Quantum state coding device and method and software-defined quantum communication system

Abstract

The invention provides a quantum state coding device and method and a software-defined quantum communication system. The device comprises a polarization coding unit, a first optical coupling unit, a polarization-to-time phase coding unit, a first transmission optical path and a second optical coupling unit, the polarization coding unit is used for modulating one path of input light pulse through at least one adjustable circular birefringence module and then outputting light pulse in a polarization coding quantum state; the polarization-to-time phase encoding unit is used for converting the optical pulse of the polarization encoding quantum state output by the polarization encoding unit into the optical pulse of the time phase encoding quantum state; and controlling the first optical coupling unit and the second optical coupling unit to output the optical pulse of the polarization coding quantum state or output the optical pulse of the time phase coding quantum state according to the quantum communication coding control instruction. According to the quantum state coding device and the quantum communication system, different coding requirements of the quantum communication system can be met by the same quantum state coding device.

Description

Technical Field

[0001] The present application relates to the field 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 frontier hotspot combining quantum physics and information science. Its current applications mainly include quantum key distribution and quantum direct communication. Based on physical principles such as the Heisenberg uncertainty relation in quantum mechanics and the quantum no-cloning theorem, quantum key distribution can share keys in real time and securely between communicating parties, and quantum direct communication can achieve information transmission security. Quantum communication can detect potential eavesdropping on communication channels and can be applied to fields with high-security information transmission requirements such as national defense, government affairs, finance, and electricity.

[0003] The physical realization of quantum communication systems, such as quantum key distribution and quantum direct communication, requires encoding and decoding of quantum states. Currently, commonly used quantum communication encoding methods include polarization encoding and time phase encoding. A quantum communication system generally chooses one of these encoding methods, so the system is not universal and cannot be flexibly networked.

[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] In view of this, the present application provides a quantum state encoding device, method and quantum communication system to solve the technical problems raised by the background technology.

[0006] According to a first aspect of the present application, a quantum state encoding device is provided, comprising: a polarization encoding unit, a first optical coupling unit, a polarization-to-time phase encoding unit, a first transmission optical path, and a second optical coupling unit;

[0007] The polarization encoding unit includes at least one adjustable circular birefringence module, and the adjustable circular birefringence module includes a first quarter wave plate, N built-in linear polarization operation modules and a second quarter wave plate connected in series in sequence; N is an integer greater than or equal to 1;

[0008] The first quarter wave plate is used to convert the left-handed circular polarization component and the right-handed circular polarization component in an input optical pulse into two orthogonal linear polarization components;

[0009] The built-in linear polarization operation module includes a linear polarization control optical path and at least one phase modulator; the input end of the linear polarization control optical path is connected to one end of the first quarter wave plate, and is used to receive the optical pulse containing the two orthogonal linear polarization components after being converted by the first quarter wave plate, and split it into two sub-optical pulses, perform phase modulation on at least one of the two sub-optical pulses through the phase modulator, so that a phase difference is generated between the two sub-optical pulses, and combine the two sub-optical pulses with the phase difference and output them through the output end;

[0010] One end of the second quarter wave plate is connected to the output end of the linear polarization control light path, and is used for converting the two orthogonal linear polarization components in a light pulse output by the linear polarization control light path into a left-handed circular polarization component and a right-handed circular polarization component, and then outputting them through the output end;

[0011] 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 end of the second quarter wave plate in the polarization coding unit;

[0012] The second optical coupling unit comprises two input ports and one output port, which are respectively a fourth port, a fifth port and a sixth port;

[0013] The polarization-to-time phase encoding unit 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;

[0014] The third port of the first optical coupling unit is connected to the input port of the polarization-to-temporal phase encoding unit, and the output port of the polarization-to-temporal phase encoding unit is connected to the fifth port of the second optical coupling unit to form a first optical output branch;

[0015] 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;

[0016] The first optical coupling unit is used 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, and the quantum communication coding control instruction is determined according to the coding requirements of the quantum communication system;

[0017] 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 output by the first optical output branch according to the quantum communication coding control instruction.

[0018] According to a second aspect of the present application, a quantum state encoding method is provided, which is applied to the above-mentioned quantum state encoding device.

[0019] According to a third aspect of the present application, a software-defined quantum communication system is provided, comprising the quantum state encoding device and the encoding control device as described above;

[0020] 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.

[0021] In summary, the quantum state encoding device, method and software-defined quantum communication system provided in the embodiments of the present application have at least the following beneficial effects:

[0022] The present application can control the output of polarization-encoded quantum state light pulses, or output time phase-encoded quantum state light pulses according to quantum communication coding control instructions, thereby realizing that the same quantum state coding device can meet the different coding requirements of the quantum communication system to achieve the coded output of multi-modal quantum state light pulses, thus meeting the coding requirements of the quantum communication system.

[0023] This application can also achieve the security requirements of quantum communication, reduce the number of lasers used, and reduce the weight and power consumption of quantum communication transmitters. The polarization-encoded quantum state of this application has strong stability and can meet the needs of space quantum communication applications for time phase-encoded quantum states. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. 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 paying any creative work.

[0025] Figure 1 A schematic diagram showing the structure of a first embodiment of a quantum state encoding device provided in an embodiment of the present application is shown;

[0026] Figure 2 A schematic structural diagram of a first embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0027] Figure 3 A schematic diagram showing the structure of a second embodiment of a quantum state encoding device provided in an embodiment of the present application is shown;

[0028] Figure 4 A schematic structural diagram of a first embodiment of a linear polarization operation module provided in an embodiment of the present application is shown;

[0029] Figure 5 A schematic structural diagram of a second embodiment of a linear polarization operation module provided in an embodiment of the present application is shown;

[0030] Figure 6 A schematic structural diagram of a third embodiment of a linear polarization operation module provided in an embodiment of the present application is shown;

[0031] Figure 7 A schematic structural diagram showing a fourth embodiment of a linear polarization operation module provided in an embodiment of the present application;

[0032] Figure 8 A schematic structural diagram of a fifth embodiment of a linear polarization operation module provided in an embodiment of the present application is shown;

[0033] Fig. 9 A schematic structural diagram of a sixth embodiment of a linear polarization operation module provided in an embodiment of the present application is shown;

[0034] Fig.10 A schematic structural diagram showing a seventh embodiment of a linear polarization operation module provided in an embodiment of the present application;

[0035] Fig.11 A schematic structural diagram of an eighth embodiment of a linear polarization operation module provided in an embodiment of the present application is shown;

[0036] Fig.12 A schematic structural diagram of a second embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0037] Fig.13 A schematic structural diagram of a third embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0038] Fig.14 A schematic structural diagram of a fourth embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0039] Fig.15 A schematic structural diagram of a fifth embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0040] Fig.16 A schematic structural diagram of a sixth embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0041] Fig.17 A schematic structural diagram of a seventh embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0042] Fig.18 A schematic structural diagram of an eighth embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0043] Fig.19A schematic structural diagram of a ninth embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0044] Fig. 20 A schematic diagram showing the structure of a tenth embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0045] Fig.21 A schematic structural diagram of an eleventh embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0046] Fig. 22 A schematic structural diagram of a twelfth embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0047] Fig.23 A schematic structural diagram of a thirteenth embodiment of a polarization coding unit provided in an embodiment of the present application is shown;

[0048] Fig.24 A schematic structural diagram of a first embodiment of a polarization-to-temporal phase encoding unit provided in an embodiment of the present application is shown;

[0049] Fig.25 A schematic diagram showing the structure of a second embodiment of a polarization-to-temporal phase encoding unit provided in an embodiment of the present application is shown;

[0050] Fig.26 A schematic structural diagram showing a third embodiment of a polarization-to-temporal phase encoding unit provided in an embodiment of the present application is shown;

[0051] Fig. 27 A schematic structural diagram showing a fourth embodiment of a polarization-to-temporal phase encoding unit provided in an embodiment of the present application is shown;

[0052] Fig.28 A schematic structural diagram showing a fifth embodiment of a polarization-to-temporal phase encoding unit provided in an embodiment of the present application is shown;

[0053] Fig.29 A schematic diagram showing the structure of a sixth embodiment of a polarization-to-temporal phase encoding unit provided in an embodiment of the present application is shown;

[0054] Fig.30 A schematic diagram showing the structure of a seventh embodiment of a polarization-to-temporal phase encoding unit provided in an embodiment of the present application is shown;

[0055] Fig.31 A schematic diagram of the structure of a software-defined quantum communication system provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0056] In order to make the above and other features and advantages of the present application more clear, the present application is further described below in conjunction with the accompanying drawings. It should be understood that the specific embodiments given herein are for the purpose of explaining to those skilled in the art and are only exemplary and not restrictive.

[0057] In the following description, many specific details are set forth to provide a thorough understanding of the present application. However, it is apparent to those skilled in the art that specific details need not be adopted to practice the present application. In other cases, well-known steps or operations are not described in detail to avoid blurring the present application.

[0058] It should be noted that the time phase encoding described in the present application includes phase encoding, that is, the time phase encoding is an encoding composed of any combination of quantum states of X phase basis, Y phase basis, and Z time basis.

[0059] The present application provides a quantum state encoding device. Figure 1 A schematic structural diagram of a first embodiment of a quantum state encoding device provided in an embodiment of the present application, the quantum state encoding device includes: a polarization encoding unit 110, a first optical coupling unit 120, a polarization-to-time phase encoding unit 130, a first transmission optical path 140 and a second optical coupling unit 150.

[0060] In one embodiment, if Figure 2 As shown, the polarization encoding unit 110 includes at least one adjustable circular birefringence module, wherein the adjustable circular birefringence module includes a first quarter wave plate 111, N built-in linear polarization operation modules 112 and a second quarter wave plate 113 connected in series in sequence; N is an integer greater than or equal to 1. Figure 2 Only an embodiment including one adjustable circular birefringence module and the adjustable circular birefringence module including only one built-in linear polarization operation module 112 is shown.

[0061] The first quarter wave plate 111 is used to convert the left-handed circular polarization component and the right-handed circular polarization component in an input optical pulse into two orthogonal linear polarization components.

[0062] In some embodiments, again referring to the attached Figure 2 As shown, the built-in linear polarization operation module 112 includes a linear polarization control optical path 114 and at least one phase modulator 115; the input end of the linear polarization control optical path 114 is connected to one end of the first quarter wave plate 111, and is used to receive the optical pulse containing the two orthogonal linear polarization components after conversion by the first quarter wave plate 111, and split it into two sub-optical pulses, and phase modulate at least one of the two sub-optical pulses through the phase modulator 115 to generate a phase difference between the two sub-optical pulses, and the two sub-optical pulses with the phase difference are combined and output through the output end.

[0063] In some embodiments, referring again to the attached Figure 2 As shown, one end of the second quarter wave plate 113 is connected to the output end of the linear polarization control light path 114, and is used to convert the two orthogonal linear polarization components in a light pulse output by the linear polarization control light path 114 into a left-handed circular polarization component and a right-handed circular polarization component and then output them through the output end.

[0064] In some embodiments, Figure 3 As shown, the first optical coupling unit 120 includes an input port and two output ports, namely a first port L, a second port M and a third port N. The first port L is connected to the output end O of the second quarter wave plate 113 in the polarization coding unit 110 .

[0065] In some embodiments, Figure 3 As shown, the second optical coupling unit 150 includes two input ports and one output port, namely a fourth port M′, a fifth port N′ and a sixth port L′.

[0066] In some embodiments, Figure 3 As shown, the polarization-to-temporal phase encoding unit 130 includes an input port P and an output port Q, and is used to perform temporal phase encoding conversion on an input optical pulse of a polarization-encoded quantum state, and output an optical pulse of a temporal phase-encoded quantum state.

[0067] In some embodiments, Figure 3 As shown, the third port N of the first optical coupling unit 120 is connected to the input port P of the polarization-to-temporal phase encoding unit 130, and the output port Q of the polarization-to-temporal phase encoding unit 130 is connected to the fifth port N' of the second optical coupling unit 150 to form a first optical output branch.

[0068] In some embodiments, Figure 3 As shown, the second port M of the first optical coupling unit 120 is connected to the fourth port M′ of the second optical coupling unit 150 through the first transmission optical path 140 to form a second optical output branch.

[0069] In some embodiments, Figure 3 As shown, the first optical coupling unit 120 is used to input the optical pulse of the polarization-encoded quantum state output by the polarization encoding unit 110 into the first optical output branch and / or the second optical output branch according to the quantum communication coding control instruction, and the quantum communication coding control instruction is determined according to the coding requirements of the quantum communication system.

[0070] In some embodiments, Figure 3As shown, the sixth port L' of the second optical coupling unit 150 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 output by the first optical output branch according to the quantum communication coding control instruction.

[0071] The present application can control the output of the polarization-encoded quantum state light pulse according to the quantum communication coding control instruction, or output the time phase-encoded quantum state light pulse, so that the same quantum state coding device can meet the different coding requirements of the quantum communication system to achieve the coded output of multi-modal quantum state light pulses, meeting the coding requirements of the quantum communication system. The present application can also meet the quantum communication security requirements, reduce the number of lasers used, and reduce the weight and power consumption of the quantum communication transmitter. The polarization-encoded quantum state of the present application has strong stability and can meet the requirements of space quantum communication applications for polarization-encoded quantum states and time phase-encoded quantum states.

[0072] In some embodiments, the first optical coupling unit 120 is an optical coupler, and the second optical coupling unit 150 is an optical switch. Figure 3 As shown, the first optical coupling unit 120 is used to input the optical pulse of the polarization-encoded quantum state output by the polarization encoding unit 110 through the first port L, and the first optical coupling unit 120 splits the optical pulse of the polarization-encoded quantum state into two sub-optical pulses, and respectively inputs the two sub-optical pulses into the first optical output branch and the second optical output branch through the third port N and the second port M. The second optical coupling unit 150 is used to select, according to the quantum communication coding control instruction, to output the optical pulse of the polarization-encoded quantum state transmitted by the second optical output branch or the optical pulse of the time phase-encoded quantum state output by the first optical output branch.

[0073] In some embodiments, the first optical coupling unit 120 is an optical switch, and the second optical coupling unit 150 is an optical switch or an optical coupler. The first optical coupling unit 120 is used to select the input of the optical pulse of the polarization-encoded quantum state to 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 150 is an optical switch, the second optical coupling unit 150 is used to connect the first optical output branch of the optical pulse of the time phase-encoded quantum state or the second optical output branch of the optical pulse of the polarization-encoded quantum state according to the quantum communication coding control instruction.

[0074] In other embodiments, when the second optical coupling unit 150 is an optical coupler, the second optical coupling unit 150 is used to output the optical pulse in the time phase coded quantum state output by the first optical output branch or the optical pulse in the polarization coded quantum state transmitted by the second optical output branch.

[0075] In some embodiments, referring to Figure 4 As shown, the linear polarization control optical path 114 includes: a third optical coupling unit 123, a fourth optical coupling unit 124, a second transmission optical path 125, and a third transmission optical path 126; the third optical coupling unit 123 and the fourth optical coupling unit 124 are connected through the second transmission optical path 125 and the third transmission optical path 126; the phase modulator 122 is arranged on the second transmission optical path 125 or the third transmission optical path 126.

[0076] In some embodiments, the third optical coupling unit 124 is used to receive the light pulse containing the two orthogonal linear polarization components after conversion by the first quarter wave plate 111, and split it into two paths of light pulses, namely a first path of light pulses and a second path of light pulses. The first path of light pulses and the second path of light pulses are respectively transmitted along the second transmission optical path 125 and the third transmission optical path 126 in the linear polarization control optical path 114.

[0077] In some embodiments, the phase modulator 122 is used to phase modulate at least one of the first optical pulse and the second optical pulse to generate a phase difference between the two optical pulses; the fourth optical coupling unit 124 is used to receive the two optical pulses that generate the phase difference and combine them into one optical pulse for output.

[0078] In any of the above embodiments, one of the two eigenpolarization states of the first quarter-wave plate 111 One of the two intrinsic polarization states of the linear polarization control optical path 114 The angle is 45°±n·90°; one of the two eigenpolarization states of the second quarter-wave plate 113 One of the two intrinsic polarization states of the linear polarization control optical path 114 The included angle is 45°±m·90°, where n and m are integers.

[0079] In some embodiments, Figure 5 As shown, the third optical coupling unit 123 is a polarization beam splitter, the fourth optical coupling unit 124 is a polarization beam combiner, and the intrinsic polarization state of the polarization beam splitter is the intrinsic polarization state of the linear polarization control optical path 114 .

[0080] In some embodiments, Figure 6 As shown, the third optical coupling unit 123 is a polarization beam splitter, the fourth optical coupling unit 124 is an optical coupler, and the intrinsic polarization state of the polarization beam splitter is the intrinsic polarization state of the linear polarization control optical path 114 .

[0081] In some embodiments, Figure 7As shown, the third optical coupling unit 123 is an optical coupler, the fourth optical coupling unit 124 is a polarization beam combiner, and the intrinsic polarization state of the polarization beam combiner is the intrinsic polarization state of the linear polarization control optical path 114 .

[0082] In some embodiments, Figure 8 As shown, the third optical coupling unit and the fourth optical coupling unit are the same polarization beam splitter 123, and the linear polarization control optical path 114 also includes: two reflectors 211 and 212, and the reflectors 211 and 212 are respectively connected to the second transmission optical path 125 and the third transmission optical path 126, and are used to reflect the light pulses input to the reflectors 211 and 212 back to the polarization beam splitter 123; the intrinsic polarization state of the polarization beam splitter 123 is the intrinsic polarization state of the linear polarization control optical path 114.

[0083] In some embodiments, the polarization beam splitter 123 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 through the third transmission optical path 126 and the second transmission optical path 125, respectively, and port A is used as an input port for receiving the optical pulse input to the linear polarization control optical path 123. Specifically, as shown in FIG. Figure 8 As shown, port B is connected to the reflector 212 through the third transmission optical path 126 , and port C is connected to the reflector 211 through the second transmission optical path 125 .

[0084] In one embodiment, when the polarization beam splitter 123 includes three ports, the input port A can also serve as an output port of the linear polarization control optical path 114 for outputting optical pulses modulated by the linear birefringence of the linear polarization control optical path 114 . In this embodiment, the polarization encoding unit 110 further includes an optical coupling unit, which includes at least three ports, namely a first port, a second port and a third port. The optical coupling unit can be arranged between the first quarter wave plate 111 and the polarization beam splitter 123, the first port of the optical coupling unit is connected to the first quarter wave plate 111, the second port of the optical coupling unit is connected to the polarization beam splitter 123, and the third port of the optical coupling unit is connected to the second quarter wave plate 113; or the optical coupling unit can be arranged before the first quarter wave plate 111, the first port of the optical coupling unit receives an input optical pulse, the second port of the optical coupling unit is connected to the first quarter wave plate 111, and the third port of the optical coupling unit is an output port. In this case, the first quarter wave plate 111 and the second quarter wave plate 113 are the same device; the optical coupling unit is an optical coupler or an optical circulator.

[0085] In yet another embodiment, Figure 8As shown, the polarization beam splitter 123 may further include an output port D, which serves as an output port of the linear polarization control light path 114 and is used to output the optical pulse modulated by the linear birefringence of the linear polarization control light path 114 .

[0086] In some of the embodiments, the reflector 211 and the reflector 212 can be polarization rotation mirrors, which can rotate the polarization state of the sub-light pulse after reflection by a certain angle compared to the polarization state of the sub-light pulse before reflection, such as 90° polarization rotation mirrors. The reflector 211 and the reflector 212 can be quarter-wave plate mirrors or 90° Faraday rotation mirrors.

[0087] It should be noted that, in the case where the reflectors 211 and 212 do not rotate the polarization states of the input sub-light pulses, the polarization beam splitter 123 only outputs the combined light pulses from port A. In the case where the reflectors 211 and 212 rotate the polarization states of the input sub-light pulses by any angle (not 0 and 90°), the polarization beam splitter 123 can output the combined light pulses from port A or port D, wherein, if the polarization states of the sub-light pulses are rotated by 90°, the combined light pulses can only be output from port D, and when the polarization states are rotated by 90°, the reflectors 211 and 212 are 90° polarization state rotating reflectors, and the 90° polarization state rotating reflectors can be quarter wave plate reflectors or 90° Faraday rotating reflectors.

[0088] In some embodiments, Fig. 9 As shown, the third optical coupling unit and the fourth optical coupling unit are the same polarization splitting unit 201 , the second transmission optical path and the third transmission optical path are the same transmission optical path 205 , and the intrinsic polarization state of the polarization splitting unit 201 is the intrinsic polarization state of the linear polarization control optical path 114 .

[0089] In some embodiments, Fig. 9 As shown, the polarization beam splitter unit 201 is a polarization beam splitter, which includes three ports, namely a first port A, a second port B and a third port C. The first port A of the polarization beam splitter is the input and output port of the linear polarization control optical path 114, the second port B and the third port C of the polarization beam splitter are connected through the same transmission optical path 205, and the intrinsic polarization state of the polarization beam splitter is the intrinsic polarization state of the polarization beam splitter unit 201.

[0090] In the above embodiment, the input and output of the linear polarization control optical path 114 are the same port. In this case, the polarization encoding unit 110 further includes an optical coupling unit, which includes at least three ports, namely a first port, a second port and a third port. The optical coupling unit can be arranged between the first quarter wave plate 111 and the polarization beam splitter, the first port of the optical coupling unit is connected to the first quarter wave plate 111, the second port of the optical coupling unit is connected to the polarization beam splitter, and the third port of the optical coupling unit is connected to the second quarter wave plate 113; or the optical coupling unit can be arranged before the first quarter wave plate 111, the first port of the optical coupling unit receives an input optical pulse, the second port of the optical coupling unit is connected to the first quarter wave plate 111, and the third port of the optical coupling unit is an output port. In this case, the first quarter wave plate 111 and the second quarter wave plate 113 are the same device; the optical coupling unit is an optical coupler or an optical circulator.

[0091] In some embodiments, Fig.10 As shown, the polarization beam splitter unit includes: a polarization beam splitter 201, a first polarizer 206 and a second polarizer 207; the polarization beam splitter 201 includes four ports, namely a first port A, a second port B, a third port C and a fourth port D, the first port A of the polarization beam splitter 201 is an input port of the linear polarization control light path 114, and the fourth port D of the polarization beam splitter 201 is an output port of the linear polarization control light path 114; the second port B and the third port C of the polarization beam splitter 201 are connected to the end of the first side of the first polarizer 206 respectively. The port of the first polarizer 206 is connected to the port on the first side of the second polarizer 207; the port on the second side of the first polarizer 206 is connected to the port on the second side of the second polarizer 207 through the transmission optical path 205; the angle between the polarization direction of the first polarizer 206 and an intrinsic polarization state of the polarization beam splitter 201 is θ, and the angle between the polarization direction of the second polarizer 207 and another intrinsic polarization state of the polarization beam splitter 201 is δ, wherein θ, δ≠n·90°, and n is an integer; the intrinsic polarization state of the polarization beam splitter 201 is the intrinsic polarization state of the polarization beam splitter unit.

[0092] In some embodiments, Fig.11As shown, the polarization beam splitting unit includes: an optical beam splitter 201, a first polarizer 206 and a second polarizer 207; the optical beam splitter 201 includes at least three ports, namely a first port A, a second port B and a third port C, and the first port A of the optical beam splitter 201 is the input port of the linear polarization control optical path 114; the second port B and the third port C of the optical beam splitter 201 are respectively connected to the port on the first side of the first polarizer 206 and the port on the first side of the second polarizer 207; the port on the second side of the first polarizer 206 and the port on the second side of the second polarizer 207 are connected through the transmission optical path 205. The polarization direction of the first polarizer 206 is The polarization direction of the second polarizer 207 is The polarization direction of the first polarizer 206 The polarization direction of the second polarizer 207 Orthogonal to each other; the polarization direction of the first polarizer 206 The polarization direction of the second polarizer 207 is the intrinsic polarization state of the polarization beam splitter unit.

[0093] In the above embodiment, when the input and output of the linear polarization control optical path 114 are the same port, the polarization encoding unit 110 further includes an optical coupling unit, the optical coupling unit includes at least three ports, namely a first port, a second port and a third port, the optical coupling unit can be arranged between the first quarter wave plate 111 and the optical beam splitter 201, the first port of the optical coupling unit is connected to the first quarter wave plate 111, the second port of the optical coupling unit is connected to the optical beam splitter 201, and the third port of the optical coupling unit is connected to the second quarter wave plate 113; or the optical coupling unit can be arranged before the first quarter wave plate 111, the first port of the optical coupling unit receives an input optical pulse, the second port of the optical coupling unit is connected to the first quarter wave plate 111, and the third port of the optical coupling unit is an output port, at this time, the first quarter wave plate 111 and the second quarter wave plate 113 are the same device; the optical coupling unit is an optical coupler or an optical circulator.

[0094] In some further embodiments, the optical beam splitter 201 further includes a fourth port D (not shown in the figure); the fourth port D of the optical beam splitter 201 is an output port of the linear polarization control optical path 114 .

[0095] exist Figure 9-11 In some implementations, the transmission optical path 205 is a free space optical path or a polarization-maintaining optical fiber.

[0096] See attached Figure 9-11In any of the figures, the phase modulator 115 is arranged on the transmission optical path 205; the phase modulator 115 includes a first port E and a second port F, which are a forward input optical port and a reverse input optical port respectively; the phase modulator 115 modulates the optical pulse input from one of the first port E and the second port F, or performs different phase modulations on the optical pulses input from the first port E and the second port F.

[0097] In the above embodiment, after the phase modulator 115 applies a high-frequency modulation electrical signal having a frequency higher than a specified threshold, the phase modulator 115 operates in a non-reciprocal state, and the ratio of the modulation efficiency of the first path of sub-optical pulses input from the forward input optical port to the modulation efficiency of the second path of sub-optical pulses input from the reverse input optical port is not less than a preset threshold. When the phase modulator 115 applies a high-frequency modulation signal having a frequency higher than a specified threshold, at the same time, the phase modulator 115 may have multiple sub-optical pulses input from the forward input optical port and multiple sub-optical pulses input from the reverse input optical port.

[0098] In some of these embodiments, refer to the attached Figure 9-11 In any of the figures, the transmission optical path 205 is coupled to the slow axes of the first port E and the second port F of the phase modulator 115 , or is coupled to the fast axes of the first port E and the second port F of the phase modulator 115 .

[0099] In some of these embodiments, refer to the attached Figure 9-11 As shown in any of the figures in the figure, the polarization encoding unit 110 of the present application further includes a polarization state rotator arranged in the transmission optical path 205, and the polarization state rotator can be a half-wave plate or a 90-degree Faraday rotator.

[0100] In some embodiments, when the input and output of the linear polarization control optical path 114 are the same port, refer to the attached Fig.12 As shown, the polarization encoding unit 110 further includes: an optical coupling unit 117 ; the optical coupling unit 117 is an optical coupler or an optical circulator, and the optical coupling unit 117 is arranged before the first quarter wave plate 111 , and the optical coupling unit 117 is connected to the first quarter wave plate 111 .

[0101] In the above-mentioned embodiment, again referring to the attached Fig.12 As shown, when the input and output of the linear polarization control optical path 114 are the same port, the first quarter wave plate 111 and the second quarter wave plate 113 can also be the same device (ie Fig.12 In this case, the optical coupling unit 117 is arranged before the first quarter wave plate 111, so that the input function and the output function of the first quarter wave plate 111 can be separated. The optical coupling unit 117 is an optical coupler or an optical circulator.

[0102] In some other embodiments, refer to the attached Fig.13 As shown, when the input and output of the linear polarization control optical path 114 are the same port, the optical coupling unit 117 can be directly arranged in series at the front end of the polarization beam splitting unit 201. At this time, the input function and the output function of the polarization beam splitting unit 201 can be separated. The first quarter wave plate 111 and the second quarter wave plate 113 are not the same device, and the optical coupling unit 117 is also separately connected to the first quarter wave plate 111 and the second quarter wave plate 113 to realize the input and output of the optical pulse. Among them, the optical coupling unit 117 is an optical coupler or an optical circulator.

[0103] In some embodiments, referring to Fig.14 As shown, when N is 2, that is, when the adjustable circular birefringence module includes two built-in linear polarization operation modules 112 , the two built-in linear polarization operation modules 112 are arranged in series between the first quarter wave plate 111 and the second quarter wave plate 113 .

[0104] In some embodiments, referring to Fig.15 As shown, the polarization encoding unit 110 of the present application further includes: M external linear polarization operation modules, such as Fig.15 The second linear polarization operation module 116 in the embodiment. The external linear polarization operation module is connected in series with the adjustable circular birefringence module, and M is an integer greater than or equal to 1. Fig.15 The structure of the adjustable circular birefringence module is Figure 2 Take the structure shown in as an example, Fig.15 As shown in FIG. 1 , the polarization encoding unit 110 includes an external linear polarization operation module.

[0105] It should be noted that the external linear polarization operation module and the built-in linear polarization operation module 112 described in the embodiment of the present application have the same structure and function. In the embodiment of the present application, the linear polarization operation module disposed in the adjustable circular birefringence module is referred to as the built-in linear polarization operation module. Fig.15 The first linear polarization operation module 112 in the adjustable circular birefringence module; the linear polarization operation module arranged outside the adjustable circular birefringence module in series is called an external linear polarization operation module, such as Fig.15 The second linear polarization operation module 116 in FIG. Fig.15 As shown, the second linear polarization operation module 116 in the embodiment of the present application can be arranged before the first quarter wave plate 111; Fig.16 As shown, the second linear polarization operation module 116 is disposed behind the second quarter wave plate 113 .

[0106] In some embodiments, when M is 2, that is, when the polarization coding unit 110 of the present application includes two external linear polarization operation modules (that is, the second linear polarization operation module 116 and the third linear polarization operation module 116), the second linear polarization operation module 116 and the third linear polarization operation module 116 are connected in series, such as Fig.17 As shown, the second linear polarization operation module 116 and the third linear polarization operation module 116 can be both arranged before the first quarter wave plate 111; or, as shown in FIG. Fig.18 As shown, the second linear polarization operation module 116 and the third linear polarization operation module 116 can be both arranged after the second quarter wave plate 113; or, as shown in FIG. Fig.19 As shown, the second linear polarization operation module 116 and the third linear polarization operation module 116 can be arranged in front of the first quarter wave plate 111, and the other can be arranged behind the second quarter wave plate 113. In this embodiment, the second linear polarization operation module 116 is arranged in front of the first quarter wave plate 111, and the third linear polarization operation module 116 is arranged behind the second quarter wave plate 113. It can be understood that the positions of the second linear polarization operation module 116 and the third linear polarization operation module 116 can be interchanged.

[0107] In some other embodiments, when M is 2, that is, when the polarization coding unit 110 of the present application includes two external linear polarization operation modules (that is, the second linear polarization operation module 116 and the third linear polarization operation module 116), the angle between the intrinsic polarization states of the second linear polarization operation module 116 and the third linear polarization operation module 116 is n·22.5°, where n is an integer.

[0108] Based on the above-mentioned embodiment, when the angle between the intrinsic polarization states of the second linear polarization operation module 116 and the third linear polarization operation module 116 is n·22.5°, the angle between the intrinsic polarization states of the second linear polarization operation module 116 and the third linear polarization operation module 116 is achieved by rotating at least one of the second linear polarization operation module 116 and the third linear polarization operation module 116.

[0109] In other embodiments, the polarization encoding unit 110 further includes: a polarization state rotator, which is arranged between the second linear polarization operation module 116 and the third linear polarization operation module 116, and the angle between the intrinsic polarization states of the second linear polarization operation module 116 and the third linear polarization operation module 116 is adjusted by the polarization state rotator.

[0110] In other embodiments, the polarization encoding unit 110 further includes: two polarization state rotators, which are respectively arranged at the front end and the rear end of one of the second linear polarization operation module 116 and the third linear polarization operation module 116, and the angle between the intrinsic polarization states of the second linear polarization operation module 116 and the third linear polarization operation module 116 is adjusted by the two polarization state rotators; optionally, one of the two polarization state rotators realizes a polarization state rotation angle γ, and the other of the two polarization state rotators realizes a polarization state rotation angle -γ.

[0111] In some embodiments, when N is greater than 1, that is, the number N of built-in linear polarization operation modules 112 is greater than 1, the device further includes N-1 optical isolation units, which can be optical isolators or optical circulators, and the N-1 optical isolation units are respectively arranged between any two adjacent built-in linear polarization operation modules.

[0112] In some embodiments, when N is greater than 1 and / or M is greater than 1, that is, the number N of built-in linear polarization operation modules 112 is greater than 1 and / or the number M of external linear polarization operation modules 116 is greater than 1, the device further includes N+M-1 optical isolation units, which are optical isolators or optical circulators, and the N+M-1 optical isolation units are respectively arranged between any two adjacent linear polarization operation modules (including built-in linear polarization operation modules and external linear polarization operation modules).

[0113] In some embodiments, the polarization state of the light pulse input into the quantum state encoding device of the present application can be any form of linear polarization state, for example, the polarization state of the light pulse input into the device can be a horizontal polarization state or a vertical polarization state.

[0114] In some embodiments, when M is 1, and the external linear polarization operation module is disposed before the first quarter wave plate 111, the polarization state of the light pulse input to the device is in, and are two eigenpolarization states of the linear polarization control optical path of the second linear polarization operation module, and θ is any value between 0 and 2π.

[0115] In some embodiments, referring to Fig. 20 As shown, the polarization encoding unit 110 of the present application may include two adjustable circular birefringence modules connected in series.

[0116] In some embodiments, when two adjustable circular birefringence modules are connected in series with an external linear polarization operation module, the external linear polarization operation module can be arranged before the two adjustable circular birefringence modules, after the two adjustable circular birefringence modules, or between the two adjustable circular birefringence modules.

[0117] In some embodiments, such as Fig.21 In the embodiment, the polarization encoding unit 110 includes two series-connected adjustable circular birefringence modules and an external linear polarization operation module, such as Fig.21 The second linear polarization operation module 116 may be arranged before the first quarter wave plate 111, that is, before the first adjustable circular birefringence module.

[0118] In some other embodiments, Fig. 22 As shown, the second linear polarization operation module 116 can be arranged between the two adjustable circular birefringence modules, that is, arranged behind the second quarter wave plate 113 of the first adjustable circular birefringence module and arranged in front of the first quarter wave plate 111 of the second adjustable circular birefringence module.

[0119] In some other embodiments, Fig.23 As shown, the second linear polarization operation module 116 can also be arranged after the two adjustable circular birefringence modules, that is, connected to the second quarter wave plate 113 of the second adjustable circular birefringence module.

[0120] In some embodiments, Fig.24 As shown, the polarization-to-time phase encoding unit 130 includes: a fifth optical coupling unit 221, a sixth optical coupling unit 222, a fourth transmission optical path 223 and a fifth transmission optical path 224, the fifth optical coupling unit 221 includes at least three ports, an input port G and two output ports I, H; the sixth optical coupling unit 222 includes at least three ports, two input ports I', H' and one output port G', the two output ports I, H of the fifth optical coupling unit 221 are connected to the two input ports I', H' of the sixth optical coupling unit 222 through the fourth transmission optical path 223 and the fifth transmission optical path 224; the optical paths of the fourth transmission optical path 223 and the fifth transmission optical path 224 are not equal.

[0121] In some embodiments, Fig.25 As shown, the fifth optical coupling unit 221 is a polarization beam splitter, and the sixth optical coupling unit 222 is a polarization beam combiner.

[0122] In some embodiments, Fig.26 As shown, the fifth optical coupling unit 221 is a polarization beam splitter, and the sixth optical coupling unit 222 is an optical coupler.

[0123] In some embodiments, Fig. 27 As shown, the fifth optical coupling unit 211 is an optical coupler, and the sixth optical coupling unit 222 is a polarization beam combiner.

[0124] In some embodiments, Fig.28As shown, the fifth optical coupling unit 221 is an optical coupler, the sixth optical coupling unit 222 is an optical coupler, and the polarization-to-time phase encoding unit 130 also includes: two polarizers 225 and 226, the polarizer 225 and the polarizer 226 are respectively arranged on the fourth transmission optical path 223 and the fifth transmission optical path 224, and the polarization directions of the polarizer 225 and the polarizer 226 are orthogonal to each other.

[0125] In some of these embodiments, refer to the attached Figure 26-28 In any of the figures, the fourth transmission optical path 223 and the fifth transmission optical path 224 are 90° twisted polarization-maintaining optical fibers, or the polarization-to-time phase encoding unit 130 of the present application further includes: a 90° polarization state rotator, which is arranged on the fourth transmission optical path 223 or the fifth transmission optical path 224, and is used to rotate the polarization state of the passing sub-light pulse by 90°.

[0126] In some embodiments, such as Fig.29 As shown, the fifth optical coupling unit and the sixth optical coupling unit are the same polarization beam splitter 221, and the polarization-to-time phase encoding unit 130 also includes: two reflectors 227 and 228, and the two output ports I and H of the polarization beam splitter 221 are respectively connected to one end of the fourth transmission optical path 223 and one end of the fifth transmission optical path 224, and the two reflectors 227 and 228 are respectively connected to the other end of the fourth transmission optical path 223 and the other end of the fifth transmission optical path 224.

[0127] In some of the above embodiments, the two reflectors 227 and 228 may be polarization rotating reflectors.

[0128] In one embodiment, when the polarization beam splitter 221 includes three ports, the input port G can also serve as the output port of the polarization-to-time phase encoding unit 130, for outputting optical pulses that have been polarization-to-time phase encoded; at this time, the polarization-to-time phase encoding unit 130 also includes an optical coupling unit, which is disposed at the front end of the polarization beam splitter 221, and the optical coupling unit can be an optical coupler or an optical circulator.

[0129] In another embodiment, when the two reflectors 227 and 228 are polarization state rotation reflectors, for example, the two reflectors 227 and 228 are quarter-wave plate reflectors or 90° Faraday rotation reflectors, the polarization beam splitter 221 may further include a fourth port G' (not shown in the figure); the fourth port G' of the polarization beam splitter 221 is the output port of the polarization-to-time phase encoding unit 130.

[0130] In some embodiments, such as Fig.30As shown, the fifth optical coupling unit and the sixth optical coupling unit are the same optical coupler 221, and the polarization-to-time phase encoding unit 130 also includes: two reflectors 227, 228 and two polarizers 225, 226, the two output ports I and H of the optical coupler 221 are respectively connected to one end of the fourth transmission optical path 223 and one end of the fifth transmission optical path 224, the two reflectors 227, 228 are respectively connected to the other end of the fourth transmission optical path 223 and the other end of the fifth transmission optical path 224; the two polarizers 225, 226 are respectively arranged on the fourth transmission optical path 223 and the fifth transmission optical path 224, and the polarization directions of the polarizer 225 and the polarizer 226 are orthogonal to each other.

[0131] In some of the embodiments, when the optical coupler 221 includes three ports, the input port G can also serve as the output port of the polarization-to-time phase encoding unit 130, for outputting optical pulses that have been polarization-to-time phase encoded; at this time, the polarization-to-time phase encoding unit 130 also includes an optical coupling unit, which is disposed at the front end of the optical coupler 221, and the optical coupling unit can be an optical coupler or an optical circulator.

[0132] In some other embodiments, the optical coupler 221 may further include a fourth port G′ (not shown in the figure); the fourth port G′ of the optical coupler 221 is the output port of the polarization-to-temporal phase encoding unit 130 .

[0133] In some of these embodiments, refer to the attached Figure 24-30 As shown in any of the figures in the figure, the time phase encoding device may further include: a polarizer; the polarizer is arranged at the output port of the polarization conversion time phase encoding unit 130, and is used to polarize the output optical pulse.

[0134] In any of the above embodiments, the quantum state encoding device of the present application also includes: a quarter wave plate and / or a polarization state rotator, which is arranged between the polarization encoding unit 100 and the polarization-to-time phase encoding unit 200, and the polarization state rotator is a half wave plate or a Faraday rotator.

[0135] In some embodiments, according to the requirements of quantum communication, the quantum state encoding device of the present application can also be used to implement the quantum state decoding process.

[0136] According to another aspect of the present application, a quantum state encoding method is provided, which is applied to the above-mentioned quantum state encoding device.

[0137] Another aspect of the present application embodiment provides a software-defined quantum communication system. Fig.31 A schematic diagram of the structure of a software-defined quantum communication system provided in an embodiment of the present application is shown as follows: Fig.31As shown, the software-defined quantum communication system 3100 may include the above-mentioned quantum state encoding device 3101 and encoding control device 3102; the encoding control device 3102 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 3101.

[0138] The quantum communication system can be a discrete variable quantum communication system or a continuous variable quantum communication system, including quantum communication systems such as the BB84 protocol, the reference frame independent protocol, the MDI protocol, and the TF protocol.

[0139] It should be understood that the specific features, operations and details described hereinabove with respect to the device of the present application may also be similarly applied to the method and system of the present application, or vice versa. In addition, each step of the method of the present application may be performed by a corresponding component or unit of the device or system of the present application.

[0140] The various technical features described above can be combined arbitrarily. Although all possible combinations of these technical features are not described, any combination of these technical features should be considered to be covered by this specification as long as there is no contradiction in such combination.

[0141] 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 it. 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 by 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, a polarization-to-temporal phase encoding unit, a first transmission optical path, and a second optical coupling unit; The polarization encoding unit includes at least one adjustable circular birefringence module, and the adjustable circular birefringence module includes a first quarter wave plate, N built-in linear polarization operation modules and a second quarter wave plate connected in series in sequence; N is an integer greater than or equal to 1; The first quarter wave plate is used to convert the left-handed circular polarization component and the right-handed circular polarization component in an input optical pulse into two orthogonal linear polarization components; The built-in linear polarization operation module includes a linear polarization control optical path and at least one phase modulator; the input end of the linear polarization control optical path is connected to one end of the first quarter wave plate, and is used to receive the optical pulse containing the two orthogonal linear polarization components after being converted by the first quarter wave plate, and split it into two sub-optical pulses, perform phase modulation on at least one of the two sub-optical pulses through the phase modulator, so that a phase difference is generated between the two sub-optical pulses, and combine the two sub-optical pulses with the phase difference and output them through the output end; One end of the second quarter wave plate is connected to the output end of the linear polarization control light path, and is used for converting the two orthogonal linear polarization components in a light pulse output by the linear polarization control light path into a left-handed circular polarization component and a right-handed circular polarization component, and then outputting them through the output end; 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 end of the second quarter wave plate in the polarization coding unit; The second optical coupling unit comprises two input ports and one output port, which are respectively a fourth port, a fifth port and a sixth port; The polarization-to-time phase encoding unit 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 polarization-to-temporal phase encoding unit, and the output port of the polarization-to-temporal phase encoding unit 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 used 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, and the quantum communication coding control instruction is determined according to 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, 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 output 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 used to input the optical pulse of the polarization-encoded quantum state output by the polarization encoding unit through the first port, split the optical pulse of the polarization-encoded quantum state 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 output 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 used to select and 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 coded quantum state or the second optical output branch that outputs the optical pulse of the polarization coded 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 output 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 linear polarization control optical path comprises: 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 phase modulator is arranged on the second transmission optical path or the third transmission optical path; The third optical coupling unit is used to receive the optical pulse containing the two orthogonal linear polarization components after conversion by the first quarter-wave plate, and split it into two paths of sub-optical pulses, namely a first path of optical pulses and a second path of optical pulses, wherein the first path of optical pulses and the second path of optical pulses are respectively transmitted along the second transmission optical path and the third transmission optical path in the linear polarization control optical path; The phase modulator performs phase modulation on at least one of the first optical pulse and the second optical pulse, so as to generate a phase difference between the two optical pulses; The fourth optical coupling unit is used to receive two paths of sub-light pulses that generate a phase difference, and combine them into one path of light pulses for output.

7. The device according to claim 1 or 6, characterized in that One of the two eigenpolarization states of the first quarter wave plate One of the two eigenpolarization states of the linear polarization control optical path The angle is 45°±n·90°; One of the two eigenpolarization states of the second quarter wave plate One of the two eigenpolarization states of the linear polarization control optical path The included angle is 45°±m·90°, where n and m are integers.

8. The device according to claim 6, characterized in that The third optical coupling unit is a polarization beam splitter, the fourth 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 linear polarization control optical path.

9. The device according to claim 6, characterized in that The third optical coupling unit is a polarization beam splitter, the fourth optical coupling unit is an optical coupler, and the intrinsic polarization state of the polarization beam splitter is the intrinsic polarization state of the linear polarization control optical path.

10. The device according to claim 6, characterized in that The third optical coupling unit is an optical coupler, the fourth 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 linear polarization control optical path.

11. The device according to claim 6, characterized in that The third optical coupling unit and the fourth optical coupling unit are the same polarization beam splitter, and the linear polarization control optical path further comprises: two reflectors, The two reflectors are respectively connected to the second transmission optical path and the third transmission optical path, and are used to reflect the light pulses input to the two reflectors back to the polarization beam splitter; the intrinsic polarization state of the polarization beam splitter is the intrinsic polarization state of the linear polarization control optical path.

12. The device according to claim 11, characterized in that The two reflectors are polarization rotating reflectors.

13. The device according to claim 6, characterized in that The third optical coupling unit and the fourth optical coupling unit are the same polarization beam splitting unit, the second transmission optical path and the third transmission optical path are the same transmission optical path, and the eigenpolarization state of the polarization beam splitting unit is the eigenpolarization state of the linear polarization control optical path.

14. The device according to claim 13, characterized in that The polarization beam splitter 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 linear 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 beam splitter unit.

15. The device according to claim 13, characterized in that The polarization beam splitting unit comprises: a polarization beam splitter, a first polarizer and a second polarizer; The polarization beam splitter comprises 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 an input port of the linear polarization control optical path, and the fourth port of the polarization beam splitter is an output port of the linear 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 the transmission optical path; the angle between the polarization direction of the first polarizer and an 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°, and n is an integer; the intrinsic polarization state of the polarization beam splitter is the intrinsic polarization state of the polarization beam splitter.

16. The device according to claim 13, characterized in that The polarization beam splitting unit comprises: a 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 of the linear 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 the transmission optical path. The polarization direction of the first polarizer is The polarization direction of the second polarizer is The polarization direction a of the first polarizer is different from the polarization direction a of the second polarizer. mutually orthogonal; the polarizing direction of the first polarizer The polarizing direction of the second polarizer is the intrinsic polarization state of the polarization beam splitting unit.

17. The device according to claim 16, characterized in that The optical beam splitter further comprises a fourth port; The fourth port of the optical beam splitter is an output port of the linear polarization control light path.

18. The device according to claim 14 or 16, characterized in that The first quarter wave plate and the second quarter wave plate are the same device.

19. The device according to claim 18, characterized in that The polarization encoding unit further comprises: an optical coupling unit; The optical coupling unit is an optical coupler or an optical circulator, and the optical coupling unit is arranged before the first quarter wave plate and connected to the first quarter wave plate.

20. The device according to claim 14 or 16, characterized in that The polarization encoding unit further comprises: an optical coupling unit; The optical coupling unit is an optical coupler or an optical circulator, and the optical coupling unit is arranged between the first quarter wave plate and the polarization beam splitting unit.

21. The device according to any one of claims 13 to 17, characterized in that The transmission optical path is a free space optical path or a polarization-maintaining optical fiber.

22. The device according to claim 21, characterized in that The polarization encoding unit further includes a half-wave plate or a 90-degree Faraday rotator arranged in the transmission optical path.

23. The device according to any one of claims 13 to 17, characterized in that The phase modulator is arranged on the transmission optical path; the phase modulator comprises a first port and a second port, which are respectively a forward input optical port and a reverse input optical port; the phase modulator modulates the optical pulse inputted from one of the first port and the second port, or performs different phase modulations on the optical pulse inputted from the first port and the second port.

24. The device according to claim 23, characterized in that The transmission optical paths are both coupled to the slow axes of the first port and the second port of the phase modulator, or are both coupled to the fast axes of the first port and the second port of the phase modulator.

25. The device according to claim 23, characterized in that After applying a high-frequency modulated electrical signal having a frequency higher than a specified threshold, the phase modulator operates in a non-reciprocal state, and a ratio of a modulation efficiency of a first path optical pulse input from a forward input optical port to a modulation efficiency of a second path optical pulse input from a reverse input optical port is not less than a preset threshold.

26. The device according to claim 1, characterized in that When N is 2, two built-in linear polarization operation modules are arranged in series between the first quarter wave plate and the second quarter wave plate.

27. The device according to claim 1, characterized in that The polarization encoding unit also includes: M external linear polarization operation modules are connected in series with the adjustable circular birefringence module, and M is an integer greater than or equal to 1.

28. The device according to claim 27, characterized in that When M is 2, two external linear polarization operation modules are connected in series and are both arranged in front of the first quarter wave plate; or both are arranged after the second quarter wave plate; or one of the external linear polarization operation modules is arranged in front of the first quarter wave plate, and the other external linear polarization operation module is arranged after the second quarter wave plate.

29. The device according to claim 27, characterized in that When M is 2, the angle between the intrinsic polarization states of the two external linear polarization operation modules is: n·22.5°, where n is an integer.

30. The device according to claim 29, characterized in that The angle between the intrinsic polarization states of the two external linear polarization operation modules is achieved by rotating at least one of the two external linear polarization operation modules; and / or The polarization encoding unit further comprises: a polarization state rotator, wherein the polarization state rotator is arranged between the two external linear polarization operation modules, and the angle between the intrinsic polarization states of the two external linear polarization operation modules is adjusted by the polarization state rotator; and / or The polarization encoding unit further comprises: two polarization state rotators, which are arranged at the front end and the rear end of one of the two external linear polarization operation modules, and the angle between the intrinsic polarization states of the two external linear polarization operation modules is adjusted by the two polarization state rotators.

31. The device according to claim 1 or 27, characterized in that The polarization encoding unit includes two tunable circular birefringence modules connected in series.

32. The device according to claim 1, characterized in that When N is greater than 1, the polarization encoding unit further includes N-1 optical isolation units, the optical isolation unit is an optical isolator or an optical circulator, and the N-1 optical isolation units are respectively arranged between any two adjacent built-in linear polarization operation modules.

33. The device according to claim 27, characterized in that When N is greater than 1 and / or M is greater than 1, the polarization encoding unit further includes N+M-1 optical isolation units, the optical isolation unit is an optical isolator or an optical circulator, and the N+M-1 optical isolation units are respectively arranged between any two adjacent linear polarization operation modules.

34. The device according to claim 1, characterized in that The polarization-to-temporal phase encoding unit comprises: a fifth optical coupling unit, a sixth optical coupling unit, a fourth transmission optical path and a fifth 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 fourth transmission optical path and the fifth transmission optical path; the optical path of the fourth transmission optical path is not equal to the optical path of the fifth transmission optical path.

35. The device according to claim 34, characterized in that The fifth optical coupling unit is a polarization beam splitter, and the sixth optical coupling unit is a polarization beam combiner.

36. The device according to claim 34, characterized in that The fifth optical coupling unit is a polarization beam splitter, and the sixth optical coupling unit is an optical coupler.

37. The device according to claim 34, characterized in that The fifth optical coupling unit is an optical coupler, and the sixth optical coupling unit is a polarization beam combiner.

38. The device according to claim 34, characterized in that The fifth optical coupling unit is an optical coupler, the sixth optical coupling unit is an optical coupler, and the polarization-to-temporal phase encoding unit further includes: two polarizers, The two polarizers are respectively arranged on the fourth transmission light path and the fifth transmission light path, and the polarization directions of the two polarizers are orthogonal to each other.

39. The device according to claim 34, characterized in that The fifth optical coupling unit and the sixth optical coupling unit are the same polarization beam splitter, and the polarization-to-temporal phase encoding unit further includes: two reflectors, The two output ports of the polarization beam splitter are respectively connected to one end of the fourth transmission optical path and one end of the fifth transmission optical path, and the two reflectors are respectively connected to the other end of the fourth transmission optical path and the other end of the fifth transmission optical path.

40. The device according to claim 39, characterized in that The two reflectors are polarization rotating reflectors.

41. The device according to claim 34, characterized in that The fifth optical coupling unit and the sixth optical coupling unit are the same optical coupler, and the polarization-to-temporal phase encoding unit further includes: two reflectors and two polarizers, The two output ports of the optical coupler are respectively connected to one end of the fourth transmission optical path and one end of the fifth transmission optical path, and the two reflectors are respectively connected to the other end of the fourth transmission optical path and the other end of the fifth transmission optical path; the two polarizers are respectively arranged on the fourth transmission optical path and the fifth transmission optical path, and the polarization directions of the two polarizers are orthogonal to each other.

42. The device according to claim 36 or 38, characterized in that The fourth transmission optical path or the fifth transmission optical path is a 90° twisted polarization-maintaining optical fiber, or, The polarization-to-temporal phase encoding unit further comprises: a 90° polarization state rotator, The 90° polarization state rotator is arranged on the fourth transmission optical path or the fifth transmission optical path, and is used to rotate the polarization state of the passing sub-light pulse by 90°.

43. The device according to any one of claims 34 to 41, characterized in that The polarization-to-temporal phase encoding unit further comprises: a polarizer; The polarizer is arranged at the output port of the polarization-to-temporal phase encoding unit and is used for polarizing the output optical pulse.

44. The device according to claim 1 or 27, characterized in that The device further comprises: a quarter wave plate and / or a polarization state rotator, which is arranged between the polarization encoding unit and the polarization-to-temporal phase encoding unit.

45. A quantum state encoding method, characterized in that: A quantum state encoding device as described in any one of claims 1-44 is used.

46. ​​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 44; 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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