Quantum state coding device and quantum communication system

Abstract

The utility model provides a quantum state coding device and a quantum communication system, the quantum state coding device comprises a first optical coupling unit, a time phase coding unit, a polarization coding unit and a second optical coupling unit, the first optical coupling unit is used for receiving one path of input optical pulse; two output ports of the first optical coupling unit are respectively connected with an input port of the time phase coding unit and an input port of the polarization coding unit, and an output port of the time phase coding unit and an output port of the polarization coding unit are respectively connected with the second optical coupling unit. By adopting the scheme, one quantum state coding device can be compatible with coding modes of various quantum communication systems, and the structure is simple.

Description

Technical Field

[0001] This application relates to the technical fields of quantum communication and optical quantum coding, and particularly to a quantum state coding device and a quantum communication system. Background Art

[0002] Quantum communication technology is a frontier and hot field that combines quantum physics and information science. Currently, its applications mainly include quantum key distribution and quantum direct communication. Based on physical principles such as the Heisenberg uncertainty relation and the quantum no-cloning theorem in quantum mechanics, quantum key distribution can securely share keys in real time between communication parties, and quantum direct communication can achieve secure information transmission. Quantum communication can detect potential eavesdropping behaviors in communication channels and can be applied to fields with high-security information transmission requirements such as national defense, government affairs, finance, and power.

[0003] The physical implementation of a quantum communication system, such as the physical implementation of quantum key distribution and quantum direct communication, requires encoding and decoding of quantum states. Currently, the practical quantum communication coding methods mainly include polarization coding and time-phase coding. Existing quantum communication systems generally adopt one of these coding methods. If quantum states of multiple coding methods are to be used, different coding devices corresponding to the coding methods need to be used. Therefore, the system is not universal and cannot be flexibly networked.

[0004] How to achieve a 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 Utility Model

[0005] This application provides a quantum state coding device and a quantum communication system to solve the above technical problems in the prior art.

[0006] According to the first aspect of this application, a quantum state coding device is provided, including: a first optical coupling unit, a time-phase coding unit, a polarization coding unit, and a second optical coupling unit. The first optical coupling unit includes an input port, a first output port, and a second output port. The second optical coupling unit includes a first input port, a second input port, and an output port;

[0007] The input port of the first optical coupling unit is the input port of the quantum state coding device and is used to receive an input optical pulse;

[0008] The first output port of the first optical coupling unit is connected to the input port of the time-phase coding unit, and the output port of the time-phase coding unit is connected to the first input port of the second optical coupling unit;

[0009] The second output port of the first optical coupler unit is connected to the input port of the polarization encoding unit, and the output port of the polarization encoding unit is connected to the second input port of the second optical coupler unit;

[0010] The time-phase encoding unit includes a time-phase encoding optical path and a first phase modulator. The input port of the time-phase encoding optical path is the input port of the time-phase encoding unit, and the output port of the time-phase encoding optical path is the output port of the time-phase encoding unit. The time-phase encoding optical path includes two transmission optical paths, namely a first transmission optical path and a second transmission optical path. The first phase modulator is disposed in the second transmission optical path. Among them, the optical path lengths of the first transmission optical path and the second transmission optical path are not equal;

[0011] The polarization encoding unit includes a polarization encoding optical path and the first phase modulator. The input port of the polarization encoding optical path is the input port of the polarization encoding unit, and the output port of the polarization encoding optical path is the output port of the polarization encoding unit. The polarization encoding optical path includes two transmission optical paths, namely a second transmission optical path and a third transmission optical path. The first phase modulator is disposed in the second transmission optical path. Among them, the optical path lengths of the second transmission optical path and the third transmission optical path are equal;

[0012] The output port of the second optical coupler unit is the output port of the quantum state encoding device.

[0013] In one embodiment, the first optical coupler unit is an optical coupler, and the second optical coupler unit is an optical switch; or

[0014] The first optical coupler unit is an optical switch, and the second optical coupler unit is an optical coupler or an optical switch.

[0015] In one embodiment, the time-phase encoding optical path further includes:

[0016] A third optical coupler unit and a fourth optical coupler unit;

[0017] The third optical coupler unit includes at least one input port and two output ports, and the fourth optical coupler unit includes two input ports and at least one output port;

[0018] The input port of the third optical coupler unit is the input port of the time-phase encoding optical path, and the two output ports of the third optical coupler unit are respectively connected to the two input ports of the fourth optical coupler unit through the first transmission optical path and the second transmission optical path;

[0019] The output port of the fourth optical coupler unit is the output port of the time-phase encoding optical path.

[0020] In one embodiment, the third optical coupling unit and the fourth optical coupling unit are optical couplers.

[0021] In one embodiment, the polarization encoding optical path further includes:

[0022] A fifth optical coupling unit and a sixth optical coupling unit;

[0023] The fifth optical coupling unit includes at least one input port and two output ports, and the sixth optical coupling unit includes two input ports and at least one output port;

[0024] The input port of the fifth optical coupling unit is the input port of the polarization encoding optical path, and the two output ports of the fifth optical coupling unit are respectively connected to the two input ports of the sixth optical coupling unit through a second transmission optical path and a third transmission optical path;

[0025] The output port of the sixth optical coupling unit is the output port of the polarization encoding optical path.

[0026] In one embodiment, the fifth optical coupling unit is a polarization beam splitter or an optical coupler, and the sixth optical coupling unit is a polarization combiner or an optical coupler.

[0027] In one embodiment, the fifth optical coupling unit and the sixth 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.

[0028] In one embodiment, the quantum state encoding device further includes:

[0029] A seventh optical coupling unit and an eighth optical coupling unit;

[0030] The seventh optical coupling unit and the eighth optical coupling unit are disposed in the second transmission optical path;

[0031] The seventh optical coupling unit includes two input ports and at least one output port, and the eighth optical coupling unit includes at least one input port and two output ports;

[0032] The output port of the seventh optical coupling unit is connected to one of the two ports of the first phase modulator, and the input port of the eighth optical coupling unit is connected to the other of the two ports of the first phase modulator;

[0033] One input port of the seventh optical coupling unit is connected to one of the output ports of the third optical coupling unit, and the other input port of the seventh optical coupling unit is connected to one of the output ports of the fifth optical coupling unit;

[0034] One output port of the eighth optical coupling unit is connected to one input port of the fourth optical coupling unit, and the other output port of the eighth optical coupling unit is connected to one input port of the sixth optical coupling unit.

[0035] In one embodiment, the seventh optical coupling unit and the eighth optical coupling unit are optical switches.

[0036] In one embodiment, the device further includes a second phase modulator, and the second phase modulator is connected in series with the first phase modulator.

[0037] According to a second aspect of the present application, there is provided a quantum communication system, including the above-mentioned quantum state encoding device.

[0038] In summary, the quantum state encoding device and the quantum communication system provided by the present application have at least the following beneficial effects:

[0039] The quantum state encoding device provided by the present application forms a first encoded optical branch by the transmission paths of the first optical coupling unit, the time-phase encoding unit, and the second optical coupling unit, and forms a second encoded optical branch by the transmission paths of the first optical coupling unit, the polarization encoding unit, and the second optical coupling unit. The optical pulse input to the first optical coupling unit can generate a quantum state optical pulse obtained by corresponding encoding and output through one of the first encoded optical branch and the second encoded optical branch. Thus, time-phase encoding or polarization encoding can be realized by using one encoding device, and the time-phase encoding unit and the polarization encoding unit share a first phase modulator, which can save the use of devices and has a simple structure. Description of the Drawings

[0040] In order to more clearly illustrate the technical solutions of the specific embodiments of the present application, the following will briefly introduce the drawings required for use in the specific embodiments in conjunction with the drawings. Obviously, the drawings in the following description are some embodiments of the present application. For those skilled in the art, other drawings or solutions can be obtained based on these drawings without creative efforts.

[0041] Figure 1 It is a structural diagram of a quantum state encoding device in an embodiment of the present application. Detailed Embodiments

[0042] In order to make the above and other features and advantages of the present application clearer, the present application will be further described below in conjunction with the 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 merely exemplary, not restrictive.

[0043] In the following description, numerous specific details are set forth to provide a thorough understanding of the present application. However, it will be apparent to those skilled in the art that the present application may be practiced without the use of these specific details. In other instances, well-known steps or operations have not been described in detail to avoid obscuring the present application.

[0044] 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 the X-phase basis, Y-phase basis, and Z-time basis.

[0045] Reference Figure 1 , the present application provides a quantum state encoding device, including: a first optical coupling unit 101, a second optical coupling unit 102, a time-phase encoding unit 103, and a polarization encoding unit 104. The first optical coupling unit 101 includes an input port, a first output port, and a second output port. The second optical coupling unit includes a first input port, a second input port, and an output port. Among them, the first optical coupling unit 101 and the second optical coupling unit 102 are devices that can achieve splitting / combining of optical pulse signals; when an optical pulse is input to the time-phase encoding unit 103, an optical pulse of a time-phase encoded quantum state is output. When an optical pulse is input to the polarization encoding unit 104, an optical pulse of a polarization encoded quantum state is output.

[0046] Specifically, the input port of the first optical coupling unit 101 is the input port of the quantum state encoding device for receiving a single input optical pulse. The first output port of the first optical coupling unit 101 is connected to the input port of the time-phase encoding unit 103, and the output port of the time-phase encoding unit 103 is connected to the first input port of the second optical coupling unit 102. In this way, the transmission path of the first optical coupling unit 101 - time-phase encoding unit 103 - second optical coupling unit 102 forms a first encoded optical branch. The output port of the second optical coupling unit 102 is the output port of the quantum state encoding device.

[0047] Specifically, the second output port of the first optical coupling unit 101 is connected to the input port of the polarization encoding unit 104, and the output port of the polarization encoding unit 104 is connected to the second input port of the second optical coupling unit 102. In this way, the transmission path of the first optical coupling unit 101 - polarization encoding unit 104 - second optical coupling unit 102 forms a second encoded optical branch.

[0048] In one embodiment, the time-phase encoding unit 103 includes a time-phase encoding optical path and a first phase modulator 105. The input port of the time-phase encoding optical path is the input port of the time-phase encoding unit 103, which is used to connect to the first output port of the first optical coupling unit 101. The output port of the time-phase encoding optical path is the output port of the time-phase encoding unit 103, which is connected to the first input port of the second optical coupling unit. The time-phase encoding optical path includes two transmission optical paths, namely the first transmission optical path and the second transmission optical path. The first phase modulator 105 is disposed in the second transmission optical path. Among them, the optical path lengths of the first transmission optical path and the second transmission optical path are not equal.

[0049] In one embodiment, the polarization encoding unit 104 includes a polarization encoding optical path and a first phase modulator 105. The input port of the polarization encoding optical path is the input port of the polarization encoding unit 104, which is connected to the second output port of the first optical coupling unit 101. The output port of the polarization encoding optical path is the output port of the polarization encoding unit 104, which is connected to the second input port of the second optical coupling unit 102. The polarization encoding optical path includes two transmission optical paths, namely the second transmission optical path and the third transmission optical path. The first phase modulator 105 is disposed in the second transmission optical path. Among them, the optical path lengths of the second transmission optical path and the third transmission optical path are equal.

[0050] In the above quantum state encoding device, the transmission paths of the first optical coupling unit 101, the time-phase encoding unit 103, and the second optical coupling unit 102 form a first encoded optical branch, and the transmission paths of the first optical coupling unit 101, the polarization encoding unit 104, and the second optical coupling unit 102 form a second encoded optical branch. An input optical pulse received by the first optical coupling unit 101 can pass through one of the first encoded optical branch and the second encoded optical branch to generate a quantum state optical pulse obtained by corresponding encoding and output. Thus, a single encoding device can be used to achieve both time-phase encoding and polarization encoding without using separate encoding devices respectively. Moreover, the time-phase encoding unit 103 and the polarization encoding unit 104 share a first phase modulator 105, which can save the use of devices and has a simple structure.

[0051] In one embodiment, the first optical coupling unit 101 is an optical coupler, and the second optical coupling unit 102 is an optical switch. Specifically, the optical coupler can be a fiber optic coupler, which can achieve the split output of an optical pulse. The optical switch has one or more selectable transmission ports. Specifically, in this embodiment, an optical switch supporting two inputs and one output is used to select one of the two inputs for output.

[0052] In this embodiment, an input optical pulse received by the input port of the first optical coupling unit 101 is split by the first optical coupling unit 101 into two sub-optical pulses, namely the first sub-optical pulse and the second sub-optical pulse. Among them, the first sub-optical pulse is input into the first encoded optical branch through the input port of the time-phase encoding unit 103, and is subjected to time-phase encoding by the time-phase encoding unit 103 to generate an optical pulse in a time-phase encoded quantum state; the second sub-optical pulse is input into the second encoded optical branch through the input port of the polarization encoding unit 104, and is subjected to polarization encoding by the polarization encoding unit 104 to generate an optical pulse in a polarization encoded quantum state. In this embodiment, the second optical coupling unit 102 is an optical switch. When it is connected to the time-phase encoding unit 103, it outputs an optical pulse in a time-phase encoded quantum state, and when it is connected to the polarization encoding unit 104, it outputs an optical pulse in a polarization encoded quantum state. In this way, by using an optical coupler to split and output the input optical pulse and an optical switch to perform alternative output, it is possible to achieve splitting and encoding of the optical pulse and alternative output, with a simple structure. Further, the optical switch can select one path of signal for output when receiving a selection instruction.

[0053] It can be understood that the first optical coupling unit 101 and the second optical coupling unit 102 can also adopt a combination of other devices to achieve alternative output of the first encoded optical branch and the second encoded optical branch in the quantum state encoding device. For example, in another embodiment, the first optical coupling unit 101 is an optical switch, and the second optical coupling unit 102 is an optical coupler or an optical switch.

[0054] When both the first optical coupling unit 101 and the second optical coupling unit 102 are optical switches, generally, the encoded optical branch selected and connected by the first optical coupling unit 101 is the same as the encoded optical branch selected and connected by the second optical coupling unit 102. Specifically, both the first optical coupling unit 101 and the second optical coupling unit 102 are connected to the first encoded optical branch, or both the first optical coupling unit 101 and the second optical coupling unit 102 are connected to the second encoded optical branch.

[0055] When the first optical coupling unit 101 is an optical switch and the second optical coupling unit 102 is an optical coupler, the first optical coupling unit 101 is connected to one encoded optical branch, then the input and output of the other encoded optical branch are empty, and the second optical coupling unit 102 couples the optical pulses output from the two encoded optical branches, and then directly outputs the required optical pulse in an encoded quantum state.

[0056] In one embodiment, the time-phase encoding optical path further includes a third optical coupling unit 1031 and a fourth optical coupling unit 1032. The third optical coupling unit 1031 includes at least one input port and two output ports, and the fourth optical coupling unit 1032 includes two input ports and at least one output port.

[0057] Among them, the input port of the third optical coupler unit 1031 is the input port of the time-phase encoding optical path, which is used to connect the first output port of the first optical coupler unit 101. The two output ports of the third optical coupler unit 1031 are respectively connected to the two input ports of the fourth optical coupler unit 1032 through the first transmission optical path and the second transmission optical path; specifically, the first output port of the third optical coupler unit 1031 is connected to the first input port of the fourth optical coupler unit 1032 through the first transmission optical path; the second output port of the third optical coupler unit 1031 is connected to the second input port of the fourth optical coupler unit 1032 through the second transmission optical path where the first phase modulator 105 is located. The output port of the fourth optical coupler unit 1032 is the output port of the time-phase encoding optical path, which is connected to the first input port of the second optical coupler unit 102.

[0058] By adopting the third optical coupler unit 1031, the fourth optical coupler unit 1032, the first transmission optical path, the second transmission optical path and the first phase modulator 105 to form the time-phase encoding unit 103, the structure is simple.

[0059] In one embodiment, the third optical coupler unit 1031 and the fourth optical coupler unit 1032 are optical couplers. Using optical couplers to realize the splitting and combining of optical pulses, the structure is simple and easy to implement.

[0060] In one embodiment, the polarization encoding optical path further includes a fifth optical coupler unit 1041 and a sixth optical coupler unit 1042. The fifth optical coupler unit 1041 includes at least one input port and two output ports, and the sixth optical coupler unit 1042 includes at least one output port and two input ports.

[0061] Among them, the input port of the fifth optical coupler unit 1041 is the input port of the polarization encoding optical path, which is used to connect the second output port of the first optical coupler unit 101. The two output ports of the fifth optical coupler unit 1041 are respectively connected to the two input ports of the sixth optical coupler unit 1042 through the second transmission optical path and the third transmission optical path. Specifically, the first output port of the fifth optical coupler unit 1041 is connected to the first input port of the sixth optical coupler unit 1042 through the second transmission optical path where the first phase modulator 105 is located; the second output port of the fifth optical coupler unit 1041 is connected to the second input port of the sixth optical coupler unit 1042 through the third transmission optical path. The output port of the sixth optical coupler unit 1042 is the output port of the polarization encoding optical path, which is connected to the second input port of the second optical coupler unit 102.

[0062] By adopting the fifth optical coupler unit 1041, the sixth optical coupler unit 1042, the second transmission optical path, the third transmission optical path and the first phase modulator 105 to form the polarization encoding unit 104, the structure is simple.

[0063] In one embodiment, the fifth optical coupling unit 1041 is a polarization beam splitter or an optical coupler, and the sixth optical coupling unit 1042 is a polarization combiner or an optical coupler, which uses simple devices.

[0064] In one embodiment, the fifth optical coupling unit and the sixth 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.

[0065] In one embodiment, the quantum state encoding device further includes: a seventh optical coupling unit 106 and an eighth optical coupling unit 107. The seventh optical coupling unit 106 includes two input ports and at least one output port, and the eighth optical coupling unit 107 includes at least one input port and two output ports.

[0066] Wherein, an output port of the seventh optical coupling unit 106 is connected to one of the two ports of the first phase modulator 105, and an input port of the eighth optical coupling unit 107 is connected to the other of the two ports of the first phase modulator 105. The seventh optical coupling unit 106, the first phase modulator 105, and the eighth optical coupling unit 107 are all located on the second transmission optical path.

[0067] Wherein, one input port of the seventh optical coupling unit 106 is connected to one of the output ports of the third optical coupling unit 1031, and the other input port of the seventh optical coupling unit 106 is connected to one of the output ports of the fifth optical coupling unit 1041.

[0068] One output port of the eighth optical coupling unit 107 is connected to one of the input ports of the fourth optical coupling unit 1032, and the other output port of the eighth optical coupling unit 107 is connected to one of the input ports of the sixth optical coupling unit 1042.

[0069] Further, if a signal is input to the input port of the seventh optical coupling unit 106 connected to the third optical coupling unit 1031, the output port of the eighth optical coupling unit 107 connected to the fourth optical coupling unit 1032 outputs a signal; if a signal is input to the input port of the seventh optical coupling unit 106 connected to the fifth optical coupling unit 1041, the output port of the eighth optical coupling unit 107 connected to the sixth optical coupling unit 1042 outputs a signal.

[0070] By adopting the structure that the two ports of the first phase modulator 105 are respectively connected to the seventh optical coupling unit 106 and the eighth optical coupling unit 107 to connect the time-phase encoding optical path and the polarization encoding optical path, the first phase modulator 105 can both form a time-phase encoding unit 103 with the time-phase encoding optical path and form a polarization encoding unit 104 with the polarization encoding optical path, realizing sharing.

[0071] In one embodiment, the seventh optical coupling unit 106 and the eighth optical coupling unit 107 are optical switches. By using an optical switch for the seventh optical coupling unit 106, alternative input of two input ports can be achieved; by using an optical switch for the eighth optical coupling unit 107, alternative output of two output ports can be achieved, enabling the first phase modulator 105 to be used to form a time-phase encoding unit 103 with the time-phase encoding optical path, or to form a polarization encoding unit 104 with the polarization encoding optical path, with convenient switching.

[0072] In one embodiment, the quantum state encoding device further includes a second phase modulator, which is connected in series with the first phase modulator. By using two phase modulators connected in series, complex signal combinations can be phase-modulated, thereby reducing the modulation complexity.

[0073] This application also provides a quantum communication system, including the quantum state encoding device in each of the above embodiments.

[0074] For the above-mentioned quantum communication system, since it includes the aforementioned quantum state encoding device, similarly, it can support two types of encoding of optical pulses and has a simple structure.

[0075] The quantum communication system can be a discrete-variable quantum communication system or a continuous-variable quantum communication system.

[0076] The above-described technical features 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 such a combination does not contain contradictions.

[0077] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit them; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and 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 this application.

Claims

1. A quantum state encoding device, characterized in that, Comprising: A first optical coupling unit, a time-phase encoding unit, a polarization encoding unit, and a second optical coupling unit. The first optical coupling unit includes an input port, a first output port, and a second output port. The second optical coupling unit includes a first input port, a second input port, and an output port; The input port of the first optical coupling unit is the input port of the quantum state encoding device, and is used to receive an input optical pulse; The first output port of the first optical coupling unit is connected to the input port of the time-phase encoding unit, and the output port of the time-phase encoding unit is connected to the first input port of the second optical coupling unit; The second output port of the first optical coupling unit is connected to the input port of the polarization encoding unit, and the output port of the polarization encoding unit is connected to the second input port of the second optical coupling unit; The time-phase encoding unit includes a time-phase encoding optical path and a first phase modulator. The input port of the time-phase encoding optical path is the input port of the time-phase encoding unit, and the output port of the time-phase encoding optical path is the output port of the time-phase encoding unit. The time-phase encoding optical path includes two transmission optical paths, namely a first transmission optical path and a second transmission optical path. The first phase modulator is arranged in the second transmission optical path. Among them, the optical path lengths of the first transmission optical path and the second transmission optical path are not equal; The polarization encoding unit includes a polarization encoding optical path and the first phase modulator. The input port of the polarization encoding optical path is the input port of the polarization encoding unit, and the output port of the polarization encoding optical path is the output port of the polarization encoding unit. The polarization encoding optical path includes two transmission optical paths, namely a second transmission optical path and a third transmission optical path. The first phase modulator is arranged in the second transmission optical path. Among them, the optical path lengths of the second transmission optical path and the third transmission optical path are equal; The output port of the second optical coupling unit is the output port of the quantum state encoding device.

2. The quantum state encoding device according to claim 1, wherein The first optical coupling unit is an optical coupler, and the second optical coupling unit is an optical switch; or The first optical coupling unit is an optical switch, and the second optical coupling unit is an optical coupler or an optical switch.

3. The quantum state encoding device according to claim 1 or 2, characterized in that, The time-phase encoding optical path further includes: A third optical coupling unit and a fourth optical coupling unit; The third optical coupling unit includes at least one input port and two output ports, and the fourth optical coupling unit includes two input ports and at least one output port; The input port of the third optical coupling unit is the input port of the time-phase encoding optical path, and the two output ports of the third optical coupling unit are respectively connected to the two input ports of the fourth optical coupling unit through the first transmission optical path and the second transmission optical path; The output port of the fourth optical coupling unit is the output port of the time-phase encoding optical path.

4. The quantum state encoding device according to claim 3, characterized in that, The third optical coupling unit and the fourth optical coupling unit are optical couplers.

5. The quantum state encoding device according to claim 3, characterized in that, The polarization encoding optical path further includes: A fifth optical coupling unit and a sixth optical coupling unit; The fifth optical coupling unit includes at least one input port and two output ports, and the sixth optical coupling unit includes two input ports and at least one output port; The input port of the fifth optical coupling unit is the input port of the polarization encoding optical path, and the two output ports of the fifth optical coupling unit are respectively connected to the two input ports of the sixth optical coupling unit through a second transmission optical path and a third transmission optical path; The output port of the sixth optical coupling unit is the output port of the polarization encoding optical path.

6. The quantum state encoding device according to claim 5, characterized in that, The fifth optical coupling unit is a polarization beam splitter or an optical coupler, and the sixth optical coupling unit is a polarization combiner or an optical coupler.

7. The quantum state encoding device according to claim 5, characterized in that, The fifth optical coupling unit and the sixth 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.

8. The quantum state encoding device according to claim 5, characterized in that, The device further includes: A seventh optical coupling unit and an eighth optical coupling unit; The seventh optical coupling unit and the eighth optical coupling unit are disposed in the second transmission optical path; The seventh optical coupling unit includes two input ports and at least one output port, and the eighth optical coupling unit includes at least one input port and two output ports; The output port of the seventh optical coupling unit is connected to one of the two ports of the first phase modulator, and the input port of the eighth optical coupling unit is connected to the other of the two ports of the first phase modulator; One input port of the seventh optical coupling unit is connected to one of the output ports of the third optical coupling unit, and the other input port of the seventh optical coupling unit is connected to one of the output ports of the fifth optical coupling unit; One output port of the eighth optical coupling unit is connected to one of the input ports of the fourth optical coupling unit, and the other output port of the eighth optical coupling unit is connected to one of the input ports of the sixth optical coupling unit.

9. The quantum state encoding device according to claim 8, wherein The seventh optical coupling unit and the eighth optical coupling unit are optical switches.

10. The quantum state encoding device according to claim 1, characterized in that, The device further includes a second phase modulator, and the second phase modulator is connected in series with the first phase modulator.

11. A quantum communication system, characterized in that, Including the quantum state encoding device according to any one of claims 1 to 10.

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