A rubidium optical pump magnetometer and its measurement method

Abstract

This application provides a rubidium optically pumped magnetometer and its measurement method, belonging to the field of magnetometer technology. The entangled photon component includes a first laser and a nonlinear optical crystal, the nonlinear optical crystal being used to convert photons emitted by the first laser into entangled photon pairs; a rubidium atom gas cell for receiving the entangled photon pairs; a laser cooling system for cooling rubidium atoms to a Bose-Einstein condensate; and an interferometer phase detection system including a second laser, a first beam splitter, a beam combiner, and a signal processor. This application introduces entangled photons to form a quantum entangled state with rubidium atoms. The introduced entangled photons, through coupling with the rubidium atom system, form an enhanced quantum interference effect. Traditional rubidium optically pumped magnetometers are limited in measurement accuracy by quantum noise, but by introducing entangled photons, the system's measurement noise is reduced, thereby achieving higher measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of magnetometer technology, specifically to a rubidium optical pump magnetometer and its measurement method. Background Technology

[0002] The rubidium optically pumped magnetometer is a highly sensitive magnetic field detection device widely used in geomagnetic field measurement, resource exploration, and earthquake prediction. Traditional rubidium optically pumped magnetometers measure external magnetic fields by interacting rubidium atoms with a laser to change the spin direction of the rubidium atoms. However, due to quantum noise and other interference factors, traditional methods have limitations in measurement accuracy, especially in achieving the Heisenberg limit, typically only reaching the standard quantum limit, i.e., a measurement accuracy of [missing value]. .

[0003] Existing technologies primarily focus on improving the stability and sensitivity of rubidium optically pumped magnetometers. Methods employed include: enhancing the stability and coherence of the laser source; optimizing the design of the optical system to reduce optical loss; and improving data processing algorithms to enhance the accuracy of measurement results. Nevertheless, traditional methods remain limited by quantum noise, making breakthroughs difficult. Precision limitations.

[0004] The measurement accuracy of traditional rubidium optically pumped magnetometers is limited by quantum noise, reaching only the standard quantum limit. To further improve the accuracy of magnetometers, especially to break through the traditional quantum limit and achieve the Heisenberg limit of 1 / n measurement accuracy, the following challenges exist in existing technologies:

[0005] 1. Insufficient suppression of quantum noise: Current technologies mainly rely on improving detection equipment and algorithms, but still fail to overcome the fundamental limitation of quantum noise.

[0006] The impact of quantum noise: In rubidium optically pumped magnetometers, quantum noise is the main factor limiting measurement accuracy. Quantum noise originates from the random motion of rubidium atoms and statistical fluctuations in photons, leading to measurement uncertainty.

[0007] Quantum noise typically decreases with increasing number of measurements, but due to its quantum nature, it cannot be effectively resolved simply by increasing the number of atoms or the measurement time.

[0008] 2. Insufficient stability of entangled states: Although quantum entanglement can theoretically improve accuracy, maintaining the stability of photon entangled states during experiments faces technical challenges.

[0009] Existing technologies attempting to improve measurement accuracy using quantum entanglement often face the problem of unstable entangled states. External environmental factors (such as temperature fluctuations and electromagnetic interference) can cause entangled states to decohere rapidly, affecting measurement results.

[0010] 3. High-precision real-time calibration requirement: During long-term magnetic field measurements, the system needs continuous calibration to ensure the accuracy of the measurement data.

[0011] In dynamic environments, rubidium optically pumped magnetometers require continuous real-time calibration to maintain measurement accuracy. Current technologies rely primarily on periodic checks for calibration, which cannot cope with constantly changing environmental conditions. Summary of the Invention

[0012] In view of the technical problems existing in the background art, this application provides a rubidium optically pumped magnetometer and its measurement method, aiming to solve the technical problems of quantum noise limitation, entangled state stability and real-time calibration existing in the prior art.

[0013] In a first aspect, embodiments of this application provide a rubidium optically pumped magnetometer, comprising:

[0014] An entangled photonic component includes a first laser and a nonlinear optical crystal, the nonlinear optical crystal being used to convert photons emitted by the first laser into entangled photon pairs;

[0015] A rubidium atom gas cell is used to receive entangled photon pairs;

[0016] Laser cooling system used to cool rubidium atoms to a Bose-Einstein condensate;

[0017] An interferometer phase detection system includes a second laser, a first beam splitter, a beam combiner, and a signal processor. The first beam splitter splits the beam emitted by the second laser into a first beam and a second beam. The second beam enters a rubidium atom gas cell to generate a third beam. The first beam and the third beam are combined by the beam combiner and then enter the signal processor. The magnetic field strength is measured based on the acquired electrical signal.

[0018] In some embodiments, the nonlinear optical crystal is one of lithium niobate crystal, potassium titanate phosphate crystal, and barium borate crystal.

[0019] In some embodiments, a first tuner, a collimating lens, and a focusing lens are provided between the first laser and the nonlinear optical crystal.

[0020] In some embodiments, a lens group and a second tuner are provided between the nonlinear optical crystal and the rubidium atom gas cell.

[0021] In some embodiments, the entangled photonic component further includes a second beam splitter and a monitoring system, the second beam splitter being used to split the beam emitted by the entangled photonic component into a fourth beam and a fifth beam, the fourth beam being injected into a rubidium atom gas cell;

[0022] The monitoring system is used to monitor entangled photon pairs in the fifth beam.

[0023] In some embodiments, the monitoring system includes a photon detector, a polarization analyzer, and an optical interferometer arranged sequentially along the direction of the fifth beam, with a coincidence counter connected to the photon detector.

[0024] In some embodiments, the laser cooling system includes a third laser, an optical shaping system, a magneto-optical trap, and a vacuum pump.

[0025] In some embodiments, the signal processor includes a preamplifier, a filter, an ADC, a digital signal processor, a calibration module, a storage module, and a communication interface.

[0026] Secondly, embodiments of this application provide a measurement method for a rubidium optically pumped magnetometer, comprising the following steps:

[0027] A first laser emits a single beam of light that passes through the nonlinear optical crystal, which is used to convert the photons emitted by the first laser into entangled photon pairs.

[0028] The laser cooling system cools the rubidium atoms to bring them into a Bose-Einstein condensate state.

[0029] The rubidium atom gas chamber receives the entangled photon pair so that the rubidium atoms in the rubidium atom gas chamber are coupled with the entangled photons;

[0030] The second laser is split into a first beam and a second beam by the first beam splitter. The second beam is injected into the rubidium atom gas chamber to polarize the atoms in the rubidium atom gas chamber and generate Larmor precession.

[0031] The first and third beams are combined by a beam combiner and then enter the signal processor to be converted into an electrical signal. The magnetic field strength is measured based on the phase difference between the first and third beams.

[0032] In some embodiments, the laser cooling system cools rubidium atoms to 1~100 μK.

[0033] The advantages of this application, which differ from existing technical solutions, include:

[0034] 1. This application introduces entangled photons to form a quantum entangled state with rubidium atoms. The introduced entangled photons, through coupling with the rubidium atom system, create an enhanced quantum interference effect. This coupling mechanism significantly reduces quantum noise during the measurement process, especially in the phase measurement stage. Traditional rubidium optically pumped magnetometers are limited in measurement accuracy by quantum noise, but by introducing entangled photons, the system's measurement noise is reduced, thereby achieving higher measurement accuracy.

[0035] Compared to traditional systems, the stable quantum entangled state makes rubidium atoms more sensitive to phase changes under the influence of an external magnetic field, enabling precise capture of minute magnetic field variations and thus improving the overall measurement sensitivity of the rubidium optically pumped magnetometer. The measurement accuracy of the rubidium optically pumped magnetometer based on entangled photons has reached the theoretically expected Heisenberg limit. Specifically, the measurement uncertainty under the same conditions is improved to 1 / n, which is of great significance in high-precision magnetic field measurements.

[0036] 2. This application uses laser cooling technology to cool rubidium atoms to a Bose-Einstein condensate, which can reduce the kinetic energy of rubidium atoms and reduce the impact of thermal noise.

[0037] The above description is merely an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application; those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0039] Figure 1 This is a schematic diagram of the structure of this application;

[0040] Explanation of reference numerals in the attached figures: 1. Entangled photon assembly; 101. First laser; 102. Nonlinear optical crystal; 103. First tuner; 104. Collimating lens; 105. Focusing lens; 106. Lens group; 107. Second tuner; 108. Monitoring system; 108a. Photon detector; 108b. Polarization analyzer; 108c. Optical interferometer; 108d. Coincidence counter; 109. Second beam splitter; 2. Rubidium atom gas cell; 3. Laser cooling system; 4. Interferometer phase detection system; 401. Second laser; 402. First beam splitter; 403. Beam combiner; 404. Signal processor; 5. Entangled photon pair. Detailed Implementation

[0041] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0043] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0044] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0045] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0046] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0047] The measurement accuracy of traditional rubidium optically pumped magnetometers is limited by quantum noise, making it difficult to achieve the Heisenberg limit of 1 / n measurement accuracy. The existing technology has the following difficulties: (1) insufficient quantum noise suppression; (2) insufficient entangled state stability; (3) no high-precision real-time calibration.

[0048] To address the technical challenges of quantum noise limitations, entangled state stability, and real-time calibration in existing technologies, this application provides a rubidium optically pumped magnetometer and its measurement method. The method involves introducing entangled photons to form a quantum entangled state with rubidium atoms. These entangled photons, through coupling with the rubidium atom system, create an enhanced quantum interference effect. This coupling mechanism significantly reduces quantum noise during the measurement process, particularly in the phase measurement stage. Traditional rubidium optically pumped magnetometers are limited in measurement accuracy by quantum noise; however, the introduction of entangled photons reduces system measurement noise, thereby achieving higher measurement accuracy.

[0049] Please refer to Figure 1 This application provides a rubidium optically pumped magnetometer, comprising:

[0050] Entangled photon assembly 1 includes a first laser 101 and a nonlinear optical crystal 102, the nonlinear optical crystal 102 being used to convert photons emitted by the first laser 101 into entangled photon pairs 5;

[0051] Rubidium atom gas chamber 2, which is used to receive entangled photon pairs 5;

[0052] Laser cooling system 3, used to cool rubidium atoms to a Bose-Einstein condensate;

[0053] The interferometer phase detection system 4 includes a second laser 401, a first beam splitter 402, a beam combiner 403, and a signal processor 404. The first beam splitter 402 is used to split the beam emitted by the second laser 401 into a first beam and a second beam. The second beam enters the rubidium atom gas cell 2 and generates a third beam. The first beam and the third beam are combined by the beam combiner 403 and then enter the signal processor 404. The magnetic field strength is measured based on the acquired electrical signal.

[0054] In some embodiments, the nonlinear optical crystal 102 is one of lithium niobate crystal, potassium titanate phosphate crystal, and barium borate crystal.

[0055] In some embodiments, a first tuner 103, a collimating lens 104, and a focusing lens 105 are provided between the first laser 101 and the nonlinear optical crystal 102.

[0056] In the technical solution of this application embodiment, when using a lithium niobate crystal to generate entangled photon pairs 5, a lens is placed between the first laser 101 and the nonlinear optical crystal 102. First, a collimating lens 104 is used to collimate the laser beam emitted from the laser source, improving its parallelism. Then, a focusing lens 105 focuses the collimated beam onto the lithium niobate crystal. This increases the interaction area between the laser and the crystal, improving the production efficiency of entangled photons. In this embodiment, the collimating lens 104 is a convex lens with a suitable focal length, placed near the laser source output port according to the laser propagation direction. The focusing lens 105, with a suitable focal length selected based on the crystal position and laser spot requirements, is placed close to the crystal.

[0057] The first tuner 103 is used to adjust the frequency and wavelength of the first laser 101 to meet the phase-matching conditions of the crystal, ensuring maximum output of entangled photons. The first tuner 103 is integrated with or connected to the laser source, and adjusts the laser parameters in real time through a feedback control mechanism. This embodiment uses a tuner based on the electro-optic effect, precisely adjusting the laser frequency by changing the voltage applied to the tuner. The tuner is placed near the laser source for easy electrical connection and signal transmission.

[0058] In some embodiments, a lens group 106 and a second tuner 107 are provided between the nonlinear optical crystal 102 and the rubidium atom gas chamber 2.

[0059] In the technical solution of this application embodiment, when the generated entangled photons are introduced into the rubidium atom gas chamber 2, a lens group 106 consisting of multiple lenses is used to shape and focus the entangled photon beam, so that it is better coupled into the rubidium atom system. These lenses are arranged between the entangled photon output path and the entrance of the rubidium atom system, and multiple lenses are used to gradually adjust the size and propagation direction of the beam to ensure that the beam is accurately injected into the rubidium atom gas chamber 2.

[0060] The second tuner 107 modulates the phase and frequency of the entangled photon beam, causing the entangled photons to interact with the spins of rubidium atoms, forming a quantum entangled state between the rubidium atoms. This quantum state effectively suppresses quantum noise of the rubidium atoms when measuring the magnetic field, significantly improving measurement accuracy. The second tuner 107 is placed after the lens group 106 to finely adjust the phase and frequency of the shaped and focused entangled photon beam. Simultaneously, the second tuner 107 needs to be connected to the control system to adjust the tuning parameters in real time according to experimental requirements and measurement feedback.

[0061] In some embodiments, the entangled photonic component 1 further includes a second beam splitter 109 and a monitoring system 108. The second beam splitter 109 is used to split the light beam emitted by the entangled photonic component 1 into a fourth beam and a fifth beam, with the fourth beam entering the rubidium atom gas chamber 2.

[0062] The monitoring system 108 is used to monitor entangled photon pairs 5 in the fifth beam.

[0063] In some embodiments, the monitoring system 108 includes a photon detector 108a, a polarization analyzer 108b, and an optical interferometer 108c arranged sequentially along the direction of the fifth beam, and a coincidence counter 108d is connected to the photon detector 108a.

[0064] In the technical solution of this application embodiment, the photon detector 108a is used to detect the intensity and arrival time of entangled photons. Common types include single-photon detectors 108a, such as silicon-based avalanche photodiodes (APDs) or superconducting nanowire single-photon detectors.

[0065] The coincidence counter 108d performs coincidence counting on the signal output by the photon detector 108a, and determines the correlation and stability of the entangled photon pair 5 by measuring the coincidence count rate.

[0066] The polarization analyzer 108b is used to measure the polarization state of entangled photons and monitor the stability of their polarization correlation characteristics.

[0067] The optical interferometer 108c determines whether the phase relationship of entangled photons is stable by monitoring the stability of interference fringes.

[0068] The photon detector 108a is placed at a suitable position in the entangled photon optical path to ensure efficient photon detection. The coincidence counter 108d is connected to the photon detector 108a, and an appropriate coincidence window time is set to accurately measure the coincidence count rate of photon pairs. The polarization analyzer 108b should be placed in the optical path for convenient measurement of the polarization state of entangled photons and should be calibrated periodically. The optical interferometer 108c requires precise adjustment of its optical path length and the angles of the mirrors and beam splitters to obtain stable interference fringes.

[0069] In some embodiments, the laser cooling system 3 includes a third laser, an optical shaping system, a magneto-optical trap, and a vacuum pump.

[0070] In the technical solutions of this application embodiment, the third laser is typically a semiconductor laser, providing the laser light required for cooling the rubidium atoms. A commonly used example is a distributed feedback semiconductor laser (DFB), with a wavelength of 780 nm, corresponding to the D2 line of rubidium atoms. The laser power is generally between tens of milliwatts and hundreds of milliwatts, and the specific power needs to be adjusted according to the number of atoms being cooled and the cooling efficiency.

[0071] Optical shaping systems include optical components such as lenses and beam splitters, used to shape laser beams into shapes and sizes suitable for cooling rubidium atoms.

[0072] The magneto-optical trap consists of six mutually perpendicular laser beams and a pair of anti-Helmholtz coils, used to trap and cool rubidium atoms. The magnetic field gradient generated by the anti-Helmholtz coils is typically between a few Gauss per centimeter and tens of Gauss per centimeter. The intensity of the six laser beams is generally between a few milliwatts per square centimeter and tens of milliwatts per square centimeter, and needs to be precisely adjusted using an optical attenuator. The frequency of the cooling laser needs to have a certain negative detuning relative to the resonant frequency of the rubidium atoms, typically ranging from a few megahertz to tens of megahertz.

[0073] Vacuum pumps are used to maintain a high vacuum environment in the laser cooling system 3, reducing collisions between atoms and other gas molecules. Molecular pumps and ion pumps are common choices, enabling the system to achieve a vacuum level in the range of 10⁻⁸ to 10⁻¹¹ Torr.

[0074] In some embodiments, the signal processor 404 includes a preamplifier, a filter, an ADC, a digital signal processor, a calibration module, a storage module, and a communication interface.

[0075] In the technical solution of this application embodiment, a preamplifier is used to initially amplify the weak electrical signal output from the interferometer to increase the signal strength and facilitate subsequent processing. The preamplifier needs to have low noise and high gain characteristics to reduce the impact of noise on the signal.

[0076] Filters are used to remove noise and spurious signals from a signal, retaining the useful signal relevant to the magnetic field measurement. Common filters include low-pass filters, high-pass filters, and band-pass filters, which are selected and configured according to the frequency characteristics of the signal.

[0077] An ADC (Analog-to-Digital Converter) converts amplified and filtered analog signals into digital signals for digital signal processing. The resolution and sampling rate of an ADC need to be appropriately selected based on the measurement accuracy and the rate of signal change.

[0078] Digital Signal Processor 404 (DSP): Executes various data processing algorithms, such as quantum noise suppression algorithms and phase analysis algorithms. It extracts information related to magnetic field strength by processing digital signals.

[0079] Calibration module: Based on pre-set calibration parameters or real-time calibration data, the processed signal is calibrated to improve measurement accuracy and stability. The calibration module can employ lookup table methods or model-based calibration methods.

[0080] Storage module: Used to store measurement data, processing results, calibration parameters, and other information for subsequent analysis and processing.

[0081] Communication interface: This interface transmits the processed results to external devices, such as computers or monitors, for user observation and further analysis. Communication interfaces can use methods such as USB or Ethernet.

[0082] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0083] Example

[0084] A rubidium optical pump magnetometer, such as Figure 1 As shown, it includes an entangled photon component 1, a rubidium atom gas cell 2, a laser cooling system 3, and an interferometer phase detection system 4.

[0085] The entangled photon assembly 1, along the beam emission direction, sequentially includes a first laser 101, a first tuner 103, a collimating lens 104, a focusing lens 105, and a lithium niobate crystal. The first tuner 103 is connected to adjust the frequency and wavelength of the first laser 101 to meet the phase matching condition of the lithium niobate crystal. The collimating lens 104 collimates the beam emitted by the first laser 101, and the focusing lens 105 focuses the collimated beam onto the lithium niobate crystal. The lithium niobate crystal converts photons in the single beam into entangled photon pairs 5, forming an entangled photon beam.

[0086] A lens group 106 and a second tuner 107 are provided between the lithium niobate crystal and the rubidium atom gas cell 2. The lens group 106 consists of multiple lens groups 106. The lens group 106 is used to shape and focus the entangled photon beam, so that it can better couple with the rubidium atoms in the rubidium atom gas cell 2. The second tuner 107 performs fine adjustment of the phase and frequency of the shaped and focused entangled photon beam. At the same time, the second tuner 107 is connected to the control system so that the tuning parameters can be adjusted in real time according to experimental requirements and measurement feedback.

[0087] The entangled photon assembly 1 also includes a second beam splitter 109 and a monitoring system 108. The second beam splitter 109 is located between the second tuner 107 and the rubidium atom gas cell 2, and is used to split the beam emitted by the entangled photon assembly 1 into a fourth beam and a fifth beam. The fourth beam enters the rubidium atom gas cell 2, and the fifth beam enters the monitoring system 108. The monitoring system 108 is used to monitor the entangled photon pairs 5 in the fifth beam, and includes a photon detector 108a, a polarization analyzer 108b, and an optical interferometer 108c arranged sequentially along the direction of the fifth beam. A coincidence counter 108d is connected to the photon detector 108a.

[0088] The laser cooling system 3 includes a third laser, an optical shaping system, a magneto-optical trap, and a vacuum pump. The third laser is a semiconductor laser used to generate cooling laser light. The wavelength of the semiconductor laser is 780 nm, corresponding to the D2 line of rubidium atoms. The magneto-optical trap consists of six mutually perpendicular laser beams and a pair of anti-Helmholtz coils, used to trap and cool rubidium atoms. The vacuum pump is an ion pump, which enables the system to achieve a vacuum level of 10 Torr, used to maintain the high vacuum environment of the laser cooling system 3 and reduce collisions between atoms and other gas molecules.

[0089] The interferometer phase detection system 4 includes a second laser 401, a first beam splitter 402, a beam combiner 403, and a signal processor 404. The first beam splitter 402 splits the beam emitted by the second laser 401 into a first beam and a second beam. The second beam enters the rubidium atom gas cell 2 to generate a third beam. The first beam and the third beam are combined by the beam combiner 403 and then enter the signal processor 404. The magnetic field strength is measured based on the acquired electrical signal. The signal processor 404 includes a preamplifier, a filter, an ADC, a digital signal processor 404, a calibration module, a storage module, and a communication interface.

[0090] A measurement method for a rubidium optically pumped magnetometer includes the following steps:

[0091] The single beam of light emitted by the first laser 101 is tuned by the first tuner 103 according to the phase matching condition of the lithium niobate crystal. The wavelength and frequency of the single beam of light are adjusted. Then, it passes through the collimating lens 104 and the focusing lens 105 in sequence for collimation and focusing before entering the lithium niobate crystal. The lithium niobate crystal converts the photons in the single beam of light into entangled photon pairs 5, forming an entangled photon beam.

[0092] The entangled photon beam passes through lens group 106 and second tuner 107, introducing the generated entangled photons into rubidium atom gas cell 2. Rubidium atom gas cell 2 receives the entangled photon pair 5, thereby coupling the rubidium atoms within the gas cell 2 with the entangled photons. The second tuner 107 adjusts the incident angle and phase of the entangled photon beam to achieve optimal coupling between the entangled photons and rubidium atoms.

[0093] Laser cooling system 3 uses laser cooling technology to cool rubidium atoms to 1~100 μK, placing them in a Bose-Einstein condensate state. Monitoring system 108 is used to monitor the stability of the entangled state, optimize the interaction between entangled photons and rubidium atoms, and ensure high entanglement is maintained during subsequent measurements.

[0094] The second laser 401 is split into a first beam and a second beam by the first beam splitter 402. The second beam enters the rubidium atom gas chamber 2, causing the atoms in the rubidium atom gas chamber 2 to polarize and generate Larmor precession. The first beam and the third beam are combined by the beam combiner 403 and then enter the signal processor 404 to be converted into an electrical signal. The magnetic field strength is measured based on the phase difference between the first beam and the third beam.

[0095] Under the influence of an external magnetic field, the interferometer phase detection system 4 detects and records the phase difference between the first beam and the second beam. The interferometer phase detection system 4 converts the phase difference into measurable interference fringes through optical interference effect. The interference fringes are processed in real time using a signal processor 404. By comparing the phase change and the magnetic field strength, high-precision magnetic field measurement results are obtained.

[0096] The measurement parameters of the rubidium optical pump magnetometer in this application embodiment and the existing rubidium optical pump magnetometer were compared to obtain the following Table 1.

[0097] Table 1. Parameter comparison between the rubidium optically pumped magnetometer in this application embodiment and existing rubidium optically pumped magnetometers.

[0098]

[0099] As can be seen from Table 1, the parameters of the rubidium optically pumped magnetometer in this embodiment are all higher than those of the traditional rubidium optically pumped magnetometer.

[0100] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A rubidium optically pumped magnetometer, characterized in that, The rubidium optically pumped magnetometer includes: An entangled photonic component includes a first laser and a nonlinear optical crystal, the nonlinear optical crystal being used to convert photons emitted by the first laser into entangled photon pairs; A rubidium atom gas chamber for receiving the entangled photon pairs; A laser cooling system for cooling rubidium atoms in the rubidium atom chamber to a Bose-Einstein condensate state; An interferometer phase detection system includes a second laser, a first beam splitter and beam combiner, and a signal processor. The first beam splitter splits the beam emitted by the second laser into a first beam and a second beam. The second beam enters a rubidium atom gas cell to generate a third beam. The first beam and the third beam are combined by the beam combiner and then enter the signal processor. The magnetic field strength is measured based on the acquired electrical signal.

2. The rubidium optical pump magnetometer according to claim 1, characterized in that, The nonlinear optical crystal is one of lithium niobate crystal, potassium titanate phosphate crystal, and barium borate crystal.

3. The rubidium optically pumped magnetometer according to claim 1, characterized in that, A first tuner, a collimating lens, and a focusing lens are provided between the first laser and the nonlinear optical crystal.

4. The rubidium optically pumped magnetometer according to claim 1, characterized in that, A lens group and a second tuner are provided between the nonlinear optical crystal and the rubidium atom gas chamber.

5. The rubidium optically pumped magnetometer according to claim 1, characterized in that, The entangled photonic component also includes a second beam splitter and a monitoring system. The second beam splitter is used to split the beam emitted by the entangled photonic component into a fourth beam and a fifth beam, and the fourth beam is injected into the rubidium atom gas cell. The monitoring system is used to monitor entangled photon pairs in the fifth beam.

6. The rubidium optically pumped magnetometer according to claim 5, characterized in that, The monitoring system includes a photon detector, a polarization analyzer, and an optical interferometer arranged sequentially along the direction of the fifth beam, and a coincidence counter is connected to the photon detector.

7. The rubidium optically pumped magnetometer according to claim 1, characterized in that, The laser cooling system includes a third laser, an optical shaping system, a magneto-optical trap, and a vacuum pump.

8. The rubidium optically pumped magnetometer according to claim 1, characterized in that, The signal processor includes a preamplifier, a filter, an ADC, a digital signal processor, a calibration module, a storage module, and a communication interface.

9. A measurement method for a rubidium optically pumped magnetometer according to any one of claims 1 to 8, characterized in that, Includes the following steps: The first laser emits a single beam of light that passes through the nonlinear optical crystal, which is used to convert the photons emitted by the first laser into entangled photon pairs. The laser cooling system cools the rubidium atoms to bring them into a Bose-Einstein condensate state. The rubidium atom gas chamber receives the entangled photon pair so that the rubidium atoms in the rubidium atom gas chamber are coupled with the entangled photons; The second laser is split into a first beam and a second beam by a first beam splitter. The second beam enters the rubidium atom gas chamber to polarize the atoms in the rubidium atom gas chamber and generate Larmor precession. The first beam and the third beam are combined by a beam combiner and then enter the signal processor to be converted into an electrical signal. The magnetic field strength is measured based on the phase difference between the first beam and the third beam.

10. The measurement method of the rubidium optical pump magnetometer according to claim 9, characterized in that, The laser cooling system cools the rubidium atoms to 1~100 μK.

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