control interferometer 300 is achieved by rotating at least one of the polarization operation module connected to the unequal-arm polarization control interferometer 300 and the unequal-arm polarization control interferometer 300.

[0191] Specifically, the angle between the intrinsic polarization state of the polarization control light path of the polarization control module connected to the unequal-arm polarization control interferometer 300 and the intrinsic polarization state of the unequal-arm polarization control interferometer 300 can be adjusted by rotating the polarization operation module connected to the unequal-arm polarization control interferometer 300. Alternatively, the angle between the intrinsic polarization state of the polarization control light path and the intrinsic polarization state of the unequal-arm polarization control interferometer 300 can be adjusted by rotating the unequal-arm polarization control interferometer 300. Alternatively, the angle between the intrinsic polarization state of the polarization control light path of the polarization control module connected to the unequal-arm polarization control interferometer 300 and the intrinsic polarization state of the unequal-arm polarization control interferometer 300 can be adjusted by rotating the polarization operation module connected to the unequal-arm polarization control interferometer 300 and the unequal-arm polarization control interferometer 300.

[0192] In another embodiment, the quantum state encoding device further includes a polarization state rotator. The polarization state rotator is disposed between the polarization manipulation module connected to the unequal-arm polarization-control interferometer and the unequal-arm polarization-control interferometer 300. The polarization state rotator adjusts the angle between the intrinsic polarization state of the polarization control optical path of the polarization manipulation module connected to the unequal-arm polarization-control interferometer and the intrinsic polarization state of the unequal-arm polarization-control interferometer 300.

[0193] In another embodiment, the angle between the intrinsic polarization state of the polarization control optical path of the polarization operation module connected to the unequal-arm polarization control interferometer 300 and the intrinsic polarization state of the unequal-arm polarization control interferometer 300 can be adjusted by rotating the polarization operation module connected to the unequal-arm polarization control interferometer 300 and / or the unequal-arm polarization control interferometer 300 and the polarization state rotator.

[0194] In order to further understand the quantum state encoding device provided by the embodiment of the present application, the polarization encoding unit uses two polarization operation modules connected in series. The polarization operation module uses the following Figure 16 The structure shown in the figure, the unequal arm polarization control interferometer adopts Figure 19 The structure of the quantum state encoding device is shown in Figure 25 shown.

[0195] In some embodiments, according to the requirements of quantum communication, the quantum state encoding device of the present application can also be used in the quantum state decoding process.

[0196] According to the present application, a quantum state encoding method is provided, which uses the above-mentioned quantum state encoding device to implement quantum state encoding.

[0197] The present application also provides a software-defined quantum communication system. Figure 26 As shown, it includes the above-mentioned quantum state encoding device 2601 and the encoding control device 2602. The encoding control device 2602 is used to generate quantum communication encoding control instructions based on the encoding requirements of the quantum communication system and send them to the quantum state encoding device 2601, so that the quantum state encoding device 2601 can select and output polarization-encoded quantum state light pulses or time phase-encoded quantum state light pulses based on the quantum communication encoding control instructions.

[0198] The quantum communication system can be a discrete variable quantum communication system or a continuous variable quantum communication system.

[0199] It should be understood that the specific features, operations, and details described hereinabove with respect to the apparatus of the present application may also be similarly applied to the method and system of the present application, or vice versa.

[0200] The various technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification as long as such combination does not conflict.

[0201] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A quantum state encoding device, characterized in that: include: A polarization encoding unit, a first optical coupling unit, an unequal-arm polarization control interferometer, a first transmission optical path, and a second optical coupling unit; The polarization encoding unit comprises at least one input port and an output port, wherein the polarization encoding unit is configured to input a light pulse through one of the input ports, generate a light pulse in a polarization-encoded quantum state based on the input light pulse, and output the light pulse through the output port; The first optical coupling unit comprises an input port and two output ports, namely a first port, a second port and a third port, wherein the first port is connected to the output port of the polarization coding unit; The second optical coupling unit comprises two input ports and one output port, namely a fourth port, a fifth port and a sixth port; The unequal-arm polarization control interferometer comprises an input port and an output port, and is used to perform time-phase encoding conversion on an input optical pulse of a polarization-encoded quantum state and output an optical pulse of a time-phase-encoded quantum state; The third port of the first optical coupling unit is connected to the input port of the unequal-arm polarization control interferometer, and the output port of the unequal-arm polarization control interferometer is connected to the fifth port of the second optical coupling unit to form a first optical output branch; The second port of the first optical coupling unit is connected to the fourth port of the second optical coupling unit through the first transmission optical path to form a second optical output branch; The first optical coupling unit is configured to input the optical pulse of the polarization-encoded quantum state output by the polarization encoding unit into the first optical output branch and / or the second optical output branch according to a quantum communication coding control instruction, wherein the quantum communication coding control instruction is determined according to a coding requirement of a quantum communication system; The sixth port of the second optical coupling unit is the output port of the quantum state encoding device, which is used to output the polarization-encoded quantum state optical pulse transmitted by the second optical output branch or the time phase-encoded quantum state optical pulse transmitted by the first optical output branch according to the quantum communication coding control instruction.

2. The device according to claim 1, characterized in that The first optical coupling unit is an optical coupler, and the second optical coupling unit is an optical switch.

3. The device according to claim 2, characterized in that The first optical coupling unit is configured to input the polarization-encoded quantum state optical pulse output by the polarization encoding unit through the first port, split the polarization-encoded quantum state optical pulse into two sub-optical pulses, and input the two sub-optical pulses into the first optical output branch and the second optical output branch through the third port and the second port, respectively; The second optical coupling unit is used to select and output the polarization-encoded quantum state optical pulse transmitted by the second optical output branch or the time phase-encoded quantum state optical pulse transmitted by the first optical output branch according to the quantum communication coding control instruction.

4. The device according to claim 1, characterized in that The first optical coupling unit is an optical switch, and the second optical coupling unit is an optical switch or an optical coupler.

5. The device according to claim 4, characterized in that The first optical coupling unit is configured to selectively input the optical pulse of the polarization-encoded quantum state into the first optical output branch or the second optical output branch according to the quantum communication coding control instruction; When the second optical coupling unit is an optical switch, the second optical coupling unit is used to connect the first optical output branch that outputs the optical pulse of the time phase encoded quantum state or the second optical output branch that outputs the optical pulse of the polarization encoded quantum state according to the quantum communication coding control instruction; When the second optical coupling unit is an optical coupler, the second optical coupling unit is used to output the optical pulse in the time phase coded quantum state transmitted by the first optical output branch or the optical pulse in the polarization coded quantum state transmitted by the second optical output branch.

6. The device according to claim 1, characterized in that The polarization encoding unit includes a polarization operation module, and the polarization operation module includes a polarization control optical path and at least one phase modulator arranged in a transmission optical path of the polarization control optical path; The polarization control optical path is used to split the input optical pulse into two sub-optical pulses; The phase modulator is used to perform phase modulation on at least one optical sub-pulse based on a modulation signal, so as to generate a specific phase difference between two optical sub-pulses; The polarization control optical path is further used to combine the two optical sub-pulses that generate phase difference and output the generated polarization-encoded quantum state optical pulses.

7. The device according to claim 6, characterized in that The polarization control optical path includes a third optical coupling unit, a fourth optical coupling unit, a second transmission optical path, and a third transmission optical path; The third optical coupling unit is connected to the fourth optical coupling unit via the second transmission optical path and the third transmission optical path; The third optical coupling unit is used to split an input optical pulse into two optical pulses, namely a first optical pulse and a second optical pulse. The first optical pulse and the second optical pulse are respectively transmitted along the second transmission optical path and the third transmission optical path, and after passing through the at least one phase modulator, are combined and output by the fourth optical coupling unit.

8. The device according to claim 7, characterized in that The third optical coupling unit and the fourth optical coupling unit are the same optical coupler, and the polarization control optical path further includes: two reflectors; The optical coupler includes at least three ports, including at least one input port and two output ports. The two output ports are connected to the two reflectors through the second transmission optical path and the third transmission optical path, respectively. The two reflectors are used to reflect the light pulses input to the two reflectors back to the optical coupler. One of the two reflectors is a quarter-wave plate reflector or a 90° Faraday rotation mirror.

9. The device according to claim 7, characterized in that The third optical coupling unit and the fourth optical coupling unit are the same polarization beam splitter, and the polarization control optical path further includes: two reflectors, The polarization beam splitter includes at least three ports, including at least one input port and two output ports. The two output ports are connected to the two reflectors through the second transmission optical path and the third transmission optical path respectively. The two reflectors are used to reflect the light pulses input to the two reflectors back to the polarization beam splitter.

10. The device according to claim 7, characterized in that The third optical coupling unit is a polarization beam splitter, and the fourth optical coupling unit is an optical coupler or a polarization beam splitter.

11. The device according to claim 7, characterized in that The third optical coupling unit is an optical coupler, and the fourth optical coupling unit is an optical coupler or a polarization beam splitter.

12. The device according to claim 11, characterized in that The second transmission optical path or the third transmission optical path is a 90° twisted polarization-maintaining optical fiber; or The polarization control optical path further includes: a 90° polarization state rotator provided on the second transmission optical path or the third transmission optical path, wherein the polarization state rotator is configured to rotate the polarization state of the passing sub-light pulse by 90°.

13. The device according to claim 11 or 12, characterized in that The polarization control optical path further includes: a first pre-optical interferometer and an intermediate optical coupling unit, wherein the first pre-optical interferometer includes the third optical coupling unit, a fourth transmission optical path, and a pre-phase modulator arranged on the fourth transmission optical path; The intermediate optical coupling unit is provided in the second transmission optical path or the third transmission optical path, and is used to receive an input optical pulse and input it to the first pre-optical interferometer; The first pre-optical interferometer is used to split the input optical pulse into two pre-optical sub-pulses, and generate a phase difference between the two pre-optical sub-pulses through the pre-phase modulator; The two ports of the third optical coupling unit are connected via the fourth transmission optical path, and are used to split the optical pulse inputted by the intermediate optical coupling unit into two preamplifier sub-optical pulses and input them into the fourth transmission optical path from different ports; The pre-phase modulator is used to perform phase modulation on one of the two pre-optical sub-pulses transmitted on the fourth transmission optical path based on the modulation signal, or to perform different phase modulation on the two pre-optical sub-pulses, so as to generate a phase difference between the two pre-optical sub-pulses; The third optical coupling unit is further used to reflect and transmit the two pre-phase sub-pulses that generate a phase difference after passing through the pre-phase modulator to generate two sub-pulses, and input the two sub-pulses into the second transmission optical path and the third transmission optical path respectively through different ports.

14. The device according to claim 11 or 12, characterized in that The polarization control optical path further includes: a second pre-optical interferometer, the second pre-optical interferometer including: a pre-optical coupling unit, a first pre-transmission optical path, a second pre-transmission optical path, a pre-phase modulator arranged in the first pre-transmission optical path or the second pre-transmission optical path, and the third optical coupling unit. The front optical coupling unit is connected to the two input ports of the third optical coupling unit through the first front transmission optical path and the second front transmission optical path respectively, and the front optical coupling unit is used to split an input optical pulse into two front sub-optical pulses, and input them into the first front transmission optical path and the second front transmission optical path respectively; The pre-phase modulator is used to perform phase modulation on one path of input pre-optical sub-pulses based on the modulation signal, so that there is a phase difference between the two paths of pre-optical sub-pulses input to the third optical coupling unit; The third optical coupling unit is used to reflect and transmit two pre-optical sub-pulses with phase difference input from different ports to generate two sub-optical pulses, and input the two sub-optical pulses into the second transmission optical path and the third transmission optical path respectively through different ports.

15. The device according to claim 7, characterized in that The third optical coupling unit and the fourth optical coupling unit are the same optical coupling unit, and the second transmission optical path and the third transmission optical path are the same transmission optical path.

16. The device according to claim 15, characterized in that The same optical coupling unit is a polarization beam splitter, which includes three ports, namely a first port, a second port and a third port. The first port of the polarization beam splitter is the input and output port of the polarization control optical path, the second port and the third port of the polarization beam splitter are connected through the same transmission optical path, and the intrinsic polarization state of the polarization beam splitter is the intrinsic polarization state of the polarization control optical path.

17. The device according to claim 15, characterized in that The same optical coupling unit includes: a polarization beam splitter, a first polarizer and a second polarizer; The polarization beam splitter includes four ports, namely a first port, a second port, a third port and a fourth port. The first port of the polarization beam splitter is the input port of the polarization control optical path, and the first port or the fourth port of the polarization beam splitter is the output port of the polarization control optical path; the second port and the third port of the polarization beam splitter are respectively connected to the port on the first side of the first polarizer and the port on the first side of the second polarizer; the port on the second side of the first polarizer and the port on the second side of the second polarizer are connected through a transmission optical path; the angle between the polarization direction of the first polarizer and one intrinsic polarization state of the polarization beam splitter is θ, and the angle between the polarization direction of the second polarizer and another intrinsic polarization state of the polarization beam splitter is δ; wherein θ, δ≠n·90°, n is an integer, and the intrinsic polarization state of the polarization beam splitter is the intrinsic polarization state of the polarization control optical path.

18. The device according to claim 15, characterized in that The same optical coupling unit includes: an optical beam splitter, a first polarizer and a second polarizer; The optical beam splitter comprises at least three ports, namely a first port, a second port and a third port. The first port of the optical beam splitter is the input port and the output port of the polarization control optical path; the second port and the third port of the optical beam splitter are respectively connected to the port on the first side of the first polarizer and the port on the first side of the second polarizer; the port on the second side of the first polarizer and the port on the second side of the second polarizer are connected through a transmission optical path, and the polarization direction of the first polarizer is The polarization direction of the second polarizer is The polarization direction of the first polarizer The polarizing direction of the second polarizer mutually orthogonal, the polarizing direction of the first polarizer The polarizing direction of the second polarizer is the eigenpolarization state of the polarization control optical path.

19. The device according to claim 15, characterized in that The same optical coupling unit includes: an optical beam splitter, a first polarizer and a second polarizer; The optical beam splitter comprises four ports, namely a first port, a second port, a third port and a fourth port. The first port of the optical beam splitter is the input port of the polarization control optical path; the second port and the third port of the optical beam splitter are respectively connected to the port on the first side of the first polarizer and the port on the first side of the second polarizer; the port on the second side of the first polarizer and the port on the second side of the second polarizer are connected through a transmission optical path; the fourth port of the optical beam splitter is the output port of the polarization control optical path, and the polarization direction of the first polarizer is The polarization direction of the second polarizer is The polarization direction of the first polarizer The polarizing direction of the second polarizer is the eigenpolarization state of the polarization control optical path.

20. The device according to any one of claims 15 to 19, characterized in that The phase modulator includes a forward input optical port and a reverse input optical port. After applying a high-frequency modulation signal with a frequency higher than a specified threshold, the phase modulator operates in a non-reciprocal state, and the ratio of the modulation efficiency of the optical pulse input from the forward input optical port to the modulation efficiency of the optical pulse input from the reverse input optical port is greater than a preset threshold.

21. The device according to any one of claims 15 to 19, characterized in that: The polarization encoding unit includes N polarization operation modules connected in series, where N is a positive integer.

22. The device according to claim 21, characterized in that When N is 2, the angle between the eigenpolarization states of the two polarization control light paths is: n·22.5°, where n is an integer.

23. The device according to claim 22, characterized in that The angle between the intrinsic polarization states of the two polarization-controlled light paths is achieved by rotating at least one of the two polarization-controlled light paths; and / or The polarization encoding unit further includes a polarization state rotator, which is arranged between the two polarization control light paths and is used to adjust the angle between the intrinsic polarization states of the two polarization control light paths.

24. The device according to claim 21, characterized in that When N is 3, when the angle between the eigenpolarization state of the first polarization-controlled optical path and the eigenpolarization state of the second polarization-controlled optical path is l·90°, the angle between the eigenpolarization state of the first polarization-controlled optical path and the eigenpolarization state of the third polarization-controlled optical path is 22.5°±m·45°, or 45°±m·90°, where l and m are integers; When the angle between the eigenpolarization state of the first polarization-controlled optical path and the eigenpolarization state of the second polarization-controlled optical path is 22.5°±a·45° or 45°±a·90°, the angle between the eigenpolarization state of the first polarization-controlled optical path and the eigenpolarization state of the third polarization-controlled optical path is n·22.5°, where a and n are integers.

25. The device according to claim 24, characterized in that The angle between the eigenpolarization state of the first polarization-controlled optical path and the eigenpolarization state of the second polarization-controlled optical path is achieved by rotating the second polarization-controlled optical path, and the angle between the eigenpolarization state of the first polarization-controlled optical path and the eigenpolarization state of the third polarization-controlled optical path is achieved by rotating the third polarization-controlled optical path; and / or, The polarization encoding unit further comprises: a first polarization state rotator and / or a second polarization state rotator, The first polarization state rotator is disposed between the first polarization control light path and the second polarization control light path, and the angle between the intrinsic polarization state of the first polarization control light path and the intrinsic polarization state of the second polarization control light path is adjusted by the first polarization state rotator; The second polarization state rotator is arranged between the second polarization control light path and the third polarization control light path, and the angle between the intrinsic polarization state of the first polarization control light path and the intrinsic polarization state of the third polarization control light path is adjusted by the first polarization state rotator and / or the second polarization state rotator.

26. The device according to claim 21, characterized in that The polarization encoding unit further includes N-1 optical isolation units, which are optical isolators or optical circulators. The N-1 optical isolation units are respectively arranged between any two adjacent polarization operation modules.

27. The device according to claim 1, characterized in that The polarization state of the optical pulse input to the polarization encoding unit is or, The polarization state of the optical pulse input to the polarization encoding unit is Where n is an integer, and are two eigenpolarization states of the polarization control optical path in the polarization encoding unit, and β is any value between 0 and 2π.

28. The device according to claim 1, wherein The unequal-arm polarization control interferometer comprises a fifth optical coupling unit, a sixth optical coupling unit, a fifth transmission optical path and a sixth transmission optical path. The fifth optical coupling unit includes at least three ports, one input port and two output ports; the sixth optical coupling unit includes at least three ports, two input ports and one output port, and the two output ports of the fifth optical coupling unit are connected to the two input ports of the sixth optical coupling unit through the fifth transmission optical path and the sixth transmission optical path; the input port of the fifth optical coupling unit is the input port of the unequal-arm polarization control interferometer, and the output port of the sixth optical coupling unit is the output port of the unequal-arm polarization control interferometer, and the optical path lengths of the fifth transmission optical path and the sixth transmission optical path are not equal.

29. The device according to claim 28, characterized in that The fifth optical coupling unit is a polarization beam splitter, the sixth optical coupling unit is a polarization beam combiner, and the intrinsic polarization state of the polarization beam splitter is the intrinsic polarization state of the unequal-arm polarization control interferometer.

30. The device according to claim 28, wherein The fifth optical coupling unit is a polarization beam splitter, the sixth optical coupling unit is an optical coupler, and the intrinsic polarization state of the polarization beam splitter is the intrinsic polarization state of the unequal-arm polarization control interferometer.

31. The device according to claim 28, characterized in that The fifth optical coupling unit is an optical coupler, the sixth optical coupling unit is a polarization beam combiner, and the intrinsic polarization state of the polarization beam combiner is the intrinsic polarization state of the unequal-arm polarization control interferometer.

32. The device according to claim 28, characterized in that The fifth optical coupling unit is an optical coupler, the sixth optical coupling unit is an optical coupler, and the unequal-arm polarization control interferometer further includes: two polarizers, The two polarizers are respectively arranged on the fifth transmission optical path and the sixth transmission optical path. The polarization directions of the two polarizers are orthogonal to each other. The polarization directions of the two polarizers are the intrinsic polarization state directions of the unequal-arm polarization control interferometer.

33. The device according to claim 28, characterized in that The fifth optical coupling unit and the sixth optical coupling unit are the same polarization beam splitter, and the unequal-arm polarization control interferometer further includes: two reflecting mirrors, The two output ports of the polarization beam splitter are respectively connected to one end of the fifth transmission optical path and one end of the sixth transmission optical path, the two reflectors are respectively connected to the other end of the fifth transmission optical path and the other end of the sixth transmission optical path, and the eigenpolarization state of the polarization beam splitter is the eigenpolarization state of the unequal-arm polarization control interferometer.

34. The device according to claim 33, characterized in that The two reflectors are quarter-wave plate reflectors or 90° Faraday rotation reflectors.

35. The device according to claim 28, characterized in that The fifth optical coupling unit and the sixth optical coupling unit are the same optical coupler, and the unequal-arm polarization control interferometer further includes: two reflectors and two polarizers. The two output ports of the optical coupler are respectively connected to one end of the fifth transmission optical path and one end of the sixth transmission optical path, and the two reflectors are respectively connected to the other end of the fifth transmission optical path and the other end of the sixth transmission optical path; the two polarizers are respectively arranged on the fifth transmission optical path and the sixth transmission optical path, and the polarization directions of the two polarizers are orthogonal to each other; the polarization directions of the two polarizers are the intrinsic polarization state directions of the unequal-arm polarization control interferometer.

36. The device according to claim 30 or 32, characterized in that The fifth transmission optical path or the sixth transmission optical path is a 90° twisted polarization-maintaining optical fiber, or, The unequal-arm polarization control interferometer further includes: a 90° polarization state rotator, The 90° polarization state rotator is arranged on the fifth transmission optical path or the sixth transmission optical path, and is used to rotate the polarization state of the passing sub-light pulse by 90°.

37. The device according to any one of claims 28 to 35, characterized in that The unequal-arm polarization control interferometer further includes: a polarizer; The polarizer is arranged at the output port of the unequal-arm polarization control interferometer and is used for polarizing the output light pulse.

38. The device according to any one of claims 16 to 19, characterized in that The angle between the intrinsic polarization state of the polarization control optical path and the intrinsic polarization state of the unequal-arm polarization control interferometer is: n·22.5°, where n is an integer.

39. The device according to claim 38, characterized in that The angle between the intrinsic polarization state of the polarization control light path and the intrinsic polarization state of the unequal-arm polarization control interferometer is achieved by rotating at least one of the polarization control light path and the unequal-arm polarization control interferometer; and / or The device also includes: a polarization state rotator, which is arranged between the polarization control light path and the unequal-arm polarization control interferometer, and the angle between the intrinsic polarization state of the polarization control light path and the intrinsic polarization state of the unequal-arm polarization control interferometer is adjusted by the polarization state rotator.

40. The device according to claim 21, characterized in that The polarization encoding unit includes N polarization operation modules connected in series, and the angle between the eigenpolarization state of the polarization control optical path of the polarization operation module connected to the unequal-arm polarization control interferometer and the eigenpolarization state of the unequal-arm polarization control interferometer is: n·22.5°, where n is an integer.

41. The device according to claim 40, characterized in that The angle between the intrinsic polarization state of the polarization control optical path of the polarization operation module connected to the unequal-arm polarization control interferometer and the intrinsic polarization state of the unequal-arm polarization control interferometer is achieved by rotating at least one of the polarization operation module connected to the unequal-arm polarization control interferometer and the unequal-arm polarization control interferometer; and / or The device also includes: a polarization state rotator, which is arranged between the polarization operation module connected to the unequal-arm polarization control interferometer and the unequal-arm polarization control interferometer, and the polarization state rotator is used to adjust the angle between the intrinsic polarization state of the polarization control light path of the polarization operation module connected to the unequal-arm polarization control interferometer and the intrinsic polarization state of the unequal-arm polarization control interferometer.

42. The device according to claim 1, wherein The device further includes: a quarter-wave plate, which is arranged between the polarization encoding unit and the first optical coupling unit, or between the first optical coupling unit and the unequal-arm polarization control interferometer.

43. A quantum state encoding method, characterized in that: Quantum state encoding is achieved by applying the quantum state encoding device described in any one of claims 1 to 42.

44. A software-defined quantum communication system, characterized in that A quantum state encoding device and an encoding control device comprising any one of claims 1 to 42; The coding control device is used to generate quantum communication coding control instructions based on the coding requirements of the quantum communication system and send them to the quantum state coding device.

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