A real-time ranging and positioning system and method based on extended light source and fast coincidence measurement algorithm.

Abstract

This invention provides a real-time ranging and positioning system and method based on an extended light source and a fast coincidence measurement algorithm. The real-time ranging system includes: an entangled light source, a first single-photon detector, a time-to-digital converter, a coincidence measurement module, a quantum transceiver module, and a corner mirror. The coincidence measurement module performs real-time coincidence measurement using a fast coincidence measurement algorithm based on the arrival time sequence of the signal beam and the arrival time sequence of the reference beam, obtaining the time difference corresponding to the peak position of the coincidence measurement curve. The distance between the target point and the real-time ranging system is then obtained based on this time difference. Furthermore, this invention splits the signal beam emitted by the light source into multiple signal sub-beams to form an extended light source, effectively reducing the cost of the measurement device while still satisfying quantum positioning measurement requirements.

Description

Technical Field

[0001] This invention relates to the field of quantum navigation and positioning technology, and in particular to a real-time ranging and positioning system and method based on extended light source and fast coincidence measurement algorithm. Background Technology

[0002] Ranging technology is fundamental for locating and navigating unknown targets, and the ranging accuracy of the positioning system directly determines the positioning accuracy. Traditional ranging technologies such as ultrasonic ranging, infrared ranging, and laser ranging are all based on classical physics, and their ranging accuracy is always limited by the standard quantum limit.

[0003] With the establishment of quantum theory, quantum mechanics has gradually penetrated into physical experiments, especially quantum theory and its applications based on quantum entanglement, which have developed rapidly. In 2001, a novel ranging method, namely quantum precision ranging, was proposed. When a quantum light source with frequency entanglement and compression properties is used as the light source for the ranging system, the measurement accuracy can be improved. The value is M times the number of entangled pulses, and N represents the average number of photons in a single pulse. This technique enables measurement accuracy to surpass the standard quantum limit, reaching the Heisenberg limit. Quantum precision ranging technology offers new opportunities for achieving high-precision navigation and positioning.

[0004] With the development of entangled light source fabrication technology, high-performance entangled photon pairs, referred to as signal light and idle light respectively, can be obtained based on spontaneous parametric down-conversion technology. In actual ranging, after the signal light is emitted to the target and reflected back to the local location, it is used to obtain the arrival time difference of the entangled photon pair with the idle light remaining locally through coincidence counting measurement. The distance information is then calculated based on this time difference. The commonly used method is to obtain the arrival time series of photons in the reference optical path and the signal optical path separately before performing coincidence measurement. If both detectors detect an event occurring at the same time, it is recorded as a coincidence. In actual measurement, due to the jitter of the detector itself and the inherent properties of the nonlinear crystal, it is not possible to require the two photons to arrive simultaneously. Instead, a threshold is set. If the arrival time difference of the two photons is within this threshold, they are considered a photon pair, and a coincidence is recorded. Traditional coincidence measurement methods require traversing every photon and multiple translations of the signal optical path, typically taking tens of minutes to calculate a single ranging signal. Furthermore, due to the high cost of quantum entanglement sources, installing multiple quantum entanglement sources during positioning would be costly. Summary of the Invention

[0005] To reduce the computation time and save costs in quantum ranging, this invention proposes a real-time ranging and positioning system and method based on extended light source and fast coincidence measurement algorithm.

[0006] In a first aspect, the present invention provides a real-time ranging system based on a fast coincidence measurement algorithm, comprising: an entangled light source, a first single-photon detector, a time-to-digital converter, a coincidence measurement module, a quantum transceiver module, and a corner reflector;

[0007] The entangled light source is used to output entangled photon pairs to form a reference beam and a signal beam;

[0008] The first single-photon detector is used to couple and receive the reference beam output by the entangled light source and output a detection signal to the first port of the time-to-digital converter;

[0009] The quantum transceiver module is used to receive the signal beam output by the entangled light source and transmit it to the corner reflector, so as to receive the signal beam reflected by the corner reflector along the original path and transmit the signal beam reflected by the corner reflector along the original path to the second port of the time-to-digital converter.

[0010] The time-to-digital converter is used to record the photon arrival time of each port to form an arrival time sequence of the signal beam and an arrival time sequence of the reference beam;

[0011] The coincidence measurement module is used to perform real-time coincidence measurement using a fast coincidence measurement algorithm based on the arrival time sequence of the signal beam and the arrival time sequence of the reference beam, to obtain the time difference corresponding to the peak position of the coincidence measurement curve, and to obtain the distance between the target point to be measured and the real-time ranging system based on the time difference.

[0012] Specifically, the fast conformity measurement algorithm includes:

[0013] Step 1: When the (t+1)th signal photon arrives at the time-to-digital converter, set the arrival time of that signal photon to TB. t Set the arrival time of the latest reference photon saved at this time to TB. t+a Then the time difference at the current moment is recorded as (TB). t -TA t+a ); where t = 0, 1, ..., M; a is a positive integer;

[0014] Step 2: Determine whether the time difference at the current moment is the same as the time difference at the previous moment. If they are the same, accumulate the coincidence count of the time difference at the current moment to obtain the accumulated count value. If they are different, return to step 1.

[0015] Step 3: Repeat steps 1 and 2 within the first preset time period to obtain a series of time differences and corresponding cumulative count values. Record the time difference corresponding to the maximum value of the cumulative count value as the peak position T. C ;

[0016] Step 4: Repeat Step 1 within the second preset time period, and only save the data located in [T] C -b,T C The time difference and corresponding cumulative count value within the range of +b]; where b is determined based on the peak width of the measurement curve;

[0017] Step 5: Perform compliance processing based on the time difference obtained in Step 4 and the corresponding accumulated count value;

[0018] Step 6: Use Gaussian fitting to fit the processed curve to obtain the time difference corresponding to the peak position of the measured curve.

[0019] Furthermore, the quantum transceiver module includes: an optical fiber coupler, an optical fiber circulator, a photon beam expander collimator, and a second single-photon detector;

[0020] The signal beam output by the entangled light source enters from the first port of the fiber optic circulator after passing through the fiber optic coupler, and then exits from the second port of the fiber optic circulator to the photon beam expander collimator, and from the photon beam expander collimator to the corner mirror; the signal beam reflected by the corner mirror is output from the third port of the fiber optic circulator to the second single-photon detector.

[0021] Furthermore, the entangled light source was constructed using a method based on a Sagnac interferometer bidirectionally pumped PPKTP crystal.

[0022] Secondly, the present invention provides a real-time ranging and positioning system based on an extended light source and a fast coincidence measurement algorithm, comprising: an entangled light source, an optical fiber beam splitter, a first single-photon detector, a time-to-digital converter, a coincidence measurement module, N quantum transceiver modules, a corner mirror, and a positioning module; where N is a positive integer.

[0023] The entangled light source is used to output entangled photon pairs to form a reference beam and a signal beam;

[0024] The fiber optic beam splitter is used to divide the signal beam output by the entangled light source into N signal sub-beams;

[0025] The first single-photon detector is used to couple and receive the reference beam output by the entangled light source and output a detection signal to the first port of the time-to-digital converter;

[0026] The nth quantum transceiver module is used to receive the nth signal sub-beam output by the fiber optic beam splitter and transmit it to the corner mirror to receive the signal beam reflected by the corner mirror along the original path, and to transmit the signal beam reflected by the corner mirror along the original path to the nth port of the time-to-digital converter; n = 1, 2, ..., N;

[0027] The time-to-digital converter is used to record the photon arrival time of each port to form the arrival time sequence of N signal sub-beams and the arrival time sequence of the reference beam;

[0028] The coincidence measurement module is used to perform real-time coincidence measurement using a fast coincidence measurement algorithm based on the arrival time sequence of n signal sub-beams and the arrival time sequence of the reference beam, to obtain the time difference corresponding to the peak position of the coincidence measurement curve, and to obtain the distance between the target point to be measured and each quantum transceiver module based on the time difference.

[0029] The positioning module is used to obtain the coordinate position of the target point based on the distance between the target point and each quantum transceiver module and the coordinate position of each quantum transceiver module.

[0030] Specifically, the fast conformity measurement algorithm includes:

[0031] Step 1: When the (t+1)th signal photon arrives at the time-to-digital converter, set the arrival time of that signal photon to TB. t Set the arrival time of the latest reference photon saved at this time to TB. t+a Then the time difference at the current moment is recorded as (TB). t -TA t+a ); where t = 0, 1, ..., M; a is a positive integer;

[0032] Step 2: Determine whether the time difference at the current moment is the same as the time difference at the previous moment. If they are the same, accumulate the coincidence count of the time difference at the current moment to obtain the accumulated count value. If they are different, return to step 1.

[0033] Step 3: Repeat steps 1 and 2 within the first preset time period to obtain a series of time differences and corresponding cumulative count values. Record the time difference corresponding to the maximum value of the cumulative count value as the peak position T. C ;

[0034] Step 4: Repeat Step 1 within the second preset time period, and only save the data located in [T] C -b,T C The time difference and corresponding cumulative count value within the range of +b]; where b is determined based on the peak width of the measurement curve;

[0035] Step 5: Perform compliance processing based on the time difference obtained in Step 4 and the corresponding accumulated count value;

[0036] Step 6: Use Gaussian fitting to fit the processed curve to obtain the time difference corresponding to the peak position of the measured curve.

[0037] Furthermore, the quantum transceiver module includes: an optical fiber coupler, an optical fiber circulator, a photon beam expander collimator, and a second single-photon detector;

[0038] The signal beam output by the entangled light source enters from the first port of the fiber optic circulator after passing through the fiber optic coupler, and then exits from the second port of the fiber optic circulator to the photon beam expander collimator, and from the photon beam expander collimator to the corner mirror; the signal beam reflected by the corner mirror is output from the third port of the fiber optic circulator to the second single-photon detector.

[0039] Furthermore, the entangled light source was constructed using a method based on a Sagnac interferometer bidirectionally pumped PPKTP crystal.

[0040] Thirdly, the present invention provides a real-time ranging method based on a fast coincidence measurement algorithm, applied to the real-time ranging system described in the first aspect, comprising:

[0041] The calibration of the real-time ranging system includes: placing the corner reflector at a preset measurement origin O, and obtaining the first time difference T according to the fast coincidence measurement algorithm. o And obtain the first optical path difference R between the signal beam and the reference beam at this time. o =c*T o c is the speed of light;

[0042] The corner reflector is placed at the target point C, and the second time difference T is obtained according to the fast coincidence measurement algorithm. c And obtain the second optical path difference R between the signal beam and the reference beam at this time. c =c*T c ;

[0043] The distance between the target point C and the measurement origin O is calculated as L = (R c -R o ) / 2.

[0044] Fourthly, the present invention provides a real-time ranging and positioning method based on an extended light source and a fast coincidence measurement algorithm, applied to the real-time ranging and positioning system described in the second aspect, comprising:

[0045] It is known that the fixed position of each quantum transceiver module is O. n (X n ,Y n The time difference between the signal sub-beam output by each quantum transceiver module and the reference beam is obtained according to the fast coincidence measurement algorithm, and the distance between the target point C and each quantum transceiver module O is obtained based on the time difference. n The distance L between n ;

[0046] When N is 2, assuming the coordinates of the target point C are (X, Y), we obtain the following system of equations:

[0047]

[0048] Solve the system of equations, and calculate the coordinates (X,Y) of the target point C based on its relative position to O1 and O2.

[0049] When N is 3, assuming the coordinates of the target point C are (X, Y, Z), we obtain the following system of equations:

[0050]

[0051] Solve the system of equations, and calculate the coordinates (X, Y, Z) of the target point C based on its relative position to O1, O2, and O3.

[0052] The beneficial effects of this invention are as follows:

[0053] The real-time ranging and positioning system and method provided by this invention adopts a fast coincidence measurement algorithm based on the difference mode, that is, the coincidence measurement is performed directly during the measurement process, which shortens the measurement time to less than 1 second and enables real-time ranging function; and when the brightness of the entangled light source meets the requirements, this invention further proposes to use a beam splitting device such as an optical fiber beam splitter or a beam splitting prism to split the signal beam emitted by the entangled light source into multiple signals to form an extended light source, which can effectively reduce the cost of the measurement device while meeting the requirements of quantum positioning measurement. Attached Figure Description

[0054] Figure 1 A schematic diagram of a real-time ranging system based on a fast coincidence measurement algorithm is provided for an embodiment of the present invention.

[0055] Figure 2 A schematic diagram of a quantum transceiver module provided in an embodiment of the present invention;

[0056] Figure 3 Arrival time series of reference beam and signal beam provided for embodiments of the present invention;

[0057] Figure 4 A schematic diagram illustrating the principle of a real-time ranging and positioning system based on an extended light source and a fast coincidence measurement algorithm, provided in an embodiment of the present invention;

[0058] Figure reference numerals: 1 is a quantum entanglement light source; 2 is the first single-photon detector; 3 is a time-to-digital converter; 4 is a coincidence measurement module; 5 is an optical fiber coupler; 6 is an optical fiber circulator; 7 is a photon beam expander collimator; 8 is a corner mirror; 9 is the second single-photon detector; 10 is an optical fiber beam splitter; 11 is quantum transceiver module 1; 12 is quantum signal transceiver module 2. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0060] Example 1

[0061] like Figure 1 As shown, this embodiment of the invention provides a real-time ranging system based on a fast coincidence measurement algorithm, including: an entangled light source, a first single-photon detector, a time-to-digital converter, a coincidence measurement module, a quantum transceiver module, and a corner mirror;

[0062] The system comprises: an entangled light source outputting entangled photon pairs to form a reference beam and a signal beam; a first single-photon detector coupled to receive the reference beam output by the entangled light source and outputting a detection signal to the first port of a time-to-digital converter; a quantum transceiver module receiving the signal beam output by the entangled light source and transmitting it to a corner mirror to receive the signal beam reflected by the corner mirror along its original path, and transmitting the signal beam reflected by the corner mirror along its original path to the second port of the time-to-digital converter; the time-to-digital converter recording the photon arrival time of each port to form an arrival time sequence of the signal beam and an arrival time sequence of the reference beam; and a coincidence measurement module performing real-time coincidence measurement using a fast coincidence measurement algorithm based on the arrival time sequences of the signal beam and the reference beam, obtaining the time difference corresponding to the peak position of the coincidence measurement curve, and obtaining the distance between the target point and the real-time ranging system based on the time difference.

[0063] As one possible implementation method, an entangled light source can be constructed by bidirectionally pumping a PPKTP crystal based on a Sagnac interferometer.

[0064] As one possible implementation method, such as Figure 2As shown, the quantum transceiver module includes: an optical fiber coupler, an optical fiber circulator, a photonic beam expander collimator, and a second single-photon detector; the signal beam output from the entangled light source enters from the first port of the optical fiber circulator after passing through the optical fiber coupler, and then exits from the second port of the optical fiber circulator to the photonic beam expander collimator, and from the photonic beam expander collimator to the corner mirror; the signal beam reflected by the corner mirror is output from the third port of the optical fiber circulator to the second single-photon detector.

[0065] like Figure 3 As shown, the arrival time sequence of the reference beam is CH-A, and the arrival time sequence of the signal beam is CH-B. The time-to-digital converter records the arrival time sequence of the reference photons. Specifically: the arrival time of the first detected reference photon is recorded as TA0 and saved; the arrival time of the second detected reference photon is recorded as TA1; and so on, the arrival time of the (n+1)th detected reference photon is recorded as TA... n In practical applications, to reduce the amount of arrival time data to be stored, an overwrite storage method can be used to store the arrival time of the reference photon. That is, when the time-to-digital converter detects a new reference photon, it automatically overwrites the arrival time of the previous reference photon with the arrival time of the new photon. For example, TA1 is used to overwrite TA0, TA2 is used to overwrite TA1, and so on, until TA0 is overwritten. n Cover TA n-1 .

[0066] The time-to-digital converter records the arrival time sequence of signal photons. Specifically: the arrival time of the first detected signal photon is recorded as TB0 and saved; the arrival time of the second detected signal photon is recorded as TB1; and so on, with the arrival time of the (n+1)th detected signal photon recorded as TB1. n Similarly, in practical applications, in order to reduce storage requirements, overlay storage can also be used to store the arrival time of signal photons.

[0067] Specifically, the fast conformity measurement algorithm includes:

[0068] S101: Record time difference, including: when the (t+1)th signal photon arrives at the time-to-digital converter, set the arrival time of that signal photon to TB. t Set the arrival time of the latest reference photon saved at this time to TB. t+a Then the time difference at the current moment is recorded as (TB). t -TA t+a ); where t = 0, 1, ..., M; a is a positive integer;

[0069] For example, when the first signal photon arrives at the time-to-digital converter, the latest arrival time of the reference photon stored in the reference optical path is TA1, corresponding to the recorded time difference (TB0-TA1);

[0070] When the second signal photon arrives at the time-to-digital converter, the latest arrival time of the reference photon stored in the reference optical path is TA2, corresponding to the recorded time difference (TB1-TA2);

[0071] When the third signal photon arrives at the time-to-digital converter, the latest arrival time of the reference photon stored in the reference optical path is TA4, corresponding to the recorded time difference (TB2-TA4).

[0072] S102: Determine whether the time difference at the current moment is the same as the time difference at the previous moment. If they are the same, accumulate the coincidence count of the time difference at the current moment to obtain the accumulated count value. If they are different, return to step S101 to continue measuring the time difference between the reference photon and the signal photon.

[0073] S103: Repeat steps S101 and S102 within the first preset time period (generally on the order of milliseconds) to obtain a series of time differences and corresponding accumulated count values. Record the time difference corresponding to the maximum value of the accumulated count value as the peak position T. C .

[0074] Specifically, due to the second-order correlation measurement principle, the accumulated count values ​​tend to follow a normal distribution. Therefore, the time difference corresponding to the maximum value of the accumulated count is taken as the approximate time difference of photon transmission between the signal optical path and the reference optical path, and the peak position is recorded as T. C .

[0075] S104: Repeat step S101 within the second preset time period, and only save the data located in [T] C -b,T C The time difference and corresponding cumulative count value within the range of +b]; where b is determined based on the peak width of the measurement curve.

[0076] Specifically, since the time jitter of a single-photon detector is typically on the order of hundreds of picoseconds, the half-width at half-maximum (WHM) of the coincidence measurement curve is also around several hundred picoseconds. Therefore, to determine the peak position of the coincidence measurement curve, it is only necessary to save the time difference information approximately 1000 picoseconds around the approximate peak position (this data can be determined based on specific experimental conditions to ensure that it includes data for the entire peak position). Therefore, in this step, when continuing to record the arrival time difference of the two signals as in step 1, it is only necessary to save the approximate peak position time difference T. CThe time difference information is approximately 1000 picoseconds to the left and right of the approximate peak position (this data can be determined based on specific experimental conditions). Data with time differences exceeding 1000 picoseconds to the left and right of the approximate peak position are discarded to reduce the data volume and speed up the coincidence measurement. Therefore, after the second preset time period, the peak position T can be obtained. C A series of time differences in the vicinity, and the cumulative count of the corresponding time differences.

[0077] S105: Perform compliance processing based on the time difference obtained in step S104 and the corresponding accumulated count value;

[0078] Specifically, due to the inherent jitter of the detector and the limitations of the nonlinear crystal itself, it is not possible to require two photons to arrive simultaneously. Therefore, a gate width is set to perform coincidence processing on the acquired time difference curves. The process is as follows: the values ​​of gate / 2 at the beginning and end of the time difference curve remain unchanged; for other data, such as a time difference of Δt, all counts within the range [Δt-gate / 2, Δt+gate / 2] are accumulated, and the value after dividing by the gate width is taken as the coincidence number corresponding to the time difference Δt. This process is repeated for each time difference, performing coincidence processing on the curve.

[0079] S106: Use Gaussian fitting to fit the processed curve to obtain the time difference corresponding to the peak position of the measured curve.

[0080] The real-time ranging system provided in this invention uses a fast coincidence measurement algorithm based on difference mode to quickly calculate distance information during photon detection. Based on this system, stationary and non-stationary targets can be detected to complete the ranging and positioning functions.

[0081] Example 2

[0082] Based on the real-time ranging system based on the fast coincidence measurement algorithm in Embodiment 1 above, this embodiment of the invention provides a real-time ranging method based on the fast coincidence measurement algorithm, comprising the following steps:

[0083] S201: Calibrate the real-time ranging system, including: placing the corner reflector at a preset measurement origin O, and obtaining the first time difference T according to the fast coincidence measurement algorithm. o And obtain the first optical path difference R between the signal beam and the reference beam at this time. o =c*T o c is the speed of light;

[0084] S202: Place the corner reflector at the target point C and obtain the second time difference T according to the fast coincidence measurement algorithm. c And obtain the second optical path difference R between the signal beam and the reference beam at this time.c =c*T c ;

[0085] S203: Calculate the distance between the target point C and the measurement origin O as L = (R... c -R o ) / 2.

[0086] Example 3

[0087] Based on the same inventive concept, such as Figure 4 As shown, this embodiment of the invention also provides a real-time ranging and positioning system based on an extended light source and a fast coincidence measurement algorithm, comprising: an entangled light source, an optical fiber beam splitter, a first single-photon detector, a time-to-digital converter, a coincidence measurement module, N quantum transceiver modules, a corner mirror, and a positioning module; where N is a positive integer.

[0088] The system comprises an entangled light source that outputs entangled photon pairs to form a reference beam and a signal beam; an optical fiber beam splitter that divides the signal beam from the entangled light source into N signal sub-beams (note that the division depends on the light intensity; for example, it can be divided into 2, 3, or more sub-beams if the light intensity is sufficient); a first single-photon detector that couples to receive the reference beam from the entangled light source and outputs a detection signal to the first port of the time-to-digital converter; and an nth quantum transceiver module that receives the nth signal sub-beam from the optical fiber beam splitter and transmits it to a corner mirror to receive the signal beam reflected by the corner mirror along its original path and transmit the signal beam reflected by the corner mirror along its original path to... The nth port of the time-to-digital converter (TDC) is used; n = 1, 2, ..., N. The TDC records the photon arrival time of each port to form the arrival time sequence of N signal sub-beams and the arrival time sequence of the reference beam. The coincidence measurement module performs real-time coincidence measurement using a fast coincidence measurement algorithm based on the arrival time sequences of the n signal sub-beams and the reference beam, obtaining the time difference corresponding to the peak of the coincidence measurement curve. Based on the time difference, the distance between the target point and each quantum transceiver module is obtained. The positioning module obtains the coordinate position of the target point based on the distance between the target point and each quantum transceiver module and the coordinate position of each quantum transceiver module. The entangled light source, quantum transceiver module, and fast coincidence measurement algorithm in this embodiment can be referred to in Embodiment 1 above, and will not be repeated here.

[0089] The real-time ranging and positioning system provided in this invention increases the number of signal optical paths by using beam splitting devices such as fiber optic beam splitters or beam splitting prisms to form an extended light source, enabling simultaneous multi-path detection. Based on a fast coincidence measurement algorithm, it achieves target ranging and positioning functions in a two-dimensional plane or three-dimensional space.

[0090] Example 4

[0091] Based on the real-time ranging and positioning system based on extended light source and fast coincidence measurement algorithm in Embodiment 3 above, this embodiment of the invention also provides a real-time ranging and positioning method based on extended light source and fast coincidence measurement algorithm, including the following steps:

[0092] It is known that the fixed position of each quantum transceiver module is O. n (X n ,Y n The time difference between the signal sub-beam output by each quantum transceiver module and the reference beam is obtained according to the fast coincidence measurement algorithm, and the distance between the target point C and each quantum transceiver module O is obtained based on the time difference. n The distance L between n ;

[0093] For example, the fixed position of the first quantum transceiver module is O1(X1,Y1), and this point is marked as the ranging zero point of the first ranging optical path. Similarly, the fixed position of the second quantum transceiver module is O2(X2,Y2), and this point is marked as the ranging zero point of the second ranging optical path. Using the above-described fast coincidence measurement algorithm, the distance from O1 to the target point C can be calculated as L1, and the distance from O2 to the target point C can be calculated as L2.

[0094] When N is 2, assuming the coordinates of the target point C are (X, Y), we obtain the following system of equations:

[0095]

[0096] Solve the system of equations, and calculate the coordinates (X,Y) of the target point C based on its relative position to O1 and O2.

[0097] When N is 3, assuming the coordinates of the target point C are (X, Y, Z), we obtain the following system of equations:

[0098]

[0099] Solve the system of equations, and calculate the coordinates (X, Y, Z) of the target point C based on its relative position to O1, O2, and O3.

[0100] The real-time ranging and positioning method provided in this invention can be used in the field of quantum capture and tracking, enabling distance measurement of moving objects and providing support for the development of quantum navigation and positioning technology based on quantum entangled light.

[0101] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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 of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A real-time ranging system based on a fast coincidence measurement algorithm, characterized in that, include: Entangled light source, first single-photon detector, time-to-digital converter, coincidence measurement module, quantum transceiver module, and corner mirror; The entangled light source is used to output entangled photon pairs to form a reference beam and a signal beam; The first single-photon detector is used to couple and receive the reference beam output by the entangled light source and output a detection signal to the first port of the time-to-digital converter; The quantum transceiver module is used to receive the signal beam output by the entangled light source and transmit it to the corner reflector, so as to receive the signal beam reflected by the corner reflector along the original path and transmit the signal beam reflected by the corner reflector along the original path to the second port of the time-to-digital converter. The time-to-digital converter is used to record the photon arrival time of each port to form an arrival time sequence of the signal beam and an arrival time sequence of the reference beam; The coincidence measurement module is used to perform real-time coincidence measurement using a fast coincidence measurement algorithm based on the arrival time sequence of the signal beam and the arrival time sequence of the reference beam, to obtain the time difference corresponding to the peak position of the coincidence measurement curve, and to obtain the distance between the target point to be measured and the real-time ranging system based on the time difference. Specifically, the fast conformity measurement algorithm includes: Step 1: When the (t+1)th signal photon arrives at the time-to-digital converter, set the arrival time of that signal photon to TB. t Set the arrival time of the latest reference photon saved at this time to TB. t+a Then the time difference at the current moment is recorded as (TB). t -TA t+a ); where t = 0, 1, ..., M; a is a positive integer; Step 2: Determine whether the time difference at the current moment is the same as the time difference at the previous moment. If they are the same, accumulate the coincidence count of the time difference at the current moment to obtain the accumulated count value. If they are different, return to step 1. Step 3: Repeat steps 1 and 2 within the first preset time period to obtain a series of time differences and corresponding cumulative count values. Record the time difference corresponding to the maximum value of the cumulative count value as the peak position T. C ; Step 4: Repeat Step 1 within the second preset time period, and only save the data located in [T] C -b,T C The time difference and corresponding cumulative count value within the range of +b]; where b is determined based on the peak width of the measurement curve; Step 5: Perform compliance processing based on the time difference obtained in Step 4 and the corresponding accumulated count value; Step 6: Use Gaussian fitting to fit the processed curve to obtain the time difference corresponding to the peak position of the measured curve.

2. The real-time ranging system based on a fast coincidence measurement algorithm according to claim 1, characterized in that, The quantum transceiver module includes: an optical fiber coupler, an optical fiber circulator, a photon beam expander collimator, and a second single-photon detector. The signal beam output by the entangled light source enters from the first port of the fiber optic circulator after passing through the fiber optic coupler, and then exits from the second port of the fiber optic circulator to the photon beam expander collimator, and from the photon beam expander collimator to the corner mirror; the signal beam reflected by the corner mirror is output from the third port of the fiber optic circulator to the second single-photon detector.

3. The real-time ranging system based on a fast coincidence measurement algorithm according to claim 1, characterized in that, The entangled light source was constructed using a method based on a Sagnac interferometer bidirectionally pumped PPKTP crystal.

4. A real-time ranging and positioning system based on extended light source and fast coincidence measurement algorithm, characterized in that, include: Entangled light source, fiber optic beam splitter, first single-photon detector, time-to-digital converter, coincidence measurement module, N quantum transceiver modules, corner mirror and positioning module; N is a positive integer; The entangled light source is used to output entangled photon pairs to form a reference beam and a signal beam; The fiber optic beam splitter is used to divide the signal beam output by the entangled light source into N signal sub-beams; The first single-photon detector is used to couple and receive the reference beam output by the entangled light source and output a detection signal to the first port of the time-to-digital converter; The nth quantum transceiver module is used to receive the nth signal sub-beam output by the fiber optic beam splitter and transmit it to the corner mirror to receive the signal beam reflected by the corner mirror along the original path, and to transmit the signal beam reflected by the corner mirror along the original path to the nth port of the time-to-digital converter; n = 1, 2, ..., N; The time-to-digital converter is used to record the photon arrival time of each port to form the arrival time sequence of N signal sub-beams and the arrival time sequence of the reference beam; The coincidence measurement module is used to perform real-time coincidence measurement using a fast coincidence measurement algorithm based on the arrival time sequence of n signal sub-beams and the arrival time sequence of the reference beam, to obtain the time difference corresponding to the peak position of the coincidence measurement curve, and to obtain the distance between the target point to be measured and each quantum transceiver module based on the time difference. The positioning module is used to obtain the coordinate position of the target point based on the distance between the target point and each quantum transceiver module and the coordinate position of each quantum transceiver module. Specifically, the fast conformity measurement algorithm includes: Step 1: When the (t+1)th signal photon arrives at the time-to-digital converter, set the arrival time of that signal photon to TB. t Set the arrival time of the latest reference photon saved at this time to TB. t+a Then the time difference at the current moment is recorded as (TB). t -TA t+a ); where t = 0, 1, ..., M; a is a positive integer; Step 2: Determine whether the time difference at the current moment is the same as the time difference at the previous moment. If they are the same, accumulate the coincidence count of the time difference at the current moment to obtain the accumulated count value. If they are different, return to step 1. Step 3: Repeat steps 1 and 2 within the first preset time period to obtain a series of time differences and corresponding cumulative count values. Record the time difference corresponding to the maximum value of the cumulative count value as the peak position T. C ; Step 4: Repeat Step 1 within the second preset time period, and only save the data located in [T] C -b,T C The time difference and corresponding cumulative count value within the range of +b]; where b is determined based on the peak width of the measurement curve; Step 5: Perform compliance processing based on the time difference obtained in Step 4 and the corresponding accumulated count value; Step 6: Use Gaussian fitting to fit the processed curve to obtain the time difference corresponding to the peak position of the measured curve.

5. A real-time ranging and positioning system based on an extended light source and a fast coincidence measurement algorithm according to claim 4, characterized in that, The quantum transceiver module includes: an optical fiber coupler, an optical fiber circulator, a photon beam expander collimator, and a second single-photon detector. The signal beam output by the entangled light source enters from the first port of the fiber optic circulator after passing through the fiber optic coupler, and then exits from the second port of the fiber optic circulator to the photon beam expander collimator, and from the photon beam expander collimator to the corner mirror; the signal beam reflected by the corner mirror is output from the third port of the fiber optic circulator to the second single-photon detector.

6. A real-time ranging and positioning system based on an extended light source and a fast coincidence measurement algorithm according to claim 4, characterized in that, The entangled light source was constructed using a method based on a Sagnac interferometer bidirectionally pumped PPKTP crystal.

7. A real-time ranging method based on a fast coincidence measurement algorithm, characterized in that, The system applied to the real-time ranging system according to any one of claims 1 to 3 includes: The calibration of the real-time ranging system includes: placing the corner reflector at a preset measurement origin O, and obtaining the first time difference T according to the fast coincidence measurement algorithm. o And obtain the first optical path difference R between the signal beam and the reference beam at this time. o =c*T o c is the speed of light; The corner reflector is placed at the target point C, and the second time difference T is obtained according to the fast coincidence measurement algorithm. c And obtain the second optical path difference R between the signal beam and the reference beam at this time. c =c*T c ; The distance between the target point C and the measurement origin O is calculated as L = (R c -R o ) / 2.

8. A real-time ranging and positioning method based on extended light source and fast coincidence measurement algorithm, characterized in that, The real-time ranging and positioning system according to any one of claims 4 to 6 includes: It is known that the fixed position of each quantum transceiver module is O. n (X n ,Y n The time difference between the signal sub-beam output by each quantum transceiver module and the reference beam is obtained according to the fast coincidence measurement algorithm, and the distance between the target point C and each quantum transceiver module O is obtained based on the time difference. n The distance L between n ; When N is 2, assuming the coordinates of the target point C are (X, Y), we obtain the following system of equations: Solve the system of equations, and calculate the coordinates (X,Y) of the target point C based on its relative position to O1 and O2. When N is 3, assuming the coordinates of the target point C are (X, Y, Z), we obtain the following system of equations: Solve the system of equations, and calculate the coordinates (X, Y, Z) of the target point C based on its relative position to O1, O2, and O3.

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