CN108650091B - Phase decoding method, phase decoding receiving device and quantum key distribution system - Google Patents
Phase decoding method, phase decoding receiving device and quantum key distribution system Download PDFInfo
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- H04B10/70—Photonic quantum communication
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- H—ELECTRICITY
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- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
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Abstract
The invention provides a phase decoding method, a receiving device and a quantum key distribution system, wherein the method comprises the following steps: polarizing and splitting an incident path of input light pulse into a first path of transmission light pulse and a second path of transmission light pulse; each of the first path of transmission light pulse and the second path of transmission light pulse is output through two associated sub-light paths after being subjected to phase decoding; the output light pulse from one of the two sub-optical paths associated with the first transmitted light pulse is directly output for detection, and the output light pulse from one of the two sub-optical paths associated with the second transmitted light pulse is directly output for detection. The invention can effectively solve the influence of the random change of the polarization state of the light pulse on the system stability, and realize stable phase decoding resistant to environmental interference. In addition, the invention can adopt the unequal arm Mach-Zehnder interferometer, and the optical pulse only needs to pass through the primary phase modulator when decoding, thereby reducing the insertion loss of the receiving end and improving the system efficiency.
Description
Technical Field
The present invention relates to the field of optical transmission secure communications, and in particular, to a phase decoding method, a phase decoding receiving device, and a quantum key distribution system.
Background
Based on the quantum key distribution technology and the one-time secret code principle, the quantum secret communication can realize information security in a public channel and gradually goes to application. For a phase coding quantum key distribution system based on an unequal arm interferometer, in the process of transmitting optical pulses through an optical fiber quantum channel, the optical fiber is made to have non-ideal conditions such as non-circular symmetry in section, non-uniform distribution of refractive index of a fiber core along radial direction and the like, and the optical fiber is influenced by temperature, strain, bending and the like in an actual environment to generate a double refraction effect, the polarization state of the optical pulses when reaching a receiving end can be randomly changed, so that an output result of the phase decoding interferometer is unstable, and the phenomenon is obviously deteriorated along with the increase of the distance of the optical fiber.
In the prior art, an unequal arm faraday-michelson interferometer is proposed that allows light pulses to remain stably output of the interference result when subjected to the random birefringence of the fibre channel and the resulting polarization state changes. However, such interferometers are large in loss, and the insertion loss of the phase modulator is one of the main factors causing the large loss. Specifically, when the phase modulator is placed on an arm of the interferometer, the light pulse passes through the phase modulator twice due to back and forth transmission, which results in a larger loss of the interferometer and lower system efficiency.
Disclosure of Invention
The invention mainly aims to provide a phase decoding method, a phase decoding receiving device and a quantum key distribution system, which are used for solving the problem of unstable output result caused by the polarization state change in the phase encoding quantum key distribution application.
The invention provides at least the following technical scheme:
1. A method of phase decoding, the method comprising:
polarization splitting is carried out on one path of input light pulse with any polarization state to obtain a first path of transmission light pulse and a second path of transmission light pulse with the polarization states mutually orthogonal;
The phase decoding is carried out on the first path of transmission light pulse and the second path of transmission light pulse respectively, and each path of transmission light pulse in the first path of transmission light pulse and the second path of transmission light pulse is output through two sub-optical paths associated with the first path of transmission light pulse and the second path of transmission light pulse after the phase decoding; and
The output light pulse from one of the two sub-light paths associated with the first transmission light pulse is directly output to a first single-photon detector for detection, and the output light pulse from one of the two sub-light paths associated with the second transmission light pulse is directly output to a second single-photon detector for detection.
2. The phase decoding method according to claim 1, characterized in that the method further comprises:
And outputting the output light pulse from the other sub-optical path of the two sub-optical paths associated with the first transmission light pulse to a third single-photon detector directly for detection, and outputting the output light pulse from the other sub-optical path of the two sub-optical paths associated with the second transmission light pulse to a fourth single-photon detector directly for detection.
3. The phase decoding method according to claim 1 or 2, wherein the phase decoding of the first transmission optical pulse and the second transmission optical pulse includes:
And for each of the first transmission light pulse and the second transmission light pulse, adopting an unequal arm Mach-Zehnder interferometer or an unequal arm Michelson interferometer to decode the phase of each transmission light pulse.
4. The phase decoding method according to claim 1, wherein a polarization maintaining device is used to maintain the polarization state of each optical pulse unchanged in the process from polarization beam splitting to phase decoding each of the transmitted optical pulses and outputting the decoded optical pulses.
5. A phase decoding reception apparatus, characterized by comprising: a polarizing beam splitter, a first phase decoder, a second phase decoder, a first single photon detector, and a second single photon detector, wherein
The polarization beam splitter is used for polarization splitting of one path of input light pulse with any incident polarization state into a first path of transmission light pulse and a second path of transmission light pulse with the polarization states mutually orthogonal;
the first phase decoder is used for performing phase decoding on the first path of transmission light pulse, and outputting the first path of transmission light pulse through two first sub-optical paths associated with the first path of transmission light pulse after the first path of transmission light pulse is subjected to phase decoding;
the second phase decoder is used for performing phase decoding on the second path of transmission light pulse, and outputting the second path of transmission light pulse through two second sub-optical paths associated with the second path of transmission light pulse after the second path of transmission light pulse is subjected to phase decoding;
The first single photon detector is directly coupled to one of the two first sub-optical paths;
The second single photon detector is directly optically coupled to one of the two second sub-optical paths.
6. The phase decoding receiving apparatus according to claim 5, further comprising a third single photon detector and a fourth single photon detector, wherein
The third single photon detector is directly coupled to the other one of the two first sub-optical paths;
The fourth single photon detector is directly optically coupled to the other of the two second sub-optical paths.
7. The phase decoding receiving apparatus according to claim 5, wherein phases modulated by the first phase decoder and the second phase decoder coincide.
8. The phase decoding receiving apparatus according to claim 5, wherein the first phase decoder and the second phase decoder use unequal arm mach-zehnder interferometers or unequal arm michelson interferometers.
9. The phase decoding receiving apparatus according to any one of claims 5 to 8, wherein the polarization beam splitter, the phase decoder, and associated discrete devices and waveguide devices that conduct light therebetween are polarization-maintaining devices.
10. A quantum key distribution system comprising the phase decoding reception device according to any one of claims 5 to 9.
11. The quantum key distribution system of claim 10, further comprising a single photon source and a phase encoder optically coupled to the single photon source, wherein the phase decoding receiving device is coupled to the phase encoder via a quantum channel.
12. The quantum key distribution system of claim 11, wherein the phase encoder employs any one of: unequal arm Mach-Zehnder interferometers, unequal arm Michelson interferometers, and unequal arm Faraday-Michelson interferometers.
The invention can effectively solve the influence of the random change of the polarization state of the input light pulse on the system stability, and realize stable phase decoding of the interference immunity of the transmission optical fiber environment. In addition, the invention has no restriction on the type of the interferometer adopted by the phase decoding receiving device, and can use the most commonly used unequal arm Mach-Zehnder interferometer, so that the optical pulse only needs to pass through the phase modulator once when decoding, thereby reducing the insertion loss of the receiving end and improving the system efficiency considerably. The invention provides a solution for establishing a high-efficiency quantum key distribution system for environmental interference immunity based on the unequal arm Mach-Zehnder interferometer. With the invention, optionally, phase decoding with low insertion loss independent of the polarization of the incoming input light pulses can be achieved at the receiving end by selecting an appropriate interferometer. The invention can provide a technical scheme of a stable and efficient quantum key distribution system with low insertion loss. In addition, the invention can reduce the requirements and complexity in the aspects of light path design and development and increase the flexibility.
Drawings
FIG. 1 is a flow chart of a phase decoding method according to a preferred embodiment of the present invention;
Fig. 2 is a schematic diagram showing the structure of a phase decoding receiving device according to a preferred embodiment of the present invention;
fig. 3 is a schematic diagram showing the construction of a phase decoding receiving device according to another preferred embodiment of the present invention;
fig. 4 is a schematic diagram showing the construction of a phase decoding receiving apparatus according to another preferred embodiment of the present invention;
Fig. 5 is a schematic diagram showing the composition and structure of a quantum key distribution system according to a preferred embodiment of the present invention.
Detailed Description
Preferred embodiments of the present application are described in detail below with reference to the attached drawing figures, which form a part of the present application and are used in conjunction with the embodiments of the present application to illustrate the principles of the present application. For the purposes of clarity and simplicity, detailed descriptions of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present application.
A phase decoding method according to a preferred embodiment of the present invention is shown in FIG. 1, and comprises the following steps:
step S101: and polarizing and splitting one path of input light pulse with any incident polarization state into a first path of transmission light pulse and a second path of transmission light pulse.
Specifically, the polarization state of the incident input light pulse may be any polarization state, and the polarization states of the first path of transmission light pulse and the second path of transmission light pulse after polarization beam splitting are mutually orthogonal.
Step S102: and respectively carrying out phase decoding on the first path of transmission light pulse and the second path of transmission light pulse, and outputting each path of transmission light pulse through two sub-optical paths associated with each path of transmission light pulse after phase decoding.
In one possible implementation manner, the phase decoding of the first transmission optical pulse and the second transmission optical pulse respectively includes: and for each of the first transmission light pulse and the second transmission light pulse, adopting an unequal arm Mach-Zehnder interferometer or an unequal arm Michelson interferometer to decode the phase of each transmission light pulse.
In addition, the first transmission optical pulse and the second transmission optical pulse may be respectively phase-decoded as follows:
For each of the first transmission light pulse and the second transmission light pulse, splitting the transmission light pulse into two sub transmission light pulses, and combining the split two sub transmission light pulses and outputting the combined two sub transmission light pulses through two sub light paths associated with the combined two sub transmission light pulses.
In this way, the two sub-output optical pulses are obtained by respectively performing phase decoding on the first path of transmission optical pulse and the second path of transmission optical pulse.
Here, specifically, two sub-transmission light pulses obtained by splitting one transmission light pulse are combined after a relative delay and output via two sub-light paths associated therewith.
In one embodiment of the invention, during phase decoding of each transmitted light pulse, the polarization state of the light pulses is controlled such that the polarization states of the respective two sub-transmitted light pulses are the same at the time of beam combination.
For example, controlling the polarization state of each light pulse may include: by using a polarization maintaining device, the polarization state of each light pulse is maintained unchanged all the time; or subjecting the polarization state of each light pulse to a known modulation.
In one embodiment of the present invention, a polarization maintaining device is used to maintain the polarization state of each light pulse unchanged during the process from polarization beam splitting to phase decoding each of the first and second transmitted light pulses to obtain sub-output light pulses.
Although not explicitly described above, it will be appreciated by those skilled in the art that phase modulation of the optical pulses is necessary at the receiving end for phase decoding.
The relative delay and phase modulation are in accordance with the requirements and specifications of the quantum key distribution protocol and are not described in detail herein.
Step S103: the output light pulse from one of the two sub-light paths associated with the first transmission light pulse is directly output to a first single-photon detector for detection, and the output light pulse from one of the two sub-light paths associated with the second transmission light pulse is directly output to a second single-photon detector for detection.
Here, the first single photon detector and the second single photon detector may be associated and synchronized for detection, and a valid detection is indicated when one and only one of the first single photon detector and the second single photon detector detects a light pulse during a door opening time.
Alternatively, the output light pulse from the other of the two sub-optical paths associated with the first transmission light pulse may be directly output to a third single-photon detector for detection, and the output light pulse from the other of the two sub-optical paths associated with the second transmission light pulse may be directly output to a fourth single-photon detector for detection. In this case, the third single photon detector and the fourth single photon detector may be associated and synchronized for detection, indicating an effective detection when one and only one of the third single photon detector and the fourth single photon detector detects a light pulse during a door opening time.
The phase decoding receiving device of the present invention comprises a polarizing beam splitter, a first and a second phase decoder, and a first and a second single photon detector. The input port of the polarization beam splitter is used for receiving one path of input light pulse with any incident polarization state and respectively outputting a first path of transmission light pulse and a second path of transmission light pulse with the polarization states mutually orthogonal through the two output ports of the polarization beam splitter. The first phase decoder is optically coupled to one output port of the polarizing beam splitter and is directly optically coupled to the first single photon detector via one of its associated two first sub-optical paths. The second phase decoder is optically coupled to the other output port of the polarizing beam splitter and is directly optically coupled to the second single photon detector via one of its associated two second sub-optical paths.
A phase decoding receiving apparatus according to a preferred embodiment of the present invention is shown in fig. 2, and includes the following components: a polarizing beam splitter 201, two phase decoders 202 and a pair of single photon detectors (not shown).
The polarization beam splitter 201 is configured to polarization-split an incident input optical pulse with any polarization state into a first transmission optical pulse and a second transmission optical pulse.
Specifically, the polarization state of the incident input light pulse may be any polarization state, and the polarization states of the first path of transmission light pulse and the second path of transmission light pulse obtained by polarization beam splitting are mutually orthogonal.
Two phase decoders 202 are optically coupled to the polarization beam splitter 201, respectively, for phase decoding the first and second transmission light pulses, respectively, and outputting each transmission light pulse via the associated two sub-optical paths after phase decoding.
Specifically, each phase decoder 202 is configured to:
splitting one path of transmission light pulse into two sub-transmission light pulses, combining the split two sub-transmission light pulses, and outputting the combined two sub-transmission light pulses through two sub-light paths associated with the combined two sub-transmission light pulses.
Here, specifically, two sub-transmission light pulses obtained by splitting one transmission light pulse are combined after a relative delay and output via two sub-light paths associated therewith. As described above, the relative delay is performed according to the specification and requirements of the quantum key distribution protocol, and will not be described herein.
It should be noted that, with the phase decoding receiving apparatus of fig. 2, an input optical pulse before polarization beam splitting may be phase-modulated according to a quantum key distribution protocol before the polarization beam splitter 201, or each of a first path of transmission optical pulse and a second path of transmission optical pulse obtained by polarization beam splitting may be phase-modulated according to a quantum key distribution protocol, or after each path of transmission optical pulse is split into two sub-transmission optical pulses, at least one path of sub-transmission optical pulse may be phase-modulated by a corresponding phase decoder 202 according to a quantum key distribution protocol.
In the case of phase modulation by the phase decoders, the phases modulated by the two phase decoders 202 coincide.
The two phase decoders 202 may alternatively employ unequal arm mach-zehnder interferometers or unequal arm michelson interferometers.
In addition, the polarization beam splitter 201, phase decoder 202, and associated discrete devices and waveguide devices used to conduct light may each be polarization maintaining devices. In this way, the polarization state of each light pulse can be maintained unchanged. The eigenstates of the orthogonal basis of the polarization beam splitter 201 coincide with the mutually orthogonal polarization states of the two transmitted light pulses obtained by polarization beam splitting. The discrete devices and waveguide devices used by the phase decoders and associated guided light may be collectively referred to herein as optical devices on the optical path between the polarizing beam splitter and each single photon detector.
In fig. 2, one of the two sub-paths for output of the upper phase decoder 202 is optically coupled to one of the pair of single-photon detectors, and one of the two sub-paths for output of the lower phase decoder 202 is optically coupled to the other of the pair of single-photon detectors. The pair of single photon detectors may be associated and configured to detect simultaneously. An effective detection is indicated when one and only one of the pair of single photon detectors detects a pulse of light during a door open time.
In an application, another pair of single photon detectors may be provided as desired. In this case, the other of the two sub-paths for output of the upper phase decoder 202 in fig. 2 is optically coupled to one of the other pair of single-photon detectors, and the other of the two sub-paths for output of the lower phase decoder 202 is optically coupled to the other of the other pair of single-photon detectors. The other pair of single photon detectors may be associated and configured to detect simultaneously. An effective detection is indicated when one and only one single photon detector of the other pair detects a pulse of light during a door open time.
A phase decoding receiving apparatus according to another preferred embodiment of the present invention is shown in fig. 3, and includes the following components: a polarizing beam splitter 301, two phase decoders 302 and 303, and a pair of single photon detectors (not shown).
The polarization beam splitter 301 polarization splits one input optical pulse into two transmission optical pulses. One path of transmission light pulse is output through two sub-light paths after being subjected to phase decoding by the phase decoder 302; the other transmission light pulse is phase-decoded by the phase decoder 303 and then output via its two sub-optical paths. Each of the phase decoders 302 and 303 employs an unequal arm mach-zehnder interferometer. One of the two sub-optical paths for output of phase decoder 302 is optically coupled to one of the pair of single-photon detectors, and one of the two sub-optical paths for output of phase decoder 303 is optically coupled to the other of the pair of single-photon detectors. The pair of single photon detectors may be associated and configured to detect simultaneously. An effective detection is indicated when one and only one of the pair of single photon detectors detects a pulse of light during a door open time.
In an application, another pair of single photon detectors may be provided as desired. In this case, the other of the two sub-paths for output of the phase decoder 302 is optically coupled to one of the other pair of single-photon detectors, and the other of the two sub-paths for output of the phase decoder 303 is optically coupled to the other of the other pair of single-photon detectors. The other pair of single photon detectors may be associated and configured to detect simultaneously. An effective detection is indicated when one and only one single photon detector of the other pair detects a pulse of light during a door open time.
The phases modulated by the phase decoder 302 and the phase decoder 303 coincide. In the phase decoding receiving device, devices on an optical path between the polarization beam splitter and the phase decoder are polarization control devices. Although phase modulation at the phase decoder 302 and the phase decoder 303 is mentioned here, it is also possible to phase modulate the input optical pulse before polarization splitting in accordance with the quantum key distribution protocol before the polarization beam splitter 301, or to phase modulate each of the two transmission optical pulses obtained by polarization splitting in accordance with the quantum key distribution protocol.
A phase decoding receiving apparatus according to another preferred embodiment of the present invention is shown in fig. 4, and includes the following components: a polarizing beam splitter 401, two phase decoders 402 and 403, and a pair of single photon detectors (not shown).
The polarization beam splitter 401 polarization splits one input optical pulse into two transmission optical pulses. One path of transmission light pulse is output through two sub-light paths after being subjected to phase decoding by the phase decoder 402; the other transmission light pulse is phase-decoded by the phase decoder 403 and then output via two sub-optical paths thereof. Phase decoders 402 and 403 each employ an unequal arm michelson interferometer. The output only sub-optical path of phase decoder 402 is optically coupled to one single photon detector of the pair of single photon detectors and the output only sub-optical path of phase decoder 403 is optically coupled to the other single photon detector of the pair of single photon detectors. The pair of single photon detectors may be associated and configured to detect simultaneously. An effective detection is indicated when one and only one of the pair of single photon detectors detects a pulse of light during a door open time.
The phases modulated by the phase decoder 402 and the phase decoder 403 coincide. In the phase decoding receiving device, devices on an optical path between the polarization beam splitter and the phase decoder are polarization control devices. Although phase modulation at the phase decoder 402 and the phase decoder 403 is mentioned here, it is also possible to phase modulate the input optical pulse before polarization splitting in accordance with the quantum key distribution protocol before the polarization beam splitter 401, or to phase modulate each of the two transmission optical pulses obtained by polarization splitting in accordance with the quantum key distribution protocol.
The phase decoding reception apparatus of the present invention, such as the one shown in any one of fig. 2 to 4, can be regarded as including two parts: a phase decoding device and a single photon detector, wherein the phase decoding device comprises a polarizing beam splitter and a phase decoder, the single photon detector may comprise one or two pairs of single photon detectors, each single photon detector being directly coupled to a respective phase decoder.
A quantum key distribution system according to a preferred embodiment of the present invention is shown in fig. 5, and comprises the following components: a single photon source 501, a phase encoder 502, a quantum channel 503, and phase decoding receiving means 504-506 as described above, wherein the phase decoding receiving means 504-506 comprises a phase decoding means 504 and a pair of single photon detectors 505, 506 directly coupled to the phase decoding means. Phase decoding receiving means 504-506 are coupled to phase encoder 502 via quantum channel 503. Specifically, phase decoding device 504 is coupled to phase encoder 502 via quantum channel 503.
In one embodiment, a single photon source 501 is used to generate single photon light pulses. The phase encoder 502 is used to phase encode the single photon light pulses generated by the single photon source 501 in accordance with a quantum key distribution protocol. The quantum channel 503 is used to transmit the phase encoded single photon light pulses to a phase decoding means 504. The phase decoding means 504 is arranged to phase decode the single photon light pulses transmitted via the quantum channel 503 in accordance with a quantum key distribution protocol.
The single photon detectors 505 and 506 in the phase decoding receiving means constitute a pair of single photon detectors as described above for detecting the output light pulses from the phase decoding means 504, the effective detection being recorded once when there is and only one response in the single photon detectors 505 and 506 during a door-open time.
In addition, as described above, another pair of single photon detectors may be added to the phase decoding receiving device according to circumstances, for example, if two sets of output results need to be recorded.
The phase decoding reception apparatus in fig. 5 may use the phase decoding reception apparatus shown in any one of fig. 2 to 4 or other phase decoding reception apparatus according to the present invention.
The single photon source 501 emits a single photon light pulse into the phase encoder 502, the phase encoder 502 performs phase encoding on the single photon light pulse, the phase encoded light pulse is transmitted to the phase decoding receiving devices 504-506 through the quantum channel 503, and the phase decoding receiving devices 504-506 perform phase decoding and detection on the incident single photon pulse. The phase encoder 502 and phase decoding receivers 504-506 phase encode and decode the light pulses, respectively, according to a quantum key distribution protocol, and perform key distribution according to the quantum key distribution protocol.
Specifically, the phase encoder 502 employs any one of the following: unequal arm Mach-Zehnder interferometers, unequal arm Michelson interferometers, and unequal arm Faraday-Michelson interferometers.
The quantum channel 503 may be an optical waveguide, an optical fiber, a free space, a discrete optical element, a planar waveguide optical element, a fiber optical element, or a light propagation channel combining any two or more of the foregoing.
In general, the idea of the invention is that: carrying out polarization diversity processing on an incident input light pulse at a receiving end, and carrying out polarization splitting on the input light pulse into two paths of transmission light pulses with mutually orthogonal polarization states, so that a polarization control type device or a polarization maintaining type device can be used for the input light pulse with any polarization state; in addition, the output light pulse obtained after the phase decoding is directly output to the single photon detector for detection at the receiving end, and the step of polarization beam combination of the output light pulse with different polarization states is omitted by properly operating the single photon detector.
Accordingly, the present invention makes it possible to: in quantum key distribution applications, the problem of system stability due to the random variation of the polarization state of the light pulses during transmission is avoided at the receiving end by using polarization-controlling or polarization-maintaining devices without the need to know or determine the polarization state of the input light pulses beforehand, i.e. eliminating the need for the aforementioned complex polarization state monitoring and/or calibration means; in addition, by operating and controlling the single photon detector from an electrical perspective, proper detection of the output light pulses is achieved while reducing the requirements and complexity in light path design and development.
In addition, the interferometer used by the phase decoding receiving device at the receiving end can be various types, including an unequal arm Mach-Zehnder interferometer, and is not limited to an unequal arm Michelson interferometer. Therefore, by selecting a proper interferometer, the problem of system stability is solved, and meanwhile, the lower insertion loss of the receiving end can be realized.
From the foregoing description, it will be appreciated that specific details and functions of the invention have been set forth in order to achieve the desired objects, but that the drawings are merely for purposes of illustration and description, and are not intended to be limiting.
Claims (12)
1. A method of phase decoding, the method comprising:
Providing a phase decoding receiving device comprising a polarizing beam splitter, a first phase decoder and a second phase decoder, and a first single photon detector and a second single photon detector;
The polarization beam splitter splits one path of input light pulse with any incident polarization state into a first path of transmission light pulse and a second path of transmission light pulse with the polarization states orthogonal to each other;
The first phase decoder and the second phase decoder are used for respectively carrying out phase decoding on the first path of transmission light pulse and the second path of transmission light pulse, and each path of transmission light pulse in the first path of transmission light pulse and the second path of transmission light pulse is output through two sub-optical paths associated with the first path of transmission light pulse and the second path of transmission light pulse after the phase decoding; and
Directly outputting the output light pulse from one of the two sub-light paths associated with the first transmission light pulse to the first single-photon detector for detection, directly outputting the output light pulse from one of the two sub-light paths associated with the second transmission light pulse to the second single-photon detector for detection,
Wherein the first single photon detector and the second single photon detector are associated and configured to detect simultaneously, indicating an active detection when one and only one of the first single photon detector and the second single photon detector detects a light pulse during a door-open time.
2. The phase decoding method of claim 1, wherein the method further comprises:
And outputting the output light pulse from the other sub-optical path of the two sub-optical paths associated with the first transmission light pulse to a third single-photon detector directly for detection, and outputting the output light pulse from the other sub-optical path of the two sub-optical paths associated with the second transmission light pulse to a fourth single-photon detector directly for detection.
3. The phase decoding method according to claim 1 or 2, wherein the phase decoding of the first and second transmission light pulses, respectively, comprises:
And for each of the first transmission light pulse and the second transmission light pulse, adopting an unequal arm Mach-Zehnder interferometer or an unequal arm Michelson interferometer to decode the phase of each transmission light pulse.
4. The phase decoding method according to claim 1, wherein a polarization maintaining device is used to maintain the polarization state of each optical pulse unchanged in the process of polarization beam splitting to phase-decode each transmitted optical pulse and outputting it after phase decoding.
5. A phase decoding reception apparatus, characterized by comprising: a polarizing beam splitter, a first phase decoder, a second phase decoder, a first single photon detector, and a second single photon detector, wherein
The polarization beam splitter is used for polarization splitting of one path of input light pulse with any incident polarization state into a first path of transmission light pulse and a second path of transmission light pulse with the polarization states mutually orthogonal;
the first phase decoder is used for performing phase decoding on the first path of transmission light pulse, and outputting the first path of transmission light pulse through two first sub-optical paths associated with the first path of transmission light pulse after the first path of transmission light pulse is subjected to phase decoding;
the second phase decoder is used for performing phase decoding on the second path of transmission light pulse, and outputting the second path of transmission light pulse through two second sub-optical paths associated with the second path of transmission light pulse after the second path of transmission light pulse is subjected to phase decoding;
The first single photon detector is directly coupled to one of the two first sub-optical paths;
the second single photon detector is directly optically coupled to one of the two second sub-optical paths,
Wherein the first single photon detector and the second single photon detector are associated and configured to detect simultaneously, indicating an active detection when one and only one of the first single photon detector and the second single photon detector detects a light pulse during a door-open time.
6. The phase decoding receiving apparatus according to claim 5, further comprising a third single photon detector and a fourth single photon detector, wherein
The third single photon detector is directly coupled to the other one of the two first sub-optical paths;
The fourth single photon detector is directly optically coupled to the other of the two second sub-optical paths.
7. The phase decoding receiving apparatus according to claim 5, wherein phases modulated by the first phase decoder and the second phase decoder coincide.
8. The phase decoding receiver of claim 5, wherein the first and second phase decoders employ unequal arm mach-zehnder interferometers or unequal arm michelson interferometers.
9. A phase decoding receiving arrangement according to any of claims 5-8, characterized in that the polarizing beam splitter, the phase decoder, and associated discrete devices and waveguide devices between which light is conducted for use are all polarization maintaining devices.
10. A quantum key distribution system comprising a phase decoding receiving device according to any one of claims 5 to 9.
11. The quantum key distribution system of claim 10, further comprising a single photon source and a phase encoder optically coupled to the single photon source, wherein the phase decoding receiving device is coupled to the phase encoder via a quantum channel.
12. The quantum key distribution system of claim 11, wherein the phase encoder employs any one of: unequal arm Mach-Zehnder interferometers, unequal arm Michelson interferometers, and unequal arm Faraday-Michelson interferometers.
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| CN109342830B (en) * | 2018-10-23 | 2021-07-02 | 山西大学 | Microwave field intensity atom measuring device of all-fiber Mach-Zehnder interferometer |
| CN109039619B (en) * | 2018-10-29 | 2023-05-26 | 中国电子科技集团公司电子科学研究院 | Quantum key distribution time bit-phase decoding method and device and corresponding system |
| CN109120401B (en) * | 2018-10-29 | 2023-07-28 | 中国电子科技集团公司电子科学研究院 | Method, device and system for decoding polarization quadrature rotation direct current modulation quantum key distribution time bit-phase |
| CN109039618B (en) * | 2018-10-29 | 2023-08-04 | 中国电子科技集团公司电子科学研究院 | Quantum key distribution phase decoding method, device and corresponding system |
| CN109039623B (en) * | 2018-10-29 | 2023-05-23 | 中国电子科技集团公司电子科学研究院 | Method and device for decoding direct current modulation quantum key distribution phase and corresponding system |
| CN109104277B (en) * | 2018-10-29 | 2023-09-15 | 中国电子科技集团公司电子科学研究院 | Method, device and corresponding system for decoding direct current modulation quantum key distribution phase |
| CN109039626B (en) * | 2018-10-29 | 2023-05-23 | 中国电子科技集团公司电子科学研究院 | Quantum key distribution time bit-phase decoding method and device controlled by phase difference |
| CN109150525B (en) * | 2018-10-29 | 2023-08-22 | 中国电子科技集团公司电子科学研究院 | Quantum key distribution phase decoding method, device and corresponding system |
| CN109039622B (en) * | 2018-10-29 | 2023-08-11 | 中国电子科技集团公司电子科学研究院 | Quantum key distribution time bit-phase decoding method and device and corresponding system |
| CN109039625B (en) * | 2018-10-29 | 2023-05-26 | 中国电子科技集团公司电子科学研究院 | Quantum key distribution time bit-phase decoding method, device and system |
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