CN115055219B - A front-stage atom pre-cooling system suitable for cold atom experiments - Google Patents

Abstract

The invention discloses a pre-atomic pre-cooling system suitable for cold atomic experiments, which is communicated with an experiment cavity and comprises the following components: a glass cavity for receiving atoms to be cooled; the vacuum cavity assembly is used for maintaining the pressure difference between the glass cavity and the experimental cavity and providing a transmission channel for the cooled atomic groups; the horizontal direction cooling device is used for expanding the horizontal cooling laser beam into an elliptical light spot and emitting the elliptical light spot to cool the temperature of the atomic group in the horizontal direction; the vertical cooling device is used for expanding the vertical cooling laser beam into an elliptical light spot and emitting the elliptical light spot to cool the temperature of the atomic group in the vertical direction; a gradient magnetic field coil assembly for providing a gradient magnetic field; the atomic group pushing assembly is arranged on one side of the glass cavity and used for transmitting a group of pushing lasers to push the cooled atomic groups from the glass cavity to the experimental cavity. The invention can make the temperature of atomic group lower, the optical thickness higher and the atomic flux larger.

Description

A front-stage atom pre-cooling system suitable for cold atom experiments

Technical field

The invention relates to the field of cold atom technology, and in particular to a front-stage atom pre-cooling system suitable for cold atom experiments.

Background technique

In the field of cold atoms, especially in atomic sensing technology, the shot noise of the system is mainly limited by the number of atoms, and an ultra-high vacuum environment is required. However, it is inefficient to directly trap and cool atoms from the ultra-high vacuum environment. In order to provide high-flux and low-speed atomic beams, two-dimensional magneto-optical traps and other methods are generally used to pre-cool the atomic clusters.

However, the traditional two-dimensional magneto-optical trap front-stage cooling technology can only cool the temperatures of the atomic groups in the two radial directions of the pushed light, but has no cooling effect on the temperature in the axial direction of the pushed light, which will leave the axial direction uncooled. The atoms cannot be effectively utilized, so the optical thickness of the atomic beam pushed upward along the optical axis is low, and the atomic beam that can be pushed into the experimental cavity is limited.

Therefore, the existing technology still needs to be improved and developed.

Contents of the invention

In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a front-stage atom pre-cooling system suitable for cold atom experiments to solve the problem that the traditional two-dimensional magneto-optical trap front-stage cooling technology can only cool atomic groups while pushing the optical path. The temperature in both directions has no cooling effect on the temperature in the direction of the pushed optical axis, which leads to the problem that the atomic beam that can be pushed into the experimental cavity is limited.

The technical solution of the present invention is as follows:

A front-stage atom pre-cooling system suitable for cold atom experiments, connected with the experimental cavity, including:

Glass cavity, used to receive atoms to be cooled;

Vacuum cavity assembly, connected between the glass cavity and the experimental cavity, used to maintain the pressure difference between the glass cavity and the experimental cavity, and provide a transmission channel for the cooled atomic groups ;

A horizontal cooling device, located in the radial direction of the glass cavity, is used to expand the horizontal cooling laser beam into an elliptical spot and emit it to cool the temperature of the atomic group in the horizontal direction;

A vertical cooling device, located in the axial direction of the glass cavity, is used to expand the vertical cooling laser beam into an elliptical spot and emit it to cool the temperature of the atomic group in the vertical direction;

A gradient magnetic field coil assembly is provided on the glass cavity and used to provide a gradient magnetic field; the horizontal direction cooling laser, the vertical direction cooling laser and the gradient magnetic field form a three-dimensional magneto-optical trap structure;

An atomic group pushing component is provided on one side of the glass cavity and is used to emit a set of pushing lasers to push the cooled atomic groups from the glass cavity to the experimental cavity.

In a further arrangement of the present invention, the vacuum chamber assembly includes:

A square vacuum chamber connected between the glass chamber and the experimental chamber;

A differential tube is arranged in the square vacuum chamber and connects the square vacuum chamber and the experimental chamber;

A first vacuum pump is connected to the square vacuum chamber, and the glass chamber is connected to the first vacuum pump through the square vacuum chamber;

A second vacuum pump is connected to the square vacuum chamber, and the experimental chamber is connected to the second vacuum pump through the square vacuum chamber.

In a further arrangement of the present invention, a fixed part is provided in the square vacuum chamber, and the differential tube is fixed on the fixed part; wherein, the contact surface between the fixed part and the differential tube is sealed with indium wire;

The side of the square vacuum chamber has four faces, each face is provided with a through hole, and two adjacent faces on the diagonal of the square vacuum chamber are connected through the through hole.

In a further arrangement of the present invention, the horizontal cooling laser includes: a first horizontal cooling laser and a second horizontal cooling laser;

The horizontal cooling device includes: a first horizontal cooling component and a second horizontal cooling component;

The first horizontal cooling laser is expanded into a first elliptical spot by the first horizontal cooling component and is reflected by the glass cavity to form a first opposing cooling light with the second horizontal cooling laser. ; Wherein, the long axis direction of the first elliptical light spot is the same as the long axis direction of the differential tube;

The second horizontal cooling laser beam expands into a second elliptical spot through the second horizontal cooling component and is reflected by the glass cavity to form a second opposing cooling light with the first horizontal cooling laser. ; Wherein, the long axis direction of the second elliptical light spot is the same as the long axis direction of the differential tube;

Wherein, the first horizontal cooling laser and the second horizontal cooling laser form a butterfly-shaped structure; the first through-beam cooling light and the second through-beam cooling light are sandwiched between a direction parallel to the differential tube. The angle is an acute angle, and the angle in the direction perpendicular to the differential tube is an obtuse angle.

In a further arrangement of the present invention, the first horizontal cooling component includes: a first wave plate, a first concave cylindrical lens, a first convex cylindrical lens and a first total mirror;

The first horizontally cooled laser beam expands through the first wave plate, the first concave cylindrical lens and the first convex cylindrical lens in sequence to form a first elliptical spot, passes through the glass cavity and passes through the The first total reflection mirror reflects to the second horizontal cooling component, and forms the first opposite cooling light with the second horizontal cooling laser reflected by the second horizontal cooling laser.

In a further arrangement of the present invention, the second horizontal cooling component includes: a second wave plate, a second concave cylindrical lens, a second convex cylindrical lens and a second total mirror;

The second horizontally cooled laser passes through the second wave plate, the second concave cylindrical lens and the second convex cylindrical lens in sequence and is expanded to form a second elliptical spot, which passes through the glass cavity and passes through the third cylindrical lens. The two total reflection mirrors reflect the first total reflection mirror, and form a second opposite cooling light with the first horizontal cooling laser.

In a further arrangement of the present invention, the vertical cooling device includes: a third wave plate, a third concave cylindrical lens, a third convex cylindrical lens, a fourth wave plate and a third total mirror;

The vertically cooled laser beam expands through the third wave plate, the third concave cylindrical lens and the third convex cylindrical lens in sequence to form a third elliptical spot, and then passes through the glass cavity and the The fourth wave plate is then reflected by the third total reflection mirror and enters the glass cavity through the fourth wave plate to form a third opposing cooling light;

Wherein, the incident direction of the vertical cooling laser is perpendicular to the plane where the horizontal cooling laser is located.

In a further arrangement of the present invention, the gradient magnetic field coil assembly includes: a first gradient magnetic field coil and a second gradient magnetic field coil; the first gradient magnetic field coil and the second gradient magnetic field coil are arranged opposite to each other in the glass cavity. Upper and lower sides.

In a further arrangement of the present invention, the first gradient magnetic field coil and the second gradient magnetic field coil are both rectangular coils; the long axis direction of the first gradient magnetic field coil and the second gradient magnetic field coil is aligned with the vertical direction. The long axis direction of the cooling laser is the same; the short axis direction of the first gradient magnetic field coil and the second gradient magnetic field coil is the same as the short axis direction of the vertical cooling laser.

In a further arrangement of the present invention, the atomic group pushing component includes: a collimator and a fourth total reflecting mirror. After the pushing laser is emitted through the collimator, it is reflected by the fourth total reflecting mirror and enters the glass cavity. body; wherein, the path of the push laser after emission coincides with the axial direction of the atomic group and passes through the middle of the differential tube.

The present invention provides a front-stage atom pre-cooling system suitable for cold atom experiments, which is connected to the experimental cavity and includes: a glass cavity for receiving atoms to be cooled; a vacuum cavity component connected to the glass Between the cavity and the experimental cavity, it is used to maintain the pressure difference between the glass cavity and the experimental cavity, and provide a transmission channel for the cooled atomic groups; a horizontal cooling device is located on the glass In the radial direction of the cavity, it is used to expand the horizontal cooling laser beam into an elliptical spot and emit it to cool the temperature of the atomic group in the horizontal direction; the vertical cooling device is located in the axial direction of the glass cavity on, used to expand the vertical cooling laser beam into an elliptical spot and emit it to cool the temperature of the atomic group in the vertical direction; a gradient magnetic field coil assembly, arranged on the glass cavity and used to provide a gradient magnetic field; The horizontal direction cooling laser, the vertical direction cooling laser and the gradient magnetic field form a three-dimensional magneto-optical trap structure; the atomic group pushing component is arranged on one side of the glass cavity and is used to emit a group of pushing lasers to push the cooled Atomic groups are pushed from the glass chamber into the experimental chamber. The invention can simultaneously pre-cool the temperatures of the atomic clusters in the radial and axial directions, so that the temperature of the atomic clusters is lower, the optical thickness is higher, and the atomic flux is larger.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For ordinary people in the art, without exerting creative efforts, other drawings can be obtained based on the structures shown in these drawings.

Figure 1 is a schematic diagram of the overall structure of the front-stage atom pre-cooling system suitable for cold atom experiments in the present invention.

Figure 2 is a schematic structural diagram of the vertical cooling device and the glass cavity in the present invention.

Figure 3 is a schematic diagram of the connection between the glass chamber, the vacuum chamber assembly and the experimental chamber in the present invention.

Figure 4 is a schematic structural diagram of the vacuum chamber assembly in the present invention.

Figure 5 is a schematic structural diagram of the vacuum chamber in the present invention.

Figure 6 is a schematic structural diagram of the differential tube in the present invention.

Marks in the drawings: 1. Glass cavity; 2. Vacuum cavity assembly; 21. Square vacuum cavity; 211. Fixed part; 212. Through hole; 22. Differential tube; 23. First vacuum pump; 24. No. Two vacuum pumps; 3. Horizontal cooling device; 31. First horizontal cooling component; 311. First wave plate; 312. First concave cylindrical lens; 313. First convex cylindrical lens; 314. First total mirror; 32. The second horizontal cooling component; 321. The second wave plate; 322. The second concave cylindrical lens; 323. The second convex cylindrical lens; 324. The second total mirror; 4. The vertical cooling device; 41. The third wave plate; 42. The third concave cylindrical lens; 43. The third convex cylindrical lens; 44. The fourth wave plate; 45. The third total mirror; 5. Gradient magnetic field coil assembly; 51. First gradient magnetic field coil ; 52. Second gradient magnetic field coil; 6. Atomic group pushing component; 61. Collimator; 62. Fourth total reflection mirror; 7. Experimental cavity.

Detailed ways

The present invention provides a front-stage atom pre-cooling system suitable for cold atom experiments, which can be applied in the technical field of atomic sensors. In order to make the purpose, technical solution and effect of the present invention clearer and clearer, the present invention will be described below with reference to the accompanying drawings and examples. To elaborate further. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.

In the embodiments and patent applications, unless the context specifically limits the article, "a", "an", "the" and "the" may also include plural forms. If there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are for descriptive purposes only and cannot be understood as indicating or implying their relative Significance or implicit indication of the quantity of a technical feature indicated. Therefore, features defined as "first" and "second" may explicitly or implicitly include at least one of these features.

It should be further understood that the word "comprising" used in the description of the present invention refers to the presence of stated features, integers, steps, operations, elements and/or components, but does not exclude the presence or addition of one or more other features, Integers, steps, operations, elements, components and/or groups thereof. It will be understood that when we refer to an element being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Additionally, "connected" or "coupled" as used herein may include wireless connections or wireless couplings. As used herein, the term "and/or" includes all or any unit and all combinations of one or more of the associated listed items.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms, such as those defined in general dictionaries, are to be understood to have meanings consistent with their meaning in the context of the prior art, and are not to be used in an idealistic or overly descriptive manner unless specifically defined as here. to explain the formal meaning.

In addition, the technical solutions in various embodiments can be combined with each other, but it must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that such a combination of technical solutions does not exist. , nor within the protection scope required by the present invention.

Please refer to Figures 1 to 6 at the same time. The present invention provides a preferred embodiment of a front-stage atom pre-cooling system suitable for cold atom experiments.

The present invention provides a front-stage atomic pre-cooling system suitable for cold atom experiments, which is connected with the experimental cavity and can push the pre-cooled atomic groups into the subsequent experimental cavity, such as a three-dimensional magneto-optical trap vacuum device.

As shown in Figures 1 to 3, the front-stage atom pre-cooling system suitable for cold atom experiments includes: glass chamber 1, vacuum chamber assembly 2, horizontal cooling device 3, vertical cooling device 4, gradient Magnetic field coil assembly 5 and atomic group pushing assembly 6. The glass chamber 1 is used to receive atoms to be cooled provided by an atomic source; the vacuum chamber assembly 2 is connected between the glass chamber 1 and the experimental chamber 7 and is used to maintain the glass. The pressure difference between the cavity 1 and the experimental cavity 7 provides a transmission channel for the cooled atomic groups; the horizontal cooling device 3 is located in the radial direction of the glass cavity 1 for horizontally The cooling laser (A, B) expands the beam into an elliptical spot and emits it to cool the temperature of the atomic group in the horizontal direction; the vertical cooling device 4 is located in the axial direction of the glass cavity 1 for The vertical cooling laser C is expanded into an elliptical spot and emitted to cool the temperature of the atomic group in the vertical direction; the gradient magnetic field coil assembly 5 is provided on the glass cavity 1 and is used to provide a gradient magnetic field; The atomic group pushing component 6 is provided on one side of the glass cavity 1 and is used to emit a set of pushing lasers D to push the cooled atomic groups from the glass cavity 1 to the experimental cavity 7 .

Specifically, the glass cavity 1 is a square cavity, and the glass cavity 1 can receive atoms to be cooled delivered by an atomic source. The glass chamber 1 and the vacuum chamber assembly 2 are connected through a vacuum pipeline, the vacuum chamber assembly 2 and the experimental chamber 7 are connected through a vacuum pipeline, and the glass chamber 1 and the experimental chamber 7 are connected through a vacuum pipeline. The vacuum chamber assembly 2 is connected, and the vacuum chamber assembly 2 can maintain the pressure difference between the glass chamber 1 and the subsequent experimental chamber 7 so that there can be enough gas in the glass chamber 1 background atomic gas, while enabling the experimental chamber 7 to maintain a sufficiently high vacuum degree. Moreover, the vacuum chamber assembly 2 is connected with the glass chamber 1 and can transport the cooled atomic groups to the subsequent experimental chamber 7 .

Among them, the horizontal direction cooling laser (A, B), the vertical direction cooling laser C and the gradient magnetic field form a three-dimensional magneto-optical trap structure, which can control two radial directions of the atomic groups in the glass cavity 1. The temperature in the direction (the horizontal direction of the atomic group, that is, the horizontal direction of the pushed laser) and the temperature in the axial direction (the vertical direction of the atomic group, that is, the radial direction of the pushed laser) are cooled, and the elliptical spot can improve the temperature of the atomic group. The optical thickness in the long axis direction of the glass cavity 1. When the pushing laser emitted by the atomic radical pushing component 6 passes through the glass cavity 1 , the cooled atomic radicals can be captured and pushed to the experimental chamber 7 after passing through the vacuum chamber component 2 .

It can be seen that in the present invention, the three-dimensional magneto-optical trap structure formed by the horizontal direction cooling laser, the vertical direction cooling laser and the gradient magnetic field can simultaneously narrow the velocity distribution of the atomic groups in three directions, and control the temperature of the atomic groups in the three directions. Cooling improves the utilization of atoms pushing the laser axis, and the cooling light is an elliptical spot, which can increase the interaction area between the cooling laser and the atoms, capture more atoms, and have a higher density. The optical thickness will increase, making the cooled atomic clusters have a lower temperature, higher optical thickness, and greater atomic flux, and can push the cooled atomic clusters into the subsequent experimental cavity 7, shortening the experimental cycle and enabling rapid Preparing atomic groups with lower temperatures and larger numbers for experimental measurements is beneficial to subsequent cold atom experiments. For example, it can be used in quantum sensing and precision measurement experiments based on cold atoms.

In some embodiments, the glass cavity 1 is coated with an anti-reflection film. The anti-reflection film can reduce the loss of cooling laser power due to reflection, which is conducive to the horizontal cooling laser and vertical cooling laser being able to pass from the glass. The outside of the cavity 1 is injected into the glass cavity 1 to capture and cool the atoms in the glass cavity 1 .

Please refer to Figures 1, 4 to 6. In a further implementation of an embodiment, the vacuum chamber assembly 2 includes: a square vacuum chamber 21, a differential tube 22, a first vacuum pump 23 and a second vacuum pump 24 . Wherein, the square vacuum chamber 21 is connected between the glass chamber 1 and the experimental chamber 7; the differential tube 22 is arranged in the square vacuum chamber 21 and connected to the square vacuum chamber. The body 21 is connected to the experimental chamber 7; the first vacuum pump 23 is connected to the square vacuum chamber 21, and the glass chamber 1 is connected to the first vacuum pump 23 through the square vacuum chamber 21; so The second vacuum pump 24 is connected to the square vacuum chamber 21 , and the experimental chamber 7 is connected to the second vacuum pump 24 through the square vacuum chamber 21 .

Specifically, the side of the square vacuum chamber 21 has four faces, each face is used to connect other vacuum cavities, and a through hole 212 is provided on each face. The diagonal lines of the square vacuum chamber 21 are Two adjacent surfaces are connected through the through hole 212. The two facing surfaces are respectively connected to the glass chamber 1 and the experimental chamber 7. The other two facing surfaces are connected to two sets of vacuum pumps respectively. The square The two diagonal surfaces of the vacuum chamber 21 are connected to each other, so that the two sets of vacuum pumps can maintain the vacuum degree of the glass chamber 1 and the experimental chamber 7 respectively. Wherein, the first vacuum pump 23 and the glass chamber 1 are connected through the through hole 212 on the square vacuum tube, and the second vacuum pump 24 and the experimental chamber 7 are connected through the through hole on the square chamber. 212 connected.

The square vacuum chamber 21 is provided with a fixed part 211. The differential tube 22 is fixed on the fixed part 211 and penetrates into the square vacuum chamber 21. The two ends of the differential tube 22 are connected respectively. In the glass cavity 1 and the experimental cavity 7, the pushing laser can push the cooled atomic groups into the experimental cavity 7 through the differential tube 22. Since the atomic source will continuously release atoms to be cooled into the glass cavity 1 during the experiment, the vacuum degree in the glass cavity 1 will be relatively poor. The atoms will be cooled and focused in the glass chamber 1, and then pushed to the experimental chamber 7. The structure composed of the square vacuum chamber 21 and the differential tube 22 can maintain the relationship between the glass chamber 1 and The pressure difference in the subsequent experimental chamber 7 enables enough background atoms in the glass chamber 1 to be cooled and focused, and at the same time, the subsequent experimental chamber 7 can maintain a sufficiently high vacuum degree.

In some embodiments, the differential tube 22 is fixed at the middle position of the square vacuum chamber 21 , that is, the fixing part 211 is located at the middle position of the square vacuum chamber 21 . In one implementation manner, the differential tube 22 is threadedly connected to the fixed part 211, and the contact surface (ie, the screw joint surface) between the fixed part 211 and the differential tube 22 is sealed with indium wire. After the vacuum installation is completed, the glass cavity 1 and the experimental cavity 7 are connected only through the differential tube 22. The above-mentioned packaging structure can make the vacuum degree of the experimental cavity 7 more than 3 orders of magnitude higher than that of the glass cavity 1. , can significantly reduce the impact of background gas in the experimental chamber 7 on experimental measurements. In some embodiments, the diameter of the inner through hole 212 of the differential tube 22 is 3-8 mm, for example, it may be 6 mm.

Please refer to Figure 1. In a further implementation of an embodiment, the horizontal cooling laser includes: a first horizontal cooling laser A and a second horizontal cooling laser B; the horizontal cooling device 3 includes: a first horizontal cooling laser Cooling component 31 and second horizontal cooling component 32; the first horizontal cooling laser A is expanded into a first elliptical spot by the first horizontal cooling component 31 and is reflected after passing through the glass cavity 1 The first counter-projection cooling light is formed with the second horizontal cooling laser B; wherein the long axis direction of the first elliptical light spot is the same as the long axis direction of the differential tube 22 and coincides with the horizontal plane; the second The horizontal cooling laser B expands into a second elliptical spot through the second horizontal cooling component 32 and is reflected by the glass cavity 1 to form a second opposing cooling light with the first horizontal cooling laser A. ; Wherein, the long axis direction of the second elliptical light spot is the same as the long axis direction of the differential tube 22 and coincides with the horizontal plane; wherein the first horizontal cooling laser A and the second horizontal cooling laser B form Butterfly-shaped structure; the angle between the first through-beam cooling light and the second through-beam cooling light in the direction parallel to the differential tube 22 is an acute angle α, and in the direction perpendicular to the differential tube 22 The included angle is an obtuse angle β.

Specifically, the first horizontal cooling component 31 includes: a first wave plate 311 , a first concave cylindrical lens 312 , a first convex cylindrical lens 313 and a first total mirror 314 . The first horizontal cooling laser A is sequentially expanded through the first wave plate 311, the first concave cylindrical lens 312 and the first convex cylindrical lens to form a first elliptical light spot, which passes through the glass cavity. 1 and is reflected by the first total reflection mirror 314 to the second horizontal cooling component 32, and forms the first opposite cooling light with the second horizontal cooling laser B.

The second horizontal cooling component 32 includes: a second wave plate 321 , a second concave cylindrical lens 322 , a second convex cylindrical lens 323 and a second total mirror 324 . The second horizontal cooling laser B passes through the second wave plate 321, the second concave cylindrical lens 322 and the second convex cylindrical lens 323 in sequence and then expands to form a second elliptical light spot, which passes through the glass cavity 1 After being reflected by the second total reflection mirror 324, it reaches the first total reflection mirror 314, and forms a second opposing cooling light with the first horizontal cooling laser A.

The first wave plate 311 and the second wave plate 321 are both quarter wave plates. The first horizontal cooling laser A becomes circularly polarized light after passing through the first wave plate 311. The first concave cylindrical lens 312 and the first convex cylindrical lens 313 then form an elliptical light spot, and then pass through the glass cavity 1 and then pass through the first total reflection mirror 314 and the second total reflection mirror 324 The second horizontal cooling laser B after reflection and beam expansion forms a set of through-beam cooling light, that is, the first through-beam cooling light. The second horizontal cooling laser passes through the second wave plate 321 and becomes circularly polarized light, and then passes through the second concave cylindrical lens 322 and the second convex cylindrical lens to form an elliptical light spot, which passes through the glass cavity. 1 and then the first horizontal cooling laser A, which is reflected by the second total reflection mirror 324 and the first total reflection mirror 314 and expanded, forms a set of opposing cooling lights, that is, the first horizontal cooling laser A Two opposing cooling lights. The first horizontal cooling laser A and the second horizontal cooling laser B form an approximately butterfly-shaped structure, which can increase the spot diameter of the atomic capture area, reduce the number of large-diameter wave plates used, and save costs.

Please refer to FIG. 1 . In some embodiments, the first through-beam cooling light and the second through-beam cooling light are sandwiched in a direction parallel to the differential tube 22 (that is, in the axial direction of the pushing laser D). The angle is 60 degrees, and the angle in the direction perpendicular to the differential tube 22 (that is, in the radial direction of the pushing laser D) is 120 degrees. The cooling laser (horizontal cooling laser and vertical cooling laser) is in the radial direction of the pushing laser. The projection component of is smaller, and the projection component in the axial direction of the push laser D is larger, so that the atomic cluster will absorb more photon momentum in the axial direction, thereby obtaining more photon recoil momentum, and making the velocity distribution of the atomic cluster The pressure is narrowed and the temperature is reduced.

Referring to Figures 1 and 2, in a further implementation of one embodiment, the vertical cooling device 4 includes: a third wave plate 41, a third concave cylindrical lens 42, a third convex cylindrical lens 43, The fourth wave plate 44 and the third total reflecting mirror 45 . The vertically cooled laser C is sequentially expanded through the third wave plate 41, the third concave cylindrical lens 42 and the third convex cylindrical lens 43 to form a third elliptical light spot, and then passes through the glass cavity. The body 1 and the fourth wave plate 44 are reflected by the third total reflection mirror 45 and enter the glass cavity 1 through the fourth wave plate 44 to form a third opposing cooling light; wherein, the vertical The incident direction of the direct cooling laser D is perpendicular to the plane where the horizontal cooling laser is located.

Specifically, the third wave plate 41 and the fourth wave plate 44 are both quarter wave plates. The vertically cooled laser C first passes through the third wave plate 41 and becomes circularly polarized light, and then passes through the third concave cylindrical lens 42 and the third convex cylindrical lens 43 in sequence, causing the light spot to become a third ellipse. shaped light spot, and the long axis direction of the elliptical light spot is the same as the long axis direction of the atomic group. The incident direction of the vertical cooling laser C is perpendicular to the plane where the horizontal cooling laser is located, and then passes through the glass cavity 1. Then pass through the fourth wave plate 44, and after being emitted by the third total mirror 45, pass through the fourth wave plate 44 again and enter the glass cavity 1, forming a group in the vertical direction. The through-beam cooling light, that is, the third through-beam cooling light, is used to cool the temperature in the axial direction of the atomic group.

Referring to FIGS. 1 and 2 , in a further implementation of an embodiment, the gradient magnetic field coil assembly 5 includes: a first gradient magnetic field coil 51 and a second gradient magnetic field coil 52 . The first gradient magnetic field coil 51 and the second gradient magnetic field coil 52 are arranged oppositely on the upper and lower sides of the glass cavity 1 .

Specifically, the first gradient magnetic field coil 51 and the second gradient magnetic field coil 52 are both rectangular coils. The long axis direction of the first gradient magnetic field coil 51 and the second gradient magnetic field coil 52 is the same as the long axis direction of the vertical cooling laser C. The first gradient magnetic field coil 51 and the second gradient magnetic field coil The short axis direction of the coil 52 is the same as the short axis direction of the vertical cooling laser light C. The first gradient magnetic field coil 51 and the second gradient magnetic field coil 52 can provide a gradient magnetic field. The horizontal direction cooling laser, the vertical direction cooling laser and the gradient magnetic field form a three-dimensional magneto-optical trap structure, so that Capture a cigar-shaped group of atoms E.

Please refer to Figures 1 and 2. In a further implementation of one embodiment, the atomic group pushing component 6 includes: a collimator 61 and a fourth total reflecting mirror 62, and the pushing laser D passes through the collimator. 61 is emitted and then reflected by the fourth total reflection mirror 62 into the glass cavity 1; wherein, the path of the push laser D after being emitted coincides with the axial direction of the atomic group and starts from the middle of the differential tube 22 pass.

Specifically, the push laser D is emitted from the collimator 61, passes through the fourth total reflection mirror 62, and coincides with the long axis direction of the atomic group, and passes through the middle of the differential tube 22 to cool the The final atomic groups are pushed to the subsequent experimental chamber 7. Among them, the frequency of the push laser D has a negative detuning from the atomic cyclic transition frequency, so that the atoms in the atomic group whose speed is opposite to that of the push laser wave vector can obtain photon momentum, thereby allowing more atoms to be Push it into the experimental chamber. The present invention can control the turning on and off of the atomic beam passing through the differential tube 22 by controlling the turning on and off of the push laser.

In summary, the present invention provides a front-stage atom pre-cooling system suitable for cold atom experiments and has the following beneficial effects:

The three-dimensional magneto-optical trap structure formed by the horizontal cooling laser, the vertical cooling laser and the gradient magnetic field can simultaneously narrow the velocity distribution of the atomic groups in three directions, cool the temperatures of the atomic groups in the three directions, and improve In order to improve the utilization rate of pushing the atoms along the laser axis, and the cooling light is an elliptical spot, this can increase the interaction area between the cooling laser and the atoms, capture more atoms, increase the density, and increase the optical thickness of the atoms. , making the cooled atomic clusters have a lower temperature, higher optical thickness, and greater atomic flux, and can push the cooled atomic clusters into subsequent experimental chambers, shortening the experimental cycle, and enabling rapid preparation of lower temperature, higher number More atomic groups can be used for experimental measurements, which is beneficial to subsequent cold atom experiments. For example, it can be used for quantum sensing and precision measurement experiments based on cold atoms.

It should be understood that the application of the present invention is not limited to the above examples. Those of ordinary skill in the art can make improvements or changes based on the above descriptions. All these improvements and changes should fall within the protection scope of the appended claims of the present invention.

Claims (8)

1. A front-stage atom pre-cooling system suitable for cold atom experiments, connected with the experimental cavity, characterized by: Glass cavity, used to receive atoms to be cooled; Vacuum cavity assembly, connected between the glass cavity and the experimental cavity, used to maintain the pressure difference between the glass cavity and the experimental cavity, and provide a transmission channel for the cooled atomic groups ;The vacuum chamber assembly includes: A square vacuum chamber connected between the glass chamber and the experimental chamber; A differential tube is arranged in the square vacuum chamber and connects the square vacuum chamber and the experimental chamber; A first vacuum pump is connected to the square vacuum chamber, and the glass chamber is connected to the first vacuum pump through the square vacuum chamber; A second vacuum pump is connected to the square vacuum chamber, and the experimental chamber is connected to the second vacuum pump through the square vacuum chamber; A horizontal cooling device, located in the radial direction of the glass cavity, is used to expand the horizontal cooling laser beam into an elliptical spot and emit it to cool the temperature of the atomic group in the horizontal direction; the horizontal cooling laser includes: A first horizontal cooling laser and a second horizontal cooling laser; wherein the first horizontal cooling laser and the second horizontal cooling laser form a butterfly-shaped structure; A vertical cooling device, located in the axial direction of the glass cavity, is used to expand the vertical cooling laser beam into an elliptical spot and emit it to cool the temperature of the atomic group in the vertical direction; A gradient magnetic field coil assembly is provided on the glass cavity and used to provide a gradient magnetic field; the gradient magnetic field coil assembly includes: a first gradient magnetic field coil and a second gradient magnetic field coil; the first gradient magnetic field coil and the third gradient magnetic field coil. Two gradient magnetic field coils are arranged oppositely on the upper and lower sides of the glass cavity; the first gradient magnetic field coil and the second gradient magnetic field coil are both rectangular coils; the horizontal direction cooling laser and the vertical direction cooling The laser and the gradient magnetic field form a three-dimensional magneto-optical trap structure to cool the temperatures in the two radial directions and the axial direction of the atomic groups in the glass cavity; An atomic group pushing component is provided on one side of the glass cavity and is used to emit a set of pushing lasers to push the cooled atomic groups from the glass cavity to the experimental cavity. 2. The front-stage atom pre-cooling system suitable for cold atom experiments according to claim 1, characterized in that a fixed part is provided in the square vacuum chamber, and the differential tube is fixed on the fixed part; wherein , the contact surface between the fixed part and the differential tube is sealed with indium wire; The side of the square vacuum chamber has four faces, each face is provided with a through hole, wherein two adjacent faces on the diagonal of the square vacuum chamber are connected through the through hole. 3. The front-stage atom pre-cooling system suitable for cold atom experiments according to claim 1, characterized in that, The horizontal cooling device includes: a first horizontal cooling component and a second horizontal cooling component; The first horizontal cooling laser is expanded into a first elliptical spot by the first horizontal cooling component and is reflected by the glass cavity to form a first opposing cooling light with the second horizontal cooling laser. ; Wherein, the long axis direction of the first elliptical light spot is the same as the long axis direction of the differential tube; The second horizontal cooling laser beam expands into a second elliptical spot through the second horizontal cooling component and is reflected by the glass cavity to form a second opposing cooling light with the first horizontal cooling laser. ; Wherein, the long axis direction of the second elliptical light spot is the same as the long axis direction of the differential tube; The angle between the first through-beam cooling light and the second through-beam cooling light in a direction parallel to the differential tube is an acute angle, and the included angle in a direction perpendicular to the differential tube is an obtuse angle. 4. The front-stage atom pre-cooling system suitable for cold atom experiments according to claim 3, characterized in that the first horizontal cooling component includes: a first wave plate, a first concave cylindrical lens, a first convex Cylindrical lens and first total mirror; The first horizontally cooled laser beam expands through the first wave plate, the first concave cylindrical lens and the first convex cylindrical lens in sequence to form a first elliptical spot, passes through the glass cavity and passes through the The first total reflection mirror reflects to the second horizontal cooling component, and forms the first opposite cooling light with the second horizontal cooling laser reflected by the second horizontal cooling component. 5. The front-stage atom pre-cooling system suitable for cold atom experiments according to claim 4, characterized in that the second horizontal cooling component includes: a second wave plate, a second concave cylindrical lens, a second convex Cylindrical lens and second total reflection mirror; The second horizontally cooled laser passes through the second wave plate, the second concave cylindrical lens and the second convex cylindrical lens in sequence and is expanded to form a second elliptical spot, which passes through the glass cavity and passes through the third cylindrical lens. The two total reflection mirrors reflect to the first total reflection mirror, and form a second opposing cooling light with the first horizontal cooling laser. 6. The front-stage atomic pre-cooling system suitable for cold atom experiments according to claim 1, characterized in that the vertical cooling device includes: a third wave plate, a third concave cylindrical lens, and a third convex cylinder. Lens, fourth wave plate and third total reflecting mirror; The vertically cooled laser beam expands through the third wave plate, the third concave cylindrical lens and the third convex cylindrical lens in sequence to form a third elliptical spot, and then passes through the glass cavity and the The fourth wave plate is then reflected by the third total reflection mirror and enters the glass cavity through the fourth wave plate to form a third opposing cooling light; Wherein, the incident direction of the vertical cooling laser is perpendicular to the plane where the horizontal cooling laser is located. 7. The front-stage atom pre-cooling system suitable for cold atom experiments according to claim 1, characterized in that the long axis direction of the first gradient magnetic field coil and the second gradient magnetic field coil is aligned with the vertical direction of the first gradient magnetic field coil. The long axis direction of the cooling laser is the same; the short axis direction of the first gradient magnetic field coil and the second gradient magnetic field coil is the same as the short axis direction of the vertical cooling laser. 8. The front-stage atom pre-cooling system suitable for cold atom experiments according to claim 1, characterized in that the atomic group pushing component includes: a collimator and a fourth total reflective mirror, and the pushing laser passes through the After being emitted from the collimator, it is reflected by the fourth total reflection mirror and enters the glass cavity; wherein, the path of the push laser after emission coincides with the axial direction of the atomic group and passes through the middle of the differential tube.