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

Abstract

The present disclosure provides a quantum state encoding and decoding device and method, and a software-defined quantum communication system. The device comprises: a quantum state encoding unit, a quantum state decoding unit, an encoding conversion module, a first optical transmission module, and a second optical transmission module. The quantum state encoding unit is used for generating an optical pulse of a polarization-encoded quantum state or an optical pulse of a time-phase-encoded quantum state. The quantum state decoding unit is used for decoding and outputting the optical pulse of the polarization-encoded quantum state or the optical pulse of the time-phase-encoded quantum state. The encoding conversion module is used for converting, according to needs, an inputted optical pulse of the polarization-encoded quantum state into an optical pulse of a time-phase-encoded quantum state for output or directly outputting the optical pulse of the polarization-encoded quantum state, or converting, according to needs, an inputted optical pulse of the time-phase-encoded quantum state into an optical pulse of the polarization-encoded quantum state for output or directly outputting the optical pulse of the time-phase-encoded quantum state. In the present disclosure, the same quantum state encoding and decoding device can meet different encoding and decoding requirements.

Description

Quantum state encoding / decoding devices, methods, and software-defined quantum communication systems Technical Field

[0001] This disclosure relates to the fields of quantum communication and optical quantum encoding and decoding technology, and in particular to a quantum state encoding and decoding device, method, and software-defined quantum communication system. Background Technology

[0002] Quantum communication technology is a cutting-edge and hotly debated field combining quantum physics and information science. Current applications primarily include quantum key distribution and quantum direct communication. Based on the Heisenberg uncertainty principle and the no-cloning theorem in quantum mechanics, quantum key distribution enables two communicating parties to securely share keys in real time, while quantum direct communication ensures secure information transmission from the outset. 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 power.

[0003] The physical implementation of quantum communication systems, such as quantum key distribution and quantum direct communication, requires encoding and decoding of quantum states. Currently, practical quantum communication systems mainly employ polarization encoding and time-phase encoding, with decoding consisting of polarization decoding and time-phase decoding. A typical quantum communication system uses one encoding method and a corresponding decoding method. Furthermore, at the nodes of a quantum communication network, both encoding and decoding functions are required.

[0004] How to make multiple quantum communication encoding methods and multiple quantum communication decoding methods compatible in the same device is an important issue in the current application of quantum communication.

[0005] Summary of the Invention

[0006] This disclosure provides a quantum state encoding / decoding device, method, and software-defined quantum communication system to solve the technical problems mentioned in the prior art.

[0007] According to a first aspect of this disclosure, a quantum state encoding / decoding device is provided, comprising: a quantum state encoding unit, a quantum state decoding unit, an encoding conversion module, a first optical transmission module, and a second optical transmission module.

[0008] The quantum state encoding unit includes at least one input port and one output port, used to generate optical pulses of polarization-encoded quantum states or optical pulses of time-phase-encoded quantum states;

[0009] The quantum state decoding unit includes an input port and at least one output port, used to decode and output optical pulses with polarization-encoded quantum states, or to decode and output optical pulses with time-phase-encoded quantum states;

[0010] The encoding conversion module includes a first encoding conversion unit, a second encoding conversion unit, a first transmission optical path, and a second transmission optical path. The first encoding conversion unit includes an input port and an output port, used to convert an input light pulse of polarization-coded quantum state into a light pulse of time-phase-coded quantum state, or to convert an input light pulse of time-phase-coded quantum state into a light pulse of polarization-coded quantum state. The second encoding conversion unit includes an input port and an output port, used to convert an input light pulse of polarization-coded quantum state into a light pulse of time-phase-coded quantum state, or to convert an input light pulse of time-phase-coded quantum state into a light pulse of polarization-coded quantum state.

[0011] The first optical transmission module includes a first optical switch and a second optical switch; the first optical switch includes an input port and two output ports, the input port being connected to the output port of the quantum state encoding unit; the second optical switch includes an output port and two input ports, the output port being connected to the input port of the quantum state decoding unit.

[0012] The second optical transmission module includes a third optical switch and a fourth optical switch; the third optical switch includes one output port and two input ports, the output port being used to output one quantum state encoded optical pulse; the fourth optical switch includes one input port and two output ports, the input port being used to input one optical pulse to be decoded;

[0013] The first output port of the first optical switch is connected to the input port of the first encoding conversion unit, and the output port of the first encoding conversion unit is connected to the first input port of the third optical switch, forming a first encoded optical branch;

[0014] The second output port of the first optical switch is connected to one port of the first transmission optical path, and the other port of the first transmission optical path is connected to the second input port of the third optical switch, forming a second coded optical branch.

[0015] The first optical switch is used to input the optical pulse of the encoded quantum state output by the quantum state encoding unit into the first encoded optical branch or the second encoded optical branch according to the quantum communication encoding control command; the third optical switch is used to output the optical pulse of the encoded quantum state output by the first encoded optical branch or the second encoded optical branch according to the quantum communication encoding control command; the quantum communication encoding control command is determined according to the encoding requirements of the quantum communication system;

[0016] The first input port of the second optical switch is connected to the output port of the second encoding conversion unit, and the input port of the second encoding conversion unit is connected to the first output port of the fourth optical switch, forming the first decoding optical branch;

[0017] The second input port of the second optical switch is connected to one port of the second transmission optical path, and the other port of the second transmission optical path is connected to the second output port of the fourth optical switch, forming a second decoding optical branch;

[0018] The fourth optical switch is used to input a light pulse into the first decoding optical branch or the second decoding optical branch according to the quantum communication decoding control command; the second optical switch is used to output the light pulse of the encoded quantum state output by the first decoding optical branch or the second decoding optical branch to the quantum state decoding unit according to the quantum communication decoding control command; the quantum communication decoding control command is determined according to the decoding requirements of the quantum communication system.

[0019] According to a second aspect of this disclosure, a quantum state encoding / decoding method is provided, wherein the quantum state encoding / decoding device described herein is used to implement quantum state encoding / decoding.

[0020] According to a third aspect of this disclosure, a software-defined quantum communication system is provided, including the aforementioned quantum state encoding / decoding device and encoding / decoding control device;

[0021] The encoding / decoding control device 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 / decoding device; and to generate quantum communication decoding control instructions based on the decoding requirements of the quantum communication system and send them to the quantum state encoding / decoding device.

[0022] In summary, the quantum state encoding / decoding device, method, and software-defined quantum communication system provided in this disclosure have at least the following beneficial effects:

[0023] This disclosure employs a quantum state encoding / decoding device comprised of a quantum state encoding unit, a quantum state decoding unit, an encoding conversion module, a first optical transmission module, and a second optical transmission module. The quantum state encoding unit generates optical pulses of polarization-encoded quantum states or time-phase-encoded quantum states. The quantum state decoding unit decodes and outputs either the polarization-encoded quantum state optical pulses or the time-phase-encoded quantum state optical pulses. The encoding conversion module converts the input polarization-encoded quantum state optical pulses into time-phase-encoded quantum state optical pulses or directly outputs polarization-encoded quantum state optical pulses, or converts the input time-phase-encoded quantum state optical pulses into polarization-encoded quantum state optical pulses or directly outputs time-phase-encoded quantum state optical pulses, as needed. This disclosure enables the same quantum state encoding / decoding device to meet different encoding / decoding requirements. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the specific embodiments of this disclosure or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 is a structural block diagram of a quantum state encoding / decoding device provided in an embodiment of this disclosure;

[0026] Figure 2 is a structural diagram of a first embodiment of a quantum state encoding / decoding device provided by the present disclosure;

[0027] Figure 3 is a structural diagram of a second embodiment of a quantum state encoding / decoding device provided by the present disclosure;

[0028] Figure 4 is a structural diagram of a third embodiment of a quantum state encoding / decoding device provided by the present disclosure;

[0029] Figure 5 is a structural diagram of a fourth embodiment of a quantum state encoding / decoding device provided by the present disclosure;

[0030] Figure 6 is a structural diagram of a fifth embodiment of a quantum state encoding / decoding device provided by the present disclosure;

[0031] Figure 7 is a structural diagram of a first embodiment of an encoding conversion unit provided by an embodiment of the present disclosure;

[0032] Figure 8 is a structural diagram of a second embodiment of an encoding conversion unit provided by an embodiment of the present disclosure;

[0033] Figure 9 is a structural diagram of a third embodiment of an encoding conversion unit provided by an embodiment of the present disclosure;

[0034] Figure 10 is a structural diagram of a fourth embodiment of an encoding conversion unit provided by an embodiment of the present disclosure;

[0035] Figure 11 is a structural diagram of a fifth embodiment of an encoding conversion unit provided by an embodiment of the present disclosure;

[0036] Figure 12 is a structural diagram of a sixth embodiment of an encoding conversion unit provided by an embodiment of the present disclosure;

[0037] Figure 13 is a structural diagram of a seventh embodiment of an encoding conversion unit provided by an embodiment of the present disclosure;

[0038] Figure 14 is a structural diagram of an eighth embodiment of an encoding conversion unit provided by an embodiment of the present disclosure;

[0039] Figure 15 is a structural diagram of a software-defined quantum communication system provided by an embodiment of the present disclosure. Detailed Implementation

[0040] To make the above and other features and advantages of this disclosure clearer, the disclosure is further described below with reference to the accompanying drawings. It should be understood that the specific embodiments given herein are for the purpose of explanation to those skilled in the art and are exemplary only, not restrictive.

[0041] In the following description, numerous specific details are set forth to provide a thorough understanding of this disclosure. However, it will be apparent to those skilled in the art that the specific details are not required to practice this disclosure. In other instances, well-known steps or operations have not been described in detail to avoid obscuring this disclosure.

[0042] Referring to Figures 1 and 2, this disclosure provides a quantum state encoding and decoding device. Figure 1 shows a structural block diagram of the device, and Figure 2 shows a structural diagram of a first embodiment of the quantum state encoding and decoding device of this disclosure. The device includes: a quantum state encoding unit 101, a quantum state decoding unit 110, an encoding conversion module 200, a first optical transmission module 300, and a second optical transmission module 400.

[0043] In some embodiments, the quantum state encoding unit 101 includes at least one input port and one output port for generating optical pulses of polarization-encoded quantum states or generating optical pulses of time-phase-encoded quantum states.

[0044] In some embodiments, the quantum state decoding unit 110 includes an input port and at least one output port for decoding and outputting optical pulses of polarization-coded quantum states or optical pulses of time-phase-coded quantum states.

[0045] In some embodiments, the encoding conversion module 200 is used to convert the input polarization-encoded quantum state light pulse into a time-phase-encoded quantum state light pulse output or directly output a polarization-encoded quantum state light pulse as needed, or to convert the input time-phase-encoded quantum state light pulse into a polarization-encoded quantum state light pulse output or directly output a time-phase-encoded quantum state light pulse as needed.

[0046] The encoding conversion module 200 includes a first encoding conversion unit 103, a second encoding conversion unit 107, a first transmission optical path 104, and a second transmission optical path 108. The first encoding conversion unit 103 includes an input port and an output port, used to convert an input light pulse of polarization-coded quantum state into a light pulse of time-phase-coded quantum state, or to convert an input light pulse of time-phase-coded quantum state into a light pulse of polarization-coded quantum state. The second encoding conversion unit 107 includes an input port and an output port, used to convert an input light pulse of polarization-coded quantum state into a light pulse of time-phase-coded quantum state, or to convert an input light pulse of time-phase-coded quantum state into a light pulse of polarization-coded quantum state.

[0047] It should be noted that the time phase encoding in the embodiments of this disclosure 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; the time phase decoding includes phase decoding, that is, the time phase decoding is decoding the encoded quantum state composed of any combination of quantum states of the X phase basis, Y phase basis, and Z time basis.

[0048] In some embodiments, the first optical transmission module 300 includes a first optical switch 102 and a second optical switch 109; the first optical switch 102 includes an input port A and two output ports B and C, wherein the input port A is connected to the output port of the quantum state encoding unit 101; the second optical switch 109 includes an output port D' and two input ports E' and F', wherein the output port D' is connected to the input port of the quantum state decoding unit 110.

[0049] In some embodiments, the second optical transmission module 400 includes a third optical switch 105 and a fourth optical switch 106; the third optical switch 105 includes an output port A' and two input ports B' and C', wherein the output port A' is used to output a quantum state encoded optical pulse; the fourth optical switch 106 includes an input port D and two output ports E and F, wherein the input port D is used to input an optical pulse to be decoded.

[0050] In some embodiments, the first output port C of the first optical switch 102 is connected to the input port of the first encoding conversion unit 103, and the output port of the first encoding conversion unit 103 is connected to the first input port C' of the third optical switch, forming a first encoded optical branch.

[0051] In some embodiments, the second output port B of the first optical switch 102 is connected to one port of the first transmission optical path 104, and the other port of the first transmission optical path 104 is connected to the second input port B' of the third optical switch 105, forming a second coded optical branch.

[0052] In some embodiments, the first optical switch 102 is used to input the optical pulse of the encoded quantum state output by the quantum state encoding unit 101 into the first encoded optical branch or the second encoded optical branch according to the quantum communication encoding control command; the third optical switch 105 is used to output the optical pulse of the encoded quantum state output by the first encoded optical branch or the second encoded optical branch according to the quantum communication encoding control command; the quantum communication encoding control command is determined according to the encoding requirements of the quantum communication system.

[0053] In some embodiments, the first input port F' of the second optical switch 109 is connected to the output port of the second encoding conversion unit 107, and the input port of the second encoding conversion unit 107 is connected to the first output port F of the fourth optical switch 106, forming a first decoding optical branch.

[0054] In some embodiments, the second input port E' of the second optical switch 109 is connected to one port of the second transmission optical path 108, and the other port of the second transmission optical path 108 is connected to the second output port E of the fourth optical switch 106, forming a second decoding optical branch.

[0055] In some embodiments, the fourth optical switch 106 is used to input a light pulse into the first decoding optical branch or the second decoding optical branch according to the quantum communication decoding control command; the second optical switch 109 is used to output the light pulse of the encoded quantum state output by the first decoding optical branch or the second decoding optical branch to the quantum state decoding unit 110 according to the quantum communication decoding control command; the quantum communication decoding control command is determined according to the decoding requirements of the quantum communication system.

[0056] It should be noted that the quantum communication encoding control instructions and quantum communication decoding control instructions can be determined according to the encoding requirements and decoding requirements of the quantum communication system, respectively. These instructions can be issued by programmable control software. For example, the first optical switch 102 can, according to the encoding requirements of the quantum communication system, issue quantum communication encoding control instructions by running the host computer (control circuit unit or processor unit) control software in the quantum communication system to configure the selection state of the optical switch. Similarly, the fourth optical switch 106 can, according to the decoding requirements of the quantum communication system, issue quantum communication decoding control instructions by running the host computer (control circuit unit or processor unit) control software in the quantum communication system to configure the selection state of the optical switch.

[0057] Furthermore, it should be noted that, generally, the coded optical branch selected for connection by the first optical switch 102 is the same as the coded optical branch selected for connection by the third optical switch 105. For example, the first optical switch 102 selects to connect to the first coded optical branch based on quantum communication coding control instructions, and the third optical switch 105 also selects to connect to the first coded optical output branch according to quantum communication coding control instructions. In this way, the output polarization-coded quantum state or time-phase-coded quantum state can be selectively controlled, achieving precise output of the required coded quantum state light pulse. Similarly, generally, the decoding optical branch selected for connection by the fourth optical switch 106 is also the same as the decoding optical branch selected for connection by the second optical switch 109, thus allowing selective control of the output polarization-coded quantum state or time-phase-coded quantum state, achieving precise output of the required coded quantum state light pulse, which is then decoded by the quantum state decoding unit 110. Thus, this disclosure improves the accuracy, flexibility, and adaptability of the quantum communication system.

[0058] The quantum state encoding and decoding device described in this embodiment enables the same device to meet different quantum state encoding and decoding requirements. Regardless of whether polarization-coded quantum state light pulses or time-phase-coded quantum state light pulses are required, the device can output the quantum state required by the quantum communication system. Furthermore, regardless of whether the input polarization-coded quantum state light pulses or time-phase-coded quantum state light pulses are input, the device can be converted into a quantum state that matches the quantum state decoding unit and decoded for output. This enables on-demand generation of encoded quantum state light pulses and matching decoding of input encoded quantum state light pulses.

[0059] Figure 3 shows a structural diagram of a second embodiment of the quantum state encoding / decoding device disclosed herein. The difference between the device in this embodiment and the first embodiment is that the device further includes: a fifth optical coupling unit 119, which includes three ports: a first port, a second port, and a third port. The first port is the encoding output port and the decoding input port of the device, used to receive one optical pulse to be decoded and output one encoded quantum state optical pulse. The second port is connected to the output port A' of the third optical switch 105, and the third port is connected to the input port D of the fourth optical switch 106. The optical pulse input from the first port of the fifth optical coupling unit 119 is output from the third port of the fifth optical coupling unit 119, and the optical pulse input from the second port of the fifth optical coupling unit 119 is output from the first port of the fifth optical coupling unit 119.

[0060] The fifth optical coupling unit 119 can be an optical circulator, a wavelength division multiplexer, or an optical switch.

[0061] Figure 4 shows a structural diagram of the third embodiment of the quantum state encoding and decoding device disclosed herein. The difference between this embodiment and the first embodiment is that the first encoding conversion unit 103 and the second encoding conversion unit 107 are the same encoding conversion unit 103. The encoding conversion unit 103 includes two ports, namely a fourth port and a fifth port; and the device described in this embodiment further includes: a first optical coupling unit 113 and a third optical coupling unit 115. The first optical coupling unit includes three ports, namely port H, port I and port J. Port H is connected to the fourth port of the encoding conversion unit 103, port I is connected to the first output port of the first optical switch 102, and port J is connected to the first input port of the second optical switch 109; the light pulse input from port H is output from port J, and the light pulse input from port I is output from port H. The third optical coupling unit 115 includes three ports, namely port H', port I' and port J'. Port H' is connected to the fifth port of the encoding conversion unit 103, port I' is connected to the first input port of the third optical switch 105, and port J' is connected to the first output port of the fourth optical switch 106; the light pulse input from port H' is output from port I', and the light pulse input from port J' is output from port H'.

[0062] In one embodiment, the first optical coupling unit 113 can be an optical circulator, a wavelength division multiplexer, or an optical switch; the third optical coupling unit 115 can be an optical circulator, a wavelength division multiplexer, or an optical switch.

[0063] Figure 5 shows a structural diagram of a fourth embodiment of the quantum state encoding / decoding device of this disclosure. The difference between this embodiment and the first embodiment is that the first transmission optical path 104 and the second transmission optical path 108 are the same transmission optical path 104. Furthermore, the device includes a second optical coupling unit 114 and a fourth optical coupling unit 116. The second optical coupling unit 114 includes three ports: port L, port M, and port N. Port L is connected to one port of the transmission optical path 104, port M is connected to the second output port of the first optical switch 102, and port N is connected to the second optical switch... The second input port of switch 109 is connected; the optical pulse input from port L is output from port N, and the optical pulse input from port M is output from port L; the fourth optical coupling unit 116 includes three ports, namely port L', port M' and port N', port L' is connected to another port of transmission optical path 104, port M' is connected to the second input port of third optical switch 105, and port N' is connected to the second output port of fourth optical switch 106; the optical pulse input from port L' is output from port M', and the optical pulse input from port N' is output from port L'.

[0064] The second optical coupling unit 114 can be an optical circulator, a wavelength division multiplexer, or an optical switch; the fourth optical coupling unit 116 can be an optical circulator, a wavelength division multiplexer, or an optical switch.

[0065] Figure 6 shows a structural diagram of the fifth embodiment of the quantum state encoding and decoding device disclosed herein. In this embodiment, the first encoding conversion unit 103 and the second encoding conversion unit 107 are the same encoding conversion unit 103, and the first transmission optical path 104 and the second transmission optical path 108 are the same transmission optical path 104. The device also includes: a first optical coupling unit 113, a third optical coupling unit 115, a second optical coupling unit 114, and a fourth optical coupling unit 116. The first optical coupling unit 113 includes three ports: port H, port I, and port J. Port H is connected to the fourth port of the encoding conversion unit 103, port I is connected to the first output port of the first optical switch 102, and port J is connected to the first input port of the second optical switch 109. The optical pulse input from port H is output from port J, and the optical pulse input from port I is output from port H. The third optical coupling unit 115 includes three ports: port H', port I', and port J'. Port H' is connected to the fifth port of the encoding conversion unit 103, port I' is connected to the first input port of the third optical switch 105, and port J' is connected to the first output port of the fourth optical switch 106. The optical pulse input from port H' is output from port I', and the optical pulse input from port J' is output from port H'. The second optical coupling unit 114 includes three ports: port L, port M, and port N. Port L is connected to one port of the transmission optical path 104, port M is connected to the second output port of the first optical switch 102, and port N is connected to the second input port of the second optical switch 109. Optical pulses input from port L are output from port N, and optical pulses input from port M are output from port L. The fourth optical coupling unit 116 includes three ports: port L', port M', and port N'. Port L' is connected to the other port of the transmission optical path 104, port M' is connected to the second input port of the third optical switch 105, and port N' is connected to the second output port of the fourth optical switch 106. Optical pulses input from port L' are output from port M', and optical pulses input from port N' are output from port L'.

[0066] In one embodiment, the first optical coupling unit 113 can be an optical circulator, a wavelength division multiplexer, or an optical switch; the third optical coupling unit 115 can be an optical circulator, a wavelength division multiplexer, or an optical switch; the second optical coupling unit 114 can be an optical circulator, a wavelength division multiplexer, or an optical switch; and the fourth optical coupling unit 115 can be an optical circulator, a wavelength division multiplexer, or an optical switch.

[0067] It is understood that the structure of the fifth optical coupling unit 119 in the second embodiment of the quantum state encoding and decoding device of this disclosure can be adapted to match any of the above embodiments, and this disclosure does not limit it.

[0068] As can be seen from the above embodiments, in some scenarios, the first encoding conversion unit 103 and the second encoding conversion unit 107 of this disclosure need to convert the input polarization-coded quantum state light pulse into a time-phase-coded quantum state light pulse output, and in other scenarios, they need to convert the input time-phase-coded quantum state light pulse into a polarization-coded quantum state light pulse output. When the two encoding conversion units are multiplexed, as in the scenarios of the embodiments described in Figures 4 and 6, when the encoding conversion unit has a fourth port input and a fifth port output, it needs to be able to convert the input polarization-coded quantum state light pulse into a time-phase-coded quantum state light pulse output or vice versa. It also needs to be able to convert the input polarization-coded quantum state light pulse into a time-phase-coded quantum state light pulse output or vice versa when the encoding conversion unit has a fifth port input and a fourth port output.

[0069] To adapt to the needs of different scenarios, regardless of whether the same encoding conversion unit is input from the fourth port and output from the fifth port or input from the fifth port and output from the fourth port, the same encoding conversion unit can convert the input polarization-encoded quantum state light pulse into a time-phase-encoded quantum state light pulse output, or it can convert the input time-phase-encoded quantum state light pulse into a polarization-encoded quantum state light pulse output. The structures of the first encoding conversion unit 103 and the second encoding conversion unit 107 provided in the embodiments of this disclosure are as follows.

[0070] It should be noted that the first encoding conversion unit 103 and the second encoding conversion unit 107 may have the same or different structures, and they may each adopt the structure of any of the following embodiments.

[0071] In one embodiment, the first encoding conversion unit 103 and the second encoding conversion unit 107 respectively include: a first encoding conversion optical coupling unit, a second encoding conversion optical coupling unit, a first encoding conversion transmission optical path, and a second encoding conversion transmission optical path.

[0072] The first encoding conversion optical coupling unit includes at least three ports: one input port and two output ports. The second encoding conversion optical coupling unit includes at least three ports: two input ports and one output port. The two output ports of the first encoding conversion optical coupling unit are connected to the two input ports of the second encoding conversion optical coupling unit through the first encoding conversion transmission optical path and the second encoding conversion transmission optical path. The input port of the first encoding conversion optical coupling unit is the input port of the corresponding encoding conversion unit, and the output port of the second encoding conversion optical coupling unit is the output port of the corresponding encoding conversion unit. The optical path lengths of the first encoding conversion transmission optical path and the second encoding conversion transmission optical path are not equal.

[0073] For ease of description, the first encoding conversion unit and the second encoding conversion unit will be collectively referred to as encoding conversion units below.

[0074] Figure 7 shows a structural diagram of the first embodiment of the encoding conversion unit of this disclosure. In this embodiment, the first encoding conversion optical coupling unit is a polarization beamsplitter 310, and the second encoding conversion optical coupling unit is a polarization beam combiner 320. The polarization beamsplitter 310 includes at least three ports: one input port O and two output ports P and Q. The polarization beam combiner 320 includes at least three ports: two input ports P' and Q' and one output port O'. The output port P of the polarization beamsplitter 310 is connected to the input port P' of the polarization beam combiner 320 through the first encoding conversion transmission optical path 330. The output port Q of the polarization beamsplitter 310 is connected to the input port Q' of the polarization beam combiner 320 through the second encoding conversion transmission optical path 340. The input port O of the polarization beamsplitter 310 is the input port of the encoding conversion unit, and the output port O' of the polarization beam combiner 320 is the output port of the encoding conversion unit. The optical path lengths of the first encoding conversion transmission optical path 330 and the second encoding conversion transmission optical path 340 are not equal.

[0075] Figure 8 shows a structural diagram of the second embodiment of the encoding conversion unit of this disclosure. In this embodiment, the first encoding conversion optical coupling unit is an optical coupler 310, and the second encoding conversion optical coupling unit is a polarization beam combiner 320. Their connection relationship is the same as that described in the previous embodiment, and will not be repeated here.

[0076] Figure 9 shows a structural diagram of the third embodiment of the encoding conversion unit module 200 of this disclosure. In this embodiment, the first encoding conversion optical coupling unit is a polarization beam splitter 310, and the second encoding conversion optical coupling unit is an optical coupler 320. Their connection relationship is the same as described in the previous embodiment, and will not be repeated here.

[0077] Figure 10 shows a structural diagram of the fourth embodiment of the encoding conversion module 200 of this disclosure. In this embodiment, the first encoding conversion optical coupling unit is an optical coupler 310, and the second encoding conversion optical coupling unit is an optical coupler 320. The encoding conversion unit 200 further includes two optical polarizers 350 and 360, wherein the optical polarizer 350 is disposed on the first encoding conversion transmission optical path 330, and the optical polarizer 360 is disposed on the second encoding conversion transmission optical path 340, and the polarization directions of the optical polarizers 350 and 360 are orthogonal to each other.

[0078] Figure 11 shows a structural diagram of the fifth embodiment of the encoding conversion unit of this disclosure. In this embodiment, the first encoding conversion optical coupling unit 310 and the second encoding conversion optical coupling unit 320 are the same optical coupling unit, which is a polarization beam splitter 370. The encoding conversion unit further includes two mirrors 371 and 372. The output port P of the polarization beam splitter 370 is connected to one end of the first encoding conversion transmission optical path 373, the mirror 371 is connected to the other end of the first encoding conversion transmission optical path 373, the output port Q of the polarization beam splitter 370 is connected to one end of the second encoding conversion transmission optical path 374, and the mirror 372 is connected to the other end of the second encoding conversion transmission optical path 374.

[0079] In this embodiment, reflectors 371 and 372 are polarization-state rotating reflectors. It is understood that reflectors 371 and 372 can be polarization-state rotating reflectors with any rotation angle, among which a 90° polarization-state rotating reflector is a commonly used case.

[0080] Figure 12 shows a structural diagram of the sixth embodiment of the encoding conversion unit of this disclosure. In this embodiment, the first encoding conversion optical coupling unit 310 and the second encoding conversion optical coupling unit 320 are the same optical coupling unit, and the same optical coupling unit is an optical coupler 370. The encoding conversion unit 200 also includes two mirrors 371 and 372, and two optical polarizers 350 and 360. The output port P of the optical coupler 370 is connected to one end of the first encoding conversion transmission optical path 373, the mirror 371 is connected to the other end of the first encoding conversion transmission optical path 373, the optical polarizer 350 is disposed on the first encoding conversion transmission optical path 373, the output port Q of the optical coupler 370 is connected to one end of the second encoding conversion transmission optical path 374, the mirror 372 is connected to the other end of the second encoding conversion transmission optical path 374, the optical polarizer 360 is disposed on the second encoding conversion transmission optical path 374, and the polarization directions of the optical polarizers 350 and 360 are orthogonal to each other.

[0081] In some embodiments, the optical coupler 370 may have at least three ports, with the input port and output port multiplexed when there are three ports, and four ports as shown in FIG12, with port O being the input port and port O” being the output port.

[0082] The six embodiments of the encoding conversion unit 200 described above represent the structure when the first encoding conversion unit 103 and the second encoding conversion unit 107 are multiplexed. In some special scenarios, the first encoding conversion unit 103 and / or the second encoding conversion unit 107 may also adopt the following structure.

[0083] When the quantum state encoding unit 101 is a polarization quantum state encoding unit, the first encoding conversion transmission optical path 330 or the second encoding conversion transmission optical path 340 in the first encoding conversion unit 103 is a 90° twisted polarization-maintaining fiber. Alternatively, the first encoding conversion unit 103 may further include a 90° polarization state rotator, which is disposed on the first encoding conversion transmission optical path 330 or the second encoding conversion transmission optical path 340 and is used to rotate the polarization state of the passing light pulse by 90°.

[0084] When the quantum state decoding unit 110 is a time-phase quantum state decoding unit, the first encoding conversion transmission optical path 330 or the second encoding conversion transmission optical path 340 in the second encoding conversion unit 107 is a 90° twisted polarization-maintaining fiber. Alternatively, the second encoding conversion unit 107 may further include a 90° polarization state rotator, which is disposed on the first encoding conversion transmission optical path 330 or the second encoding conversion transmission optical path 340 and is used to rotate the polarization state of the passing light pulse by 90°.

[0085] When the quantum state encoding unit 101 is a polarization quantum state encoding unit, the first encoding conversion unit 103 further includes an optical polarizer, which is disposed at the output port of the first encoding conversion unit 103 and is used to polarize the output light pulse.

[0086] When the quantum state decoding unit 110 is a time-phase quantum state decoding unit, the second encoding conversion unit 107 further includes an optical polarizer, which is disposed at the output port of the second encoding conversion unit 107 and is used to polarize the output light pulse.

[0087] When the quantum state encoding unit 101 is a time-phase quantum state encoding unit, the first encoding conversion unit 103 can also adopt the structure shown in Figure 13, where the first encoding conversion optical coupling unit is an optical coupler 310 and the second encoding conversion optical coupling unit is an optical coupler 320. Alternatively, the first encoding conversion unit 103 can also adopt the structure shown in Figure 14, where the first encoding conversion optical coupling unit 310 and the second encoding conversion optical coupling unit 320 are the same optical coupler 370. The first encoding conversion unit 103 further includes two mirrors 371 and 372. The output port P of the optical coupler 370 is connected to one end of the first encoding conversion transmission optical path 373, and the output port Q of the optical coupler is connected to one end of the second encoding conversion transmission optical path 374. Mirror 371 is connected to the other end of the first encoding conversion transmission optical path 373, and mirror 372 is connected to the other end of the second encoding conversion transmission optical path 374. Optionally, one of the mirrors 371 and 372 is a 90° polarization state rotating mirror.

[0088] When the first encoding conversion optical coupling unit in the first encoding conversion unit 103 is an optical coupler, and the second encoding conversion optical coupling unit is an optical coupler or a polarization combiner, and when the quantum state encoding unit 101 is a time-phase quantum state encoding unit, the first encoding conversion transmission optical path 330 or the second encoding conversion transmission optical path 340 in the first encoding conversion unit 103 is a 90° twisted polarization-maintaining fiber. Alternatively, the first encoding conversion unit 103 further includes a 90° polarization state rotator, which is disposed on the first encoding conversion transmission optical path 330 or the second encoding conversion transmission optical path 340, and is used to rotate the polarization state of the passing light pulse by 90°. Thus, this disclosure can realize the encoding conversion process from time-phase encoded quantum state to polarization encoded quantum state.

[0089] When the quantum state decoding unit 110 is a polarization quantum state decoding unit, the second encoding conversion unit 107 can also adopt the structure shown in Figure 13 or Figure 14. When the first encoding conversion optical coupling unit in the second encoding conversion unit 107 is an optical coupler, and the second encoding conversion optical coupling unit is an optical coupler or a polarization combiner, and when the quantum state decoding unit 110 is a polarization quantum state decoding unit, the first encoding conversion transmission optical path 330 or the second encoding conversion transmission optical path 340 in the second encoding conversion unit 107 is a 90° twisted polarization-maintaining fiber. Alternatively, the second encoding conversion unit 107 further includes a 90° polarization state rotator, which is disposed on the first encoding conversion transmission optical path 330 or the second encoding conversion transmission optical path 340, and is used to rotate the polarization state of the passing light pulse by 90°. Thus, this disclosure can realize the encoding conversion process from time-phase encoded quantum state to polarization encoded quantum state.

[0090] Optionally, in any of the above embodiments, one of the first optical switch and the third optical switch can be replaced by an optical coupler, and one of the second optical switch and the fourth optical switch can be replaced by an optical coupler.

[0091] This disclosure provides a quantum state encoding and decoding method, which uses the aforementioned quantum state encoding and decoding device to implement quantum state encoding and decoding.

[0092] According to this disclosure, a software-defined quantum communication system is provided. Figure 15 shows a structural diagram of a software-defined quantum communication system according to an embodiment of this disclosure, including the aforementioned quantum state encoding / decoding device 1501 and encoding / decoding control device 1502. The encoding / decoding control device 1502 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 / decoding device 1501. The encoding / decoding control device 1502 is also used to generate quantum communication decoding control instructions based on the decoding requirements of the quantum communication system and send them to the quantum state encoding / decoding device 1501.

[0093] The quantum communication system can be a discrete-variable quantum communication system or a continuous-variable quantum communication system. The protocols of the quantum communication system include, but are not limited to, BB84, BBM92, E91, MDI, TF, frame-independent, and coherent state protocols.

[0094] It should be understood that the specific features, operation and details described herein with respect to the apparatus of this disclosure can also be similarly applied to the methods and systems of this disclosure, or vice versa.

[0095] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, provided that such combination does not contain contradictions.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit them. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A quantum state encoding and decoding apparatus, wherein, The application relates to a quantum state encoding and decoding system. The quantum state encoding unit comprises at least one input port and one output port, and is used for generating a polarized encoding quantum state light pulse or a time phase encoding quantum state light pulse. The quantum state decoding unit comprises one input port and at least one output port, and is used for decoding and outputting a polarized encoding quantum state light pulse or a time phase encoding quantum state light pulse. The encoding conversion module comprises a first encoding conversion unit, a second encoding conversion unit, a first transmission light path and a second transmission light path. The first light transmission module comprises a first optical switch and a second optical switch. The second light transmission module comprises a third optical switch and a fourth optical switch. The first output port of the first optical switch is connected with the input port of the first encoding conversion unit, the output port of the first encoding conversion unit is connected with the first input port of the third optical switch, and a first encoding light branch is formed. The second output port of the first optical switch is connected with one port of the first transmission light path, and the other port of the first transmission light path is connected with the second input port of the third optical switch, and a second encoding light branch is formed. The first optical switch is used for inputting the encoding quantum state light pulse output by the quantum state encoding unit into the first encoding light branch or the second encoding light branch according to a quantum communication encoding control instruction. The third optical switch is used for outputting the encoding quantum state light pulse output by the first encoding light branch or the second encoding light branch according to a quantum communication encoding control instruction. The quantum communication encoding control instruction is determined according to the encoding requirement of a quantum communication system. The first input port of the second optical switch is connected with the output port of the second encoding conversion unit, the input port of the second encoding conversion unit is connected with the first output port of the fourth optical switch, forming a first decoding optical branch; The second input port of the second optical switch is connected with one port of the second transmission optical path, the other port of the second transmission optical path is connected with the second output port of the fourth optical switch, forming a second decoding optical branch; The fourth optical switch is used for inputting one optical pulse into the first decoding optical branch or the second decoding optical branch according to quantum communication decoding control instructions; the second optical switch is used for outputting the optical pulse of the encoded quantum state output by the first decoding optical branch or the second decoding optical branch to a quantum state decoding unit according to quantum communication decoding control instructions; the quantum communication decoding control instructions are determined according to quantum communication system decoding requirements.

2. The apparatus of claim 1, wherein, The first encoding conversion unit and the second encoding conversion unit respectively comprise: a first encoding conversion optical coupling unit, a second encoding conversion optical coupling unit, a first encoding conversion transmission optical path and a second encoding conversion transmission optical path, The first encoding conversion optical coupling unit comprises at least three ports, one input port and two output ports; the second encoding conversion optical coupling unit comprises at least three ports, two input ports and one output port, the two output ports of the first encoding conversion optical coupling unit are connected with the two input ports of the second encoding conversion optical coupling unit through the first encoding conversion transmission optical path and the second encoding conversion transmission optical path; the input port of the first encoding conversion optical coupling unit is the input port of the corresponding encoding conversion unit, the output port of the second encoding conversion optical coupling unit is the output port of the corresponding encoding conversion unit, and the optical path length of the first encoding conversion transmission optical path is not equal to that of the second encoding conversion transmission optical path.

3. The apparatus of claim 2, wherein, The first encoding conversion optical coupling unit is a polarization beam splitter, and the second encoding conversion optical coupling unit is a polarization beam combiner.

4. The apparatus of claim 2, wherein, The first encoding conversion optical coupling unit is an optical coupler, and the second encoding conversion optical coupling unit is a polarization beam combiner.

5. The apparatus of claim 2, wherein, The first encoding conversion optical coupling unit is a polarization beam splitter, and the second encoding conversion optical coupling unit is an optical coupler.

6. The apparatus of claim 2, wherein, The first encoding conversion optical coupling unit is an optical coupler, and the second encoding conversion optical coupling unit is an optical coupler; the first encoding conversion unit and the second encoding conversion unit further comprise: two optical polarizers, The two optical polarizers are respectively arranged on the first encoding conversion transmission optical path and the second encoding conversion transmission optical path, and the polarization directions of the two optical polarizers are orthogonal to each other. The first encoding conversion optical coupling unit and the second encoding conversion optical coupling unit are the same polarization beam splitter, and the first encoding conversion unit and the second encoding conversion unit further comprise: two mirrors, 7. The apparatus of claim 2, wherein, ​ The two output ports of the polarization beam splitter are connected with one end of the first encoding conversion transmission light path and one end of the second encoding conversion transmission light path respectively, and the two mirrors are connected with the other end of the first encoding conversion transmission light path and the other end of the second encoding conversion transmission light path respectively.

8. The apparatus of claim 7, wherein, The two mirrors are polarization state rotation mirrors.

9. The apparatus of claim 2, wherein, The first encoding conversion light coupling unit and the second encoding conversion light coupling unit are the same optical coupler, and the first encoding conversion unit and the second encoding conversion unit further comprise two mirrors and two optical polarizers, The two output ports of the optical coupler are connected with one end of the first encoding conversion transmission light path and one end of the second encoding conversion transmission light path respectively, and the two mirrors are connected with the other end of the first encoding conversion transmission light path and the other end of the second encoding conversion transmission light path respectively; the two optical polarizers are arranged on the first encoding conversion transmission light path and the second encoding conversion transmission light path respectively, and the polarization directions of the two optical polarizers are orthogonal to each other.

10. The apparatus of claim 5 or 6, wherein, In the case that the quantum state encoding unit is a polarization quantum state encoding unit, the first encoding conversion transmission light path or the second encoding conversion transmission light path of the first encoding conversion unit is a 90° twisted polarization maintaining optical fiber, or the first encoding conversion unit further comprises a 90° polarization state rotator arranged on the first encoding conversion transmission light path or the second encoding conversion transmission light path, for rotating the polarization state of the passing light pulse by 90°; and / or In the case that the quantum state decoding unit is a time-phase quantum state decoding unit, the first encoding conversion transmission light path or the second encoding conversion transmission light path of the second encoding conversion unit is a 90° twisted polarization maintaining optical fiber, or the second encoding conversion unit further comprises a 90° polarization state rotator arranged on the first encoding conversion transmission light path or the second encoding conversion transmission light path, for rotating the polarization state of the passing light pulse by 90°.

11. The device of any one of claims 3 to 9, wherein, In the case that the quantum state encoding unit is a polarization quantum state encoding unit, the first encoding conversion unit further comprises an optical polarizer arranged at the output port of the first encoding conversion unit, for polarizing the output light pulse; and / or In the case that the quantum state decoding unit is a time-phase quantum state decoding unit, the second encoding conversion unit further comprises an optical polarizer arranged at the output port of the second encoding conversion unit, for polarizing the output light pulse.

12. The apparatus of claim 2, wherein, The first encoding conversion light coupling unit is an optical coupler, and the second encoding conversion light coupling unit is an optical coupler.

13. The apparatus of claim 2, wherein, The first encoding conversion light coupling unit and the second encoding conversion light coupling unit are the same optical coupler, and the first encoding conversion unit and the second encoding conversion unit further comprise two mirrors, The two output ports of the optical coupler are connected with one end of the first encoding conversion transmission light path and one end of the second encoding conversion transmission light path respectively, and the two mirrors are connected with the other end of the first encoding conversion transmission light path and the other end of the second encoding conversion transmission light path respectively; the two optical polarizers are arranged on the first encoding conversion transmission light path and the second encoding conversion transmission light path respectively, and the polarization directions of the two optical polarizers are orthogonal to each other. and one end of the second encoding conversion transmission optical path, and the two mirrors are connected with the other end of the first encoding conversion transmission optical path and the other end of the second encoding conversion transmission optical path respectively.

14. The apparatus of claim 13, wherein, One of the two mirrors is a 90° polarization state rotation mirror.

15. The apparatus of claim 4 or 12, wherein, In the case that the quantum state encoding unit is a time-phase quantum state encoding unit, the first encoding conversion transmission optical path or the second encoding conversion transmission optical path of the first encoding conversion unit is a 90° twisted polarization maintaining optical fiber, or the first encoding conversion unit further comprises: a 90° polarization state rotator, which is arranged on the first encoding conversion transmission optical path or the second encoding conversion transmission optical path, and is used for rotating the polarization state of the passing light pulse by 90°; and / or In the case that the quantum state decoding unit is a polarization quantum state decoding unit, the first encoding conversion transmission optical path or the second encoding conversion transmission optical path of the second encoding conversion unit is a 90° twisted polarization maintaining optical fiber, or the second encoding conversion unit further comprises: a 90° polarization state rotator, which is arranged on the first encoding conversion transmission optical path or the second encoding conversion transmission optical path, and is used for rotating the polarization state of the passing light pulse by 90°.

16. The apparatus of any one of claims 12 to 14, wherein, The quantum state encoding unit is a time-phase quantum state encoding unit, and the quantum state decoding unit is a polarization quantum state decoding unit.

17. The device of any one of claims 1 to 9, wherein, The first encoding conversion unit and the second encoding conversion unit are the same encoding conversion unit, and the encoding conversion unit comprises two ports, which are a fourth port and a fifth port respectively. The device further comprises: a first optical coupling unit and a third optical coupling unit, The first optical coupling unit comprises three ports, which are a port H, a port I and a port J respectively, the port H is connected with the fourth port of the encoding conversion unit, the port I is connected with the first output port of the first optical switch, and the port J is connected with the first input port of the second optical switch; the light pulse input from the port H is output from the port J, and the light pulse input from the port I is output from the port H; The third optical coupling unit comprises three ports, which are a port H', a port I' and a port J' respectively, the port H' is connected with the fifth port of the encoding conversion unit, the port I' is connected with the first input port of the third optical switch, and the port J' is connected with the first output port of the fourth optical switch; the light pulse input from the port H' is output from the port I', and the light pulse input from the port J' is output from the port H'.

18. The apparatus of claim 17, wherein, The first transmission optical path and the second transmission optical path are the same transmission optical path; The device further comprises: a second optical coupling unit and a fourth optical coupling unit, The second optical coupling unit comprises three ports, which are a port L, a port M and a port N respectively, the port L is connected with one port of the transmission optical path, the port M is connected with the second output port of the first optical switch, and the port N is connected with the second input port of the second optical switch; the light pulse input from the port L is output from the port N, and the light pulse input from the port M is output from the port L; The fourth optical coupling unit comprises three ports, port L', port M' and port N', the port L' is connected with another port of the transmission optical path, the port M' is connected with the second input port of the third optical switch, and the port N' is connected with the second output port of the fourth optical switch; the optical pulse input from the port L' is output from the port M', and the optical pulse input from the port N' is output from the port L'. The first transmission optical path and the second transmission optical path are the same transmission optical path.

19. The apparatus of claim 1, wherein, The device further comprises a second optical coupling unit and a fourth optical coupling unit, The second optical coupling unit comprises three ports, port L, port M and port N, the port L is connected with one port of the transmission optical path, the port M is connected with the second output port of the first optical switch, and the port N is connected with the second input port of the second optical switch; the optical pulse input from the port L is output from the port N, and the optical pulse input from the port M is output from the port L. The fourth optical coupling unit comprises three ports, port L', port M' and port N', the port L' is connected with another port of the transmission optical path, the port M' is connected with the second input port of the third optical switch, and the port N' is connected with the second output port of the fourth optical switch; the optical pulse input from the port L' is output from the port M', and the optical pulse input from the port N' is output from the port L'. The device further comprises a fifth optical coupling unit, 20. The apparatus of claim 1, wherein, The fifth optical coupling unit comprises three ports, a first port, a second port and a third port, the first port is an encoding output port and a decoding input port of the device, used for receiving one optical pulse to be decoded and outputting one quantum state encoding optical pulse; the second port is connected with the output port of the third optical switch, and the third port is connected with the input port of the fourth optical switch; The optical pulse input from the first port is output from the third port, and the optical pulse input from the second port is output from the first port. The fifth optical coupling unit is an optical circulator, or a wavelength division multiplexer, or an optical switch. The first optical coupling unit is an optical circulator, or a wavelength division multiplexer, or an optical switch; the third optical coupling unit is an optical circulator, or a wavelength division multiplexer, or an optical switch.

21. The apparatus of claim 20, wherein, The second optical coupling unit is an optical circulator, or a wavelength division multiplexer, or an optical switch; the fourth optical coupling unit is an optical circulator, or a wavelength division multiplexer, or an optical switch.

22. The apparatus of claim 17, wherein, The quantum state encoding and decoding device is applied to quantum state encoding and decoding.

23. The apparatus of claim 18 or 19, wherein, The quantum state encoding and decoding device and a coding and decoding control device are included.

24. A method of quantum state encoding and decoding, wherein, The coding and decoding control device is used for generating quantum communication encoding control instructions based on quantum communication system encoding requirements, and sending the instructions to the quantum state encoding and decoding device; and generating quantum communication decoding control instructions based on quantum communication system decoding requirements, and sending the instructions to the quantum state encoding and decoding device.

25. A software-defined quantum communication system, wherein, ​ ​

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