Atomic gravimeter based on grating chip

Abstract

The invention discloses an atomic gravimeter based on a grating chip, and the atomic gravimeter comprises a vacuum cavity which releases atom steam into the vacuum cavity through an atom source, and the inner side or outer side of the upper part of the vacuum cavity is provided with the grating chip; the first coil assembly provides a gradient magnetic field for the vacuum cavity, diffraction light of the grating chip and incident light of the first incident light assembly form an intersection area in the vacuum cavity, and an atom capture area is formed in the area; the second incident light assembly and the second coil assembly are coaxially arranged, the axis of the second incident light assembly and the axis of the second coil assembly penetrate through the atom capture area, and the second coil assembly provides a uniform magnetic field into the vacuum cavity; the photoelectric detection assembly is arranged at the lower part of the vacuum cavity and is used for detecting an atomic fluorescence signal; the microwave antenna is disposed on the vacuum chamber, and the emission direction faces the interior of the vacuum chamber. According to the invention, based on the grating chip, the gravity measurement can be realized by using fewer laser beams, the structure of the gravimeter is simplified, the size of the atomic gravimeter is reduced, and the robustness and practicability of the system are enhanced.

Description

Technical Field

[0001] The invention relates to the field of precision measurement technology, and in particular to an atomic gravimeter based on a grating chip. Background Art

[0002] Atomic gravimeters use lasers to manipulate the quantum state of atoms to achieve atomic interference and resolve gravitational acceleration information from the phase of atomic interference fringes. They have extremely high accuracy and advantages such as high sampling rate and long service life. Atomic gravimeters can serve in fields such as geophysical surveys, precision metrology and inertial navigation.

[0003] The working process of an atomic gravimeter generally includes four stages: atom capture, state preparation, atomic interference, and final state detection. Each stage requires quantum manipulation of atoms by lasers of different frequencies or directions. Traditional atomic gravimeters often require multiple laser beams to achieve gravity measurement, which makes the structure of the atomic gravimeter relatively complex and the miniaturization work relatively difficult. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides an atomic gravimeter based on a grating chip.

[0005] The present invention discloses an atomic gravimeter based on a grating chip, comprising:

[0006] A vacuum chamber, which maintains a vacuum environment through a vacuum component and releases atomic vapor into the chamber through an atomic source, and a grating chip is installed on the inner side or outer side of the upper side wall;

[0007] A first coil group and a first incident light component are coaxially arranged with the grating chip, the first coil group is used to provide a gradient magnetic field into the vacuum chamber, the incident light of the first incident light component is perpendicular to the diffraction surface of the grating chip, and the diffracted light of the grating chip and the incident light of the first incident light component form an intersection area in the vacuum chamber, and an atomic capture area is formed in the intersection area;

[0008] a second incident light component and a second coil group coaxially arranged therewith, wherein the axes of the second incident light component and the second coil group pass through the atom capture region, and the second coil group is used to provide a uniform magnetic field into the vacuum cavity;

[0009] A photoelectric detection component, which is arranged at the lower part of the vacuum chamber and is used to detect atomic fluorescence signals;

[0010] The microwave antenna is arranged on the vacuum chamber and its emission direction is toward the atom trapping region.

[0011] As a further improvement of the present invention, the first coil group, the first incident light component and the grating chip are coaxially arranged in the horizontal direction; the second coil group and the second incident light component are coaxially arranged in the vertical direction; the center of the first coil group coincides with the intersection area.

[0012] As a further improvement of the present invention, the first incident light component comprises a first optical fiber and a first lens which are coaxially arranged; the first optical fiber and the first lens are arranged at the upper part of the vacuum chamber and are placed on the opposite side of the grating chip; the incident light of the first optical fiber is vertically irradiated on the diffraction surface of the grating chip after passing through the first lens;

[0013] The second incident light component includes a coaxially arranged reflector, a second optical fiber and a third lens. The reflector is arranged at the bottom of the vacuum chamber, and the second optical fiber and the third lens are arranged at the top of the vacuum chamber. The incident light of the second optical fiber passes through the atomic capture area through the third lens and then irradiates the reflector, and the reflector reflects the incident light along the original path.

[0014] The present invention discloses an atomic gravimeter based on a grating chip, comprising:

[0015] A vacuum chamber, which maintains a vacuum environment through a vacuum component and releases atomic vapor into the chamber through an atomic source, and a grating chip is installed on the inner side or the outer side of the upper part;

[0016] A first coil group, a second coil group and an incident light component are coaxially arranged with the grating chip, the grating chip is provided with a light hole for the light beam to pass through; the first coil group is used to provide a gradient magnetic field into the vacuum chamber, and the second coil group is used to provide a uniform magnetic field into the vacuum chamber; the incident light of the incident light component is perpendicular to the diffraction surface of the grating chip, and the diffracted light of the grating chip and the incident light of the incident light component form an intersection area in the vacuum chamber, and an atomic capture area is formed in the intersection area;

[0017] A photoelectric detection component, which is arranged at the lower part of the vacuum chamber and is used to detect atomic fluorescence signals;

[0018] The microwave antenna is arranged on the vacuum chamber and its emission direction is toward the atom trapping region.

[0019] As a further improvement of the present invention, the grating chip, the first coil group, the second coil group and the incident light component are all coaxially arranged in the vertical direction; and the center of the first coil group coincides with the intersection area.

[0020] As a further improvement of the present invention, the grating chip is installed on the top outer side of the vacuum chamber, and the diffraction surface of the grating chip faces the inside of the vacuum chamber.

[0021] As a further improvement of the present invention, the incident light assembly includes a first optical fiber, a first lens, an optical switch, and a reflector that are coaxially arranged;

[0022] The first optical fiber and the first lens are installed at the bottom of the vacuum chamber, and the optical switch and the reflector are installed at the top of the vacuum chamber. The optical switch is used to block the light beam passing through the light hole of the grating chip when atoms are captured, and the reflector is used to reflect the incident light along the original path.

[0023] As a further improvement of the present invention, the grating chip is installed in a position close to the top inside the vacuum chamber, and the diffraction surface of the grating chip is arranged to face upward.

[0024] As a further improvement of the present invention, the incident light assembly includes a first optical fiber, a first lens, an optical switch, and a reflector that are coaxially arranged;

[0025] The first optical fiber and the first lens are installed on the top of the vacuum chamber, and the optical switch and the reflector are installed on the bottom of the vacuum chamber. The optical switch is used to block the light beam passing through the light hole of the grating chip when atoms are captured, and the reflector is used to reflect the incident light along the original path.

[0026] As a further improvement of the present invention, the photoelectric detection component includes a photoelectric detector and a second lens; the second lens is used to converge the atomic fluorescence signal to the photoelectric detector; and the photoelectric detector is used to detect the atomic fluorescence signal.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] Compared with traditional atomic gravimeters, the present invention can realize gravity measurement using fewer laser beams based on the grating chip, which simplifies the structure of the atomic gravimeter while also reducing the overall volume of the atomic gravimeter, making it more portable and adaptable to various environmental conditions, thereby enhancing the robustness and practicality of the system.

[0029] Compared with traditional atomic gravimeters, the present invention can realize gravity measurement using fewer laser beams based on the grating chip, which simplifies the structure of the atomic gravimeter and also reduces the overall volume of the atomic gravimeter, making it more portable and adaptable to various environmental conditions.

[0030] Compared with traditional atomic gravimeters, the present invention can effectively reduce the probability of system failure, improve the stability of long-term operation, enhance robustness and also improve practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of an atomic gravimeter based on a grating chip disclosed in the first embodiment of the present invention;

[0032] Figure 2 A schematic diagram of atom capture of an atomic gravimeter based on a grating chip according to the first embodiment of the present invention;

[0033] Figure 3 A schematic diagram of state preparation, atomic interference, and final state detection of an atomic gravimeter based on a grating chip disclosed in the first embodiment of the present invention;

[0034] Figure 4 This is a working flow chart of the atomic gravimeter based on the grating chip disclosed in the first embodiment of the present invention;

[0035] Figure 5 A schematic structural diagram of an atomic gravimeter based on a grating chip disclosed in a second embodiment of the present invention;

[0036] Figure 6 A schematic diagram of atom capture of an atomic gravimeter based on a grating chip according to a second embodiment of the present invention;

[0037] Figure 7 A schematic diagram of state preparation, atomic interference, and final state detection of an atomic gravimeter based on a grating chip disclosed in the second embodiment of the present invention;

[0038] Figure 8 This is a working flow chart of an atomic gravimeter based on a grating chip disclosed in the second embodiment of the present invention;

[0039] Fig. 9 This is a schematic diagram of the structure of an atomic gravimeter based on a grating chip disclosed in the third embodiment of the present invention.

[0040] In the figure:

[0041] 1. Grating chip; 101. Light hole; 2. First coil group; 3. Vacuum cavity; 4. Magnetic shielding mechanism; 401. Lower light opening; 402. Upper light opening; 403. Side light opening; 5. First optical fiber; 6. First lens; 7. First wave plate; 8. Reflector; 9. Second wave plate; 10. Atom capture region; 11. Second coil group; 12. Second lens; 13. Photodetector; 14. Atom source; 15. Vacuum assembly; 16. Microwave antenna; 17. Second optical fiber; 18. Third lens; 19. Third wave plate; 20. Optical switch; 100. First incident light; 200. Diffracted light; 300. Second incident light; 400. Atomic fluorescence signal; 500. Atomic cluster; 600. Reflected light. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0044] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0046] Embodiment 1:

[0047] like Figure 1-3As shown, an atomic gravimeter based on a grating chip according to the present invention comprises a vacuum chamber 3, a grating chip 1, a first coil group 2, a first incident light component, a second incident light component, a second coil group 11, a photoelectric detection component and a microwave antenna 16, wherein the vacuum chamber 3 maintains a vacuum environment through a vacuum component 15, and releases atomic vapor into the interior thereof through an atomic source 14, and a grating chip 1 is installed on the inner side or outer side of the upper side wall of the vacuum chamber 3; the first coil group 2 and the first incident light component are coaxially arranged with the grating chip 1, the first coil group 2 is used to provide a gradient magnetic field into the vacuum chamber 3, and the incident light component of the first incident light component is provided with a photoelectric detection component. The incident light is perpendicular to the diffraction surface of the grating chip 1, and the diffracted light 200 of the grating chip 1 and the incident light of the first incident light component form an intersection area in the vacuum chamber 3, and an atomic capture area 10 is formed in the intersection area; the second incident light component and the second coil group 11 are coaxially arranged, wherein the axis of the second incident light component and the second coil group 11 passes through the atomic capture area 10, and the second coil group 11 is used to provide a uniform magnetic field into the vacuum chamber 3; the photoelectric detection component is arranged at the lower part of the vacuum chamber 3, which is used to detect atomic fluorescence signals; the microwave antenna 16 is arranged on the vacuum chamber 3, and its emission direction is toward the atomic capture area 10.

[0048] In this embodiment, compared with the traditional atomic gravimeter, it can realize gravity measurement using fewer laser beams based on the grating chip 1, which simplifies the structure of the atomic gravimeter and also reduces the overall volume of the atomic gravimeter, making it more portable and adaptable to various environmental conditions.

[0049] Specific:

[0050] like Figure 1 As shown, in the above embodiment, preferably, the first coil group 2, the first incident light component and the grating chip 1 are all coaxially arranged in the horizontal direction; the second coil group 11 and the second incident light component are all coaxially arranged in the vertical direction; the center of the first coil group 2 coincides with the intersection area; the function of the first coil group 2 is to provide a gradient magnetic field in space, and the gradient magnetic field can work together with the intersection area to achieve atomic capture and cooling. In this embodiment, the atomic capture area 10 is at the center of the gradient magnetic field.

[0051] In the above embodiment, preferably, the first incident light component includes a first optical fiber 5 and a first lens 6 which are coaxially arranged; the first optical fiber 5 and the first lens 6 are arranged at the upper part of the vacuum chamber 3 and are placed on the opposite side of the grating chip 1; the first incident light 100 of the first optical fiber 5 is vertically irradiated on the diffraction surface of the grating chip 1 after passing through the first lens 6. In this embodiment, the first lens 6 is used to collimate the divergent first incident light 100 emitted by the first optical fiber 5 into parallel light to form a large-diameter light beam, the diameter of which is adapted to the size of the grating chip 1.

[0052] In the above embodiment, preferably, in order to achieve polarization adjustment of the first incident light 100, a first wave plate 7 is further arranged between the first lens 6 and the diffraction surface of the grating chip 1 in this embodiment, and the first wave plate 7 is coaxially arranged with the first lens 6, the grating chip 1 and the first optical fiber 5.

[0053] In the above embodiment, preferably, the second incident light component includes a coaxially arranged reflector 8, a second optical fiber 17 and a third lens 18, the reflector 8 is arranged at the bottom of the vacuum chamber 3, the second optical fiber 17 and the third lens 18 are arranged at the top of the vacuum chamber 3, the incident light of the second optical fiber 17 passes through the atom capture region 10 through the third lens 18 and then irradiates the reflector 8, and the reflector 8 reflects the second incident light 300 along the original path. In actual use, the second incident light 300 emitted by the second optical fiber 17 will be vertically irradiated on the reflector 8, and the second incident light 300 will be reflected back along the original path through the reflector 8. In this embodiment, in order to reduce the measurement noise of the gravimeter, a vibration elimination method can be used to reduce the influence of vibration on the reflector 8, such as passive vibration isolation and active vibration isolation technology.

[0054] In the above embodiment, preferably, the first lens 6 and the third lens 18 may also be other beam expanding devices such as a collimator.

[0055] In the above embodiment, preferably, in order to achieve polarization adjustment of the reflected light 600, a second wave plate 9 is further provided on the reflecting surface of the reflector 8 in this embodiment, and the second wave plate 9 is coaxially arranged with the reflector 8, the second optical fiber 17 and the third lens 18, and the axis of the above components passes through the atomic capture region 10. In this embodiment, the second optical fiber 17 is used to emit laser to the atomic group 500 to achieve atomic interference. The laser is a dual-frequency laser, and the frequency difference of the dual-frequency laser is close to the frequency difference between the fine energy levels of the atomic ground state, such as Raman light.

[0056] In the above embodiment, optionally, the second wave plate 9 can also be selected according to the polarization configuration of the light.

[0057] In the above embodiment, preferably, in order to achieve polarization adjustment of the second incident light 300 , a third wave plate 19 is provided on the light output side of the third lens 18 in this embodiment, and the third wave plate 19 is coaxially arranged with the reflector 8 , the second optical fiber 17 and the third lens 18 .

[0058] In the above embodiment, optionally, the third wave plate 19 can also be selected to be not used according to the polarization configuration of the light.

[0059] In the above embodiment, preferably, the second coil group 11 is used to provide a uniform magnetic field to achieve the necessary link of atomic interference. In this embodiment, the second coil group 11 can also use a plurality of coils or solenoids to achieve a uniform magnetic field.

[0060] In the above embodiment, preferably, the photoelectric detection assembly is arranged on one side close to the bottom of the vacuum chamber 3. The photoelectric detection assembly includes a photoelectric detector 13 and a second lens 12 arranged in the incident light direction of the photoelectric detector 13; the second lens 12 is used to converge the atomic fluorescence signal 400 to the photoelectric detector 13; the photoelectric detector 13 is used to detect the atomic fluorescence signal 400.

[0061] In the above embodiment, preferably, there may be multiple second lenses 12 , and the multiple second lenses 12 are coaxially arranged.

[0062] In the above embodiment, preferably, a magnetic shielding mechanism 4 is further included, and the magnetic shielding mechanism 4 is arranged outside the vacuum chamber 3. The magnetic shielding mechanism 4 is provided with a lower light opening 401 corresponding to the position of the reflector 8 and the second wave plate 9, a side light opening 403 corresponding to the incident direction of the first optical fiber 5, and an upper light opening 402 corresponding to the incident direction of the second optical fiber 17. The magnetic shielding mechanism 4 is made of a high magnetic permeability material.

[0063] In this embodiment, by providing the magnetic shielding mechanism 4, the external magnetic field can be effectively shielded, ensuring that the measurement process is not affected by external magnetic field fluctuations, thereby improving the stability of the measurement results.

[0064] like Figure 2 As shown, in the above embodiment, preferably, the diffraction surface of the grating chip 1 is composed of three fan-shaped diffraction surfaces B (such as Figure 2 As shown in a), each diffraction surface B includes a diffraction light 200.

[0065] In the above embodiment, preferably, it also includes an optical part, an electrical control part and a software part, wherein the optical part includes a laser and an optical path, which generates lasers for atomic quantum state manipulation; the electrical control part includes a radio frequency drive module, a power supply module, a feedback control module, an acquisition module, etc., which are used to realize atomic quantum state manipulation, atomic interference, and collect atomic interference signals; the software part is used to realize the control of the atomic gravimeter, process the collected signals, and solve the gravitational acceleration measurement value, data storage and other functions. The above optical part, electrical control part and software part are all the same as the principles of the existing atomic gravimeter, and will not be repeated here.

[0066] like Figure 2-4 As shown, in the above embodiment, preferably, the workflow of the atomic gravimeter disclosed in this embodiment includes four stages: atom capture, state preparation, atomic interference and final state detection. The following is a description of the working method of each stage:

[0067] 1. Atom capture stage (such as Figure 2 (shown)

[0068] 1. The vacuum component 15 maintains the vacuum environment in the vacuum chamber 3. At this time, the air pressure in the vacuum chamber 3 can generally be reduced to 1×10 -7 Pa level, and releases rarefied atomic vapor into the vacuum chamber 3 through the atomic source 14;

[0069] 2. The first incident light 100 emitted by the first optical fiber 5 is incident on the diffraction surface of the grating chip 1 after being collimated by the first lens 6, and the first incident light 100 and the diffracted light 200 of the grating chip 1 form a cross region in the vacuum chamber 3, and the cross region constitutes a light trap necessary for atomic capture, and the atomic capture region 10 is located in the light cross region;

[0070] 3. At the same time, the first coil group 2 generates the gradient magnetic field required for atomic capture. The first incident light 100, the diffracted light 200 and the gradient magnetic field cooperate to achieve atomic capture. The captured atoms are spherical atomic clusters 500, and the atomic temperature is a few microkelvins to more than ten microkelvins.

[0071] Second, the state preparation stage (such as Figure 3 (shown)

[0072] 1. Close the first optical fiber 5 and the first coil group 2, open the second coil group 11 to provide a uniform magnetic field, and apply microwave pulses to the captured atomic group 500 through the microwave antenna 16 to select atoms of a specific energy level to realize the state preparation process.

[0073] At this stage, the frequency of the microwave is equal to the frequency difference of the ground state fine energy level of the atom. 87 Taking Rb atoms as an example, the frequency of microwaves is about 6.834 GHz.

[0074] At this stage, the second optical fiber 17 can also be used to act on the captured atomic group 500 with a phase-coherent dual-frequency Raman laser (referred to as Raman light) to achieve state preparation, such as the Raman rate selection method, or microwaves and Raman light can be used together to achieve state preparation.

[0075] 3. Atomic interference stage (such as Figure 3 (shown)

[0076] 1. Turn on the second coil group 11 to provide a uniform magnetic field, and apply a number of Raman light pulses to the atomic group 500 at a certain time interval through the second optical fiber 17 to achieve atomic interference operation; the atoms in the atomic group 500 that completes the atomic interference are distributed on two ground state fine energy levels with a certain probability.

[0077] At this stage, the second incident light 300 of the second optical fiber 17 vertically hits the reflector 8 and returns along the original path through the reflector 8 .

[0078] 4. Final state detection stage (such as Figure 3 (shown)

[0079] 1. After the atomic interference is over, the second coil group 11 is closed. When the atomic group 500 falls to the collection area of ​​the photodetector 13, the second optical fiber 17 emits a laser beam resonating with the atomic cyclic transition to the atomic group 500, and the atomic fluorescence signal 400 at a certain ground state fine energy level is converged by the second lens 12 to the photodetector 13 and collected;

[0080] 2. For atoms at another ground state fine energy level, the second optical fiber 17 emits laser light that cyclically transitions with the energy level to the atomic group 500 , and the atomic fluorescence signal 400 of the energy level will be converged by the second lens 12 to the photodetector 13 for collection.

[0081] 5. Data processing stage

[0082] 1. The atomic detection signals at two ground state energy levels after atomic interference are obtained in the final state detection stage. The current atomic interference population probability is solved through these two atomic detection signals, and the chirp rate of Raman light is changed step by step to obtain the population probability distributed according to the sine law (that is, the atomic interference fringes are sampled);

[0083] 2. Calculate the gravitational acceleration value through atomic interference fringes.

[0084] In this stage, the method for calculating the gravity acceleration value is: fitting the interference fringe phase according to the interference fringe sampling points and obtaining the gravity measurement value;

[0085] The method for calculating the gravitational acceleration value can also be adopted: the Raman light chirp rate is locked at a certain point of the atomic interference fringes through feedback control to calculate the gravity measurement value in real time.

[0086] In the above embodiments, preferably, Figure 3 A in the figure represents the falling position of the atomic group 500 at different times.

[0087] Embodiment 2:

[0088] like Figure 5-8As shown, an atomic gravimeter based on a grating chip according to the present invention comprises a vacuum chamber 3, a grating chip 1, a first coil group 2, a second coil group 11, an incident light component, a photoelectric detection component and a microwave antenna 16, wherein the vacuum chamber 3 maintains a vacuum environment through a vacuum component 15, and releases atomic vapor into the interior thereof through an atomic source 14, and a grating chip 1 is installed on the inner side or the outer side of the upper part thereof; the first coil group 2, the second coil group 11, the incident light component and the grating chip 1 are coaxially arranged, and a light passage for the light beam to pass through is provided on the grating chip 1. Hole 101; the first coil group 2 is used to provide a gradient magnetic field into the vacuum chamber 3, and the second coil group 11 is used to provide a uniform magnetic field into the vacuum chamber 3; the incident light of the incident light component is perpendicular to the diffraction surface of the grating chip 1, and the diffracted light of the grating chip 1 and the incident light of the incident light component form an intersection area in the vacuum chamber 3, and an atomic capture area 10 is formed in the intersection area; the photoelectric detection component is arranged at the lower part of the vacuum chamber 3, which is used to detect atomic fluorescence signals; the microwave antenna 16 is arranged on the vacuum chamber 3, and its emission direction is toward the atomic capture area 10.

[0089] Specific:

[0090] like Figure 5 As shown, in the above embodiment, preferably, the grating chip 1, the first coil group 2, the second coil group 11 and the incident light component are all coaxially arranged in the vertical direction; the center of the first coil group 2 coincides with the intersection area; the function of the first coil group 2 is to provide a gradient magnetic field in space, and the gradient magnetic field can work together with the intersection area to achieve atomic capture and cooling. In this embodiment, the atomic capture area 10 is at the center of the gradient magnetic field.

[0091] In the above embodiment, preferably, the grating chip 1 is mounted on the top outside of the vacuum chamber 3, and the diffraction surface of the grating chip 1 faces the inside of the vacuum chamber 3, and a light hole 101 for the light beam to pass through is provided at the center of the grating chip 1.

[0092] In the above embodiment, preferably, the incident light assembly includes a first optical fiber 5, a first lens 6, an optical switch 20 and a reflector 8 which are coaxially arranged; wherein the first optical fiber 5 and the first lens 6 are installed at the bottom of the vacuum chamber 3, and the optical switch 20 and the reflector 8 are installed at the top of the vacuum chamber 3. The first incident light 100 of the first optical fiber 5 is vertically irradiated onto the diffraction surface of the grating chip 1 after passing through the first lens 6. In this embodiment, the first lens 6 is used to collimate the divergent first incident light 100 emitted by the first optical fiber 5 into parallel light to form a large-diameter light beam, the diameter of which is adapted to the size of the grating chip 1.

[0093] In the above embodiment, preferably, the first lens 6 may also be other beam expanding devices such as a collimator.

[0094] In the above embodiment, preferably, in order to achieve polarization adjustment of the first incident light 100, a first wave plate 7 is further arranged between the first lens 6 and the diffraction surface of the grating chip 1 in this embodiment, and the first wave plate 7 is coaxially arranged with the first lens 6, the grating chip 1 and the first optical fiber 5.

[0095] In the above embodiment, optionally, the first wave plate 7 may also be selected according to the polarization configuration of the light.

[0096] In the above embodiment, preferably, the optical switch 20 is used to block the light beam passing through the light hole 101 of the grating chip 1 when the atom is captured, and the reflector 8 is used to reflect the incident light along the original path. In actual use, the first incident light 100 emitted by the first optical fiber 5 will be vertically irradiated on the reflector 8, and the first incident light 100 will be reflected back along the original path via the reflector 8. In this embodiment, in order to reduce the measurement noise of the gravimeter, a vibration elimination method can be used to reduce the influence of vibration on the reflector 8, such as passive vibration isolation and active vibration isolation technology.

[0097] In the above embodiment, preferably, in order to achieve polarization adjustment of the reflected light 600, a second wave plate 9 is further provided on the reflective surface of the reflector 8 in this embodiment, and the second wave plate 9 is coaxially arranged with the reflector 8, the first optical fiber 5 and the first lens 6, and the axis of the above components passes through the atomic capture region 10. In this embodiment, the first optical fiber 5 can emit laser to the atomic group 500 to achieve atomic interference, and the laser is a dual-frequency laser, and the frequency difference of the dual-frequency laser is close to the frequency difference between the fine energy levels of the atomic ground state, such as Raman light.

[0098] In the above embodiment, preferably, the second coil group 11 is used to provide a uniform magnetic field to achieve the necessary link of atomic interference. In this embodiment, the second coil group 11 can also use a plurality of coils or solenoids to achieve a uniform magnetic field.

[0099] In the above embodiment, preferably, the photoelectric detection assembly is arranged on one side close to the bottom of the vacuum chamber 3. The photoelectric detection assembly includes a photodetector 13 and a second lens 12 arranged in the incident light direction of the photodetector 13; the second lens 12 is used to converge the atomic fluorescence signal 400 to the photodetector 13; the photodetector 13 is used to detect the atomic fluorescence signal 400. In this embodiment, the setting height of the photodetector 13 is lower than the setting height of the second coil group 11, and higher than the setting height of the vacuum assembly 15.

[0100] In the above embodiment, preferably, there may be multiple second lenses 12 , and the multiple second lenses 12 are coaxially arranged.

[0101] In the above embodiment, preferably, a magnetic shielding mechanism 4 is further included, and the magnetic shielding mechanism 4 is arranged outside the vacuum chamber 3. The magnetic shielding mechanism 4 is provided with an upper light opening 402 corresponding to the position of the reflector 8, the second wave plate 9 and the optical switch 20, and the magnetic shielding mechanism 4 is provided with a lower light opening 401 corresponding to the incident direction of the first optical fiber 5. The magnetic shielding mechanism 4 is made of a high magnetic permeability material.

[0102] In this embodiment, by providing the magnetic shielding mechanism 4, the external magnetic field can be effectively shielded, ensuring that the measurement process is not affected by external magnetic field fluctuations, thereby improving the stability of the measurement results.

[0103] In the above embodiment, preferably, it also includes an optical part, an electrical control part and a software part, wherein the optical part includes a laser and an optical path, which generates lasers for atomic quantum state manipulation; the electrical control part includes a radio frequency drive module, a power supply module, a feedback control module, an acquisition module, etc., which are used to realize atomic quantum state manipulation, atomic interference, and collect atomic interference signals; the software part is used to realize the control of the atomic gravimeter, process the collected signals, and solve the gravitational acceleration measurement value, data storage and other functions. The above optical part, electrical control part and software part are all the same as the principles of the existing atomic gravimeter, and will not be repeated here.

[0104] like Figure 6-8 As shown, in the above embodiment, preferably, the workflow of the atomic gravimeter disclosed in this embodiment includes four stages: atom capture, state preparation, atomic interference and final state detection. The following is a description of the working method of each stage:

[0105] 1. Atom capture stage (such as Figure 6 (shown)

[0106] 1. The vacuum component 15 maintains the vacuum environment in the vacuum chamber 3. At this time, the air pressure in the vacuum chamber 3 can generally be reduced to 1×10 -7 Pa level, and releases rarefied atomic vapor into the vacuum chamber 3 through the atomic source 14;

[0107] 2. Turn off the optical switch 20, the first incident light 100 of the first optical fiber 5 is incident on the diffraction surface of the grating chip 1 after being collimated by the first lens 6, and the first incident light 100 and the diffracted light 200 of the grating chip 1 form a cross region in the vacuum chamber 3, and the cross region constitutes the light trap necessary for atomic capture, and the atomic capture region 10 is located in the light cross region;

[0108] 3. At the same time, the first coil group 2 generates the gradient magnetic field required for atomic capture. The first incident light 100, the diffracted light 200 and the gradient magnetic field cooperate to achieve atomic capture. The captured atoms are spherical atomic clusters 500, and the atomic temperature is a few microkelvins to more than ten microkelvins.

[0109] Second, the state preparation stage (such as Figure 7 (shown)

[0110] 1. Close the first optical fiber 5 and the first coil group 2, open the second coil group 11 to provide a uniform magnetic field, and apply microwave pulses to the captured atomic group 500 through the microwave antenna 16 to select atoms of a specific energy level to realize the state preparation process.

[0111] At this stage, the frequency of the microwave is equal to the frequency difference of the ground state fine energy level of the atom. 87 Taking Rb atoms as an example, the frequency of microwaves is about 6.834 GHz.

[0112] In this stage, the first optical fiber 5 can also be used to act on the captured atomic group 500 with Raman light to achieve state preparation, such as Raman rate selection method, or microwaves and Raman light can be used together to achieve state preparation.

[0113] 3. Atomic interference stage (such as Figure 7 (shown)

[0114] 1. Turn on the second coil group 11 to provide a uniform magnetic field, and turn on the optical switch 20;

[0115] 2. The first optical fiber 5 sequentially applies a number of Raman light pulses to the atomic cluster 500 at certain time intervals to realize atomic interference operation; the atoms in the atomic cluster 500 that completes the atomic interference are distributed on two ground state fine energy levels with a certain probability.

[0116] In this stage, the second incident light 300 of the first optical fiber 5 hits the reflector 8 vertically and returns through the reflector 8 along the original path. At this time, the second incident light 300 and the reflected light 600 are in a combined beam state.

[0117] 4. Final state detection stage (such as Figure 3 (shown)

[0118] 1. After the atomic interference is over, the second coil group 11 is closed. When the atomic group 500 falls to the collection area of ​​the photodetector 13, the first optical fiber 5 emits a laser beam resonating with the atomic cyclic transition to the atomic group 500, and the atomic fluorescence signal 400 at a certain ground state fine energy level is converged by the second lens 12 to the photodetector 13 and collected;

[0119] 2. For atoms at another ground state fine energy level, the first optical fiber 5 emits a laser that cyclically transitions with the energy level to the atomic group 500 , and the atomic fluorescence signal 400 of the energy level will be converged by the second lens 12 to the photodetector 13 and collected.

[0120] 5. Data processing stage

[0121] 1. The atomic detection signals at two ground state energy levels after atomic interference are obtained in the final state detection stage. The current atomic interference population probability is solved through these two atomic detection signals, and the chirp rate of Raman light is changed step by step to obtain the population probability distributed according to the sine law (that is, the atomic interference fringes are sampled);

[0122] 2. Calculate the gravitational acceleration value through atomic interference fringes.

[0123] At this stage, the method for calculating the gravity acceleration value can be: fitting the interference fringe phase according to the interference fringe sampling points and obtaining the gravity measurement value;

[0124] Alternatively, the Raman light chirp rate can be locked at a certain point of the atomic interference fringes by means of feedback control to solve the gravity measurement value in real time.

[0125] Embodiment 3:

[0126] like Fig. 9 As shown, an atomic gravimeter based on a grating chip provided according to the present invention is different from the atomic gravimeter disclosed in Example 2 in terms of the orientation of the diffraction surface of the grating chip 1 and the specific arrangement of the incident light component. The rest are consistent with the technical features disclosed in Example 2 and will not be elaborated herein.

[0127] Specific:

[0128] In the above embodiment, preferably, the grating chip 1 is installed on the inner side of the vacuum chamber 3 near the top, and the diffraction surface of the grating chip 1 is arranged upward. A light hole 101 is arranged at the center of the grating chip 1 for the light beam to pass through.

[0129] In the above embodiment, preferably, the incident light assembly includes a coaxially arranged first optical fiber 5, a first lens 6, an optical switch 20 and a reflector 8; wherein the first optical fiber 5 and the first lens 6 are mounted on the top of the vacuum chamber 3, and the optical switch 20 and the reflector 8 are mounted on the bottom of the vacuum chamber 3. The first incident light 100 of the first optical fiber 5 is vertically irradiated on the diffraction surface of the grating chip 1 after passing through the first lens 6.

[0130] In the above embodiment, preferably, in order to achieve polarization adjustment of the first incident light 100, a first wave plate 7 is further arranged between the first lens 6 and the diffraction surface of the grating chip 1 in this embodiment, and the first wave plate 7 is coaxially arranged with the first lens 6, the grating chip 1 and the first optical fiber 5.

[0131] In the above embodiment, optionally, the first wave plate 7 may also be selected according to the polarization configuration of the light.

[0132] In the above embodiment, preferably, in order to achieve polarization adjustment of the reflected light 600, a second wave plate 9 is also provided on the reflecting surface of the reflector 8 in this embodiment. The second wave plate 9 is coaxially arranged with the reflector 8, the first optical fiber 5 and the first lens 6, and the axis of the above components passes through the atomic capture region 10.

[0133] In the above embodiment, optionally, the second wave plate 9 can also be selected according to the polarization configuration of the light.

[0134] In the above embodiment, preferably, a magnetic shielding mechanism 4 is further included, and the magnetic shielding mechanism 4 is arranged outside the vacuum chamber 3. The magnetic shielding mechanism 4 is provided with a lower light opening 401 corresponding to the position of the reflector 8, the second wave plate 9 and the optical switch 20, and the magnetic shielding mechanism 4 is provided with an upper light opening 402 corresponding to the incident direction of the first optical fiber 5. The magnetic shielding mechanism 4 is made of a high magnetic permeability material. In this embodiment, by providing the magnetic shielding mechanism 4, the external magnetic field can be effectively shielded, ensuring that the measurement process is not affected by the external magnetic field fluctuation, and improving the stability of the measurement result.

[0135] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An atomic gravimeter based on a grating chip, characterized in that: include: A vacuum chamber, which maintains a vacuum environment through a vacuum component and releases atomic vapor into the chamber through an atomic source, and a grating chip is installed on the inner side or outer side of the upper side wall; A first coil group and a first incident light component are coaxially arranged with the grating chip, the first coil group is used to provide a gradient magnetic field into the vacuum chamber, the incident light of the first incident light component is perpendicular to the diffraction surface of the grating chip, and the diffracted light of the grating chip and the incident light of the first incident light component form an intersection area in the vacuum chamber, and an atomic capture area is formed in the intersection area; a second incident light component and a second coil group coaxially arranged therewith, wherein the axes of the second incident light component and the second coil group pass through the atom capture region, and the second coil group is used to provide a uniform magnetic field into the vacuum cavity; A photoelectric detection component, which is arranged at the lower part of the vacuum chamber and is used to detect atomic fluorescence signals; The microwave antenna is arranged on the vacuum chamber and its emission direction is toward the atom trapping region.

2. The atomic gravimeter according to claim 1, characterized in that: The first coil group, the first incident light component and the grating chip are all coaxially arranged in the horizontal direction; the second coil group and the second incident light component are all coaxially arranged in the vertical direction; the center of the first coil group coincides with the intersection area.

3. The atomic gravimeter according to claim 2, characterized in that: The first incident light component comprises a first optical fiber and a first lens which are coaxially arranged; the first optical fiber and the first lens are arranged at the upper part of the vacuum chamber and are placed on the opposite side of the grating chip; the incident light of the first optical fiber is vertically irradiated on the diffraction surface of the grating chip after passing through the first lens; The second incident light component includes a coaxially arranged reflector, a second optical fiber and a third lens. The reflector is arranged at the bottom of the vacuum chamber, and the second optical fiber and the third lens are arranged at the top of the vacuum chamber. The incident light of the second optical fiber passes through the atomic capture area through the third lens and then irradiates the reflector, and the reflector reflects the incident light along the original path.

4. An atomic gravimeter based on a grating chip, characterized in that: include: A vacuum chamber, which maintains a vacuum environment through a vacuum component and releases atomic vapor into the chamber through an atomic source, and a grating chip is installed on the inner side or the outer side of the upper part; A first coil group, a second coil group and an incident light component are coaxially arranged with the grating chip, the grating chip is provided with a light hole for the light beam to pass through; the first coil group is used to provide a gradient magnetic field into the vacuum chamber, and the second coil group is used to provide a uniform magnetic field into the vacuum chamber; the incident light of the incident light component is perpendicular to the diffraction surface of the grating chip, and the diffracted light of the grating chip and the incident light of the incident light component form an intersection area in the vacuum chamber, and an atomic capture area is formed in the intersection area; A photoelectric detection component, which is arranged at the lower part of the vacuum chamber and is used to detect atomic fluorescence signals; The microwave antenna is arranged on the vacuum chamber and its emission direction is toward the atom trapping region.

5. The atomic gravimeter according to claim 4, characterized in that: The grating chip, the first coil group, the second coil group and the incident light component are all coaxially arranged in the vertical direction; the center of the first coil group coincides with the intersection area.

6. The atomic gravimeter according to claim 4, characterized in that: The grating chip is installed on the outside of the top of the vacuum chamber, and the diffraction surface of the grating chip faces the inside of the vacuum chamber.

7. The atomic gravimeter according to claim 6, characterized in that: The incident light assembly includes a first optical fiber, a first lens, an optical switch, and a reflector that are coaxially arranged; The first optical fiber and the first lens are installed at the bottom of the vacuum chamber, and the optical switch and the reflector are installed at the top of the vacuum chamber. The optical switch is used to block the light beam passing through the light hole of the grating chip when atoms are captured, and the reflector is used to reflect the incident light along the original path.

8. The atomic gravimeter according to claim 4, characterized in that: The grating chip is installed in a position near the top of the vacuum chamber, and the diffraction surface of the grating chip is arranged upward.

9. The atomic gravimeter according to claim 8, characterized in that: The incident light assembly includes a first optical fiber, a first lens, an optical switch, and a reflector that are coaxially arranged; The first optical fiber and the first lens are installed on the top of the vacuum chamber, and the optical switch and the reflector are installed on the bottom of the vacuum chamber. The optical switch is used to block the light beam passing through the light hole of the grating chip when atoms are captured, and the reflector is used to reflect the incident light along the original path.

10. The atomic gravimeter according to claim 1 or 4, characterized in that: The photoelectric detection assembly includes a photoelectric detector and a second lens; the second lens is used to converge the atomic fluorescence signal to the photoelectric detector; The photodetector is used to detect the atomic fluorescence signal.

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