Apparatus and method for producing a cold atom beam

Abstract

The application relates to a cold atom beam preparation device and a preparation method. The cold atom beam preparation device comprises a vacuum chamber, a magnetic field element arranged outside the vacuum chamber, a transverse cooling module and a longitudinal cooling module. The transverse cooling module is used for injecting two pairs of first lasers and two pairs of second lasers into the vacuum chamber. The longitudinal cooling module is used for injecting two pairs of moving optical glue lasers into the vacuum chamber. Each pair of moving optical glue lasers is emitted along a direction which forms an angle with a third direction and a transverse plane. The third direction is the emission direction of the atom beam, the transverse plane is perpendicular to the third direction, and the light path direction of the first laser, the light path direction of the second laser and the third direction are perpendicular to each other. The cold atom beam preparation device has a simple structure, realizes transverse cooling of the atom beam and longitudinal cooling of the atom beam, generates longitudinal velocity of the atom vapor and controls the longitudinal velocity of the atom beam, and obtains a cold atom beam which has low three-dimensional cooling temperature and controllable longitudinal velocity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of quantum precision measurement based on cold atoms, and particularly to a cold atom beam preparation device and a preparation method. BACKGROUND

[0002] With the increasing application value of cold atom beam sources in the fields of atomic interference, atomic frequency standard and atomic lithography, the optical performance requirements of the cold atom beam source are also increasing.

[0003] In the traditional technology, there are several ways to obtain a continuous cold atom beam source. One is to use a hot atom beam as a basis, and to cool the transverse velocity of the atom beam by laser using a transversely cooled hot atom beam source, or to use a Zeeman decelerator to decelerate and cool the atom beam in the transverse direction by laser. Another is to directly cool and trap atoms from a hot atom vapor using a magneto-optical trap.

[0004] Based on the above-mentioned ways of obtaining a cold atom beam, the existing preparation device for preparing a cold atom beam generally needs to use multiple vacuum chambers to realize three-dimensional cooling and longitudinal velocity control of the atom beam, which has a complex structure and a large device volume. SUMMARY

[0005] Therefore, it is necessary to provide a cold atom beam preparation device and a preparation method to solve the technical problem of the complex structure of the existing cold atom beam preparation device.

[0006] A cold atom beam preparation device, the continuous cold atom beam preparation device comprising:

[0007] a vacuum chamber;

[0008] a magnetic field element arranged outside the vacuum chamber;

[0009] a transverse cooling module arranged outside the vacuum chamber and configured to inject two first lasers along a first direction and two second lasers along a second direction into the vacuum chamber;

[0010] a longitudinal cooling module arranged outside the vacuum chamber and configured to inject two pairs of moving optical glue lasers into the vacuum chamber, each pair of the moving optical glue lasers being emitted along a direction forming an angle with a third direction and a transverse plane, the third direction being an emission direction of the atom beam, the transverse plane being perpendicular to the third direction, and the first direction, the second direction and the third direction being perpendicular to each other;

[0011] wherein the first lasers, the second lasers and the two pairs of moving optical glue lasers meet at a point in the vacuum chamber.

[0012] In one of the embodiments, the vacuum chamber comprises a front end cavity wall and a rear end cavity wall arranged in the third direction, and the front end cavity wall is provided with a first mirror arranged at an angle with the third direction and the transverse plane.

[0013] In one of the embodiments, the vacuum chamber further comprises a side cavity wall connected between the front end cavity wall and the rear end cavity wall, and the side cavity wall is provided with a first perspective window and a second perspective window arranged in the third direction, and the second perspective window is arranged close to the first mirror relative to the first perspective window.

[0014] In one of the embodiments, the rear end cavity wall is provided with a plurality of third perspective windows arranged in a direction perpendicular to the third direction.

[0015] In one of the embodiments, the rear end cavity wall is provided with a second mirror arranged at an angle with the third direction and the transverse plane, and the side cavity wall is further provided with a fourth perspective window, and the fourth perspective window and the second perspective window are respectively arranged on two sides of the first perspective window.

[0016] In one of the embodiments, the first mirror is arranged on the front end cavity wall through a first prism, and the first prism is provided with a first through hole arranged in the third direction, and the front end cavity wall is provided with a second through hole in communication with the first through hole.

[0017] In one of the embodiments, a spray hole plate is arranged between the first prism and the front end cavity wall, and the spray hole plate is in communication with the first through hole and the second through hole.

[0018] In one of the embodiments, an atomic furnace is arranged outside the vacuum chamber, and the atomic furnace is in communication with the vacuum chamber.

[0019] In one of the embodiments, a cold atom beam preparation method is further provided, and the cold atom beam preparation method uses the cold atom beam preparation device as described above, and the cold atom beam preparation method comprises the following steps:

[0020] A magnetic field is applied to the vacuum chamber;

[0021] Atomic vapor is injected into the vacuum chamber;

[0022] Two pairs of first laser beams and two pairs of second laser beams are injected into the vacuum chamber to form a magneto-optical trap in the vacuum chamber to transversely cool the atomic vapor;

[0023] Two pairs of moving optical adhesive laser beams are injected into the vacuum chamber to form a moving optical adhesive action area in the vacuum chamber to longitudinally cool the atomic vapor.

[0024] The frequency of the moving optical molasses laser is adjusted to control the longitudinal velocity of the atomic vapor.

[0025] In one embodiment, the magnetic field element is configured to apply a two-dimensional gradient magnetic field or a three-dimensional gradient magnetic field to the vacuum chamber.

[0026] The preparation device for the cold atomic beam, the vacuum chamber provides a vacuum environment for preparing the cold atomic beam, and is configured to accommodate the atomic vapor. The atomic vapor is transversely cooled, longitudinally cooled and accelerated in the vacuum chamber by the cooperation of the magnetic field element, the transverse cooling module and the longitudinal cooling module, so that a continuous cold atomic beam is prepared. Specifically, the magnetic field element is configured to apply a magnetic field to the inside of the vacuum chamber. The transverse cooling module is configured to provide two pairs of first lasers and two pairs of second lasers to the vacuum chamber. The two pairs of first lasers and the two pairs of second lasers form a magneto-optical trap together with the magnetic field. The first lasers and the second lasers are perpendicular to each other in the vacuum chamber and are both perpendicular to the direction of the atomic beam, so that the atomic beam is cooled in the direction perpendicular to the direction of the atomic beam, i.e., the atomic beam is transversely cooled. The longitudinal cooling module is configured to provide two pairs of moving optical molasses lasers to the vacuum chamber. The frequencies of the two pairs of moving optical molasses lasers are offset, so that a moving optical molasses action region is formed in the vacuum chamber. The directions of the moving optical molasses lasers form an acute angle with the direction of the atomic beam. The atomic beam is longitudinally cooled by the moving optical molasses lasers, so that the atomic vapor has a longitudinal velocity and the longitudinal velocity of the atomic beam is controlled. The preparation device for the cold atomic beam has a simple structure, and the atomic vapor is transversely cooled, longitudinally cooled and accelerated in one vacuum chamber.

[0027] The preparation method for the cold atomic beam is performed by using the preparation device for the continuous cold atomic beam. In the vacuum chamber, the atomic beam is cooled in the direction perpendicular to the direction of the atomic beam by applying a magnetic field and two pairs of first lasers and two pairs of second lasers in the vacuum chamber, i.e., the atomic beam is transversely cooled. The two pairs of moving optical molasses lasers form a moving optical molasses action region in the vacuum chamber. The atomic beam is longitudinally cooled by the moving optical molasses lasers, so that the atomic vapor has a longitudinal velocity and the longitudinal velocity of the atomic beam is controlled, thereby preparing a cold atomic beam with a low three-dimensional cooling temperature, an adjustable longitudinal most probable velocity and a large flux. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A simplified side view of the preparation device for the cold atomic beam provided in Embodiment One of the present application;

[0029] Figure 2A simplified front view of the preparation device of the cold atom beam provided in Embodiment One of the present application;

[0030] Figure 3 A simplified magnetic field diagram in the vacuum chamber provided in Embodiment One of the present application;

[0031] Figure 4 A simplified front view of the preparation device of the cold atom beam provided in Embodiment Two of the present application;

[0032] Figure 5 A simplified flow chart of the preparation method of the cold atom beam provided in Embodiment of the present application.

[0033] Explanation of reference numerals:

[0034] 1 - vacuum chamber; 101 - front end cavity wall; 1011 - second through hole; 102 - rear end cavity wall; 103 - side cavity wall;

[0035] 11 - flange; 12 - differential tube;

[0036] 2 - magnetic field element;

[0037] 31 - first laser; 32 - second laser;

[0038] 41 - first mobile optical adhesive laser; 42 - second mobile optical adhesive laser;

[0039] 51 - first perspective window; 52 - second perspective window; 53 - third perspective window; 54 - fourth perspective window;

[0040] 61 - first mirror; 601 - first prism; 6011 - first through hole; 62 - second mirror; 602 - second prism;

[0041] 7 - jet orifice plate;

[0042] 8 - atom furnace;

[0043] 9 - magnetic shielding shell. DETAILED DESCRIPTION

[0044] In order to make the above objectives, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below. In the following description, a lot of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0045] In the description of the application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0046] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0047] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0048] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0049] It is to be noted that when an element such as a layer, film, region or substrate is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element or intervening elements can also be present. In addition, it will be understood that when a layer is referred to as being "formed on" or "formed over" another layer, it can be directly formed on or over the other layer or intervening layers can also be present. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. The terminology used herein, such as "vertical," "horizontal," "upper," "lower," "left," "right," and the like, is for the purpose of illustration only and does not limit the present application.

[0050] In combination Figure 1 And Figure 2 , Figure 1 A simplified side view of a device for preparing a cold atom beam is shown in an embodiment of the present application, Figure 2 A simplified front view of a device for preparing a cold atom beam is shown in an embodiment of the present application. An embodiment of the present application provides a device for preparing a cold atom beam, comprising a vacuum chamber 1, a magnetic field element 2, a transverse cooling module and a longitudinal cooling module.

[0051] In some embodiments, the magnetic field element 2 is disposed outside the vacuum chamber 1, the transverse cooling module is disposed outside the vacuum chamber 1 and is configured to inject two beams of first laser light 31 along a first direction and two beams of second laser light 32 along a second direction into the vacuum chamber 1, and the longitudinal cooling module is disposed outside the vacuum chamber 1 and is configured to inject two pairs of moving optical glue laser light into the vacuum chamber 1, each pair of moving optical glue laser light being injected along a direction that forms an angle with a third direction and a transverse plane, the third direction being the direction of the atom beam, the transverse plane being perpendicular to the third direction, the first direction, the second direction and the third direction being perpendicular to each other, the first direction being in the direction indicated by the arrow ab shown in Figure 1 And Figure 2 the direction indicated by the arrow cd shown in Figure 1 the direction indicated by the arrow ef shown in Figure 2 In some embodiments, the first laser light 31, the second laser light 32 and the two pairs of moving optical glue laser light converge at the same region in the vacuum chamber 1, where the same region is a three-dimensional space region.

[0052] The preparation device of the cold atom beam of the embodiment of the present application, the vacuum chamber 1 provides a vacuum environment for preparing the cold atom beam, and is used for containing the atomic vapor. Under the cooperation of the magnetic field element 2, the transverse cooling module and the longitudinal cooling module, the atomic vapor is transversely cooled, longitudinally cooled and accelerated in the vacuum chamber to prepare a continuous cold atom beam. Specifically, the magnetic field element 2 is used for applying a magnetic field to the inside of the vacuum chamber 1. The transverse cooling module provides two pairs of first lasers 31 and two pairs of second lasers 32 in the vacuum chamber 1. The two pairs of first lasers 31 and the two pairs of second lasers 32 form a magneto-optical trap together with the magnetic field. The first lasers 31 and the second lasers 32 are perpendicular to each other in the direction of the light path in the vacuum chamber 1 and are both perpendicular to the direction of the outgoing atom beam, so as to apply a force to the atom beam in the direction perpendicular to the direction of the outgoing atom beam to cool the atom beam, that is, to transversely cool the atom beam. The longitudinal cooling module provides two pairs of moving optical adhesive lasers in the vacuum chamber 1. The frequencies of the two pairs of moving optical adhesive lasers are offset respectively, so as to form a moving optical adhesive action area in the vacuum chamber 1. The direction of the light path of the moving optical adhesive lasers forms an acute angle with the direction of the outgoing atom beam. The moving optical adhesive lasers are used for longitudinally cooling the atom beam, generating a longitudinal velocity of the atomic vapor and controlling the longitudinal velocity of the atom beam. The preparation device of the cold atom beam of the embodiment has a simple structure, and the atomic vapor is transversely cooled, longitudinally cooled and accelerated in the vacuum chamber 1.

[0053] The preparation device of the cold atom beam of the embodiment of the present application realizes three-dimensional cooling of the atomic vapor by using the magneto-optical trap and the moving optical adhesive technology in the same vacuum chamber, and simultaneously accelerates the atomic vapor in a specified direction to form a continuous cold atom beam.

[0054] It should be noted that the technology of irradiating the atomic group by the multiple pairs of lasers to make the atoms receive damping forces in three directions perpendicular to each other and intersecting each other, so as to cool the atoms to form a cold atom cloud, is called optical adhesive technology. On the basis of the optical adhesive technology, the frequencies of the two pairs of lasers are offset respectively, so that the atomic cloud is cooled to a specified velocity in the direction of the laser beam. The frequency offset of the two pairs of lasers is equivalent to the movement of the optical adhesive in the laboratory reference system. This technology is called moving optical adhesive technology. The two pairs of lasers with frequency offset are called moving optical adhesive lasers.

[0055] In some embodiments, the two pairs of moving optical adhesive laser beams emitted by the longitudinal cooling module into the vacuum chamber 1 are two pairs of first moving optical adhesive laser beams 41 and two pairs of second moving optical adhesive laser beams 42. The first moving optical adhesive laser beams 41 and the second moving optical adhesive laser beams 42 are both arranged at an angle with respect to the third direction and the transverse plane. The frequencies of the first moving optical adhesive laser beams 41 and the second moving optical adhesive laser beams 42 are offset, forming a moving optical adhesive action area inside the vacuum chamber 1.

[0056] In some embodiments, the transverse cooling module and the longitudinal cooling module can be devices for emitting laser beams. The first laser beams 31, the second laser beams 32, the first moving optical adhesive laser beams 41, and the second moving optical adhesive laser beams 42 can pass through the perspective windows arranged on the cavity wall of the vacuum chamber 1 into the interior of the vacuum chamber 1.

[0057] In some embodiments, the vacuum chamber 1 includes a front cavity wall 101 and a rear cavity wall 102 arranged at intervals along the third direction. The front cavity wall 101 is provided with a first mirror 61 arranged at an angle with respect to the third direction and the transverse plane. The first mirror 61 arranged inside the vacuum chamber 1 can be used to change the direction of the laser beams emitted into the vacuum chamber 1, making the arrangement of the perspective windows for auxiliary laser beams on the cavity wall of the vacuum chamber 1 more flexible.

[0058] In some embodiments, the vacuum chamber 1 further includes a side cavity wall 103 connected between the front cavity wall 101 and the rear cavity wall 102. The side cavity wall 103 is provided with a first perspective window 51 and a second perspective window 52 arranged at intervals along the third direction. The second perspective window 52 is arranged close to the first mirror 61 with respect to the first perspective window 51, so that the first mirror 61 reflects the laser beams entering the vacuum chamber 1 through the second perspective window 52 and changes the direction of the laser beams.

[0059] In the above structure, the first perspective window 51 arranged on the side cavity wall 103 is used for the laser beams generated by the transverse cooling module to pass through, so that the directions of the first laser beams 31 and the second laser beams 32 are perpendicular to the direction of the atomic beam. The second perspective window 52 arranged on the side cavity wall 103 is used for the laser beams generated by the longitudinal cooling module to pass through. At the same time, the second perspective window 52 cooperates with the first mirror 61 to change the direction of the first moving optical adhesive laser beams 41 and the second moving optical adhesive laser beams 42 entering the vacuum chamber 1 through the second perspective window 52, so that the first moving optical adhesive laser beams 41 and the second moving optical adhesive laser beams 42 are both arranged at an angle with respect to the third direction and the transverse plane, and the length of the device for preparing the cold atomic beam is reduced.

[0060] In some embodiments, the side cavity wall 103 of the vacuum chamber 1 is a cylindrical structure, and the first perspective window 51 is provided with four first perspective windows 51, which are evenly spaced along the circumference of the side cavity wall 103. Two of the first perspective windows 51 are arranged in a first direction, and are respectively used for the two first lasers 31 to enter the vacuum chamber 1. The other two first perspective windows 51 are arranged in a second direction, and are respectively used for the two second lasers 32 to enter the vacuum chamber 1. The above structure is arranged so that the two first lasers 31 and the two second lasers 32 enter the vacuum chamber 1 in a cross direction, and the optical path direction of the first laser 31 is perpendicular to the optical path direction of the second laser 32.

[0061] In some embodiments, the rear cavity wall 102 is provided with a plurality of third perspective windows 53, which are arranged in a direction perpendicular to the third direction. The third perspective window 53 is used for the first moving optical adhesive laser 41 and the second moving optical adhesive laser 42 generated by the longitudinal cooling module to pass through. In cooperation with the second perspective window 52 and the first mirror 61, the two pairs of moving optical adhesive lasers generated by the longitudinal cooling module enter the vacuum chamber 1.

[0062] In the above structure, the third perspective window 53 can satisfy that the optical path direction of the first moving optical adhesive laser 41 and the second moving optical adhesive laser 42 entering the vacuum chamber 1 is obliquely from the rear cavity wall 102 to the front cavity wall 101. The first moving optical adhesive laser 41 and the second moving optical adhesive laser 42 entering through the second perspective window 52 are reflected by the first mirror 61, and the optical path direction in the vacuum chamber 1 is obliquely from the front cavity wall 101 to the rear cavity wall 102, forming a cross direction with the laser beams entering through the third perspective window 53. In this way, the two first moving optical adhesive lasers 41 and the two second moving optical adhesive lasers 42 enter the vacuum chamber 1 in a cross direction, and the optical path direction of the first moving optical adhesive laser 41 and the second moving optical adhesive laser 42 is arranged at an angle with the third direction and the transverse plane.

[0063] In some embodiments, the first mirror 61 is arranged on the front cavity wall 101 through a first prism body 601, one side of the first prism body 601 is perpendicular to the third direction and is fixedly connected with the front cavity wall 101, and the remaining sides of the first prism body 601 can be used to support and fix the first mirror 61.

[0064] In the above structure, the first mirror 61 arranged on the first prism body 601 is arranged at an angle with the third direction and the transverse plane by using the feature that the angles between the sides arranged along the circumference of the first prism body 601.

[0065] In some embodiments, the side cavity wall 103 of the vacuum chamber 1 is a cylindrical structure, and the second view window 52 is provided with a plurality of second view windows 52 arranged along the circumference of the side cavity wall 103; the first prism 601 is provided with a plurality of first mirrors 61, and the plurality of first mirrors 61 are arranged one-to-one with the plurality of second view windows 52.

[0066] In some embodiments, the second view window 52 and the third view window 53 are respectively provided with two second view windows 52 and two third view windows 53. The two second view windows 52 are arranged symmetrically along the axial direction of the side cavity wall 103, and are respectively used for allowing a first moving optical glue laser 41 and a second moving optical glue laser 42 to enter the vacuum chamber 1. The two third view windows 53 are arranged symmetrically along the axial direction of the side cavity wall 103, and are respectively used for allowing another first moving optical glue laser 41 and another second moving optical glue laser 42 to enter the vacuum chamber 1. Further, the first prism 601 is a triangular prism, and is provided with two first mirrors 61 arranged symmetrically along the axial direction of the side cavity wall 103. Each first mirror 61 corresponds to a second view window 52. The above structure is arranged in cooperation with the second view window 52 and the first mirror 61 and the third view window 53, so that the two pairs of first moving optical glue lasers 41 and the two pairs of second moving optical glue lasers 42 generated by the longitudinal cooling module are symmetrically distributed along the axial direction of the atom beam in the vacuum chamber 1.

[0067] In some embodiments, the first prism 601 is provided with a first through hole 6011 along the third direction, and the front end cavity wall 101 is provided with a second through hole 1011 in communication with the first through hole 6011. The first through hole 6011 of the first prism 601 and the second through hole 1011 of the front end cavity wall 101 are used to output the cold atom beam prepared in the vacuum chamber 1, so that the cold atom beam in the vacuum chamber 1 can enter a subsequent working vacuum chamber.

[0068] In some embodiments, a jet plate 7 is arranged between the first prism 601 and the front end cavity wall 101, and the jet plate 7 is in communication with the first through hole 6011 and the second through hole 1011. The jet plate 7 is used to output the cooled atom beam.

[0069] In some embodiments, an atom furnace 8 is arranged outside the vacuum chamber 1, and the atom furnace 8 is in communication with the vacuum chamber 1. The atom furnace 8 is used to form a corresponding atom vapor in the vacuum chamber.

[0070] In some embodiments, a rubidium source is heated by the atom furnace 8 to generate rubidium vapor, and the rubidium vapor diffuses into the vacuum chamber 1. It should be noted that the preparation device of the cold atom beam in the present embodiment is not dependent on the specific atom species used, nor is it dependent on the form of the atom source.

[0071] In some embodiments, the differential pipe 12 is arranged outside the front cavity wall 101 and is communicated with the second through hole 1011 on the front cavity wall 101, and the differential pipe 12 is arranged to maintain the pressure difference between the vacuum chamber 1 and the subsequent working vacuum chamber.

[0072] In some embodiments, a flange 11 is arranged outside the cavity wall of the vacuum chamber 1, so that the vacuum chamber 1 can be mounted on other devices as a device.

[0073] In some embodiments, a magnetic shielding shell 9 is arranged outside the vacuum chamber 1, which is used to shield external magnetic field noise and geomagnetic field, so as to avoid interference of the cold atom beam preparation device.

[0074] In some embodiments, the cavity wall material of the vacuum chamber 1 can be selected from aluminum alloy, stainless steel, titanium or other metal materials.

[0075] In some embodiments, the magnetic field element 2 can be selected from permanent magnet, energized coil or other devices for generating magnetic field. The static gradient magnetic field formed by the magnetic field element 2 is not limited to two-dimensional gradient magnetic field or three-dimensional gradient magnetic field.

[0076] In combination with Figure 3 , Figure 3 A simplified magnetic field diagram in the vacuum chamber in an embodiment of the present application is shown.

[0077] In some embodiments, the magnetic field element 2 is a permanent magnet, which is in the shape of a long strip and extends along the third direction. Four magnetic field elements 2 are arranged outside the vacuum chamber 1 along the circumferential direction of the side cavity wall 103 and are located inside the magnetic shielding shell 9. The positions of the magnetic poles and the directions of the magnetic induction lines are shown in Figure 3 The permanent magnet has two polarities, N represents the north pole and S represents the south pole in the figure, and the direction of the magnetic force line is from the north pole to the south pole of the magnet. A relatively weak gradient static magnetic field is required in the vacuum chamber 1, and the center of the vacuum chamber 1 is taken as the coordinate origin, the magnetic field at the coordinate origin is zero, the magnetic field intensity increases linearly along the coordinate axis on both sides, and the directions are opposite.

[0078] In combination with Figure 4 , Figure 4 A simplified front view of the cold atom beam preparation device in an embodiment of the present application is shown.

[0079] In some embodiments, the rear cavity wall 102 is provided with a second reflecting mirror 62, which is arranged at an angle with the third direction and the transverse plane; the side cavity wall 103 is further provided with a fourth perspective window 54, and the fourth perspective window 54 and the second perspective window 52 are located on both sides of the first perspective window 51 respectively, and the second reflecting mirror 62 faces the fourth perspective window 54, so that the second reflecting mirror 62 reflects the laser beam entering the vacuum chamber 1 through the fourth perspective window 54 and changes the direction of the light path of the laser beam.

[0080] In the above structure, the fourth perspective window 54 cooperates with the second mirror 62 to satisfy that the optical path direction of the mobile optical sticky glue laser in the vacuum chamber 1 is obliquely from the rear end cavity wall 102 to the front end cavity wall 101. And the second perspective window 52 cooperates with the first mirror 61 to satisfy that the optical path direction of the mobile optical sticky glue laser in the vacuum chamber 1 is obliquely from the front end cavity wall 101 to the rear end cavity wall 102. Thus, the two beams of the first mobile optical sticky glue laser 41 can be injected into the vacuum chamber 1, and the two beams of the second mobile optical sticky glue laser 42 can be injected into the vacuum chamber 1. In addition, the optical path direction of the first mobile optical sticky glue laser 41 and the optical path direction of the second mobile optical sticky glue laser 42 are both arranged at an angle with the third direction and the transverse plane. Furthermore, by arranging the fourth perspective window 54 through which the laser beam generated by the longitudinal cooling module passes on the side cavity wall 103, the length of the preparation device of the cold atom beam can be further reduced.

[0081] In some embodiments, the rear end cavity wall 102 is provided with a second prism 602, and the second mirror 62 is arranged on the rear end cavity wall 102 through the second prism 602. One side of the second prism 602 is perpendicular to the third direction and is fixedly connected with the rear end cavity wall 102, and the remaining sides of the second prism 602 can be used to support and fix the second mirror 62.

[0082] In some embodiments, two second perspective windows 52 and two fourth perspective windows 54 are arranged respectively, the two second perspective windows 52 are arranged symmetrically along the axial direction of the side cavity wall 103, and are respectively used for injecting one beam of the first mobile optical sticky glue laser 41 and one beam of the second mobile optical sticky glue laser 42 into the vacuum chamber 1. The two fourth perspective windows 54 are arranged symmetrically along the axial direction of the side cavity wall 103, and are respectively used for injecting another beam of the first mobile optical sticky glue laser 41 and another beam of the second mobile optical sticky glue laser 42 into the vacuum chamber 1. Further, the first prism 601 and the second prism 602 can be a three-prism, the first prism 601 is provided with two first mirrors 61 arranged symmetrically along the axial direction of the side cavity wall 103, and each first mirror 61 corresponds to one second perspective window 52. The second prism 602 is provided with two second mirrors 62 arranged symmetrically along the axial direction of the side cavity wall 103, and each second mirror 62 corresponds to one fourth perspective window 54. Under the cooperation of the second perspective window 52 and the first mirror 61 and the cooperation of the fourth perspective window 54 and the second mirror 62, two pairs of mobile optical sticky glue lasers obliquely irradiate on the atom beam, and there is an angle between the atom beam and the atom beam.

[0083] In the embodiment of the present application, the moving optical glue laser and the atom beam propagate along straight lines, and the moving optical glue laser is obliquely incident on the atom beam, so that the moving optical glue laser and the atom beam have an included angle, and the moving optical glue laser and the atom beam gradually spatially separate along with the propagation of the atom beam. The small-angle oblique incidence of the moving optical glue laser can spatially separate the laser beam and the atom beam, thereby reducing the background light intensity carried by the atom beam and improving the signal-to-noise ratio of the subsequent system.

[0084] In combination Figure 5 , Figure 5 A simplified flowchart of a preparation method of a cold atom beam in an embodiment of the present application is shown.

[0085] The embodiment of the present application also provides a preparation method of a cold atom beam, which uses the preparation device of the cold atom beam as described above, and the preparation method of the cold atom beam comprises the following steps:

[0086] S10, a magnetic field is applied to the vacuum chamber 1.

[0087] S20, atom vapor is injected into the vacuum chamber 1. By heating the atom oven 8 connected to the vacuum chamber 1, the atom oven 8 heats a rubidium source to generate rubidium vapor, and the rubidium vapor diffuses into the vacuum chamber 1.

[0088] S30, the transverse cooling module and the longitudinal cooling module respectively inject laser beams into the vacuum chamber 1 to form a magneto-optical trap in the vacuum chamber 1 to transversely cool the atom vapor, and form a moving optical glue action area in the vacuum chamber 1 to longitudinally cool the atom vapor, and the specific operation is as follows:

[0089] Two pairs of first laser beams 31 and two pairs of second laser beams 32 are injected into the vacuum chamber 1, and the two pairs of first laser beams 31 and the two pairs of second laser beams 32 form a magneto-optical trap in the vacuum chamber 1 under the action of the magnetic field, so that the atom vapor is subjected to the balanced force of the two pairs of laser beams in the transverse direction, thereby achieving transverse cooling of the atom vapor.

[0090] Two pairs of moving optical glue laser beams are injected into the vacuum chamber 1, and the two pairs of moving optical glue laser beams include two pairs of first moving optical glue laser beams 41 and two pairs of second moving optical glue laser beams 42, which are frequency-adjustable, to form a moving optical glue action area in the vacuum chamber 1, so that the atom vapor is subjected to the superimposed force of the two pairs of laser beams with frequency shift in the longitudinal direction, thereby achieving longitudinal cooling and longitudinal velocity control of the atom vapor.

[0091] S40, adjust the frequency of the moving optical sticky glue laser to control the longitudinal velocity of the atomic vapor. Wherein, the frequency of the first moving optical sticky glue laser 41 and the second moving optical sticky glue laser 42 can be adjusted by the longitudinal cooling module, by changing the size of the moving optical sticky glue laser frequency, the longitudinal velocity of the cold atom beam can be controlled, which can be specifically represented as:

[0092] v=(f1-f2)×(λ / cosα)

[0093] In the formula: v is the longitudinal velocity of the cold atom beam, f1 is the frequency of the moving optical sticky glue laser, f2 is the frequency of the first laser 31 and the second laser 32; λ is the wavelength of the moving optical sticky glue laser; α is the angle between the moving optical sticky glue laser and the atomic beam.

[0094] In some embodiments, before step S20 is implemented, the vacuum chamber 1 is vacuumized by a vacuum pump to make the air pressure in the vacuum chamber 1 not higher than 1×10 -5 Pa.

[0095] In some embodiments, the vacuum chamber 1 is applied with a two-dimensional gradient magnetic field by the magnetic field element 2. The two-dimensional gradient magnetic field and the two-dimensional magnetic optical trap obtained by the two pairs of first lasers 31 and the two pairs of second lasers 32 are used for transverse cooling of the atomic vapor.

[0096] In some embodiments, the vacuum chamber 1 is applied with a two-dimensional gradient magnetic field or a three-dimensional gradient magnetic field by the magnetic field element 2. The three-dimensional gradient magnetic field and the two-dimensional magnetic optical trap obtained by the two pairs of first lasers 31 and the two pairs of second lasers 32 are used for transverse cooling and preliminary longitudinal cooling of the atomic vapor.

[0097] In some embodiments, the transverse cooling module and the longitudinal cooling module are performed at the same time.

[0098] In some embodiments, the magnetic field inside the vacuum chamber 1 of the cold atom beam preparation device is always present. However, for the moving optical sticky glue action area formed in the vacuum chamber 1, whether the magnetic field exists in the vacuum chamber 1 does not affect the longitudinal cooling module to perform longitudinal cooling on the atomic vapor.

[0099] In some embodiments, when the longitudinal cooling module shoots the moving optical sticky glue laser into the vacuum chamber 1, the frequency of the laser of the ejecting light can be added to the moving optical sticky glue laser, so as to realize the simultaneous action of the ejecting light and the moving optical sticky glue laser.

[0100] In some embodiments, the first laser 31 and the second laser 32 can use a laser light source with a wavelength of 780 nm. The first laser 31 and the second laser 32 are both red detuned circularly polarized light. The optical rotation direction of the two pairs of first lasers 31 is the same, and the optical rotation direction of the two pairs of second lasers 32 is the same.

[0101] In some embodiments, the first moving optical molasses laser 41 and the second moving optical molasses laser 42 can be selected from laser light sources with a wavelength of 780 nm, and each laser is circularly polarized light. The optical rotation directions of the two beams of the first moving optical molasses laser 41 are the same, and the optical rotation directions of the two beams of the second moving optical molasses laser 42 are the same.

[0102] In some embodiments, the first moving optical molasses laser 41 and the second moving optical molasses laser 42 can be selected from laser light sources with a wavelength of 780 nm, and each laser is linearly polarized light. The polarization directions of the two beams of the first moving optical molasses laser 41 are perpendicular to each other, and the polarization directions of the two beams of the second moving optical molasses laser 42 are perpendicular to each other.

[0103] In some embodiments, when the atomic vapor velocity distribution is wide, periodic frequency chirp or frequency modulation is added to the first laser 31 and the second laser 32 of the transverse cooling module to increase the atomic beam flux.

[0104] The above-mentioned method for preparing a cold atom beam uses the above-mentioned preparation device of a continuous cold atom beam to achieve the cooling of the atomic beam by applying a magnetic field and two beams of the first laser 31 and two beams of the second laser 32 in the vacuum chamber 1 to apply a force to the atomic beam in a direction perpendicular to the direction of the atomic beam, i.e., transverse cooling of the atomic beam. Two pairs of moving optical molasses lasers in the vacuum chamber 1 form a moving optical molasses action region in the vacuum chamber 1, and the atomic beam is longitudinally cooled by the force of the moving optical molasses laser, the atomic vapor is longitudinally accelerated, and the longitudinal most probable velocity of the atomic beam is controlled, thereby preparing a cold atom beam with a low cooling temperature, a longitudinally adjustable most probable velocity, and a large flux.

[0105] It should be noted that the method for preparing a cold atom beam in the present embodiment does not depend on the specific atomic species used and does not depend on the form of the atomic source.

[0106] The technical features of the above-mentioned embodiments can be combined in any way. To make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0107] The above-mentioned embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be construed as limiting the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. A cold atom beam preparation apparatus, characterized in that, The cold atom beam preparation apparatus includes: Vacuum chamber (1); A magnetic field element (2) is disposed outside the vacuum chamber (1); A transverse cooling module is disposed outside the vacuum chamber (1) and is used to inject two beams of first laser (31) and two beams of second laser (32) that are directed against each other in a first direction into the vacuum chamber (1). A longitudinal cooling module is located outside the vacuum chamber (1) and is used to inject two pairs of moving optical adhesive lasers into the vacuum chamber (1). Each pair of moving optical adhesive lasers is directed at each other along a direction that forms an angle with a third direction and a transverse plane. The third direction is the emission direction of the atomic beam. The transverse plane is perpendicular to the third direction. The first direction, the second direction and the third direction are perpendicular to each other. The first laser (31), the second laser (32), and the two pairs of moving optical adhesive lasers converge in the same area in the vacuum chamber (1); The two pairs of moving optical adhesive lasers injected into the vacuum chamber (1) by the longitudinal cooling module are two opposing first moving optical adhesive lasers (41) and two opposing second moving optical adhesive lasers (42). The first moving optical adhesive laser (41) and the second moving optical adhesive laser (42) are circularly polarized light or linearly polarized light. When the laser is circularly polarized light, the optical rotation of the opposing lasers is the same. When the laser is linearly polarized light, the polarization directions of the opposing lasers are perpendicular to each other. The longitudinal cooling module controls the longitudinal velocity of the atomic vapor by adjusting the frequency of the moving optical adhesive laser, specifically as follows: In the formula: The longitudinal velocity of the cold atom beam. The frequency of the moving optical adhesive laser, The frequencies of the first laser (31) and the second laser (32); The wavelength of the moving optical adhesive laser; The angle between the moving optical adhesive laser and the atomic beam.

2. The cold atom beam preparation apparatus according to claim 1, characterized in that, The vacuum chamber (1) includes a front cavity wall (101) and a rear cavity wall (102) arranged at intervals along the third direction. A first reflector (61) is provided on the front cavity wall (101), and the first reflector (61) is arranged at an angle to the third direction and the transverse plane.

3. The cold atom beam preparation apparatus according to claim 2, characterized in that, The vacuum chamber (1) further includes a side cavity wall (103) connecting the front cavity wall (101) and the rear cavity wall (102). A first perspective window (51) and a second perspective window (52) are provided on the side cavity wall (103) at intervals along the third direction. The second perspective window (52) is located close to the first reflector (61) relative to the first perspective window (51).

4. The apparatus for preparing a cold atom beam according to claim 2, characterized in that, The rear cavity wall (102) is provided with a plurality of third perspective windows (53), and the plurality of third perspective windows (53) are spaced apart along a direction perpendicular to the third direction.

5. The cold atom beam preparation apparatus according to claim 3, characterized in that, A second reflector (62) is provided on the rear cavity wall (102). The second reflector (62) is set at an angle to the third direction and the transverse plane. A fourth perspective window (54) is also provided on the side cavity wall (103). The fourth perspective window (54) and the second perspective window (52) are located on both sides of the first perspective window (51).

6. The apparatus for preparing a cold atom beam according to claim 2, characterized in that, The first reflector (61) is disposed on the front end cavity wall (101) via a first prism (601). The first prism (601) is provided with a first through hole (6011) in the third direction. The front end cavity wall (101) is provided with a second through hole (1011) that communicates with the first through hole (6011).

7. The cold atom beam preparation apparatus according to claim 6, characterized in that, A nozzle plate (7) is provided between the first prism (601) and the front end cavity wall (101), and the nozzle plate (7) connects the first through hole (6011) and the second through hole (1011).

8. The apparatus for preparing a cold atom beam according to any one of claims 1-7, characterized in that, An atomic furnace (8) is provided outside the vacuum chamber (1), and the atomic furnace (8) is connected to the vacuum chamber (1).

9. A method for preparing a cold atom beam, characterized in that, Using the cold atom beam preparation apparatus according to any one of claims 1-7, the cold atom beam preparation method comprises the following steps: A magnetic field is applied to the vacuum chamber (1); Inject atomic vapor into the vacuum chamber (1); Two opposing first laser beams (31) and two opposing second laser beams (32) are injected into the vacuum chamber (1) to form a magneto-optical trap in the vacuum chamber (1) for lateral cooling of atomic vapor; Two pairs of moving optical adhesive lasers are injected into the vacuum chamber (1) to form a moving optical adhesive action area in the vacuum chamber (1) and longitudinally cool the atomic vapor; The frequency of the moving optical adhesive laser is adjusted to control the longitudinal velocity of the atomic vapor.

10. The method for preparing a cold atom beam according to claim 9, characterized in that, A two-dimensional gradient magnetic field or a three-dimensional gradient magnetic field is applied to the vacuum chamber (1) by the magnetic field element (2).

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