CN117254855A - Method, device, medium and equipment for optimizing based on quantum bit error rate - Google Patents
Method, device, medium and equipment for optimizing based on quantum bit error rate Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
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- H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
- H04B10/0795—Performance monitoring; Measurement of transmission parameters
- H04B10/07953—Monitoring or measuring OSNR, BER or Q
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/508—Pulse generation, e.g. generation of solitons
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
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Abstract
The invention provides a method, a device, a medium and equipment for optimizing based on a quantum bit error rate, wherein the method comprises the following steps: preparing the qubit information into an optical pulse output by a light source; transmitting the prepared optical pulse to a receiving end; receiving the prepared light pulse from the transmitting end; decoding quantum bit information carried in the received optical pulse; changing the delay position of the gating signal according to a preset step length; counting the quantity of inconsistent quantum bit information at each delay position; determining a quantum bit error rate at each delay location based on a ratio between the number of non-identical quantum bit information at each delay location and the number of quantum bit information used for preparation; the delay position of the gating signal applied to the single photon detector is locked to the delay position corresponding to the minimum value in the quantum bit error rate. The invention can find the optimal delay position for the gating signal applied to the single photon detector so as to ensure that the single photon detector has high detection efficiency and accuracy.
Description
Technical Field
The present invention relates to the field of quantum communications technologies, and in particular, to a method, an apparatus, a medium, and a device for optimizing based on a quantum bit error rate.
Background
In general, in a quantum communication system (in particular, a quantum key distribution system), a quantum bit error rate (Quantum Bit Error Rate, QBER) is used to measure an error rate of a quantum bit in a transmission or measurement process, and the lower the quantum bit error rate, the more accurate the quantum bit or measurement result transmitted by the quantum communication system, which means that the quantum communication system has a high security key generation rate. Thus, the quantum bit error rate is one of the key performance indicators of a quantum communication system, which can be used to evaluate the quality and security of the quantum communication system.
In the related art, a periodic gating signal is mainly applied to a single photon detector to control the single photon detector to detect an optical signal received by the single photon detector, in other words, the gating signal is a control signal for controlling when the single photon detector starts detecting photons. Therefore, the gating signal controls the time when the single photon detector detects photons to determine the detection efficiency and accuracy of the single photon detector. However, as the surrounding environment changes, in a quantum communication system, the path length of a photon transmitted from an emitting end to a receiving end may change, for example, when the photon is transmitted from the emitting end to the receiving end through an optical fiber, the photon may generate propagation delay due to bending of the optical fiber, temperature change, pressure change, and the like, which may result in that a single photon detector disposed in the receiving end may not always be able to be turned on at a proper timing (particularly, when the photon reaches the receiving end) under the control of a gating signal. In addition, if the gating signal is not properly turned on, the single photon detector may be misoperated when the single photon detector should not be detected. For example, if the gating signal turns on the single photon detector prematurely, the single photon detector may already be in operation before the photon arrives, thereby producing a false positive. This reduces the detection efficiency and accuracy of the single photon detector, thereby increasing the quantum bit error rate of the system. Therefore, the timing at which the gating signal turns on the single photon detector operation is very important for stability of system performance.
Disclosure of Invention
The invention aims to provide a method, a device, a medium and equipment for optimizing based on a quantum bit error rate.
According to an aspect of the present invention, there is provided a method for optimizing based on a quantum bit error rate, the method comprising: preparing qubit information into an optical pulse output by a light source by using an optical coding module; transmitting the prepared light pulse to a receiving end through an optical fiber or free space; receiving the prepared light pulses from the emitting end via an optical fiber or free space; decoding qubit information carried in the received light pulses using an optical decoding module, wherein the optical decoding module comprises a single photon detector that detects the received light pulses by a gating signal applied to the single photon detector; changing delay positions of a gating signal applied to the single photon detector according to a preset step length to acquire qubit information obtained through decoding at each delay position of the gating signal; comparing the qubit information obtained by the decoding at each delay position of the gating signal with the qubit information used for the preparation to count the quantity of the qubit information which is not consistent with the qubit information used for the preparation and obtained by the decoding at each delay position of the gating signal; determining a quantum bit error rate at each delay position of the gating signal based on a ratio between a number of quantum bit information inconsistent with the quantum bit information for the preparation and a number of quantum bit information for the preparation obtained by the decoding at each delay position of the gating signal; and locking the delay position of the gating signal applied to the single photon detector to the delay position of the gating signal corresponding to the minimum value in the quantum bit error rate at each delay position of the gating signal.
According to one embodiment of the invention, the gating signal causes the single photon detector to be in an on state for a time window corresponding to a high level of the gating signal and causes the single photon detector to be in an off state for a time window corresponding to a low level of the gating signal.
According to one embodiment of the invention, the optical encoding module is comprised in the transmitting end and the optical decoding module is comprised in the receiving end.
According to one embodiment of the invention, the qubit information is prepared into the optical pulse in at least one of a polarization state, a phase state and a time state of the optical pulse.
According to one embodiment of the invention, the quantum communication system comprising the transmitting end and the receiving end is a quantum key distribution system based on a COW quantum key distribution protocol.
According to one embodiment of the invention, the single photon detector comprises a data detector for detecting light pulses and a monitoring detector for monitoring coherence between the light pulses.
According to one embodiment of the invention, the optical decoding module detects the received light pulses by the data detector.
According to another aspect of the present invention, there is also provided an apparatus for optimizing based on a quantum bit error rate, the apparatus comprising: an optical preparation unit configured to prepare qubit information into an optical pulse output from the light source using the optical encoding module; an optical transmission unit configured to transmit the prepared optical pulse to a receiving end via an optical fiber or free space; a light receiving unit configured to receive the prepared light pulses from the emitting end via an optical fiber or free space; a light detection unit configured to decode qubit information carried in a received light pulse using an optical decoding module, wherein the optical decoding module comprises a single photon detector that detects the received light pulse by a gating signal applied to the single photon detector; a gating signal stepping unit configured to change delay positions of a gating signal applied to the single photon detector by a predetermined step length to obtain qubit information obtained by the decoding at each delay position of the gating signal; a qubit comparison unit configured to compare qubit information obtained by the decoding at each delay position of the gating signal with qubit information for the preparation, to count the number of qubit information obtained by the decoding at each delay position of the gating signal that is inconsistent with the qubit information for the preparation; a bit error rate calculation unit configured to determine a bit error rate at each delay position of the gating signal based on a ratio between a number of qubit information inconsistent with the qubit information for the preparation and a number of qubit information for the preparation obtained by the decoding at each delay position of the gating signal; and a gating signal locking unit configured to lock a delay position of a gating signal applied to the single photon detector to a delay position of the gating signal corresponding to a minimum value among quantum bit error rates at respective delay positions of the gating signal.
According to one embodiment of the invention, the gating signal causes the single photon detector to be in an on state for a time window corresponding to a high level of the gating signal and causes the single photon detector to be in an off state for a time window corresponding to a low level of the gating signal.
According to one embodiment of the invention, the optical encoding module is comprised in the transmitting end and the optical decoding module is comprised in the receiving end.
According to one embodiment of the invention, the qubit information is prepared into the optical pulse in at least one of a polarization state, a phase state and a time state of the optical pulse.
According to one embodiment of the invention, the quantum communication system comprising the transmitting end and the receiving end is a quantum key distribution system based on a COW quantum key distribution protocol.
According to one embodiment of the invention, the single photon detector comprises a data detector for detecting light pulses and a monitoring detector for monitoring coherence between the light pulses.
According to one embodiment of the invention, the optical decoding module detects the received light pulses by the data detector.
According to another aspect of the invention there is also provided a computer readable storage medium storing a computer program which, when executed by a processor, implements a method of optimizing based on a quantum bit error rate as described above.
According to another aspect of the present invention, there is also provided a computer apparatus including: a processor; a memory storing a computer program which, when executed by a processor, implements a method of optimizing based on a qubit error rate as described above.
The method, the device, the medium and the equipment for optimizing based on the quantum bit error rate find the optimal delay position for the gating signal applied to the single photon detector, so that the single photon detector is started at a proper time, and the single photon detector is ensured to have high detection efficiency and accuracy. For quantum communication systems, false positives (such as, but not limited to, dark counts, etc.) due to turning on single photon detectors at improper times can be effectively avoided. Thus, the quantum bit error rate of the quantum communication system can be minimized, and the system bit rate is improved.
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The above objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.
Fig. 1 shows a schematic flow chart of a method of optimizing based on a quantum bit error rate according to an exemplary embodiment of the invention.
Fig. 2 shows an exemplary data interaction procedure for optimizing based on a quantum bit error rate in a quantum communication system based on a COW quantum key distribution protocol according to an exemplary embodiment of the present invention.
Fig. 3 is a schematic block diagram illustrating an apparatus for optimizing based on a quantum bit error rate according to an exemplary embodiment of the present invention.
Detailed Description
In a single photon detector, the gating signal is a signal that is used to control its on and off. When the gating signal is at a high level, the single photon detector is in an on state and can receive an optical signal; when the gating signal is at a low level, the single photon detector is in an off state and does not receive an optical signal. In other words, the gating signal may cause the single photon detector to be in an on state for a time window corresponding to a high level of the gating signal and cause the single photon detector to be in an off state for a time window corresponding to a low level of the gating signal. Therefore, in the single photon detector, the gating signal can be used to control the working mode of the detector, and by changing the delay position of the gating signal, the single photon detector can receive the optical signal at a proper time, which is very important for applications requiring accurate measurement of the time sequence characteristic of the optical signal or time resolution of the optical signal. In addition, by changing the delay position of the gating signal, the background noise of the single photon detector in the process of detecting the optical signal can be reduced, so that the signal-to-noise ratio and the detection sensitivity of the single photon detector can be improved. In addition, by changing the delay position of the gating signal, the dark count rate of the single photon detector in a specific time window can be limited, so that the generation of false signals can be reduced.
Therefore, the delay position of the gating signal is properly set, so that the detection efficiency and accuracy of the single photon detector can be improved.
Therefore, the invention provides a method, a device, a medium and equipment for optimizing based on the quantum bit error rate.
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Fig. 1 shows a schematic flow chart of a method of optimizing based on a quantum bit error rate according to an exemplary embodiment of the invention.
Referring to fig. 1, the method illustrated in fig. 1 may include the following steps.
In step 101, qubit information is prepared into an optical pulse output by an optical source using an optical encoding module.
Here, as a non-limiting example, the qubit information may be prepared into the optical pulse in at least one of a polarization state, a phase state, and a time state of the optical pulse.
In step 102, the prepared light pulses are transmitted to the receiving end via an optical fiber or free space.
In step 103, the prepared light pulses are received from the transmitting end via an optical fiber or free space.
In step 104, the qubit information carried in the received light pulses is decoded using an optical decoding module, wherein the optical decoding module comprises a single photon detector that detects the received light pulses by a gating signal applied to the single photon detector.
In step 105, delay positions of the gating signal applied to the single photon detector are changed by a predetermined step to obtain qubit information obtained by decoding at the respective delay positions of the gating signal.
In step 106, the qubit information obtained by decoding at each delay position of the gating signal is compared with the qubit information for preparation to count the number of qubit information obtained by decoding at each delay position of the gating signal that is inconsistent with the qubit information for preparation.
In step 107, the qubit error rate at each delay position of the gating signal is determined based on a ratio between the number of qubit information obtained by decoding at each delay position of the gating signal that is inconsistent with the qubit information used for preparation and the number of qubit information used for preparation.
At step 108, the delay position of the gating signal applied to the single photon detector is locked to the delay position of the gating signal corresponding to the minimum of the quantum bit error rates at the respective bias voltages of the gating signal.
In short, the delay position of the gating signal applied to the single photon detector is adjusted and locked according to the quantum bit error rate, so that the single photon detector is started at a proper time, and the single photon detector is ensured to have high detection efficiency and accuracy.
In some examples, a quantum communication system may be constructed that includes a transmitting end and a receiving end, between which a stable quantum channel may be established to enable optical communication via optical fibers or free space, in which system an optical encoding module may be included in the transmitting end and an optical decoding module may be included in the receiving end. Then, at the transmitting end, a series of qubits are generated and sent to the receiving end over a quantum channel. These qubits may be single photon states (either polarization or phase as previously described) or may be temporal or other quantum states. The present invention is not limited in this regard. Next, at the receiving end, an optical decoding module or other qubit detection system may be used to receive and detect the transmitted qubit sequence, and compare the received qubit sequence with the qubits at the time of transmission to calculate a qubit error rate from the comparison result, which may be calculated using, for example, but not limited to, the following equation.
Where QBER is the bit error rate, the number of erroneous qubits is the number of qubits in the received qubit sequence that do not correspond to the qubit sequence at the time of transmission, and the total number of qubits is the total number of qubits in the qubit sequence at the time of transmission.
Through the calculation, the quantum bit error rate under each delay position of the gating signal can be obtained, then the delay position of the gating signal applied to the single photon detector is locked to the delay position of the gating signal corresponding to the minimum value in the quantum bit error rate under each delay position of the gating signal, so that the accurate setting of the delay position of the gating signal is realized, and the single photon detector is ensured to have high detection efficiency and accuracy.
It should be noted that, the calculation of the bit error rate of the qubit requires a large number of qubits to be counted to obtain an accurate result. Therefore, multiple tests and statistics are typically performed to obtain a more accurate quantum bit error rate.
It can be seen that using the method shown in fig. 1, the optimum delay position can be found for the gating signal applied to the single photon detector. For quantum communication systems, false positives (such as, but not limited to, dark counts, etc.) due to turning on single photon detectors at improper times can be effectively avoided. Thus, the quantum bit error rate of the quantum communication system can be minimized, and the system bit rate is improved.
In the following, a detailed implementation of optimizing based on a quantum bit error rate according to an exemplary embodiment of the present invention will be described in further detail by taking a quantum communication system based on a COW quantum key distribution protocol as an example.
Fig. 2 shows an exemplary data interaction procedure based on the quantum bit error rate optimization in a quantum communication system based on the COW (Coherent One Way) quantum key distribution protocol according to an exemplary embodiment of the present invention.
Referring to fig. 2, in the quantum communication system shown in fig. 2, an optical encoding module having a light source Laser and an intensity modulator IM disposed therein may be included in an emitter Alice having a data detector D disposed therein for detecting light pulses B And a monitoring detector D for checking coherence between the light pulses M1 And D M2 Can be included in the receiving end Bob, where a beam splitter can be used to split a portion of the light pulses to enter the monitor detector D via the unequal arm interferometer M-Z M1 And D M2 Simultaneously beam-splitting another part of the light pulse to enter the data detectorD B 。
In the quantum communication system shown in fig. 2, the light source Laser and the intensity modulator IM may randomly emit light pulses carrying one of the following three signal states based on the COW quantum key distribution protocol: bit 0 signal state (logic 0), bit1 signal state (logic 1) and decoy signal state (decoy state). In the light pulse sequence emitted by the light source Laser, the interval isCan generate coherent interference at the output end of the unequal-arm interferometer M-Z, and monitor the detector D M1 And D M2 It can be monitored whether the result of its intervention reaches a desired value.
In the quantum communication system shown in fig. 2, the optimization may be performed in accordance with the data interaction procedure shown in fig. 2.
In S201, the receiving end Bob enables the data detector D B Disabling monitor detector D M1 And D M2 And at S202, notifying the transmitting end Alice to enter the optimizing state.
In S203, the transmitting end Alice prepares qubit information into an optical pulse according to the optimizing notification, and sends the optical pulse to the receiving end Bob.
In S204, the receiving end Bob acquires the data applied to the data detector D B An initial value delay of the delay position of the gate control signal and an average value tmp_qber of the quantum bit error rate obtained by a plurality of times of calculation, and is applied to a data detector D B The step value of the delay position of the gate signal is set to delay_step, and during the step, the progressive direction of the delay position of the gate signal can be set to be firstly decreased and then applied to the data detector D B The delay value of the gate signal of (a) is set to be day_current=delay-delay_step to the data detector D B And applying a gating signal after adjusting the delay position.
In S205, the receiving end Bob passes through the data detector D B Receiving an optical pulse transmitted by an emitting end Alice, and calculating according to a comparison result between quantum bit information carried by the received optical pulse and quantum bit information prepared into the optical pulse by the emitting end AliceIf qber is smaller than tmp_qber, tmp_qber is updated to be the current value qber, and the delay value of the gating signal is controlled to continue to decrease according to bias_step cycle; if qber is greater than tmp_qber, the progressive direction of the delay value of the gating signal is changed to increment and applied to the data detector D B The delay value of the gate signal of (a) is set to delay_current=delay+delay_step to continue to the data detector D B And applying a gating signal after adjusting the delay position.
In S206, the receiving end Bob continues to pass through the data detector D B Receiving an optical pulse transmitted by an emitting end Alice, calculating a quantum bit error rate qber according to a comparison result between quantum bit information carried by the received optical pulse and quantum bit information prepared into the optical pulse by the emitting end Alice, if qber is smaller than tmp_qber, updating tmp_qber into a current value qber, and controlling the application to a data detector D B The delay value of the gating signal of (2) is further stepped according to the previously set delay_step and then is further set for application to the data detector D B Delay_current of the gate signal of (2) to continue to the data detector D B And applying a gating signal after adjusting the delay position.
Next, the receiving end Bob continues to calculate the qubit error rate qber until the current qber is greater than tmp_qber, at which time it stops stepping according to the previously set delay_step, and determines the last delay_current as being applied to the data detector D B The optimum delay value of the gating signal of (2) is then applied to the data detector D B The delay position of the gate control signal is locked to the delay_current of the last time, and in S207, the transmitting terminal Alice is notified to complete the optimization.
Finally, the receiving end Bob enables the monitoring detector D M1 And D M2 And notifying the system that the minimum quantum bit error rate is found, sending the state to the transmitting end Alice, and notifying the transmitting end Alice that the minimum quantum bit error rate is found, so that the whole system enters a new working state.
It should be appreciated that although fig. 2 illustrates an example of optimizing based on a quantum bit error rate in a quantum communication system based on a COW quantum key distribution protocol according to an exemplary embodiment of the present invention, the present invention is not limited thereto, and optimizing based on a quantum bit error rate may be performed in a quantum communication system based on other quantum key distribution protocols as needed.
Fig. 3 is a schematic block diagram illustrating an apparatus for optimizing based on a quantum bit error rate according to an exemplary embodiment of the present invention.
Referring to fig. 3, the apparatus shown in fig. 3 may include at least an optical preparation unit 301, an optical transmission unit 302, an optical reception unit 303, an optical detection unit 304, a gating signal stepping unit 305, a qubit comparison unit 306, an error rate calculation unit 307, and a gating signal locking unit 308.
In the apparatus shown in fig. 3, the light preparation unit 301 may be configured to prepare qubit information into light pulses output by the light source using the optical encoding module; the optical transmission unit 302 may be configured to transmit the prepared optical pulse to the receiving end via an optical fiber or free space; the light receiving unit 303 may be configured to receive the prepared light pulses from the emitting end via an optical fiber or free space; the light detection unit 304 may be configured to decode qubit information carried in the received light pulses using an optical decoding module, wherein the optical decoding module comprises a single photon detector that detects the received light pulses by a gating signal applied to the single photon detector; the gating signal stepping unit 305 may be configured to change delay positions of the gating signal applied to the single photon detector by a predetermined step size to obtain qubit information obtained by decoding at each delay position of the gating signal; the qubit comparison unit 306 may be configured to compare the qubit information obtained by decoding at each delay position of the gating signal with the qubit information for preparation to count the number of the qubit information obtained by decoding at each delay position of the gating signal that is inconsistent with the qubit information for preparation; the bit error rate calculation unit 307 may be configured to determine the bit error rate at each delay position of the gating signal based on a ratio between the number of qubit information inconsistent with the qubit information for preparation and the number of qubit information for preparation obtained by decoding at each delay position of the gating signal; gating signal lock unit 308 may be configured to lock a delay position of a gating signal applied to a single photon detector to a delay position of the gating signal corresponding to a minimum value of quantum bit error rates at respective delay positions of the gating signal.
In short, the delay position of the gating signal applied to the single photon detector can be adjusted and locked according to the quantum bit error rate, so that the single photon detector is started at a proper time, and the single photon detector is ensured to have high detection efficiency and accuracy.
It can be seen that using the arrangement shown in fig. 3, the optimum delay position can be found for the gating signal applied to the single photon detector. For quantum communication systems, false positives (such as, but not limited to, dark counts, etc.) due to turning on single photon detectors at improper times can be effectively avoided. Thus, the quantum bit error rate of the quantum communication system can be minimized, and the system bit rate is improved.
Furthermore, a computer-readable storage medium storing a computer program may also be provided according to an exemplary embodiment of the present invention. The computer readable storage medium stores a computer program which, when executed by a processor, causes the processor to perform a method of optimizing based on a quantum bit error rate according to an exemplary embodiment of the present invention. The computer readable recording medium is any data storage device that can store data which can be read out by a computer system. Examples of the computer-readable recording medium include: read-only memory, random access memory, compact disc read-only, magnetic tape, floppy disk, optical data storage device, and carrier waves (such as data transmission through the internet via wired or wireless transmission paths).
Furthermore, a computing device may be provided in accordance with an exemplary embodiment of the present invention. The computing device includes a processor and a memory. The memory is used for storing a computer program. The computer program is executed by a processor to cause the processor to perform a method of optimizing based on a quantum bit error rate according to an exemplary embodiment of the present invention.
While the present application has been shown and described with reference to the preferred embodiments, it will be understood by those skilled in the art that various modifications and changes may be made to these embodiments without departing from the spirit and scope of the present application as defined by the appended claims.
Claims (16)
1. A method for optimizing based on a quantum bit error rate, comprising:
preparing qubit information into an optical pulse output by a light source by using an optical coding module;
transmitting the prepared light pulse to a receiving end through an optical fiber or free space;
receiving the prepared light pulses from the emitting end via an optical fiber or free space;
decoding qubit information carried in the received light pulses using an optical decoding module, wherein the optical decoding module comprises a single photon detector that detects the received light pulses by a gating signal applied to the single photon detector;
changing delay positions of a gating signal applied to the single photon detector according to a preset step length to acquire qubit information obtained through decoding at each delay position of the gating signal;
comparing the qubit information obtained by the decoding at each delay position of the gating signal with the qubit information used for the preparation to count the quantity of the qubit information which is not consistent with the qubit information used for the preparation and obtained by the decoding at each delay position of the gating signal;
determining a quantum bit error rate at each delay position of the gating signal based on a ratio between a number of quantum bit information inconsistent with the quantum bit information for the preparation and a number of quantum bit information for the preparation obtained by the decoding at each delay position of the gating signal;
and locking the delay position of the gating signal applied to the single photon detector to the delay position of the gating signal corresponding to the minimum value in the quantum bit error rate at each delay position of the gating signal.
2. The method of claim 1, wherein the gating signal causes the single photon detector to be in an on state for a time window corresponding to a high level of the gating signal and causes the single photon detector to be in an off state for a time window corresponding to a low level of the gating signal.
3. The method of claim 1, wherein the optical encoding module is included in the transmitting end and the optical decoding module is included in the receiving end.
4. The method of claim 1, wherein the qubit information is prepared into the optical pulse in at least one of a polarization state, a phase state, and a time state of the optical pulse.
5. A method according to claim 3, wherein the quantum communication system comprising the transmitting end and the receiving end is a quantum key distribution system based on a COW quantum key distribution protocol.
6. The method of claim 5, wherein the single photon detector comprises a data detector for detecting light pulses and a monitor detector for monitoring coherence between light pulses.
7. The method of claim 6, wherein the optical decoding module detects the received light pulses by the data detector.
8. An apparatus for optimizing based on a quantum bit error rate, comprising:
an optical preparation unit configured to prepare qubit information into an optical pulse output from the light source using the optical encoding module;
an optical transmission unit configured to transmit the prepared optical pulse to a receiving end via an optical fiber or free space;
a light receiving unit configured to receive the prepared light pulses from the emitting end via an optical fiber or free space;
a light detection unit configured to decode qubit information carried in a received light pulse using an optical decoding module, wherein the optical decoding module comprises a single photon detector that detects the received light pulse by a gating signal applied to the single photon detector;
a gating signal stepping unit configured to change delay positions of a gating signal applied to the single photon detector by a predetermined step length to obtain qubit information obtained by the decoding at each delay position of the gating signal;
a qubit comparison unit configured to compare qubit information obtained by the decoding at each delay position of the gating signal with qubit information for the preparation, to count the number of qubit information obtained by the decoding at each delay position of the gating signal that is inconsistent with the qubit information for the preparation;
a bit error rate calculation unit configured to determine a bit error rate at each delay position of the gating signal based on a ratio between a number of qubit information inconsistent with the qubit information for the preparation and a number of qubit information for the preparation obtained by the decoding at each delay position of the gating signal;
and a gating signal locking unit configured to lock a delay position of a gating signal applied to the single photon detector to a delay position of the gating signal corresponding to a minimum value among quantum bit error rates at respective delay positions of the gating signal.
9. The apparatus of claim 8, wherein the gating signal causes the single photon detector to be in an on state for a time window corresponding to a high level of the gating signal and causes the single photon detector to be in an off state for a time window corresponding to a low level of the gating signal.
10. The apparatus of claim 8, wherein the optical encoding module is included in the transmitting end and the optical decoding module is included in the receiving end.
11. The apparatus of claim 8, wherein the qubit information is prepared into the optical pulse in at least one of a polarization state, a phase state, and a time state of the optical pulse.
12. The apparatus of claim 10, wherein the quantum communication system comprising the transmitting end and the receiving end is a quantum key distribution system based on a COW quantum key distribution protocol.
13. The apparatus of claim 12, wherein the single photon detector comprises a data detector for detecting light pulses and a monitor detector for monitoring coherence between light pulses.
14. The apparatus of claim 13, wherein the optical decoding module detects the received light pulses by the data detector.
15. A computer readable storage medium storing a computer program, characterized in that the method of optimizing based on a qubit error rate according to any one of claims 1 to 7 is implemented when the computer program is executed by a processor.
16. A computing device, comprising:
a processor;
a memory storing a computer program which, when executed by a processor, implements the method of optimizing based on a qubit error rate of any one of claims 1 to 7.
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Denomination of invention: Method, device, medium, and device for optimizing based on quantum bit error rate Granted publication date: 20240209 Pledgee: Huaxia Bank Co.,Ltd. Hefei Economic and Technological Development Zone Branch Pledgor: Guokaike Quantum Technology (Anhui) Co.,Ltd. Registration number: Y2024980017847 |