A two-dimensional planar positioning system and method based on quantum entangled light

Abstract

The present invention relates to a two-dimensional plane positioning system and method based on quantum entangled light, belonging to the field of quantum navigation technology. The present invention realizes the rapid and efficient coupling of quantum signals by means of the coaxial transmission of the visible light beam emitted by the reference light source. Through the optical path structure design of the auxiliary positioning device, only by rotating the right-angle prism mirror therein can a 360-degree change in the ranging direction and the extraction of the azimuth angle be achieved. The two-dimensional plane high-precision positioning based on quantum entangled light can be finally realized by using the distance and azimuth angle information of the target point to be measured.

Description

Technical Field

[0001] The present invention relates to a two-dimensional plane positioning system and method based on quantum entangled light, belonging to the technical field of quantum navigation and positioning. Background Technique

[0002] Ranging technology is the basis for realizing the positioning and navigation of unknown targets, and the ranging accuracy of the positioning system determines its positioning accuracy. Traditional ranging technologies, such as ultrasonic ranging, infrared ranging, and laser ranging, are all ranging technologies based on classical physics, and their ranging accuracy is always limited by the standard quantum limit and cannot meet the requirements of high-precision positioning. In order to obtain higher positioning accuracy, it is necessary to seek a new ranging technology that can break through the standard quantum limit. With the establishment of quantum theory, quantum mechanics has gradually penetrated into physical experiments, and the advantages of the second-order correlation characteristics of quantum entangled light in measurement have become increasingly prominent. Relevant theoretical and experimental studies have shown that a ranging system based on quantum entangled light can break through the limitation of the shot noise limit and reduce the measurement accuracy to the Heisenberg limit, providing a new technical support for realizing high-precision positioning.

[0003] The ranging technology based on quantum entangled light emits entangled photons to the point to be measured and couples and receives the reflected signal, and uses the coincidence counting measurement method to obtain the arrival time difference of the entangled photon pairs, and then solves the distance information according to this time difference. In the measurement process, the level of the quantum signal coupling efficiency determines the magnitude of the coincidence count value of the entangled photon pairs, which in turn affects the signal-to-noise ratio of the coincidence measurement curve and the coincidence measurement accuracy. Therefore, it is crucial to achieve fast and efficient coupling of entangled photon pairs. Entangled photon signals are usually in the invisible band, and the signal intensity is at the single-photon level, which cannot be recognized by the naked eye. In order to efficiently and quickly couple and receive the signal, it is essential to add an auxiliary positioning module in the visible light band to the ranging system.

[0004] When there is only one measurement source in the positioning system, in order to realize the two-dimensional positioning of the target point, on the basis of the known distance information of the point to be measured, the azimuth angle information of the target point in the known coordinate system still needs to be obtained. The currently commonly used method is to place the measuring device on a turntable for overall rotation to obtain the azimuth angle. For example, the Chinese patent application document with the application publication number CN112904351A discloses a single-source positioning method based on the correlation characteristics of quantum entangled light. This method places the quantum entangled source transceiver detection device on a turntable, continuously emits signal photons to detect the target during the rotation of the turntable, and when the coincidence count value reaches the maximum, records the angle between the signal photon emission direction and the reference direction at this time, and takes it as the included angle between the to-be-determined target and the local access point. Combining the distance information of the target to be located can realize the positioning of the target. Although this method can realize the positioning of the two-dimensional plane, it needs to rely on a turntable. When the detection device is large in volume, the specific operation process is not convenient enough and errors are likely to occur. Summary of the Invention

[0005] The object of the present invention is to provide a two-dimensional plane positioning system and method based on quantum entangled light, so as to solve the problems of complex operation and inconvenient measurement existing in the two-dimensional plane positioning of current quantum entangled light.

[0006] The present invention provides a two-dimensional plane positioning system based on quantum entangled light to solve the above technical problems. The positioning system includes an entangled photon pair generator, a beam splitter, a first single-photon detector, a second single-photon detector, a time-to-digital converter, a coincidence counting measurement module, a reference light source, an auxiliary positioning device, and a quadrant detector; the entangled photon pair generator is used to generate entangled photon pairs, the beam splitter is used to split the generated entangled photon pairs into signal light and idler light, the first single-photon detector is used to directly receive the idler light, the signal light is used to transmit along the same optical path as the reference light source, the signal light reaches the second single-photon detector through the auxiliary positioning device, the reference light source reaches the quadrant detector through the auxiliary positioning device, the angle of the reference light source reaching the center position of the quadrant detector is determined by adjusting the auxiliary positioning device, and the angle of the target point to be measured is determined according to the adjusted angle of the auxiliary positioning device; the time-to-digital converter is used to obtain the photon arrival time sequences detected by the first single-photon detector and the second single-photon detector; the coincidence counting measurement module is used to perform coincidence counting according to the time sequences of the two signals to obtain the distance to the target point to be measured; the positioning of the target point to be measured is realized according to the distance and the angle.

[0007] The present invention realizes the rapid and efficient coupling of quantum signals by means of the coaxial transmission of the visible light beam emitted by the reference light source and the signal photons. Through the optical path structure design of the auxiliary positioning device, only by rotating the right-angle prism mirror therein can a 360-degree change in the ranging direction and the extraction of the azimuth angle be realized. The high-precision positioning of the two-dimensional plane based on quantum entangled light can be finally realized by using the distance and azimuth angle information of the target point to be measured.

[0008] Further, the auxiliary positioning device includes a long-pass dichroic mirror, a right-angle prism mirror, a hollow roof prism mirror, and a short-pass dichroic mirror. The long-pass dichroic mirror is used to transmit the signal light and reflect the reference light source, so that the signal light and the reference light source are transmitted along the same optical path to a right-angle reflecting surface of the right-angle prism mirror. After being reflected by the right-angle reflecting surface, it reaches the hollow roof prism mirror. The hollow roof prism mirror reflects it back to another right-angle reflecting surface of the right-angle prism mirror, and is reflected by the right-angle reflecting surface to the short-pass dichroic mirror. The short-pass dichroic mirror is used to transmit the reference light source, so that the reference light source reaches the quadrant detector. The short-pass dichroic mirror is used to reflect the signal light, so that the signal light reaches the second single-photon detector.

[0009] In the present invention, a right-angle prism mirror and a hollow roof prism mirror are used as auxiliary positioning devices, which are easier to adjust when determining the azimuth of a target point by using the auxiliary positioning devices.

[0010] Further, before measurement, the two-dimensional plane positioning system needs to be adjusted. By adjusting the positions and angles of the hollow roof prism mirror, the second single-photon detector, and the quadrant detector, when the signal photon reaches the optimal coupling efficiency, the irradiation point of the reference beam is located at the center position of the quadrant detector, and the positions and angles of the second single-photon detector and the quadrant detector are fixed accordingly.

[0011] Before measurement in the present invention, the positions and angles of the second single-photon detector and the quadrant detector are determined by adjusting the auxiliary positioning device to ensure that the signal photon reaches the optimal coupling efficiency when the irradiation point of the reference beam is located at the center position of the quadrant detector, so that it can be judged whether the signal photon reaches the optimal coupling efficiency by directly observing the position of the irradiation point of the reference beam on the quadrant detector during measurement, further improving the accuracy of subsequent measurement.

[0012] Further, during measurement, the hollow roof prism mirror is placed at the target point to be measured and its reflecting surface is pointed to the origin. The right-angle prism mirror is rotated to transmit the signal photon and the reference light to the target point to be measured, and the reference light source is made to reach the center position of the quadrant detector, and the rotation angle at this time is recorded. This rotation angle is the deflection angle between the origin and the target point to be measured relative to the positive direction of the X-axis; the reference light source is turned off, and the absolute distance between the origin and the target point to be measured is obtained by coincidence counting measurement of the arrival time sequence of the entangled photon pair; the target point to be measured is positioned according to the rotation angle and the obtained absolute distance; the origin refers to the irradiation point of the entangled beam on the reflecting surface of the polarization beam splitter, and the positive direction of the X-axis is opposite to the outgoing direction of the entangled photon pair.

[0013] During measurement in the present invention, the signal photon and the reference light are transmitted to the target point to be measured by rotating the right-angle prism mirror. The rotation angle when the reference light source reaches the center position of the quadrant detector is used as the angle of the target point to be measured. The angle of the target point to be measured is determined by means of visible light, and thus the positioning of the target point to be measured is realized. This process is convenient and can accurately determine the relative angle information of the target point to be measured.

[0014] Further, when the system determines the absolute distance between the origin and the target point, it is necessary to calibrate the inherent optical path difference between the signal light and the idler light. The calibration process is as follows:

[0015] A. Establish a plane coordinate system. Arbitrarily select two points on the X-axis, with the first point closer to the origin than the second point. Place the positioning device at the origin of the coordinates, and place the hollow roof prism mirrors at the first point respectively. Based on the arrival time series of the entangled photon signals detected by the first single-photon detector and the second single-photon detector, use the coincidence counting measurement method to obtain the first distance information;

[0016] B. Place the positioning device at the origin of the coordinates, and place the hollow roof prism mirrors at the second point respectively. Based on the arrival time series of the entangled photon signals detected by the first single-photon detector and the second single-photon detector, use the coincidence counting measurement method to obtain the second distance information;

[0017] C. Place the positioning device at the first point and place the hollow roof prism at the second point. Obtain the third distance information through the coincidence counting measurement method;

[0018] D. Determine the intrinsic optical path difference based on the distance information obtained in steps A, B, and C. The intrinsic optical path difference is equal to the first distance information plus the third distance information minus the second distance information.

[0019] During the entire calibration process of the present invention, it is not necessary to know the exact positions of the two selected points, and the calibration of the intrinsic optical path difference can be quickly and conveniently achieved, thereby improving the accuracy of distance measurement.

[0020] Furthermore, the absolute distance between the origin and the target point to be measured is:

[0021]

[0022] where L0 is the intrinsic optical path difference between the signal light and the idler light, L OR is the absolute distance between the measurement point and the target point to be measured, is the distance value of the target point to be measured obtained by performing coincidence counting measurement using the arrival time series of the entangled photon pairs.

[0023] The present invention also provides a two-dimensional plane positioning method based on quantum entangled light, and this method includes the following steps:

[0024] 1) Generate entangled photon pairs, and divide the generated entangled photon pairs into signal light and idler light, so that the idler light is directly coupled and received by the first single-photon detector locally at the measurement;

[0025] 2) Transmit the signal light and the reference light source along the same optical path to the right-angle prism mirror;

[0026] 3) Set a hollow roof prism mirror at the target point to be measured, and direct its reflecting surface towards the right-angle reflecting surface of the right-angle prism mirror. The right-angle prism mirror transmits the signal photons and the reference light to the hollow roof prism mirror at the target point to be measured. After being reflected by the hollow roof prism mirror, it reaches the other right-angle reflecting surface of the right-angle prism mirror, and the signal light is transmitted to the second single-photon detector by this right-angle reflecting surface, and the reference light is transmitted to the quadrant detector. Rotate the right-angle prism mirror to make the reference light source reach the center position of the quadrant detector, and record the rotation angle at this time;

[0027] 4) Turn off the reference light source, and perform coincidence counting measurement through the arrival time sequence of the entangled photon pairs to obtain the absolute distance between the origin and the target point to be measured; position the target point to be measured according to the rotation angle and the obtained absolute distance.

[0028] With the help of the coaxial transmission of the visible light beam emitted by the reference light source and the signal photons, the present invention realizes the fast and efficient coupling of quantum signals. Through the optical path structure design of the auxiliary positioning device, only by rotating the right-angle prism mirror therein can the 360-degree change in the ranging direction and the extraction of the azimuth angle be realized. The high-precision positioning of the two-dimensional plane based on quantum entangled light can be finally realized by using the distance and azimuth angle information of the target point to be measured.

[0029] Further, the method further includes determining the positions of the second single-photon detector and the quadrant detector before measurement. By adjusting the positions and angles of the hollow roof prism mirror, the second single-photon detector and the quadrant detector, when the signal photons reach the best coupling efficiency, the irradiation point of the reference light beam is located at the center position of the quadrant detector, and the positions and angles of the second single-photon detector and the quadrant detector are fixed accordingly.

[0030] Before measurement, the present invention determines the positions and angles of the second single-photon detector and the quadrant detector through the adjustment of the auxiliary positioning device to ensure that the signal photons reach the best coupling efficiency when the irradiation point of the reference light beam is located at the center position of the quadrant detector, so that during measurement, it can be judged whether the signal photons reach the best coupling efficiency by directly observing the position of the irradiation point of the reference light beam on the quadrant detector, further improving the accuracy of subsequent measurement.

[0031] Further, in step 4), when determining the absolute distance between the origin and the target point, it is necessary to calibrate the inherent optical path difference between the signal light and the idler light. The calibration process is as follows:

[0032] A. Establish a plane coordinate system. Arbitrarily select two points on the X-axis, with the first point closer to the origin than the second point. Place the positioning device at the coordinate origin, and place the hollow roof prism mirrors at the first point respectively. Based on the arrival time sequence of the entangled photon signals detected by the first single-photon detector and the second single-photon detector, use the coincidence counting measurement method to obtain the first distance information; where the origin refers to the center point of the beam splitter, and the positive direction of the X-axis is opposite to the emission direction of the entangled photon pair.

[0033] B. Place the positioning device at the coordinate origin, and place the hollow roof prism mirrors at the second point respectively. Based on the arrival time sequence of the entangled photon signals detected by the first single-photon detector and the second single-photon detector, use the coincidence counting measurement method to obtain the second distance information.

[0034] C. Place the positioning device at the first point and place the hollow roof prism at the second point. Obtain the third distance information through the coincidence counting measurement method.

[0035] D. Determine the intrinsic optical path difference based on the distance information obtained in steps A, B, and C. The intrinsic optical path difference is equal to the first distance information plus the third distance information minus the second distance information.

[0036] During the entire calibration process of the present invention, it is not necessary to know the exact positions of the two selected points, and the calibration of the intrinsic optical path difference can be quickly and conveniently realized, thereby improving the accuracy of distance measurement.

[0037] Furthermore, the absolute distance between the origin and the target point to be measured is:

[0038]

[0039] where L0 is the intrinsic optical path difference between the signal light and the idler light, L OR is the absolute distance between the measurement point and the target point to be measured, is the distance value of the target point to be measured obtained by using the arrival time sequence of the entangled photon pair for coincidence counting measurement. Description of the Drawings

[0040] Figure 1 is a schematic diagram of the generation principle of the quantum entanglement light source adopted by the present invention;

[0041] Figure 2 is a schematic diagram of the two-dimensional plane positioning principle based on quantum entanglement light of the present invention;

[0042] Figure 3 is a schematic diagram of the target point coordinate measurement principle adopted by the present invention;

[0043] Figure 4 is a schematic diagram of the three-dimensional coordinate system adopted for the two-dimensional plane positioning based on quantum entanglement light of the present invention. Detailed implementation manners

[0044] The following further describes the detailed implementation manners of the present invention in conjunction with the accompanying drawings.

[0045] The present invention uses a quantum entanglement source to generate entangled photon pairs with consistent frequencies. The entangled photon pairs are split into two paths of signals by a polarization beam splitter. One path is the signal light, which is used to transmit to the target point to be measured and reflected. The other path is the idler light, which is used to stay locally for coincidence counting measurement with the reflected signal light to calculate the distance information to the target point. With the aid of a reference light source, a quadrant detector, and an auxiliary positioning device, the signal light and the reference light source are transmitted along the same optical path. The signal light reaches the second single-photon detector through the auxiliary positioning device, and the reference light source reaches the quadrant detector through the auxiliary positioning device. By adjusting the auxiliary positioning device to make the reference light source reach the center position of the quadrant detector, the azimuth angle of the target point to be measured is determined according to the adjusted angle of the auxiliary positioning device. Precise positioning of the target point is achieved based on the distance and azimuth angle of the target point to be measured.

[0046] System embodiment

[0047] The two-dimensional plane positioning system of the present invention is as Figure 2 shown. The positioning system includes an entangled photon pair generator, a polarization beam splitter, a first single-photon detector, a second single-photon detector, a time-to-digital converter, a coincidence counting measurement module, a reference light source, a quadrant detector, and an auxiliary positioning device. The entangled photon pair generator is used to generate entangled photon pairs. The beam splitter is used to split the generated entangled photon pairs into signal light and idler light. The first single-photon detector is used to receive the idler light. The reference light source reaches the quadrant detector through the auxiliary positioning device. By adjusting the auxiliary positioning device to make the reference light source reach the center position of the quadrant detector, the angle of the target point to be measured is determined according to the adjusted angle of the auxiliary positioning device. The time-to-digital converter is used to obtain the photon arrival time sequences detected by the first single-photon detector and the second single-photon detector. The coincidence counting measurement module is used to perform coincidence counting according to the time sequences of the two paths of signals to obtain the distance to the target point to be measured. Positioning of the target point to be measured is achieved based on the distance and angle.

[0048] Among them, the polarization entanglement light source is generated by a quantum entanglement light source generating device, and its generation principle is as Figure 1 shown, including a femtosecond laser, a first half-wave plate, a lens, a potassium titanyl phosphate (PPKTP) crystal, a long-pass dichroic mirror, a second half-wave plate, and a polarization beam splitter. The femtosecond laser is used to emit 780 nm femtosecond pulsed pump light. After adjusting the polarization state of the light beam by the first half-wave plate, it is focused by the lens to the center of the PPKTP crystal, and entangled photon pairs with consistent frequencies are generated through the spontaneous parametric down-conversion process, and their wavelength is 1560 nm. Figure 1The mid-long wavelength pass dichroic mirror can filter out the remaining pump light after parametric down-conversion. The temperature of the PPKTP crystal is controlled by a precision thermostat. The repetition frequency of the femtosecond pulsed laser is used as the trigger signal for the first single-photon detector and the second single-photon detector in the positioning system, enabling them to operate in Geiger mode to improve the detection signal-to-noise ratio of the quantum entanglement signal. The generated polarization-entangled light source is split into two paths by a polarization beam splitter. One path is the signal light, and the other path is the idler light. The idler light is directly received by the first single-photon detector locally, and the signal light is coupled and received by the second single-photon detector through an auxiliary positioning device.

[0049] The auxiliary positioning device includes a long wavelength pass dichroic mirror, a right-angle prism mirror, a hollow roof prism mirror, and a short wavelength pass dichroic mirror. The long wavelength pass dichroic mirror is used to transmit the signal light and reflect the reference light source, so that the signal light and the reference light source are transmitted along the same optical path to a right-angle reflecting surface of the right-angle prism mirror. After being reflected by this right-angle reflecting surface, it reaches the hollow roof prism mirror. The hollow roof prism mirror reflects it back to another right-angle reflecting surface of the right-angle prism mirror, and is reflected by this right-angle reflecting surface to the short wavelength pass dichroic mirror. The short wavelength pass dichroic mirror is used to transmit the reference light source to make the reference light source reach the quadrant detector, and the short wavelength pass dichroic mirror is used to reflect the signal light to make the signal light reach the second single-photon detector. The reference light source in this embodiment is a collimated laser beam in the visible light band of 633 nm. After being reflected by the long wavelength pass dichroic mirror, it is combined with the signal photons and transmitted along the same optical path as the signal light. Subsequently, it is separated from the signal light at the short wavelength pass dichroic mirror and received by the quadrant detector.

[0050] Before using this positioning system for measurement, it is necessary to determine the positions and angles of the second single-photon detector and the quadrant detector through the adjustment of the auxiliary positioning device to ensure that the signal photons achieve the best coupling efficiency when the irradiation point of the reference beam is located at the center position of the quadrant detector. As Figure 3 and Figure 4 shown, a coordinate system is established in the two-dimensional plane. Taking the irradiation point of the entangled light beam on the reflection surface of the beam splitter as the coordinate origin, the positive direction of the X-axis is opposite to the outgoing direction of the entangled light beam, and the direction perpendicular to the X-axis in the horizontal plane is defined as the Y-axis direction. The hollow roof prism mirror is placed at point A in the X-axis direction. The positions and angles of the hollow roof prism mirror, the second single-photon detector, and the quadrant detector are adjusted respectively, so that when the signal photons achieve the best coupling efficiency, the irradiation point of the reference beam is exactly located at the center position of the quadrant detector; at this time, fix the azimuth angles of the quadrant detector and the second single-photon detector and do not adjust them during the actual positioning process.

[0051] Since there is an inherent optical path difference between the signal light and the idler light in the positioning system, in order to obtain the absolute distance of the target point to be located during the positioning process, it is also necessary to calibrate the inherent optical path difference. The calibration process is as follows:

[0052] 1) Arbitrarily select two points in the X-axis direction, one as point A and the other as point B. Place the positioning device at the coordinate origin O, place the hollow roof prism mirror at point A, and transmit the entangled photon signals detected by the first single-photon detector and the second single-photon detector to the time-to-digital converter to obtain two time series; perform coincidence counting operation on the two time series to obtain a coincidence measurement curve; use the least squares method to perform nonlinear fitting on the coincidence measurement data, and the abscissa value corresponding to the peak position of the curve is the arrival time difference Δτ of the two photon signals. The product of the arrival time difference Δτ and the speed of light c is the distance obtained by the coincidence measurement method, defined as L1. Define the true distance between point O and point A as L OA , then the inherent optical path difference L0 is the measured distance L1 minus twice the true distance L OA .

[0053] 2) Place the positioning device at the coordinate origin O, place the hollow roof prism mirror at point B, and use the coincidence counting measurement method in step 1) to obtain distance information, defined as L2. The true distance between point O and point B is L OB , then the inherent optical path difference L0 is the measured distance L2 minus twice the true distance L OB .

[0054] 3) Place the positioning device at point A of the coordinate, place the hollow roof prism mirror at point B, and use the coincidence counting measurement method in step 1) again to obtain the distance information between the two, defined as L3. The true distance between point A and point B is L AB , then the inherent optical path difference L0 is the measured distance L3 minus twice the true distance L AB .

[0055] 4) According to the measurement results in steps 1)-3) and the relationship with the inherent optical path difference, establish the following equations:

[0056]

[0057] Based on the above equations, the inherent optical path difference L0 between the signal light and the idler light can be obtained without knowing the specific positions of A and B:

[0058] L0 = L1 + L3 - L2

[0059] Through the above process, the calibration of the inherent optical path difference can be realized, and the accurate ranging based on quantum entangled light can be carried out by using the calibrated inherent optical path difference.

[0060] During actual measurement, the hollow roof prism mirror needs to be placed at the target point R to be measured and the reflecting surface should be pointed towards the coordinate origin O. The right-angle prism mirror enables the signal photons and the reference light to be transmitted to the target point R to be measured. By finely adjusting the tilt angle of the hollow roof prism mirror and rotating the right-angle prism mirror, the reference light beam can be adjusted to the center position of the quadrant detector. At this time, the signal photons can also achieve the best coupling efficiency, and the rotation angle at this time is the deflection angle of the target point to be measured relative to the positive direction of the X-axis.

[0061] After the adjustment is completed, turn off the reference light source and conduct distance measurement. During the measurement, coincidence counting is performed on the arrival time sequence of the entangled photon pairs, and a distance value is measured. Calculate the absolute distance L between the coordinate origin and the target point to be measured according to the calibrated inherent optical path difference between the signal light and the idler light in the positioning system. OR , and the specific calculation formula is as follows:

[0062]

[0063] During the above actual measurement process, the rotation angle θ of the right-angle prism mirror is the positive deflection angle of the target point to be measured relative to the X-axis in the coordinate system. If the coordinates of the target point R to be measured are (x R , y R ), then it satisfies the following relationship:

[0064]

[0065] According to the above equations, after obtaining the absolute distance L between the coordinate origin and the point to be measured OR and the positive deflection angle θ of the target point to be measured relative to the X-axis in the coordinate system, the coordinates of the target point R to be measured can be calculated:

[0066]

[0067] Through the above process, the present invention can conveniently achieve the positioning of the target point to be measured. By means of the coaxial transmission of the visible light beam emitted by the reference light source and the signal photons, the rapid and efficient coupling of quantum signals can be realized. Through the design of the optical path structure of the auxiliary positioning device, only by rotating the right-angle prism mirror therein can a 360-degree change in the ranging direction and the extraction of the azimuth angle be achieved. Using the distance and azimuth angle information of the target to be measured, high-precision positioning in a two-dimensional plane based on quantum entangled light can be finally realized.

[0068] Method Embodiment

[0069] The present invention divides the generated entangled photon pairs into signal light and idler light, and directly couples and receives the idler light by a first single-photon detector during measurement; the signal light and a reference light source are transmitted along the same optical path to a right-angle prism mirror; a hollow roof prism mirror is arranged at a point to be measured, and its reflecting surface is directed to the right-angle reflecting surface of the right-angle prism mirror. The right-angle prism mirror transmits the signal photons and the reference light to the hollow roof prism mirror at the point to be measured. After being reflected by the hollow roof prism mirror, it reaches another right-angle reflecting surface of the right-angle prism mirror, and this right-angle reflecting surface transmits the signal light to a second single-photon detector and the reference light to a quadrant detector. The right-angle prism mirror is rotated to make the reference light source reach the central position of the quadrant detector, and the rotation angle at this time is recorded; the reference light source is turned off, and the absolute distance between the origin and the point to be measured is obtained through coincidence counting measurement based on the arrival time sequence of the entangled photon pairs; the point to be measured is positioned according to the rotation angle and the obtained absolute distance. The specific implementation process of this method has been described in detail in the system embodiment and will not be elaborated here.

Claims

1. A two-dimensional plane positioning system based on quantum entangled light, characterized in that, The positioning system includes an entangled photon pair generator, a beam splitter, a first single-photon detector, a second single-photon detector, a time-to-digital converter, a coincidence counting measurement module, a reference light source, an auxiliary positioning device, and a quadrant detector; the entangled photon pair generator is used to generate entangled photon pairs, the beam splitter is used to split the generated entangled photon pairs into signal light and idler light, the first single-photon detector is used to directly receive the idler light, the signal light and the reference light source are transmitted along the same optical path, the signal light reaches the second single-photon detector through the auxiliary positioning device, the reference light source reaches the quadrant detector through the auxiliary positioning device, and when the reference light source reaches the center position of the quadrant detector, the angle of the target point to be measured is determined according to the angle adjusted by the auxiliary positioning device; the time-to-digital converter is used to obtain the photon arrival time series detected by the first single-photon detector and the second single-photon detector; the coincidence counting measurement module is used to perform coincidence counting according to the time series of the two signals to obtain the distance from the target point to be measured; the positioning of the target point to be measured is realized according to the distance and the angle; The auxiliary positioning device includes a long-pass dichroic mirror, a right-angle prism mirror, a hollow roof prism mirror, and a short-pass dichroic mirror. The long-pass dichroic mirror is used to transmit the signal light and reflect the reference light source, so that the signal light and the reference light source are transmitted along the same optical path to a right-angle reflecting surface of the right-angle prism mirror. After being reflected by this right-angle reflecting surface, it reaches the hollow roof prism mirror. The hollow roof prism mirror reflects it back to another right-angle reflecting surface of the right-angle prism mirror, and is reflected by this right-angle reflecting surface to the short-pass dichroic mirror. The short-pass dichroic mirror is used to transmit the reference light source to make the reference light source reach the quadrant detector, and the short-pass dichroic mirror is used to reflect the signal light to make the signal light reach the second single-photon detector.

2. The two-dimensional plane positioning system based on quantum entangled light according to claim 1, characterized in that, Before measurement, the two-dimensional plane positioning system needs to be adjusted. By adjusting the positions and angles of the hollow roof prism mirror, the second single-photon detector, and the quadrant detector, when the signal photons reach the best coupling efficiency, the irradiation point of the reference beam is located at the center position of the quadrant detector, and the positions and angles of the second single-photon detector and the quadrant detector are fixed accordingly.

3. The two-dimensional plane positioning system based on quantum entangled light according to claim 2, characterized in that, During measurement, the hollow roof prism mirror is placed at the target point to be measured and its reflecting surface is pointed to the origin. The right-angle prism mirror is rotated to make the signal photons and the reference light transmit to the target point to be measured, and make the reference light source reach the center position of the quadrant detector, and record the rotation angle at this time. This rotation angle is the deflection angle relative to the positive direction of the X-axis between the target point to be measured; the reference light source is turned off, and the absolute distance between the origin and the target point to be measured is obtained by coincidence counting measurement through the arrival time series of the entangled photon pairs; the target point to be measured is positioned according to the rotation angle and the obtained absolute distance; the origin refers to the irradiation point of the entangled light beam on the reflecting surface of the polarization beam splitter, and the positive direction of the X-axis is opposite to the emission direction of the entangled photon pairs.

4. The two-dimensional plane positioning system based on quantum entangled light according to claim 3, characterized in that, When the system determines the absolute distance between the origin and the target point, it is necessary to calibrate the inherent optical path difference between the signal light and the idler light. The calibration process is as follows: A. Establish a plane coordinate system. Arbitrarily select two points on the X-axis, with the first point closer to the origin than the second point. Place the positioning device at the coordinate origin, and place the hollow roof prism mirrors at the first point respectively. Based on the arrival time sequence of the entangled photon signals detected by the first single-photon detector and the second single-photon detector, use the coincidence counting measurement method to obtain the first distance information; B. Place the positioning device at the coordinate origin, and place the hollow roof prism mirrors at the second point respectively. Based on the arrival time sequence of the entangled photon signals detected by the first single-photon detector and the second single-photon detector, use the coincidence counting measurement method to obtain the second distance information; C. Place the positioning device at the first point and place the hollow roof prism at the second point. Obtain the third distance information through the coincidence counting measurement method; D. Determine the inherent optical path difference based on the distance information obtained in steps A, B, and C. The inherent optical path difference is equal to the first distance information plus the third distance information minus the second distance information.

5. The two-dimensional plane positioning system based on quantum entangled light according to claim 4, characterized in that, The absolute distance between the origin and the target point to be measured is: where L0 is the inherent optical path difference between the signal light and the idler light, and L OR is the absolute distance between the measurement point and the target point to be measured, is the distance value of the target point to be measured obtained by coincidence counting using the arrival time sequence of entangled photon pairs.

6. A two-dimensional plane positioning method based on quantum entangled light, characterized in that, This method includes the following steps: 1) Generate entangled photon pairs, and divide the generated entangled photon pairs into signal light and idler light, so that the idler light is directly coupled and received by the first single-photon detector; 2) Transmit the signal light and the reference light source along the same optical path to the right-angle prism mirror; 3) Set a hollow roof prism mirror at the target point to be measured, and direct its reflecting surface towards the right-angle reflecting surface of the right-angle prism mirror. The right-angle prism mirror transmits the signal photons and the reference light to the hollow roof prism mirror at the target point to be measured. After being reflected by the hollow roof prism mirror, it reaches the other right-angle reflecting surface of the right-angle prism mirror, and this right-angle reflecting surface transmits the signal light to the second single-photon detector and the reference light to the quadrant detector. Rotate the right-angle prism mirror to make the reference light source reach the center position of the quadrant detector, and record the rotation angle at this time; 4) Turn off the reference light source, and perform coincidence counting measurement through the arrival time sequence of the entangled photon pairs to obtain the absolute distance between the origin and the target point to be measured; Locate the target point to be measured according to the rotation angle and the obtained absolute distance.

7. The two-dimensional plane positioning method based on quantum entangled light according to claim 6, characterized in that, This method also includes determining the positions of the second single-photon detector and the quadrant detector before measurement. By adjusting the positions and angles of the hollow roof prism mirror, the second single-photon detector, and the quadrant detector, when the signal photons reach the optimal coupling efficiency, the irradiation point of the reference beam is located at the center position of the quadrant detector, and the positions and angles of the second single-photon detector and the quadrant detector are fixed accordingly.

8. The two-dimensional plane positioning method based on quantum entangled light according to claim 6 or 7, characterized in that, In step 4), when determining the absolute distance between the origin and the target point, it is necessary to calibrate the inherent optical path difference between the signal light and the idler light. The calibration process is as follows: A. Establish a plane coordinate system. Arbitrarily select two points on the X-axis, with the first point closer to the origin than the second point. Place the positioning device at the coordinate origin, and place the hollow roof prism mirrors at the first point respectively. Based on the arrival time series of the entangled photon signals detected by the first single-photon detector and the second single-photon detector, use the coincidence counting measurement method to obtain the first distance information; where the origin refers to the center point of the beam splitter, and the positive direction of the X-axis is opposite to the emission direction of the entangled photon pair. B. Place the positioning device at the coordinate origin, and place the hollow roof prism mirrors at the second point respectively. Based on the time difference between the arrival of the entangled photon signals detected by the first single-photon detector and the second single-photon detector, use the coincidence counting measurement method to obtain the second distance information. C. Place the positioning device at the first point and place the hollow roof prism at the second point, and obtain the third distance information through the coincidence counting measurement method. D. Determine the inherent optical path difference based on the distance information obtained in steps A, B, and C. The inherent optical path difference is equal to the first distance information plus the third distance information minus the second distance information.

9. The two-dimensional plane positioning method based on quantum entangled light according to claim 8, characterized in that, The absolute distance between the origin and the target point to be measured is: where L0 is the inherent optical path difference between the signal light and the idler light, and L OR is the absolute distance between the measurement point and the target point to be measured, is the distance value of the target point to be measured obtained by coincidence counting using the arrival time sequence of entangled photon pairs.

Images