Falling cold atom device and working method thereof

Abstract

The present invention provides a falling cold atom device and a working method thereof, which relate to the field of quantum precision measurement technology. The cooling light is output through a cooling light optical fiber, the light propagation direction is changed through a cooling light reflector, the polarization direction of the light is changed after passing through a quarter wave plate, and then a grating chip is vertically irradiated. The grating chip generates three or four diffracted lights. The part where the generated diffracted light overlaps with the incident light cooperates with a pair of anti-Helmholtz coils to complete the cooling of the atoms. A grating magneto-optical trap structure is adopted to reduce the number of wave plates and reflectors used, and the overall volume of the device is effectively reduced. A getter is arranged on a vacuum conduit, and the getter is used instead of an ion pump, which has a smaller volume, thereby alleviating the problem that the existing magneto-optical trap has a complex structure and a large volume, and cannot meet the requirements of miniaturization of the device. In addition, the free-falling motion mode of the atoms of the present invention due to the action of gravity can be applied to quantum frequency standards and precision measurement systems such as falling atomic clocks and atomic gravimeters.

Description

Technical Field

[0001] The invention relates to the technical field of quantum precision measurement, and in particular to a falling cold atom device and a working method thereof. Background Art

[0002] Laser cooling technology can be used to obtain atomic samples that are close to static and have almost no interaction between atoms. It has been widely used in fields such as quantum frequency standards and precision measurements, such as atom interferometers, atomic clocks, and gravimeters, and has played an important role in national defense, global positioning, and instant communications.

[0003] Magneto-optical trap is a commonly used method to obtain cold atoms. Traditional magneto-optical trap uses three pairs of orthogonal circularly polarized lasers and a pair of anti-Helmholtz coils to cool atoms at the intersection of the lasers.

[0004] However, the traditional six-beam laser magneto-optical trap is large in size and requires the use of six quarter-wave plates, three mirrors and three laser collimation heads. In addition, a type of quantum standard and precision measurement system based on the physical spatial movement of atoms, such as atom interferometers and fountain clocks, not only needs to cool hot atoms through magneto-optical traps, but also needs to manipulate the movement of atoms in physical space. Therefore, the structure of this type of system is more complex and larger in size, which cannot meet the current requirements for miniaturization of devices. Summary of the invention

[0005] The purpose of the present invention is to provide a falling cold atom device and a working method thereof, so as to alleviate the technical problems existing in the prior art that the magneto-optical trap has a complex structure, a large volume and cannot meet the requirements of device miniaturization.

[0006] In a first aspect, the present invention provides a falling cold atom device, comprising a grating magnetic optical trap and a vacuum component;

[0007] The grating magnetic light trap comprises a grating chip, a pair of anti-Helmholtz coils respectively arranged on the light-incoming side and the backlight side of the grating chip, a quarter-wave plate arranged on the backlight side away from the grating chip, a cooling light reflector arranged on the quarter-wave plate away from the grating chip, and a cooling light beam expander and a cooling light optical fiber directed toward the cooling light reflector;

[0008] The vacuum component is arranged between the anti-Helmholtz coil and the grating chip on the backlight side, and the vacuum component comprises a vacuum conduit and a vacuum chamber, and a getter is arranged on the vacuum conduit.

[0009] In an alternative embodiment,

[0010] The falling cold atom device also includes an atomic action component;

[0011] The atomic action component includes a resonant light beam expander and a resonant light optical fiber directed into the vacuum chamber, an image sensor arranged on a side of the vacuum chamber away from the resonant light beam expander, a standing light wave first reflector arranged on the upper side of the vacuum chamber, a standing light wave beam expander and a standing light wave optical fiber directed toward the first standing light wave reflector, and a standing light wave second reflector arranged on the lower side of the vacuum chamber.

[0012] In an alternative embodiment,

[0013] The falling cold atom device also includes a detection component;

[0014] The detection component is located on one side of the vacuum chamber, and the detection component and the grating magnetic light trap are located on the same side. The detection component includes a detection light expansion beam and a detection light optical fiber directed toward the vacuum chamber. The detection component also includes a fluorescence detector arranged on a side of the vacuum chamber away from the vacuum duct and a detection light reflector arranged on the same side as the quarter wave plate.

[0015] In an alternative embodiment,

[0016] The falling cold atom device also includes an atom source;

[0017] The atom source is arranged on a side of the vacuum chamber away from the vacuum duct.

[0018] In an alternative embodiment,

[0019] The falling cold atom device also includes a magnetic shielding component;

[0020] The magnetic shielding assembly comprises a first magnetic shielding cylinder and a second magnetic shielding cylinder which are arranged on the periphery of the anti-Helmholtz coil, and a third magnetic shielding cylinder which is arranged on the atomic source.

[0021] In an alternative embodiment,

[0022] The upper and lower sides of the first magnetic shielding tube, the second magnetic shielding tube and the third magnetic shielding tube all have cylindrical and detachably connected end covers, and the sides of the first magnetic shielding tube and the second magnetic shielding tube are provided with light holes for laser feeding in, feeding out and observation windows;

[0023] A pair of Helmholtz coils is arranged in the first magnetic shielding cylinder, and the pair of Helmholtz coils are respectively located on the upper and lower sides of the vacuum chamber. The Helmholtz coils are made of solenoid coils to generate a uniform magnetic field.

[0024] In an alternative embodiment,

[0025] The grating chip is configured as a silicon-based gold-plated grating, and diffraction grooves are engraved on the grating chip;

[0026] The vacuum chamber is made of titanium metal, and the light port and observation window of the vacuum chamber are both made of sapphire glass;

[0027] The windows made of sapphire glass are all coated with an anti-reflection film;

[0028] The vacuum degree of the vacuum chamber is maintained at 10 -7 Pa~10 -9 Pa;

[0029] The anti-Helmholtz coil is a cylindrical coil that can provide the required gradient magnetic field for atomic cooling;

[0030] The cooling light output by the cooling light optical fiber is configured as pumping light and re-pumping light.

[0031] In an alternative embodiment,

[0032] The standing light wave is the opposite light that completes the atomic state selection and interaction process when the falling cold atom device is applied to an atom interferometer.

[0033] In an alternative embodiment,

[0034] The image sensor is a charge coupled device camera, which is used for real-time monitoring of atomic groups and detection of the number of atoms in coordination with resonant light.

[0035] In a second aspect, the present invention provides a working method based on a falling cold atom device, comprising the following steps:

[0036] Turn on the cooling light and anti-Helmholtz coil. The cooling light irradiates the grating chip vertically. The diffracted light after diffraction by the grating chip converges with the incident light, and the atoms injected by the atomic source are captured and cooled at the convergence point.

[0037] Sub-Doppler cooling of atoms is achieved by controlling the cooling light parameters;

[0038] After sub-Doppler cooling, the cooling light and anti-Helmholtz coil are turned off, and the Helmholtz coil, resonant light, and standing light wave are turned on to complete the interaction with the cold atoms;

[0039] After the laser interacts with the cold atoms, the detection light is turned on to collect the fluorescence of the cold atoms.

[0040] The falling cold atom device provided by the present invention uses cooling light output through a cooling light optical fiber, changes the light propagation direction through a cooling light reflector, changes the polarization direction of the light through a quarter wave plate, and then vertically irradiates a grating chip. The grating chip generates three or four diffracted lights. The overlapping part of the generated diffracted light and the incident light cooperates with a pair of anti-Helmholtz coils to complete the cooling of the atoms. A grating magneto-optical trap structure is adopted to reduce the number of wave plates and reflectors used, effectively reducing the overall volume of the device, and a getter is arranged on the vacuum duct, and the getter is used instead of an ion pump, which has a smaller volume, thereby alleviating the technical problems in the prior art that the magneto-optical trap has a complex structure and a large volume and cannot meet the requirements of miniaturization of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A schematic diagram of the installation structure of a grating chip in a falling cold atom device provided in an embodiment of the present invention;

[0043] Figure 2 A schematic diagram of the overall structure of a falling cold atom device provided in an embodiment of the present invention;

[0044] Figure 3 A schematic diagram of the installation structure of the resonance light beam expansion and the resonance light optical fiber in the falling cold atom device provided in an embodiment of the present invention;

[0045] Figure 4 A schematic diagram of the installation structure of the standing light wave beam expander and the standing light wave optical fiber in the falling cold atom device provided in an embodiment of the present invention;

[0046] Figure 5 A schematic diagram of the installation structure of a fluorescence detector in a falling cold atom device provided in an embodiment of the present invention;

[0047] Figure 6 A schematic structural diagram of a falling cold atom device with a magnetic shielding component provided in an embodiment of the present invention.

[0048] Icons: 1-grating chip; 2-atom source; 3-cooling light fiber; 4-anti-Helmholtz coil; 5-cooling light beam expander; 6-cooling light reflector; 7-quarter wave plate; 8-vacuum chamber; 9-ion pump; 10-getter; 11-resonance light beam expander; 12-resonance light fiber; 13-standing light wave first reflector; 14-image sensor; 15-standing light wave second reflector; 16-standing light wave beam expander; 17-Helmholtz coil; 18-standing light wave fiber; 19-detection light fiber; 20-vacuum duct; 21-detection light reflector; 22-detection light beam expander; 23-first magnetic shielding tube; 24-second magnetic shielding tube; 25-third magnetic shielding tube; 26-fluorescence detector. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions 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. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0050] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0051] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0052] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0053] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0054] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0055] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0056] The traditional magneto-optical trap uses three pairs of orthogonally irradiated circularly polarized lasers and a pair of anti-Helmholtz coils 4 to achieve cooling of atoms at the intersection of the lasers. It requires six quarter-blades, three reflectors, and three laser collimation heads, which makes it large in size and cannot meet the requirements of miniaturization.

[0057] In view of this, if Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the falling cold atom device provided in this embodiment includes a grating magnetic light trap and a vacuum component; the grating magnetic light trap includes a grating chip 1, a pair of anti-Helmholtz coils 4 respectively arranged on the light-incoming side and the backlight side of the grating chip 1, a quarter-wave plate 7 arranged on the backlight side of the anti-Helmholtz coil 4 away from the grating chip 1, a cooling light reflector 6 arranged on the quarter-wave plate 7 away from the grating chip 1, and a cooling light beam expander 5 and a cooling light optical fiber 3 directed to the cooling light reflector 6; the vacuum component is arranged between the anti-Helmholtz coil 4 on the backlight side and the grating chip 1, and the vacuum component includes a vacuum duct 20 and a vacuum chamber 8, and a getter 10 is arranged on the vacuum duct 20.

[0058] The falling cold atom device provided in the present embodiment uses cooling light output through a cooling light optical fiber 3, changes the light propagation direction through a cooling light reflector 6, changes the polarization direction of the light through a quarter wave plate 7, and then vertically irradiates a grating chip 1. The grating chip 1 generates three or four diffracted lights. The overlapping part of the generated diffracted light and the incident light cooperates with a pair of anti-Helmholtz coils 4 to complete the cooling of the atoms. A grating magneto-optical trap structure is adopted to reduce the number of wave plates and reflectors used, effectively reducing the overall volume of the device, and a getter 10 is arranged on the vacuum duct 20. The getter 10 is used instead of the ion pump 9, which has a smaller volume, thereby alleviating the technical problems in the prior art that the magneto-optical trap has a complex structure and a large volume and cannot meet the requirements of miniaturization of the device.

[0059] It should be noted that the up, down, left, right, front, and back in the following text all refer to Figure 4 , Figure 4 The side facing the vacuum chamber 8 is the front side, the side facing away from the front side is the rear side, the side viewed from right to left is the right side, the side viewed from left to right is the left side, the side viewed from top to bottom is the upper side, and the side viewed from bottom to top is the lower side.

[0060] Regarding the structure and shape of the grating MOT, specifically:

[0061] The grating magneto-optical trap comprises a grating chip 1, a pair of anti-Helmholtz coils 4, a quarter-wave plate 7, a cooling light reflector 6, a cooling light beam expander 5 and a cooling light optical fiber 3; a pair of anti-Helmholtz coils 4 are respectively arranged on the left and right sides of the grating chip 1, the quarter-wave plate 7 is located on the left side of the left anti-Helmholtz coil 4, the cooling light reflector 6 is located on the left side of the quarter-wave plate 7, the cooling light beam expander 5 and the cooling light optical fiber 3 are connected to each other, and the cooling light beam expander 5 and the cooling light optical fiber 3 are located on the rear side of the cooling light reflector 6 from front to back.

[0062] The anti-Helmholtz coil 4 is a cylindrical coil that can provide the required gradient magnetic field for atomic cooling; the cooling light output by the cooling light fiber 3 is set as pump light and re-pump light, and the pump light and the re-pump light are coupled and emitted through the cooling light fiber 3, and the beam diameter is increased through the cooling light beam expander 5. Under the action of the cooling light reflector 6, the transmission direction of the cooling light is changed, and a circularly polarized wide beam laser is formed after passing through the quarter wave plate 7, and the anti-Helmholtz coil 4 that can provide the required gradient magnetic field is used to complete the capture and cooling of atoms on the surface of the grating chip 1.

[0063] The grating chip 1 is configured as a gold-plated silicon substrate, and diffraction grooves are engraved on the grating chip 1; the grating chip 1 has high diffraction efficiency and a large capture area, thereby ensuring that after the cooling light vertically irradiates the grating chip 1, a high-efficiency diffraction beam can be generated, thereby effectively improving the ability to trap and cool atoms.

[0064] Regarding the structure and shape of the vacuum component, specifically:

[0065] The vacuum assembly ensures that the working medium is in a high vacuum environment. The vacuum assembly includes a vacuum conduit 20 and a vacuum chamber 8. The getter 10 is connected to the vacuum chamber 8 through the vacuum conduit 20 to maintain the vacuum chamber 10. -7 Pa—10 -9 The vacuum degree of Pa, the vacuum chamber 8 uses non-magnetic titanium metal as the cavity material, which can effectively reduce the impact of the environmental magnetic field on atoms and increase the robustness of the vacuum chamber 8 to a certain extent. The laser incident and output and observation windows are made of sapphire glass coated with an anti-reflection film of a specific wavelength.

[0066] It should be noted that an ion pump 9 can also be set on the vacuum duct 20. The ion pump 9 and the getter 10 work together to form a vacuum environment in the vacuum chamber 8. Removing the ion pump 9 can further reduce the size of the device. Whether to install the ion pump 9 depends on actual conditions.

[0067] Regarding the structure and shape of the atomic action components, specifically:

[0068] The atomic action component includes a resonant light beam expander 11 and a resonant light optical fiber 12 arranged from front to back on the rear side of the vacuum chamber 8, an image sensor 14 arranged on the front side of the vacuum chamber 8, the image sensor 14 is a charge coupled device camera, which is used for real-time monitoring of atomic groups and cooperating with the resonant light to complete the detection of the number of atoms, a standing light wave first reflector 13 arranged on the upper side of the vacuum chamber 8, a standing light wave beam expander 16 and a standing light wave optical fiber 18 arranged from left to right on the right side of the standing light wave first reflector 13, and a standing light wave second reflector 15 arranged on the lower side of the vacuum chamber 8.

[0069] The standing light wave is the opposite light that completes the atomic state selection and interaction process when the falling cold atom device is used in an atom interferometer.

[0070] Regarding the structure and shape of the detection component, specifically:

[0071] The detection system includes a detection light beam expander 22 and a detection light optical fiber 19 arranged on the right side of the vacuum chamber 8 from left to right, a fluorescence detector 26 arranged on the front side of the vacuum chamber 8, and a detection light reflector 21 arranged on the left side of the vacuum chamber 8.

[0072] Regarding the structure and shape of the magnetic shielding assembly, specifically:

[0073] The magnetic shielding assembly can prevent atoms from being affected by the external environmental magnetic field to a certain extent, and includes a first magnetic shielding tube 23, a second magnetic shielding tube 24 and a third magnetic shielding tube 25 from the inside to the outside. The upper and lower sides of the magnetic shielding tube are cylindrical and have detachable end covers at both ends. They are made of BoMo alloy and have a thickness of 1-2mm. The magnetic shielding tube can effectively shield the influence of the environmental magnetic field on atoms. The first magnetic shielding tube 23 and the second magnetic shielding tube 24 are provided with light holes for laser feed in, feed out, and observation windows on the sides.

[0074] A pair of Helmholtz coils 17 are disposed in the first magnetic shielding tube 23. The Helmholtz coils 17 are made of copper wires and provide a uniform magnetic field in the space where atoms are trapped and moved, and are parallel to the standing light wave, for Zeeman splitting the energy levels of atoms.

[0075] The falling cold atom device provided in this embodiment has a more compact structure, can greatly reduce the volume, and is practical. The falling cold atom device can be compatible with systems such as atomic gravimeters and falling atomic clocks, and to a certain extent meets the current requirements for miniaturization of quantum standards and precision measurement systems.

[0076] The working method of the falling cold atom device provided in this embodiment includes the following steps: turning on the cooling light and the anti-Helmholtz coil 4, the cooling light irradiates the grating chip 1 vertically, the diffracted light after diffraction by the grating chip 1 converges with the incident light, and the atoms injected by the atomic source 2 are captured and cooled at the convergence point; the sub-Doppler cooling of the atoms is completed by controlling the cooling light parameters; after the sub-Doppler cooling, the cooling light and the anti-Helmholtz coil 4 are turned off, and the Helmholtz coil 17, the resonance light, and the standing light wave are turned on to complete the interaction with the cold atoms; after the laser interacts with the cold atoms, the detection light is turned on to collect the fluorescence of the cold atoms.

[0077] Specifically, the first step: cooling, using cooling light output through cold light optical fiber, the cooling light includes pump light and re-pump light, the light propagation direction is changed through a reflector, and the polarization direction of the light is changed after passing through a quarter wave plate 7, and then vertically irradiated to the reflective grating chip 1, the grating chip 1 will generate three or four diffracted lights, the one-dimensional grating chip 1 generates three diffracted lights, and the two-dimensional grating chip 1 generates four diffracted lights. The part where the generated diffracted light overlaps with the incident light cooperates with a pair of anti-Helmholtz coils 4 to complete the cooling of the atoms.

[0078] The second step: post-cooling. After the atomic cooling is completed, the post-cooling stage is completed by increasing the detuning of the cooling light and reducing the optical power of the cooling light. This process is called polarization gradient cooling.

[0079] The third step: state selection. During the polarization gradient cooling process, the state of atoms is selected by changing the switching timing and frequency of the pump light and re-pump light in the cooling light. This state selection method eliminates the state selection cavity in the fountain clock and reduces the volume.

[0080] Step 4: Atomic excitation. After the state selection is completed, the atoms fall through the microwave cavity due to the action of gravity to complete the atomic excitation.

[0081] Step 5: Atom detection. After being excited, the atoms fall into the detection area. The detection light is turned on to act on the excited atoms. The signal is collected through the fluorescence collector to get the signal we need.

[0082] The working method of the falling cold atom device provided in this embodiment, in which atoms freely fall due to gravity, can be applied to quantum frequency standards and precision measurement systems such as falling atomic clocks and atomic gravimeters.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A falling cold atom device, characterized in that: include: It includes a grating magneto-optical trap and a vacuum assembly; The grating magnetic light trap comprises a grating chip (1), a pair of anti-Helmholtz coils (4) respectively arranged on the light-incoming side and the backlight side of the grating chip (1), a quarter-wave plate (7) arranged on the backlight side of the anti-Helmholtz coil (4) away from the grating chip (1), a cooling light reflector (6) arranged on the side of the quarter-wave plate (7) away from the grating chip (1), and a cooling light beam expander (5) and a cooling light optical fiber (3) directed toward the cooling light reflector (6); The vacuum component is arranged between the anti-Helmholtz coil (4) on the backlight side and the grating chip (1), the vacuum component comprises a vacuum conduit (20) and a vacuum chamber (8), and a getter (10) is arranged on the vacuum conduit (20); A pair of anti-Helmholtz coils (4) are respectively arranged on the left and right sides of the grating chip (1); The atoms in the vacuum chamber (8) fall freely due to the action of gravity.

2. The falling cold atom device according to claim 1, characterized in that: The falling cold atom device also includes an atomic action component; The atomic action component comprises a resonant light beam expander (11) and a resonant light optical fiber (12) directed into the vacuum chamber (8), an image sensor (14) arranged on a side of the vacuum chamber (8) away from the resonant light beam expander (11), a standing light wave first reflector (13) arranged on the upper side of the vacuum chamber (8), a standing light wave beam expander (16) and a standing light wave optical fiber (18) directed toward the standing light wave first reflector (13), and a standing light wave second reflector (15) arranged on the lower side of the vacuum chamber (8).

3. The falling cold atom device according to claim 2, characterized in that: The falling cold atom device also includes a detection component; The detection component is located on one side of the vacuum chamber (8), and the detection component and the grating magnetic light trap are located on the same side. The detection component includes a detection light expansion beam (22) and a detection light optical fiber (19) directed toward the vacuum chamber (8). The detection component also includes a fluorescence detector (26) located on a side of the vacuum chamber (8) away from the vacuum duct (20) and a detection light reflector (21) located on the same side as the quarter wave plate (7).

4. The falling cold atom device according to claim 3, characterized in that: The falling cold atom device further comprises an atom source (2); The atomic source (2) is arranged on a side of the vacuum chamber (8) away from the vacuum duct (20).

5. The falling cold atom device according to claim 4, characterized in that: The falling cold atom device also includes a magnetic shielding component; The magnetic shielding assembly comprises a first magnetic shielding cylinder (23) and a second magnetic shielding cylinder (24) which are arranged on the periphery of the anti-Helmholtz coil (4), and a third magnetic shielding cylinder (25) which is arranged on the atomic source (2).

6. The falling cold atom device according to claim 5, characterized in that: The upper and lower sides of the first magnetic shielding tube (23), the second magnetic shielding tube (24) and the third magnetic shielding tube (25) all have cylindrical and detachably connected end covers, and the sides of the first magnetic shielding tube (23) and the second magnetic shielding tube (24) are provided with light holes for laser feed in, feed out and observation windows; A pair of Helmholtz coils (17) are arranged in the first magnetic shielding cylinder (23), and the pair of Helmholtz coils (17) are respectively located on the upper and lower sides of the vacuum chamber (8), and the Helmholtz coils (17) are made of solenoid coils to generate a uniform magnetic field.

7. The falling cold atom device according to claim 5, characterized in that: The grating chip (1) is configured as a silicon-based gold-plated substrate, and a diffraction groove is engraved on the grating chip (1); The vacuum chamber (8) is made of titanium metal, and the light port and the observation window of the vacuum chamber (8) are both provided with sapphire glass; The windows made of sapphire glass are all coated with an anti-reflection film; The vacuum degree of the vacuum chamber (8) is maintained at 10 -7 Pa~10 -9 Pa; The anti-Helmholtz coil (4) is a cylindrical coil, which can provide the required gradient magnetic field for atomic cooling; The cooling light output by the cooling light optical fiber (3) is configured as pumping light and re-pumping light.

8. The falling cold atom device according to claim 7, characterized in that: The standing light wave is the opposite light that completes the atomic state selection and interaction process when the falling cold atom device is applied to an atom interferometer.

9. The falling cold atom device according to claim 2, characterized in that: The image sensor (14) is a charge coupled device camera, which is used for real-time monitoring of atomic groups and detecting the number of atoms in coordination with resonance light.

10. A working method based on the falling cold atom device according to any one of claims 1 to 9, characterized in that: The following steps are involved: Turning on the cooling light and the anti-Helmholtz coil (4), the cooling light irradiates the grating chip (1) vertically, the diffracted light after diffraction by the grating chip (1) converges with the incident light, and the atoms injected by the atomic source (2) are captured and cooled at the convergence point; Sub-Doppler cooling of atoms is achieved by controlling the cooling light parameters; After sub-Doppler cooling, the cooling light and the anti-Helmholtz coil (4) are turned off, and the Helmholtz coil (17) is turned on to complete the interaction between the resonant light and the standing light wave and the cold atoms; After the laser interacts with the cold atoms, the detection light is turned on to collect the fluorescence of the cold atoms.

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