CN1333622C - Cold atomic beam generating method and device - Google Patents

Abstract

The invention relates to a method and device for generating a cold atom beam. The method comprises the following steps: heating a hot atom source in a vacuum chamber to form a corresponding atomic saturated vapor pressure atmosphere in the vacuum chamber; cooling the hot atoms to below 200 μk by using a three-dimensional MOT, and capturing the hot atoms to form a cold atom cloud; making the laser radiation pressure unbalanced in this direction by a quarter-wave plate reflector with a small hole in the three-dimensional MOT, so that the cold atoms are emitted in this direction; four straight wires arranged in a cone and carrying currents in opposite directions are arranged in the emission direction of the cold atom beam, so that when the atoms are emitted, they will not expand in the lateral direction and be emitted forward under the action of a magnetic field; thus, a continuous cold atom beam with a low emission speed, a large flux and a very small lateral speed is obtained; and at the same time, a laser beam perpendicular to the atomic beam is arranged in the emission direction of the cold atom beam, which is used for the state preparation of the atomic beam and realizes the emission of the cold atom beam with a consistent state.

Description

A method and device for generating a cold atomic beam

technical field

The invention relates to a cold atomic beam generator, in particular, it can provide a cold atomic beam generating method and generating device with good monochromaticity for an atomic interferometer.

technical background

There are two main forms of atom beams used in atom interferometers: hot atom beams and cold atom beams. The longitudinal velocity of the atomic beam used by the thermal atomic beam atomic interferometer is relatively high (the longitudinal velocity is the moving speed of the atomic beam in the forward direction, usually >200m/s), but it is aimed at the requirement of good signal-to-noise ratio and detection accuracy of the atomic interferometer , according to the Sagnac effect, the performance of the atom interferometer can be significantly improved by using a cold atom beam (velocity <30m/s), so it is very necessary to develop a continuous cold atom beam. Since the late 1970s, people have used the radiation pressure effect of the light field on neutral atoms, and used lasers to cool (reduce the speed) atoms, reducing the speed of atoms from hundreds of meters or even thousands of meters per second to several centimeters per second. to the speed of tens of meters, and then capture the atoms. The cold atomic cloud obtained by cooling and trapping has obtained many far-reaching practical and theoretical applications, such as atomic frequency standard, atomic clock, atomic interference, Bose-Einstein condensate, etc.

At present, there are three main methods of cold atom forms used in atom interferometers:

(1) Optical glue forms cold atomic beams of atomic fountains, as described in Document 1: M. Kasevich, S. Chu, Phys. Rev. Lett., 1991, 67: 181-184).

(2) A cold atomic beam decelerated by the laser acting on the hot atomic beam in the Zeeman coil in the opposite direction, such as document 2: W.D.Phillips, J.V.Prodan, H.J.Metcalf, J.Opt.Soc.Am.B, 1985 , 2(11):1751-1767; W.DeGraffenreid, J.Ramirez-Serran, Y.-M.Liu, J.Weiner, Rev.Sci.Instrum., 2000, 71(10):3668-3676) as recorded.

(3) A two-dimensional magneto-optical trap (hereinafter referred to as MOT) is used to cool and trap atoms, and then a pair of unbalanced lasers are formed in the direction perpendicular to the two-dimensional MOT to trap the cold atoms The cloud is pushed out along the direction of the unbalanced laser beam to form a cold atomic beam, as document 3: K.Dieckmann, R.J.C.Spreeuw, M.Weidemuller et al., Phys.Rev.A, 1998,

58(5):3891-3895).

For the first method of obtaining cold atomic beams, the obtained cold atomic beams have a very low longitudinal velocity (the longitudinal velocity is the velocity in the forward direction of the atomic beam), and the longitudinal velocity distribution is also very narrow, with good optical properties. But its optical system of corresponding device is complicated with it, and operating skill requirement is high, and is only suitable for the atom interference on the gravitational direction (that is, on the vertical direction), and the atomic flux is also low; In the second method, because will use Zeeman coil , its volume is huge, the coil current is relatively large, and cooling water is required. Although the flux of the obtained cold atomic beam is relatively large, the lateral velocity of the obtained cold atomic beam is relatively large, which brings large background noise to the interference of atoms. In the 2D MOT of the third method, the quadrupole magnetic field formed by four current-carrying wires is used to compress the atoms. The beam tends to heat and expand in the lateral direction during flight, which brings difficulties to the atomic wave splitting and interference of the subsequent atomic interference and greatly introduces background noise, and the effective atomic flux is also low.

Of course, the existing cold atom beams obtained by these three methods can be used in the following fields besides atom interferometers: loading atoms to MOT, studying atom collisions, atomic spectroscopy, and so on.

Therefore, in order to build an atomic interferometer with good performance and compact structure, it is necessary to start from the optical properties of the cold atomic beam, that is, the longitudinal velocity and its distribution and the transverse velocity (the transverse velocity is the velocity orthogonal to the direction of the longitudinal velocity) and its distribution. The amount, the structure of the atomic beam source system is considered, and in order to effectively divide the atomic beam and improve the signal-to-noise ratio, it is necessary to overcome the difficulty that the atoms in the atomic beam are in different states.

Contents of the invention

The purpose of the present invention is to: overcome the following deficiencies in the existing methods for obtaining cold atomic beams and corresponding devices for the application of atomic interference:

(1) The transverse velocity is high and the atomic flux is low;

(2) The obtained cold atomic beam cannot meet the requirements of low longitudinal velocity, narrow longitudinal velocity and large flux at the same time, so the application to atomic interferometer is limited;

(3) The device for generating cold atomic beams has a complex structure and a large volume;

(4) The internal energy states of the atoms in the cold atomic beam are inconsistent, and it is necessary to perform state preparation to make them in the same state;

Therefore, a cold atomic beam generating device and method for building a high-precision atomic interferometer with good optical characteristics, large flux, consistent state, compact structure, and stable performance is provided.

The purpose of the present invention is achieved like this;

The invention provides a cold atomic beam generation method, comprising the following steps:

1. First evacuate the vacuum chamber to a vacuum degree of not less than 10 ^-7 Pa;

2. Heating the hot atom source connected to the vacuum chamber through the flange to form an atomic steam atmosphere in the vacuum chamber, and the hot atomic steam fills the vacuum chamber 16 to form a corresponding atomic saturated vapor pressure atmosphere in the vacuum chamber;

3. In the atomic steam atmosphere formed in step 2, use the three-dimensional MOT to cool the hot atoms to below 200μk, and be trapped to form a cloud of cold atoms;

4. In the asymmetric three-dimensional magneto-optical trap provided by the present invention, a quarter-wave plate reflector with a small hole is arranged on a laser beam direction, so that the laser radiation pressure is unbalanced in this direction, and the cold atoms Emerge along this direction; in the extruding direction of the cold atom beam, there are also four tapered straight wires carrying currents in opposite directions, so that the atoms will not expand in the transverse direction and move toward the cold atom beam under the action of the magnetic field In this way, a continuous cold atomic beam with low exit velocity, large flux and very small transverse velocity is obtained:

5. At the same time, in the outgoing direction of the cold atomic beam, a laser beam perpendicular to the atomic beam is set for the state preparation of the atomic beam, so as to realize the exiting cold atomic beam with the same state. The laser beams involved here are all output by the same laser, and then obtained after being split and modulated by an acousto-optic modulator.

The cold atomic beam generation device provided by the present invention includes: a vacuum chamber and an optical path system arranged outside and inside the vacuum chamber; wherein the vacuum chamber 16 is provided with quartz glass windows 14, 17, 18, 19, 21, 22, 23, 26 , 27, 30, the quartz glass window 17 is opposite to the quartz glass window 22, the quartz glass window 26 is opposite to the quartz glass window 30, and these two pairs of quartz glass windows are mutually orthogonal; the quartz glass window 19 is opposite to the quartz glass window 27, and Orthogonal to the quartz glass window 18; the quartz glass window 14, 17, 22, 26, 30 is used to form a three-dimensional MOT, the quartz glass window 18 is used for the state preparation of the atomic beam, and also includes the quartz glass window 21, 23, 19, 27 It is used as an observation window or a function expansion window; there are two grooves on the inner wall of the vacuum chamber 16, and the fixing clips 29 and 31 are arranged in the grooves, and the magnetic guiding straight wire 12 is installed on the inner wall of the vacuum chamber 16 through the fixing clips 29 and 31 and form a tapered arrangement; and one end of the tapered magnetic guidance straight wire 12 is connected to the external power supply through the terminal post 15 from the vacuum chamber 16; in addition, the 1/4 wave plate reflector 9 is placed in the vacuum chamber 16 The inner 1/4 wave plate reflector is fixed on the clamp 28. The anti-Helmholtz coil 6 is set outside the vacuum chamber, and the center of the anti-Helmholtz coil 6 is in the vacuum chamber, where the quartz glass window 17 is opposite to 22, and the orthogonal center formed by the quartz glass window 26 and the opposite 30 coincides position.

The optical path system includes: an acousto-optic modulator 37, a 1/4 wave plate 36, a beam expander collimator 35 and a beam splitter 4 are arranged on the front optical path of the output light of the first laser 32, and three beams are formed after splitting Laser, these three beams of lasers are mutually orthogonal in space; Then these three beams of laser beams enter vacuum chamber 16 through quartz glass window 14, quartz glass window 17 and quartz glass window 26 respectively, wherein two laser beams pass through quartz glass window 22 and After 30 is emitted, it is reflected by a mirror 38 and a mirror 40 perpendicular to it to form two pairs of beams respectively; while the other beam of laser, that is, the unbalanced MOT laser beam 10 in the horizontal direction, passes through the quartz glass The window 14 is incident into the vacuum chamber 16 along the vacuum chamber axis, and is reflected by the 1/4 wave plate reflector 9 with a small hole of φ1-2mm in the center perpendicular to it in the advancing direction. In this way, six orthogonal laser beams are formed, the orthogonal centers of which coincide with the orthogonal centers formed by the quartz glass windows 17, 22, 26, 30. In addition, the re-pump laser beam 34 emitted by the second laser 33 is merged into any laser beam generated by the laser 32 through a mirror, and is used for the re-pump laser of the MOT cooling atoms. Therefore, together with the anti-Helmholtz coil 6 placed outside the vacuum chamber, a three-dimensional MOT is formed. In addition, the laser beam 13 emitted from the first laser for state preparation is incident through the quartz glass window. The optical path system and state preparation laser beams forming the three-dimensional MOT of the present invention, except the laser beam 34, all the beams are provided by the laser 32.

In the above-mentioned technical scheme, it also includes quartz glass windows 21, 23, 19, 27 that are used as observation windows or function expansion windows by flanges on the vacuum chamber wall, wherein the quartz glass windows 17 and 22 are opposite, and the quartz glass windows Windows 26 and 30 are opposite and the two pairs are orthogonal to each other.

In the above-mentioned technical scheme, in order to improve the beam frequency, polarization properties and spot quality, it also includes that an acousto-optic modulator 37, a 1/4 wave plate 36 and a beam expander collimator 35 are arranged in front of the beam splitter 4, and in order to change For the propagation direction of the light after passing through the beam splitter 4, reflectors 3, 3', 3' at a angle of 45° to the laser beam are arranged on the propagating optical path as required.

In the above technical solution, the aperture of the small hole opened on the quarter-wave plate reflector is: φ1-2mm.

In the above-mentioned technical solution, the clamps 29, 31 and 28 are made of ceramics, the diameters of the clamps 29 and 31 are adjustable, and one end of the magnetic guiding straight wire 12 is installed on the clamp 29, and the other end is installed On the hoop 31 , and the diameters of the hoop 29 and the hoop 31 are large and small to form a tapered arrangement of the magnetic guiding straight wires 12 .

In the above technical solution, there are at least four magnetic guiding straight wires 12 .

In the above technical solution, all the flanges mentioned are standard flanges.

In the atomic steam chamber of the cold atomic beam generation device provided by the present invention, an asymmetric three-dimensional MOT is used to cool the atoms and be trapped to form a cold atomic cloud. A quarter-wave plate mirror with a small hole (φ1-2mm) is placed in the direction, because the existence of the small hole makes the laser radiation pressure on the atoms in this direction unbalanced, thereby pushing the trapped atomic cloud to Emit to form a beam of cold atoms. During the exit process of the cold atomic beam, four straight wires arranged in a tapered shape are arranged in the direction coaxial with the small hole to compress and guide the outgoing atomic beam laterally, and finally use a laser with a special frequency to exit the cold atomic beam. The cold atomic beam is prepared in a state, so that a continuous cold atomic beam with good optical properties can be obtained. The main technical indicators that the cold atomic beam source of the present invention can achieve are as follows: longitudinal atomic velocity <30m/s, longitudinal velocity distribution <5m/s, transverse velocity <10cm/s, atomic beam flux >10 ⁸ /s order of magnitude, The vacuum degree of the whole cold atom beam source system is not lower than 10 ^-7 Pa. The cold atomic beam has good optical properties and strong coherence, and can be well applied in many fields such as atomic interferometer, atomic clock and atomic frequency standard.

The beneficial effects of the present invention are that the device of the present invention can be used to obtain cold atomic beams with low speed, good optical characteristics, large flux, and consistent and continuous states. The atomic beams can not only be well applied to atomic interferometers, but Gaining practical application in the study of atomic optics. The cold atomic beam generating device has reasonable structure, compact structure and stable and reliable performance.

Description of drawings

Fig. 1 is the structural representation of the cold atomic beam generating device of the present invention

Fig. 2 is a schematic diagram of the principle of the cold atomic beam generating device of the present invention

Fig. 3 (a) is the front view of the vacuum chamber of the cold atomic beam generating device of the present invention

Fig. 3 (b) is the top view of the vacuum chamber of the cold atomic beam generating device of the present invention

Graphic description:

1. Hot atom source; 2. Hot atom vapor; 3, 3, 3′, 3′′, mirrors;

4. Beam splitter; 5. MOT laser beam; 6. Anti-Helmholtz coil;

7. Small hole; 8. Cold atom beam; 9. 1/4 wave plate anti-mirror;

10. Non-equilibrium MOT laser beam; 11. Cold atom cloud; 12. Magnetically guided straight wire;

13. State prepared laser beam; 14. Quartz glass window; 15. Terminal post;

16. Vacuum chamber; 17. Quartz glass window; 18. Quartz glass window;

19. Quartz glass window; 20. Vacuum ion pump interface; 21. Quartz glass window;

22. Quartz glass window; 23. Quartz glass window; 24. Thermal Rb atom source interface;

25. Vacuum molecular pump interface; 26. Quartz glass window; 27. Quartz glass window;

28. 1/4 wave plate mirror fixing clamp; 29. Tapered magnetic guide straight wire fixing clamp;

30. Quartz glass window; 31. Tapered magnetic guiding straight wire fixing clamp;

32. First laser; 33. Second laser; 34. Laser beam;

35. Beam expander collimator; 36. 1/4 wave plate; 37. Acousto-optic modulator 37;

38. Reflector; 40. Reflector;

Detailed ways

Example 1:

The device and method for generating cold atomic beams of the present invention will be further described in detail below with reference to the drawings and examples.

Referring to Fig. 3(a) and Fig. 3(b), a cold atomic beam generating device is manufactured, including: a vacuum chamber and an optical system.

The vacuum chamber 16 that adopts stainless steel material is welded with the flange that encapsulates quartz glass window 14,17,18,19,21,22,23,26,27,30, wherein quartz glass window 17 is opposite to 22, quartz glass window Glass windows 26 and 30 are opposite, and these two pairs of quartz glass windows are mutually orthogonally arranged on the wall of vacuum chamber 16; In the vacuum chamber 16, there are grooves at positions 70mm, 305mm and 320mm away from the left end face, and a clamp 29, 31 and 28 made of ceramics is installed in each groove. The diameters of the clamps 29 and 31 are adjustable, and the magnetic guidance One end of the straight wire 12 is installed on the clamp 29, and the other end is installed on the clamp 31, and the diameters of the clamp 29 and the clamp 31 are large and small to form a tapered arrangement of the magnetic guide straight wire 12; The 1/4 wave plate reflector 9 of φ 1-2mm aperture is placed on the hoop 28 that ceramics is made. The magnetic guiding straight wire 12 is made of common vacuum conductive material. One end of the magnetic guiding straight wire 12 is connected to the external power supply through the terminal 15 from the vacuum chamber. A conventional anti-Helmholtz coil 6 is used to cover the vacuum chamber, the center of the anti-Helmholtz coil 6 is the same as the orthogonal center formed by the quartz glass window 17 and the opposite 22, and the quartz glass window 26 and the opposite 30. coincide. All flanges in the device are CF25 or CF35 standard flanges. The quartz glass windows 19, 21, 23 and 27 welded on the vacuum chamber are all observation windows or function expansion windows.

With reference to Fig. 1 and 2, and in conjunction with Fig. 3 (a), 3 (b), the optical path system of cold atomic beam generating device is realized as follows: form the optical path system and state preparation laser beam of three-dimensional MOT of the present invention, except laser beam 34 , all light beams are provided by the first laser 32, and the first laser 32 adopts a semiconductor laser with a power of 400 mW. The optical path of the three-dimensional MOT system is as follows: a beam splitter 4 is set on the optical path in front of the output light of the laser 32, and three beams of laser beams are formed after beam splitting, and these three beams of laser beams are orthogonal to each other in space. The reflector 3, 3', 3' that forms a certain angle (such as 30°, 45°, 60°, etc., to change the propagation direction of the laser beam) with the laser beam is set as required in front of each laser beam to change the propagation direction. Then these three laser beams will first pass through the acousto-optic modulator 37, 1/4 wave plate 36 and beam expander collimator 35 before passing through the beam splitter 4 and then enter the vacuum chamber through the quartz glass windows 14, 17 and 26. , where two beams are emitted through the quartz glass windows 22 and 30, and then reflected along the outgoing direction by the reflectors 38 and 40 perpendicular thereto; and the other beam, that is, the unbalanced MOT laser beam 10 in the horizontal direction, It enters the vacuum chamber through the quartz glass window 14 along the axis of the vacuum chamber, and is reflected by the 1/4 wave plate mirror 9 perpendicular to it in the advancing direction. In this way, six orthogonal laser beams are formed, the orthogonal centers of which coincide with the orthogonal centers formed by the quartz glass windows 17, 22, 26, 30. In addition, the re-pump laser beam 34 emitted by the second low-power semiconductor laser 33 (with a power of 100 mW) is merged into a laser beam generated by the laser 32, which is used for the re-pump laser of the MOT cooling atoms. Therefore, together with the anti-Helmholtz coil 6 placed outside the vacuum chamber, a three-dimensional MOT is formed. In addition, the laser beam used for state preparation is also emitted by the first laser, and the output laser beam 13 is incident through the quartz glass window 18 .

Example 2:

The method for generating the cold atomic beam of the present invention will be further described in detail below on the device of Example 1 and using the hot atom source as rubidium (Rb) atoms.

Referring to FIG. 1, the hot Rb atom vapor 2 generated by the hot Rb atom source 1 first fills the vacuum chamber 16, forming a saturated vapor pressure atmosphere of Rb atoms in the vacuum chamber. Then it is carried out on the device of Example 1, and the atoms in the hot Rb atom atmosphere are cooled and trapped to form cold atom clouds 11 under the action of the three-dimensional MOT of Example 1. The three-dimensional MOT is formed in the following way: the laser beam emitted by the laser is split by the beam splitter 4 to form three orthogonal laser beams with equal power; one of the laser beams is converted into a circular beam by a 1/4 wave plate Polarized laser beam 5, if the laser beam is σ ⁺ , then in the forward direction, after passing through a 1/4 wave plate and a mirror, it forms a pair of three-dimensional MOT laser beams with laser beam 5, and the other pair is the same as this; three pairs The unbalanced laser beam 10 in the horizontal direction of the three-dimensional MOT laser beam is obtained by opening a small hole 7 on the 1/4 wave plate reflector. In this way, the three pairs of mutually orthogonal laser beams, the re-pump laser beam combined into a certain laser beam and the anti-Helmholtz coil 6 form a three-dimensional MOT of the present invention. Due to the effect of the unbalanced laser beam 10, the cold atom cloud 11 is subjected to the radiation pressure of the unbalanced light field, and some atoms of the cold atom cloud are pushed out of the small hole 7 in the horizontal direction to form a cold atom beam 8.

The implementation principle of the cold atomic beam generation method will be further described below in conjunction with the accompanying drawings. As shown in FIG. 2 , the formed cold atomic beam is laterally compressed and guided by the quadrupole magnetic field formed by the tapered magnetic guiding straight wire 12 during the advancing distance. After being guided by magnetic compression, the cold atomic beam emerges from the small hole 7, and then the state preparation of the cold atomic beam is completed after the action of the state preparation laser beam 13 perpendicular to the cold atomic beam. Thus, a continuous cold atomic beam with low longitudinal velocity (here in the horizontal direction) and longitudinal velocity distribution, very small transverse velocity, large flux, and uniform state is obtained. Taking Rb atoms as an example, the cold atomic beam index obtained in a certain experiment is as follows: the longitudinal velocity is 24.5m/s, the longitudinal velocity distribution is 5.5m/s, the transverse velocity is 8cm/s, and the atomic beam flux is 1.01×10 ⁹ /s, 93% of the atoms in the atomic beam are in the 5 ² S _1/2 (F=1) state.

Claims (8)

1. A cold atomic beam generating device, comprising: a vacuum chamber, and an optical path system that is arranged inside and outside the vacuum chamber and is made up of a laser, a beam splitter, a reflector and a 1/4 wave plate reflector; wherein the vacuum chamber (16 ) are provided with quartz glass windows (14), (17), (18), (19), (21), (22), (23), (26), (27), (30), quartz glass windows (17) is opposite to quartz glass window (22), and quartz glass window (26) is opposite to quartz glass window (30), and these two pairs of quartz glass windows are mutually orthogonal; Quartz glass window (19) and quartz glass window (27) ) opposite, and orthogonal to the quartz glass window (18); it is characterized in that: there are 2 grooves on the inner wall of the vacuum chamber (16), and a fixing clip (29) and a fixing clip (31) are arranged in the groove, and the magnetic The guiding straight wire (12) is installed on the inner wall of the vacuum chamber (16) through the fixing clip (29) and the fixing clip (31), and forms a tapered arrangement; wherein one end of the magnetic guiding straight wire (12) passes through the vacuum The terminal post (15) on the chamber wall passes through the vacuum chamber (16) and is connected to the external power supply; in addition, the 1/4 wave plate reflector (9) is placed in the fixed clip (28) in the vacuum chamber (16). ); the anti-Helmholtz coil (6) is sleeved outside the vacuum chamber, and the center of the anti-Helmholtz coil (6) is in the vacuum chamber quartz glass window (17) and the opposite quartz glass window (22), and quartz At the position where the glass window (26) coincides with the orthogonal center formed by the opposite quartz glass window (30); The optical path system includes: an acoustic light modulator (37), a 1/4 wave plate (36), a beam expander collimator (35) and a beam splitter (4) are arranged on the front optical path of the first laser (32) output light ), forming three beams of lasers after splitting, the three beams of lasers are mutually orthogonal in space, reflectors (3), reflectors (3′) and reflectors (3 "); Then these three beams of laser beams are incident into the vacuum chamber (16) through the quartz glass window (14), the quartz glass window (17) and the quartz glass window (26) respectively after being reflected by the reflector, wherein two beams of laser beams pass through the quartz glass window After the glass windows (22) and (30) are emitted, they are reflected by a reflector (38) and a reflector (40) perpendicular to it; The glass window (14) is incident into the vacuum chamber (16) along the vacuum chamber axis, and is reflected by a 1/4 wave plate reflector (9) with a φ1-2mm aperture in the center perpendicular to it in the advancing direction, so that Formed six beams of orthogonal laser beams, its orthogonal center coincides with the orthogonal center formed by quartz glass window (17), quartz glass window (22), quartz glass window (26), and quartz glass window (30); in addition, The re-pumping laser beam (34) that the second laser (33) sends is merged into any beam of laser light that the laser (32) produces by a reflector, and is used for the re-pumping laser of the MOT cooling atoms; A laser also extracts the state to prepare the laser beam (13). 2. The cold atomic beam generating device according to claim 1, characterized in that: it also includes quartz glass windows (21) and quartz glass windows (21) that are used as observation windows or function expansion windows by flanges on the vacuum chamber wall. (23), quartz glass window (19), quartz glass window (27). 3. by the described cold atomic beam generating device of claim 1, it is characterized in that: the reflector (3), reflector (3 ') and reflector ( 3″) at 30°, 45° or 60° to the laser beam. 4. The cold atom beam generating device according to claim 1, characterized in that: the aperture of the small hole opened on the said 1/4 wave plate reflector is: φ1-2mm. 5. The cold atom beam generating device according to claim 1, characterized in that: said fixing clip (29), fixing clip (31) and fixing clip (28) are made of ceramics, and the fixing clip The diameter of hoop (29) and fixed clamp (31) is adjustable, and one end of magnetic guide straight wire (12) is installed on fixed clamp (29), and the other end is installed on the fixed clamp (31), and fixed clamp The diameters of the hoop (29) and the fixing clip (31) are large and small and form a tapered arrangement of magnetic guiding straight wires (12). 6. The cold atom beam generator according to claim 1, characterized in that there are at least four magnetic guiding straight wires (12). 7. The cold atom beam generating device according to claim 2, characterized in that: said flanges are all selected from standard flanges. 8. A method for applying the cold atomic beam generating device of claim 1 to produce a cold atomic beam, comprising the following steps: 1) First, evacuate the vacuum chamber to a vacuum degree of not less than 10 ^-7 Pa; 2) Heating the hot atom source in the vacuum chamber to form an atomic steam atmosphere in the vacuum chamber to form a corresponding atomic saturated vapor pressure atmosphere; 3) In the atomic vapor atmosphere formed in step 2), use the three-dimensional MOT to cool the hot atoms to below 200 μk, and be trapped to form a cloud of cold atoms; 4) A quarter-wave plate mirror with a small hole is placed in the direction of the laser beam in the three-dimensional MOT, so that the pressure of the laser radiation in this direction is unbalanced and the cold atoms are emitted along this direction; in the cold atom beam In the direction of emission, there are also four tapered straight magnetic guidance wires carrying current directions opposite to each other. When the atoms are emitted, they will not expand in the transverse direction under the action of the magnetic field and eject forward; the emission velocity is obtained. Low, high-flux, continuous beams of cold atoms with very small transverse velocities; 5) At the same time, in the outgoing direction of the cold atomic beam, a laser beam output by another laser perpendicular to the atomic beam is provided to prepare the state of the atomic beam, so as to realize the exiting cold atomic beam with the same state.

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