Three-dimensional cooling atomic beam preparation device and preparation method

Abstract

The invention relates to a three-dimensional cooling atomic beam preparation device and method. The three-dimensional cooling atomic beam preparation device is characterized in that the emergent end of an atomic gas chamber is connected with the incident end of an atomic collimator; the emergent end of the atom collimator is connected with the incident end of the cooling cavity, the emergent end of the cooling cavity is connected with the incident end of the detection cavity through a pipeline, and the pipeline is connected with a vacuum pump; the three-dimensional cooling laser pair acts on the cooling cavity, and the upper detection laser and the lower detection laser oppositely act on the detection cavity up and down; the cut-off laser acts on the rear end of the cooling cavity; the atomic gas chamber is used for generating hot atoms; the atom collimator is used for forming a hot atom beam and enabling the hot atom beam to enter the cooling cavity; the cooling cavity forms a cold atom beam under the combined action of the three-dimensional cooling laser pair and enables the cold atom beam to enter the detection cavity; the two detection lasers enable an electric signal of the cold atom beam to form a fluorescence signal to be output; and the fluorescence collection device is used for collecting fluorescence signals and inputting the fluorescence signals into the computer for processing to obtain information such as three-dimensional temperature, flux, speed and speed distribution of the cold atom beam. According to the invention, high-flux and three-dimensional low-temperature atomic beam output is realized at the same time.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of quantum inertial measurement technology, in particular to a three-dimensional cooled atomic beam preparation device and a preparation method. BACKGROUND

[0002] Atomic interferometer gyro has the advantages of high sensitivity, low long-term drift and simultaneous measurement of multiple inertial parameters, and has broad application prospects in inertial navigation, basic physics research and resource exploration. At present, the common atomic interferometer gyro has two configurations, which respectively use cold atom group and atomic beam as sensitive medium. The cold atom group interferometer gyro works in pulse mode, and the atomic control is relatively accurate, but there is a measurement dead zone and small measurement bandwidth. The atomic beam interferometer gyro uses atomic beam for inertial measurement, which can continuously obtain the motion information of the external carrier, has large measurement bandwidth, and is more suitable for dynamic environment application.

[0003] Thanks to the development of laser control technology, there are many methods to realize the preparation of atomic beam at present, but all have obvious shortcomings. The two-dimensional magnetic optical trap and three-dimensional magnetic optical trap technology can obtain a high flux atomic beam, and the transverse temperature can also reach the Doppler limit, but there is no effective control means in the direction of atomic motion, resulting in a large longitudinal temperature of the atomic beam. The United States Naval Research Laboratory proposed a method of using two-dimensional magnetic optical trap combined with three-dimensional optical glue to realize the preparation of three-dimensional low-temperature atomic beam, but the flux of the atomic beam is greatly lost. How to reduce the velocity distribution in the direction of atomic motion and at the same time maintain a high atomic flux has become one of the bottleneck problems restricting the engineering application of atomic interferometer gyro. SUMMARY

[0004] The present application is directed to the deficiencies of the prior art, and proposes a three-dimensional cooled atomic beam preparation device and a preparation method, which can simultaneously realize high flux and three-dimensional low-temperature atomic beam output.

[0005] One of the above-mentioned purposes of the present application is achieved by the following technical solution: A three-dimensional cooled atomic beam preparation device, comprising an atomic gas chamber, a cooling cavity, a detection cavity, an atomic collimator, a vacuum pump, a fluorescence collection device, a computer, a three-dimensional cooling laser pair, an upper detection laser, a lower detection laser and a truncation laser. The exit end of the atomic gas chamber is connected to the incident end of the atomic collimator; the center of the atomic collimator is coaxial with the atomic emission direction of the atomic gas chamber; the exit end of the atomic collimator is connected to the incident end of the cooling chamber, and the exit end of the cooling chamber is connected to the incident end of the detection chamber through a pipeline, on which the vacuum pump is connected; the three-dimensional cooling laser acts on the cooling chamber, and the upper and lower detection lasers are opposite each other and act on the detection chamber; the cutoff laser acts on the rear end of the cooling chamber 2; the atomic gas chamber contains atoms for generating thermal atoms; The atom collimator is used to filter out atoms with excessive divergence angles, forming a hot atom beam, which then enters the cooling cavity. The cooling cavity, under the combined action of the three-dimensional cooling laser pair, forms a cold atom beam, which then enters the detection cavity. The upper and lower detection lasers are used to convert the cold atom beam into a fluorescence signal. The fluorescence collection device is located outside the detection cavity to collect the fluorescence signal and convert it into an electrical signal, which is then input into a computer for processing to obtain information such as the three-dimensional temperature, flux, velocity, and velocity distribution of the cold atom beam.

[0006] Furthermore, the atoms housed in the atomic gas chamber are alkali metal atoms or alkaline earth metal atoms. Furthermore, the atomic gas chamber is wrapped with heating and insulation materials, and the atomic concentration inside the atomic gas chamber can be controlled by controlling the heating temperature.

[0007] Moreover, the atomic collimator is a capillary array made of stainless steel or glass, and the capillary array adopts an equilateral triangle configuration, which is coaxially fixed to the external vacuum pipe.

[0008] Furthermore, the three-dimensional cooling laser pair includes an upper left cooling laser, a lower right cooling laser, a lower left cooling laser, an upper right cooling laser, and a front cooling laser; the upper left and lower right cooling lasers are arranged opposite each other to form a first cooling laser pair; the lower left and upper right cooling lasers are arranged opposite each other to form a second cooling laser pair; the front cooling laser and the rear cooling laser are arranged opposite each other to form a third cooling laser pair; the frequency detuning of the first and second cooling laser pairs is greater than that of the third cooling laser pair; the first and second cooling laser pairs are located in the same plane; the front and rear cooling lasers constituting the third cooling laser pair are in opposite directions, perpendicular to the direction of motion of the thermal atomic beam, and perpendicular to the plane containing the first and second cooling laser pairs.

[0009] Furthermore, the laser power of the first cooling laser pair and the second cooling laser pair is 30mW-50mW, and the angle between them and the direction of atomic beam motion is ±15°~±45°.

[0010] Moreover, the upper probe laser, lower probe laser, and cutoff laser have the same frequency and all resonate with the atomic transition spectral lines.

[0011] The second objective of this invention is achieved through the following technical solution: A method for fabricating an atomic beam preparation device based on the above-mentioned three-dimensional cooling includes the following steps: Step 1: First, use an atomic collimator to achieve preliminary selection of the transverse temperature of the thermal atoms, forming a thermal atomic beam; Step 2: Then, the three-dimensional cooling laser is used to act on the hot atomic beam, so that the atoms form an optical adhesive state, thereby further suppressing the transverse velocity distribution of the hot atomic beam 7, while reducing the longitudinal velocity distribution and improving its three-dimensional coherence, thus forming a cooled atomic beam. Step 3: The cooled atomic beam enters the detection cavity. The flux and three-dimensional temperature information of the cold atomic beam are obtained by the upper and lower detection lasers. The velocity and velocity distribution information of the cold atomic beam are obtained by the cut-off laser. The detected information is then transmitted to the computer for processing through a fluorescence collection device.

[0012] The advantages and positive effects of this invention are as follows: 1. This invention proposes a preparation device and method for three-dimensional cooling of atomic beams based on a combination of mechanical (atomic collimator) and optical (three-dimensional cooling laser pair) methods. It achieves the preparation of cold atomic beams with high throughput and narrow velocity distribution with small volume and system complexity, and is applicable to any type of atom and molecule. It provides a new approach to improve the performance of atomic interference and quantum inertial measurement.

[0013] 2. By controlling parameters such as the diameter and aspect ratio of the atomic collimator and the frequency, power, diameter, and cooling angle of the cooling laser, this invention can achieve precise control of parameters such as flux, velocity, velocity distribution, and size of the atomic beam under relatively small size constraints, which is of great significance for reducing the size and power consumption of high-performance atomic beam preparation devices. Attached Figure Description

[0014] Fig. 1 This is a simplified structural diagram of the three-dimensional cooled atomic beam preparation device of the present invention; Fig. 2 This is a schematic diagram of the three-dimensional cooling of atomic beams in this invention, 2a is the front view and 2b is the left view; Fig. 3 This is a schematic diagram of atomic beam detection according to the present invention. Detailed Implementation

[0015] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] A three-dimensional cooled atomic beam preparation apparatus, please see [link / reference]. Figs. 1-3 The invention comprises an atomic gas chamber 1, a cooling chamber 2, a detection chamber 3, an atomic collimator 4, a vacuum pump 5, a fluorescence collection device 9, a computer 10, an upper left cooling laser 201, a lower right cooling laser 202, a lower left cooling laser 203, an upper right cooling laser 204, a front cooling laser 205, a rear cooling laser 206, an upper detection laser 301, a lower detection laser 302, and a cutoff laser 303. The upper left cooling laser 201 and the lower right cooling laser 202 are arranged opposite each other, forming a first cooling laser pair; the lower left cooling laser 203 and the upper right cooling laser 204 are arranged opposite each other, forming a second cooling laser pair; and the front cooling laser 205 and the rear cooling laser 206 are arranged opposite each other, forming a third cooling laser pair. The upper detection laser 301 and the lower detection laser 302 are arranged opposite each other.

[0017] An atomic gas chamber 1, an atomic collimator 4, a cooling chamber 2, a detection chamber 3, a pipeline connecting the cooling chamber and the detection chamber, and a vacuum pump 5 connected to the pipeline form a closed space. Under the action of the vacuum pump 5, an ultra-high vacuum is maintained, typically on the order of 10⁻⁷ Pa to 10⁻⁸ Pa. Both the cooling chamber 2 and the detection chamber 3 are made of non-magnetic metals, such as titanium alloy, aluminum alloy, non-magnetic stainless steel, and glass; in this embodiment, aluminum alloy is used. Atoms 6 are emitted from the atomic gas chamber 1 and undergo preliminary lateral velocity selection by the atomic collimator 4 to form a hot atomic beam 7. The hot atomic beam 7 enters the cooling chamber 2 and, after being acted upon by a three-dimensional cooling laser pair, forms a cold atomic beam 8. The cold atomic beam 8 enters the detection chamber 3 and, under the action of the upper detection laser 301, the lower detection laser 302, and the cutoff laser 303, forms fluorescence. The fluorescence is collected by a fluorescence collection device 9, and the electrical signal is processed by a computer 10 to obtain information such as the temperature, flux, and velocity distribution of the cold atomic beam 8.

[0018] The atomic gas chamber 1 is used to generate thermal atoms 6. The atomic gas chamber contains 1-5g of alkali metal atoms or alkaline earth metal atoms; in this embodiment, it contains 2g of rubidium alkali metal atoms. The atomic gas chamber 1 is made of copper alloy, and its outer end face is wrapped with heating and insulation materials. By controlling the heating temperature, the atomic concentration inside the atomic gas chamber 1 can be controlled, thereby controlling the emission velocity and flux of the thermal atoms 6. The emission end of the atomic gas chamber 1 is connected to the incident end of the atomic collimator 4.

[0019] The center of the atomic collimator 4 is coaxial with the atomic emission direction of the atomic gas chamber 1, used to filter out atoms with excessive divergence angles. It is typically made of a capillary array of stainless steel or glass; in this embodiment, it is made of stainless steel capillary material. The stainless steel capillary has an inner diameter of 150 μm, an outer diameter of 250 μm, and a length of 4 cm. The capillary array adopts an equilateral triangle configuration with a diameter of 1-6 mm; in this embodiment, the diameter is 4 mm. The equilateral triangle configuration is coaxially fixed to the external vacuum pipe. After passing through the atomic collimator 4, the hot atoms 6 form a hot atomic beam 7 with a divergence angle of 37.5 mrad, a beam flux on the order of 10¹³ / s, and an adjustable longitudinal velocity of 200-300 m / s.

[0020] like Fig. 2 As shown, the lasers used for three-dimensional cooling of the hot atomic beam 7 include three pairs of cooling lasers, all acting on the cooling cavity 2. The frequency detuning of the first and second cooling laser pairs is greater than that of the third cooling laser pair. The first and second cooling laser pairs are located in the same plane. The laser frequencies of these two pairs are detuned by 30MHz to 50MHz relative to the resonant frequency of rubidium atoms (F=2→F'=3). The laser power is adjustable from 30mW to 50mW, and the angle between them and the direction of the atomic beam is adjustable from ±15° to ±45°. The front cooling laser 205 and the rear cooling laser 206 constituting the third cooling laser pair are in opposite directions, perpendicular to the direction of the hot atomic beam 7 and perpendicular to the plane containing the other two pairs of cooling lasers. The laser frequency of the third cooling laser pair is detuned by 5MHz to 10MHz relative to the resonant frequency of rubidium atoms (F=2→F'=3). The laser power is adjustable from 20mW to 40mW. After three-dimensional cooling, the hot atomic beam 7 forms the cold atomic beam 8, with a flux typically in the range of 10¹¹ to 10¹² and a longitudinal velocity adjustable from 100 to 200 m / s.

[0021] like Fig. 3As shown, the probe laser used to detect the characteristics of the cold atom beam 8 includes an upper probe laser 301, a lower probe laser 302, and a cutoff laser 303 positioned opposite each other. The upper probe laser 301 and the lower probe laser 302 act on the center of the probe cavity 3, while the cutoff laser 303 acts on the rear end of the cooling cavity 2. The upper probe laser 301, the lower probe laser 302, and the cutoff laser 303 have the same frequency, all resonating with the atomic transition line F=2→F'=3. The upper probe laser 301 and the lower probe laser 302, used alone, can obtain information such as the flux and three-dimensional temperature of the cold atom beam 8. When used in conjunction with the cutoff laser 303, they can obtain information on the velocity and velocity distribution of the cold atom beam 8. In this embodiment of the invention, the center distance between the cutoff laser 303 and the upper probe laser 301 and the lower probe laser 302 is 400 mm. The power of the upper probe laser 301 and the lower probe laser 302 is 10 mW, and the spot size is 20 mm × 5 mm. The power of the cutoff laser is 20 mW, and the spot diameter is 20 mm. When the cutoff laser 303 is turned on, the time information of the cold atom beam 8 from the cutoff laser 303 to the probe laser 301 is recorded. The duration is on the order of 2-10 ms. The above data is processed in the computer 10 to obtain the velocity distribution information of the cold atom beam 8.

[0022] The core of the fabrication method for the three-dimensional cooled atomic beam preparation device lies in first using an atomic collimator 4 to achieve preliminary selection of the lateral temperature of hot atoms 6, forming a hot atomic beam 7; then, a three-dimensional cooling laser is used to act on the hot atomic beam, causing the atoms to form an optical adhesive state, thereby further suppressing the lateral velocity distribution of the hot atomic beam 7 and reducing the longitudinal velocity distribution, thus improving its three-dimensional coherence and forming a cooled atomic beam 8; the cooled atomic beam enters the detection cavity, and the flux and three-dimensional temperature information of the cold atomic beam are obtained through the upper and lower detection lasers, and the velocity and velocity distribution information of the cold atomic beam are obtained in conjunction with the cutoff laser, and the detected information is transmitted to a computer through a fluorescence collection device for processing.

[0023] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A three-dimensional, cooled atomic beam current preparation apparatus, characterized by: The device comprises an atomic cell, a cooling cavity, a detecting cavity, an atomic collimator, a vacuum pump, a fluorescence collecting device, a computer, a three-dimensional cooling laser pair, an upper detecting laser, a lower detecting laser and a cutting laser; The exit end of the atomic cell is connected with the entrance end of the atomic collimator; the center of the atomic collimator is coaxial with the atomic exit direction of the atomic cell; the exit end of the atomic collimator is connected with the entrance end of the cooling cavity, and the exit end of the cooling cavity is connected with the entrance end of the detecting cavity through a pipeline, and the vacuum pump is connected on the pipeline; the three-dimensional cooling laser pair acts on the cooling cavity, the upper detecting laser and the lower detecting laser are opposite to each other and act on the detecting cavity; the cutting laser acts on the rear end of the cooling cavity; the atomic cell is internally provided with atoms for generating hot atoms; the atomic collimator is used for filtering out atoms with too large divergence angle, forming a hot atom beam and making the hot atom beam enter the cooling cavity. The cooling cavity forms a cold atom beam after the joint action of the three-dimensional cooling laser pair, and makes the cold atom beam enter the detecting cavity; the upper detecting laser and the lower detecting laser are used for forming a fluorescence signal from the cold atom beam; the fluorescence collecting device is arranged outside the detecting cavity and is used for collecting the fluorescence signal and converting it into an electric signal, which is then input into the computer for processing to obtain information such as three-dimensional temperature, flux, velocity and velocity distribution of the cold atom beam.

2. The three-dimensional, cooled atomic beam current preparation apparatus of claim 1, wherein: The atoms internally provided in the atomic cell are alkali metal atoms or alkaline earth metal atoms.

3. The three-dimensional, cooled atomic beam current preparation apparatus of claim 1, wherein: The atomic cell is externally wrapped with a heating material and a heat preservation material, and the concentration of the atoms in the atomic cell is controlled by controlling the heating temperature.

4. The three-dimensional, cooled atomic beam current preparation apparatus of claim 1, wherein: The atomic collimator is made of a capillary array of stainless steel or glass, and the capillary array adopts an equilateral triangle configuration which is coaxially and fixedly connected with the external vacuum pipeline.

5. The three-dimensional, cooled atomic beam current preparation apparatus of claim 1, wherein: The three-dimensional cooling laser pair comprises a left upper cooling laser, a right lower cooling laser, a left lower cooling laser, a right upper cooling laser and a front cooling laser; the left upper cooling laser and the right lower cooling laser are oppositely arranged to form a first cooling laser pair; the left lower cooling laser and the right upper cooling laser are oppositely arranged to form a second cooling laser pair; the front cooling laser and the rear cooling laser are oppositely arranged to form a third cooling laser pair; the frequency mismatch of the first cooling laser pair and the second cooling laser pair is greater than that of the third cooling laser pair, and the first cooling laser pair and the second cooling laser pair are located in the same plane; the front cooling laser and the rear cooling laser of the third cooling laser pair are opposite in direction, perpendicular to the movement direction of the hot atom beam and perpendicular to the plane in which the first cooling laser pair and the second cooling laser pair are located.

6. The three-dimensional, cooled atomic beam current preparation apparatus according to claim 5, characterized in that The laser power of the first cooling laser pair and the second cooling laser pair is 30-50 mW, and the included angle with the movement direction of the atom beam is ±15°-±45°.

7. The three-dimensional, cooled atomic beam current preparation apparatus of claim 1, wherein: The upper detecting laser, the lower detecting laser and the cutting laser have the same frequency and resonate on the transition spectrum line of the atom.

8. A method of producing a three-dimensional cooled atomic beam according to any one of claims 1 to 7, characterized in that: The device comprises the following steps: Step 1: first, the atomic collimator is used to preliminarily select the transverse temperature of the hot atom to form a hot atom beam; Step 2, then, by using three-dimensional cooling laser on the thermal atomic beam, the atomic atoms form optical adhesive state, realize the further inhibition of the thermal atomic beam transverse velocity distribution, reduce the longitudinal velocity distribution, improve its three-dimensional coherence, form the cooled atomic beam; Step 3, the cooled atomic beam enters into the detection cavity, through the upper detection laser and the lower detection laser, the flux, three-dimensional temperature information of the cold atomic beam are obtained, the velocity and velocity distribution information of the cold atomic beam are obtained by cooperating with the cutting laser; and through the fluorescence collection device, the detected information is transmitted to the computer, and the computer is processed.

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