A high-flow integrated low-speed atomic source generating device and a generating method thereof

Abstract

The application discloses a high-flow integrated low-speed atomic source generating device and a generating method thereof. The integrated Zeeman magnetic field coil is wound by a metal wire, and a very smooth Zeeman magnetic field gradient can be obtained by inputting one current; the cooling laser is only one beam, the action dissonance range is large, and the adjustment precision requirement is low; the low-speed atom is generated by the Zeeman deceleration method, the high-speed atom sprayed from the atomic furnace can be directly used, and most of the high-speed atoms are converted into low-speed atoms; the cooling laser improves the proportion of the thermal atom cooled by the Zeeman magnetic field gradient; the integrated Zeeman magnetic field coil and the center position of the atomic furnace are staggered with the center of the vacuum cavity in the x direction, and the effect that the atom beam current can be effectively captured and the atom beam current does not hit the captured atom can be achieved; the atom beam current switch can be selected to be closed, and the atom beam current is completely isolated; the low-speed atomic isotope is selected by selecting the appropriate cooling laser frequency.

Description

Technical Field

[0001] This invention relates to neutral atom deceleration technology, specifically to a device and method for generating a high-flow integrated low-speed atom source. Background Technology

[0002] Ultracold atom experimental platforms are widely used for highly coherent quantum simulation, quantum computing, and quantum precision measurement. Experiments based on this platform offer advantages such as good repeatability, high precision, simple operation, short experimental cycles, and a wide range of adjustable parameters. Laser cooling technology is fundamental to cooling atomic systems to near absolute zero to achieve ultracold atom experiments. In ultracold atom experiments, to minimize the experimental time per round, the loading time of the three-dimensional magneto-optical trap needs to be as short as possible, which requires a high-flow-rate, low-speed atom source generation device. Traditional generation methods include two-dimensional magneto-optical traps and Zeeman deceleration. Zeeman deceleration is universally applicable to various atoms, and its low-speed atom generation efficiency is an order of magnitude higher than that of two-dimensional magneto-optical traps, resulting in high deceleration efficiency. However, existing Zeeman magnetic field schemes require segmented current control using multiple coils, which is difficult to design and complex to control. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention proposes a device for generating a high-flow integrated low-speed atomic source.

[0004] One object of the present invention is to provide a device for generating a high-flow integrated low-speed atomic source.

[0005] The high-flow integrated low-speed atomic source generation device of the present invention includes: a vacuum chamber, an atomic furnace, an integrated Zeeman magnetic field coil, a cooling laser, an atomic beam switch, and an observation window; wherein, the atomic furnace includes a heating vessel and a capillary tube; the integrated Zeeman magnetic field coil includes, from the inside out, a coaxial differential tube, a sealed cavity, a water-cooled layer, and a magnetic field coil, the differential tube is hollow inside and located at the center of the integrated Zeeman magnetic field coil, the central axis of the differential tube is the geometric center of the integrated Zeeman magnetic field coil, and the magnetic field coil is made by winding a metal wire around the outer wall of the water-cooled layer; an observation window is provided on one side wall of the vacuum chamber, and on the other side wall opposite the observation window of the vacuum chamber... An atomic transmission port is provided at the top; the atomic transmission port is sealed and connected to the end of the integrated Zeeman magnetic field coil; the beginning of the integrated Zeeman magnetic field coil is connected to the end of the capillary of the atomic furnace through an atomic beam switch, and a nozzle is provided at the end of the capillary; the beginning of the capillary of the atomic furnace is connected to the outlet of the heating tank; the horizontal plane is located in the yz plane, and the vertical direction is the x direction; the central axis of the vacuum chamber is along the z direction, the central axes of the integrated Zeeman magnetic field coil and the capillary are located on the same straight line along the z direction, the central axis of the vacuum chamber is parallel to the central axis of the integrated Zeeman magnetic field coil and is offset along the x direction, and the central axis of the vacuum chamber is located outside the outer wall of the differential tube;

[0006] The metal is located in the heating chamber of the atomic furnace. Heating the metal generates thermal atoms, which are ejected through the nozzle of the atomic furnace's capillary, forming a nearly collimated thermal atom source. The emission direction of the thermal atom source is parallel to the z-axis and has a divergence angle. The beam flow rate of the thermal atom source is adjusted by changing the temperature of the heating chamber, and the divergence angle is adjusted by changing the ratio of the inner diameter to the length of the capillary. The direction of the thermal atom source ejected from the atomic furnace is aligned with the geometric center of the integrated Zeeman magnetic field coil, ensuring that most of the thermal atoms ejected from the atomic furnace can pass through the differential tube at the center of the integrated Zeeman magnetic field coil. The thermal atom source is controlled by an atomic beam switch, passing through the differential tube of the integrated Zeeman magnetic field coil and entering the vacuum cavity through the atomic transmission port. The cooling laser is a circularly polarized laser beam focused at the nozzle of the atomic furnace. The relationship between the polarization direction and the magnetic field direction of the integrated Zeeman magnetic field coil is as follows: with the magnetic field direction, it is a left-handed spiral circularly polarized beam; against the magnetic field direction, it is a right-handed spiral circularly polarized beam. The magnetic field direction is parallel to the central axis of the integrated Zeeman magnetic field coil. The direction of the coil current varies, pointing from the beginning to the end of the integrated Zeeman magnetic field coil or from the end to the beginning. The transmission direction of the cooling laser is located in the xz plane with the central axis of the vacuum cavity and forms an angle with the z direction. The cooling laser is obliquely incident into the vacuum cavity through the observation window and converged to the nozzle of the atomic furnace through the differential tube of the integrated Zeeman magnetic field coil. The closer the laser is to the atomic furnace, the higher the optical power density. The cooling laser effectively restricts the beam direction, ensuring the overall efficiency of the hot atoms reaching the vacuum cavity. The cooling laser also acts as an optical waveguide, guiding the hot atoms to the center of the vacuum cavity. Based on the Maxwell-Boltzmann velocity distribution, the initial and final velocities of the hot atoms, the detuning of the Doppler cooling spectral frequency corresponding to the relative atomic isotopes of the cooling laser, and the acceleration applied by the cooling laser, the length of the integrated Zeeman magnetic field coil from the beginning to the end, the end magnetic field, and the magnetic field variation parameters are obtained. Thus, the axial magnetic field distribution on the central axis is obtained. The axial magnetic field distribution on the central axis is used for Zeeman deceleration and is called the Zeeman magnetic field gradient.The Zeeman magnetic field gradient is simulated using the Helmholtz coil magnetic field curve plotting method to obtain the wire winding density, roll number, and coil current required to achieve the Zeeman magnetic field gradient. This allows the integrated Zeeman magnetic field coil to generate a decelerating Zeeman magnetic field that matches the velocity of the hot atoms. The magnitude of the Zeeman magnetic field decreases from the beginning to the end, and the detuning of the cooling laser frequency is proportional to the intercept of the Zeeman magnetic field gradient. By adjusting the intercept of the Zeeman magnetic field gradient through the frequency of the cooling laser, a set Zeeman magnetic field gradient can be obtained under a single current. This Zeeman magnetic field gradient can match the velocity of the hot atoms, enabling a single hot atom to interact with the cooling laser and decelerate at any spatial position throughout its flight. The cooling laser cools the hot atoms, causing their velocity curves to decrease linearly with position. For hot atoms whose initial velocity is no higher than the upper limit of the capture velocity corresponding to the maximum magnetic field of the integrated Zeeman magnetic field coil, their final velocity is lower than the upper limit of the atomic velocity that the magneto-optical trap can capture. After cooling by the laser, the resulting atomic beam enters the vacuum cavity. The central axis of the vacuum cavity is vertically offset from the central axis of the integrated Zeeman magnetic field coil, ensuring that the atomic beam entering the vacuum cavity does not affect the experiment at the center of the vacuum cavity. The atomic beam is captured by the magneto-optical trap of the vacuum cavity, obtaining a low-velocity atomic source. Furthermore, by adjusting the frequency of the cooling laser, low-velocity atomic isotopes are selected to be captured by the magneto-optical trap of the vacuum cavity, obtaining a predetermined low-velocity atomic isotope source.

[0007] According to the Maxwell-Boltzmann velocity distribution k B Let m be the Boltzmann constant, v be the mass, v be the velocity, and T be the temperature, respectively. The maximum atomic distribution velocity is calculated by substituting the atomic mass and the heating reference temperature, and is defined as the initial velocity v of the hot atom. i The frequency of the cooling laser must be sufficient to interact with the hot atoms in the integrated Zeeman magnetic field coil, while avoiding interference with the atoms already trapped in the magneto-optical trap. Therefore, the detuning amount δ0 of its relative atomic isotope-corresponding Doppler cooling spectral line frequency should be 16–24 times the linewidth Γ, i.e. It is generally believed that any velocity that can be cooled by a cooling laser under zero magnetic field can be trapped by a magneto-optical trap; therefore, the terminal velocity of a hot atom is defined. Here Let λ be the wave vector, and λ be the wavelength of the Doppler cooling spectral line corresponding to the atomic isotope. The Zeeman slowing principle is based on laser cooling achieved through Zeeman splitting of the magnetic field, causing resonance between the laser and atoms. kv + δ0 = Z0B, where Z0 is the Zeeman frequency shift constant and B is the ideal Zeeman magnetic field strength. Based on this, the Zeeman magnetic field gradient satisfies... in For the terminal magnetic field, These are parameters related to the change in the magnetic field. The length of the integrated Zeeman magnetic field coil from start to finish, where the acceleration applied by the cooling laser is... I represents the actual intensity of the cooling laser light. sat The saturation light intensity of the atom is given. After obtaining the Zeeman magnetic field gradient, it is substituted into the Helmholtz coil magnetic field curve plotting method for simulation to obtain the required wire winding density, roll number, and coil current. During the simulation, machine learning is used to optimize the parameter selection.

[0008] The method for plotting the magnetic field curve of a Helmholtz coil is based on the Biot-Saffar theorem. The program I wrote for calculating and plotting magnetic fields is suitable for obtaining the magnetic field distribution along the central axis in the case of multi-turn circular coils. i,j Let μi be the magnetic field strength of the j-th turn of the i-th layer at a distance z from the center of that turn, and μ0 be the free permeability. i,j Let be the winding radius of the coil, and Current be the coil current. The winding density and number of turns of the wire will determine the shape of the magnetic field distribution; the magnitude of the coil current will determine the magnification factor of the curve.

[0009] The atom transport port is connected to the end of the integrated Zeeman magnetic field coil via a flange seal.

[0010] The central axis of the vacuum chamber is located 3-5 mm outside the outer wall of the differential tube.

[0011] The angle between the transmission direction of the cooling laser and the horizontal direction is 2.5 to 3 milliradians, and it passes through the center of the vacuum cavity and the center of the capillary nozzle of the atomic furnace.

[0012] The divergence angle of a near-collimated thermal atomic source is 10–40 milliradians, which is proportional to the ratio of the capillary's inner diameter to its length. The temperature of the heating vessel is proportional to the beam flow rate of the thermal atomic source.

[0013] The observation window is surrounded by a heat shield, and by controlling the temperature at 30±5℃ below the atomic melting point, it effectively prevents atoms after deceleration from adhering to the cavity mirror surface and contaminating the vacuum window.

[0014] The atomic furnace is placed in a heat-shielded box and is divided into multiple sections for heating: the heating tube is divided into two to three sections for heating, with the temperature decreasing from bottom to top along the direction of gravity, with a decreasing gradient of 5 to 10°C. The temperature at the bottom of the heating tank is the heating reference temperature, which should be higher than the melting point of the metal. The higher the temperature, the greater the atomic flow rate. The capillary is divided into three to four sections for heating, with the temperature decreasing from the heating tank to the capillary nozzle, with a decreasing gradient of 10 to 20°C. The temperature at the highest point is consistent with the heating reference temperature.

[0015] The cooling laser frequency is at a red detuning of 16 to 24 times the linewidth of the Doppler cooling frequency corresponding to the atomic isotope, such as 670.977 nm for lithium 6 isotope and 670.962 nm for lithium 7 isotope.

[0016] Another objective of this invention is to provide a method for generating a high-flow integrated low-speed atomic source.

[0017] The method for generating a high-flow integrated low-speed atomic source according to the present invention includes the following steps:

[0018] 1) The metal is placed in the heating tank of the atomic furnace and heated to generate thermal atoms. The thermal atoms are ejected through the nozzle of the capillary tube of the atomic furnace to form a near-collimated thermal atom source. The emission direction of the thermal atom source is parallel to the z-direction and has a divergence angle. The beam flow rate of the thermal atom source is adjusted by changing the temperature of the heating tank of the atomic furnace and the divergence angle of the thermal atom source is adjusted by changing the ratio of the inner diameter to the length of the capillary tube of the atomic furnace.

[0019] 2) The direction of the hot atom source ejected from the nuclear furnace is aligned with the geometric center of the integrated Zeeman magnetic field coil to ensure that most of the hot atoms ejected from the nuclear furnace can pass through the differential tube at the center of the integrated Zeeman magnetic field coil;

[0020] 3) The thermal atom source, controlled by an atomic beam switch, enters the vacuum chamber through the atomic transmission port via the differential tube of the integrated Zeeman magnetic field coil.

[0021] 4) The cooling laser is a circularly polarized laser beam focused at the nozzle of the atomic furnace. The polarization direction is related to the magnetic field direction of the integrated Zeeman magnetic field coil as follows: with the magnetic field direction, it is a left-handed spiral circularly polarized beam, and against the magnetic field direction, it is a right-handed spiral circularly polarized beam. The magnetic field direction is parallel to the central axis of the integrated Zeeman magnetic field coil. Depending on the direction of the coil current, it points from the beginning to the end of the integrated Zeeman magnetic field coil or from the end to the beginning of the integrated Zeeman magnetic field coil. The transmission direction of the cooling laser is located in the xz plane with the central axis of the vacuum cavity and has an angle with the z direction. The cooling laser is obliquely incident into the vacuum cavity through the observation window and focused at the nozzle of the atomic furnace through the differential tube of the integrated Zeeman magnetic field coil. The closer the position is to the atomic furnace, the higher the optical power density. The cooling laser effectively restricts the beam direction and ensures the overall efficiency of hot atoms reaching the vacuum cavity. The cooling laser also acts as an optical waveguide, guiding hot atoms to the center of the vacuum cavity.

[0022] 5) Based on the Maxwell-Boltzmann velocity distribution, the initial and final velocities of the hot atoms, the detuning of the Doppler cooling spectral frequency corresponding to the relative atomic isotopes of the cooling laser, and the acceleration applied by the cooling laser, the length of the integrated Zeeman magnetic field coil from the beginning to the end, the end magnetic field, and the magnetic field variation parameters are obtained, thereby obtaining the axial magnetic field distribution on the central axis. The axial magnetic field distribution on the central axis is used for Zeeman deceleration and is called the Zeeman magnetic field gradient.

[0023] 6) The Zeeman magnetic field gradient is substituted into the Helmholtz coil magnetic field curve plotting method for simulation to obtain the wire winding density and roll number and the coil current required to realize the Zeeman magnetic field gradient. Thus, the integrated Zeeman magnetic field coil generates a decelerating Zeeman magnetic field that matches the velocity of the hot atom. The magnitude of the Zeeman magnetic field decreases from the beginning to the end, and the detuning of the frequency of the cooling laser is proportional to the intercept of the Zeeman magnetic field gradient. By adjusting the intercept of the Zeeman magnetic field gradient through the frequency of the cooling laser, the set Zeeman magnetic field gradient can be obtained under a single current. The Zeeman magnetic field gradient can match the velocity of the hot atom. The Zeeman magnetic field gradient allows a single hot atom to interact with the cooling laser and decelerate at any spatial position during the entire flight process, realizing the cooling of the hot atom by the cooling laser. The velocity curve of the hot atom conforms to the linear decrease with position. For hot atoms whose initial velocity is not higher than the upper limit of the capture velocity corresponding to the maximum magnetic field of the integrated Zeeman magnetic field coil, the final velocity is lower than the upper limit of the atomic velocity that the magneto-optical trap can capture. After being cooled by the cooling laser, the atomic beam enters the vacuum cavity.

[0024] 7) The central axis of the vacuum cavity is vertically offset from the central axis of the integrated Zeeman magnetic field coil, so that the atomic beam entering the vacuum cavity does not affect the experiment at the center of the vacuum cavity. The atomic beam is captured by the magneto-optical trap of the vacuum cavity to obtain a low-speed atomic source.

[0025] 8) By adjusting the frequency of the cooling laser, low-speed atomic isotopes are selected to be captured by the magneto-optical trap of the vacuum cavity to obtain the set low-speed atomic isotope source.

[0026] In step 1), the atomic furnace is placed in a heat-shielded box and heated in multiple sections: the heating tube is heated in two to three sections, with the temperature decreasing from bottom to top along the direction of gravity, with a decreasing gradient of 5 to 10°C. The temperature at the bottom of the heating tank is the heating reference temperature, which should be higher than the melting point of the metal. The higher the temperature, the greater the atomic flow rate. The capillary is heated in three to four sections, with the temperature decreasing from the heating tank to the capillary nozzle, with a decreasing gradient of 10 to 20°C. The temperature at the highest point is consistent with the heating reference temperature.

[0027] Advantages of this invention:

[0028] 1. Simple operation: The integrated Zeeman magnetic field coil of this invention is made of a single metal wire. Only one current input is needed to obtain a very smooth Zeeman magnetic field gradient, without the need to adjust the current and magnetic field distribution of each part. At the same time, there is only one cooling laser, which can be used for a large detuning range and has low adjustment precision requirements, greatly reducing the threshold for obtaining low-speed atoms. 2. Generation of high-flow-rate low-speed atoms: This invention uses the Zeeman deceleration method to generate low-speed atoms. Compared with the two-dimensional magneto-optical trap capturing atoms from the background gas, the Zeeman magnetic field can directly utilize the high-speed atoms ejected from the atomic furnace, converting most of the high-speed atoms into low-speed atoms, which greatly improves the capture rate of the subsequent three-dimensional magneto-optical trap. In addition, the cooling laser is focused onto the atomic furnace nozzle, which has a gathering effect on the ejected high-speed atoms, increasing the proportion of high-speed atoms cooled by Zeeman deceleration.

[0029] 3. Minimal impact of atomic beam on subsequent experiments: The integrated Zeeman magnetic field coil and the center of the atomic furnace in this invention are offset from the center of the vacuum cavity in the x-direction, which is sufficient to effectively capture atoms without allowing the atomic beam to hit the captured atoms; especially in subsequent experiments with ultracold atoms, since the atomic scale is below 100μm, there is no interaction between the atomic beam and the atomic clusters; for particularly precise experiments, the atomic beam switch can be turned off to completely isolate the atomic beam.

[0030] 4. Ability to select one or more low-speed atomic isotopes: Due to the universality of the Zeeman magnetic field gradient, this invention selects low-speed atomic isotopes by choosing a suitable cooling laser frequency and sends them to the experimental area; it can also obtain a variety of low-speed atoms and their isotopes by combining multiple cooling laser frequencies. Attached Figure Description

[0031] Figure 1 This is a structural block diagram of an embodiment of the high-flow integrated low-speed atomic source generation device of the present invention;

[0032] Figure 2 This is a schematic diagram of the structure of an embodiment of the high-flow integrated low-speed atomic source generation device of the present invention;

[0033] Figure 3 This is a schematic diagram of the segmented heating of the atomic furnace in one embodiment of the high-flow integrated low-speed atomic source generation device of the present invention;

[0034] Figure 4 This is a schematic diagram of the design of an integrated Zeeman coil, representing one embodiment of the high-flow integrated low-speed atomic source generation device of the present invention.

[0035] Figure 5 This is a spatial distribution diagram of the magnetic field gradient of an integrated Zeeman coil, which is an embodiment of the high-flow integrated low-speed atomic source generation device of the present invention. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0037] like Figure 1 and 2 As shown, the high-flow integrated low-speed atomic source generation device of this embodiment includes: a vacuum chamber 1, an atomic furnace 2, an integrated Zeeman magnetic field coil 3, a cooling laser, an atomic beam switch 5, and an observation window 6; wherein, the atomic furnace 2 includes a heating tank and a capillary tube 9; the integrated Zeeman magnetic field coil 3 includes, from the inside out, a coaxial differential tube, a sealed cavity, a water-cooled layer, and a magnetic field coil, the differential tube is hollow and vacuum-sealed inside, located at the center of the integrated Zeeman magnetic field coil 3, the central axis of the differential tube is the geometric center of the integrated Zeeman magnetic field coil 3, and the magnetic field coil is made of a metal wire wound around the outer wall of the water-cooled layer; an observation window 6 is provided on one side wall of the vacuum chamber 1, and the vacuum chamber 1 and the observation window 6 are opposite each other. An atomic transmission port is provided on the other side wall; the atomic transmission port is sealed to the end of the integrated Zeeman magnetic field coil 3; the beginning of the integrated Zeeman magnetic field coil 3 is connected to the end of the capillary of the atomic furnace 2 through the atomic beam switch 5, and a nozzle is provided at the end of the capillary; the beginning of the capillary of the atomic furnace 2 is connected to the outlet of the heating tank; the horizontal plane is located in the yz plane, and the vertical direction is the x direction; the central axis of the vacuum chamber 1 is along the z direction, the central axes of the integrated Zeeman magnetic field coil 3 and the capillary are located on the same straight line along the z direction, the central axis of the vacuum chamber 1 is parallel to the central axis of the integrated Zeeman magnetic field coil 3 and is offset along the x direction, and the central axis of the vacuum chamber 1 is located outside the outer wall of the differential tube.

[0038] like Figure 3 As shown, the metal is located in the heating vessel of the atomic furnace 2. The heating vessel is divided into two sections for heating, namely the first and second sections 11 and 12, respectively. The heating temperature of the first section 11 is 390℃, and the heating temperature of the second section 12 is 385℃. The capillary is divided into four sections for heating, namely the first to fourth sections 21 to 24. The heating temperature of the first section 21 is 390℃, the heating temperature of the second section 22 is 380℃, the heating temperature of the third section 23 is 360℃, and the heating temperature of the fourth section 24 is 340℃.

[0039] like Figure 4 As shown, a starting baffle 7 and an ending baffle 8 are respectively provided at the beginning and end of the integrated Zeeman magnetic field coil; the integrated Zeeman magnetic field coil is mounted on the first and second supports 31 and 32; a first water-cooling interface 33 and a second water-cooling interface 34 are respectively provided at the bottom of the ending baffle 8 and the top of the starting baffle 7 to connect to the water-cooling layer of the integrated Zeeman magnetic field coil; the differential tube 9 of the atomic furnace is located at the center of the integrated Zeeman magnetic field coil.

[0040] In this embodiment, a 3mm × 1.2mm square flat copper wire is used for winding. A single layer is wound within the same xy plane, with the number of turns decreasing along the z-direction. It is divided into thirteen parts, totaling 107 layers. The first part includes layer 1 with 28 turns; the second part includes layers 2-11, each with 24 turns; the third part includes layers 12-20, each with 22 turns; the fourth part includes layers 21-24, each with 20 turns; the fifth part includes layers 25-36, each with 18 turns; and the sixth part includes layers 107... Layers 37-49, each with 16 wraps; Part 7 includes layers 50-62, each with 14 wraps; Part 8 includes layers 63-73, each with 12 wraps; Part 9 includes layers 74-84, each with 10 wraps; Part 10 includes layers 85-94, each with 8 wraps; Part 11 includes layers 95-101, each with 6 wraps; Part 12 includes layers 102-105, each with 4 wraps; Part 13 includes layers 106-107, each with 2 wraps. (For example...) Figure 5 As shown, an 8A DC current is applied to both ends of the magnetic field coil, generating a Zeeman magnetic field gradient deceleration region of approximately 30cm in the center of the coil, so that individual atoms can interact with the cooling laser and decelerate throughout their flight.

[0041] The method for generating a high-flow integrated low-speed atomic source in this embodiment includes the following steps:

[0042] 1) The metal is placed in the heating tank of the atomic furnace and heated to generate thermal atoms. The thermal atoms are ejected through the nozzle of the capillary tube of the atomic furnace to form a near-collimated thermal atom source. The emission direction of the thermal atom source is parallel to the z-direction and has a divergence angle. The beam flow rate of the thermal atom source is adjusted by changing the temperature of the heating tank of the atomic furnace and the divergence angle of the thermal atom source is adjusted by changing the ratio of the inner diameter to the length of the capillary tube of the atomic furnace.

[0043] 2) The direction of the hot atom source ejected from the nuclear furnace is aligned with the geometric center of the integrated Zeeman magnetic field coil to ensure that most of the hot atoms ejected from the nuclear furnace can pass through the differential tube at the center of the integrated Zeeman magnetic field coil;

[0044] 3) The thermal atom source, controlled by an atomic beam switch, enters the vacuum chamber through the atomic transmission port via the differential tube of the integrated Zeeman magnetic field coil.

[0045] 4) The cooling laser is a circularly polarized laser beam focused at the nozzle of the atomic furnace. The polarization direction is related to the magnetic field direction of the integrated Zeeman magnetic field coil as follows: with the magnetic field direction, it is a left-handed spiral circularly polarized beam, and against the magnetic field direction, it is a right-handed spiral circularly polarized beam. The magnetic field direction is parallel to the central axis of the integrated Zeeman magnetic field coil, and depending on the current direction, it points from the beginning to the end or from the end to the beginning of the integrated Zeeman magnetic field coil. The transmission direction of the cooling laser is located in the xz plane with the central axis of the vacuum cavity and has an angle with the z direction. The cooling laser is obliquely incident into the vacuum cavity through the observation window and focused at the nozzle of the atomic furnace through the differential tube of the integrated Zeeman magnetic field coil. The closer the position is to the atomic furnace, the higher the optical power density. The cooling laser effectively restricts the beam direction and ensures the overall efficiency of hot atoms reaching the vacuum cavity. The cooling laser also acts as an optical waveguide, guiding hot atoms to the center of the vacuum cavity.

[0046] 5) Based on the Maxwell-Boltzmann velocity distribution

[0047] k B Let m be the Boltzmann constant, v be the mass, velocity, and temperature of the atom, respectively, to obtain the initial velocity v of the hot atom. i According to the initial velocity v of the hot atom i The detuning δ0 of the Doppler cooling spectral frequency corresponding to the atomic isotope and the acceleration applied by the cooling laser light. I represents the actual intensity of the cooling laser light. sat The saturation light intensity of the atom is used to obtain the terminal magnetic field. Magnetic field variation parameters

[0048] The length of the integrated Zeeman magnetic field coil from start to finish The Zeeman magnetic field gradient is obtained based on the terminal magnetic field, magnetic field variation parameters, and the length of the integrated Zeeman magnetic field coil from the beginning to the end.

[0049]

[0050] 6) The Zeeman magnetic field gradient is substituted into the Helmholtz coil magnetic field curve plotting method for simulation. Then, deep learning algorithms are used for iterative optimization to obtain the wire winding density, roll number, and coil current required to achieve the Zeeman magnetic field gradient. This allows the integrated Zeeman magnetic field coil to generate a decelerating Zeeman magnetic field that matches the velocity of the hot atoms. The magnitude of the Zeeman magnetic field decreases from the beginning to the end, and the detuning of the cooling laser frequency is proportional to the intercept of the Zeeman magnetic field gradient. By adjusting the intercept of the Zeeman magnetic field gradient through the frequency of the cooling laser, a set Zeeman magnetic field gradient can be obtained under a single current. This gradient matches the velocity of the hot atoms, allowing individual hot atoms to interact with the cooling laser and decelerate at any spatial position throughout their flight. This achieves cooling of the hot atoms by the cooling laser, resulting in a linear decrease in the velocity curve of the hot atoms with position. For hot atoms whose initial velocity is not higher than the upper limit of the capture velocity corresponding to the maximum magnetic field of the integrated Zeeman magnetic field coil, the final velocity is lower than the magnetic field velocity.

[0051] The upper limit of the atomic velocity that the optical trap can capture is obtained by cooling with a cooling laser to obtain an atomic beam that enters the vacuum cavity.

[0052] 7) The central axis of the vacuum cavity is vertically offset from the central axis of the integrated Zeeman magnetic field coil, so that the atomic beam entering the vacuum cavity does not affect the experiment at the center of the vacuum cavity. The atomic beam is captured by the magneto-optical trap of the vacuum cavity to obtain a low-speed atomic source.

[0053] 8) By adjusting the cooling laser frequency, the detuning amount δ0 of the Doppler cooling spectral line frequency corresponding to the atomic isotope of the cooling laser should be 20 times the linewidth of the red detuning. Low-velocity atomic isotopes are captured by the magneto-optical trap of the vacuum cavity, obtaining the set low-velocity atomic isotope source. By increasing the intensity of the cooling laser, the maximum low-velocity atomic flux exceeds 10. 10 Items per second.

[0054] Finally, it should be noted that the purpose of disclosing the embodiments is to help further understand the present invention. However, those skilled in the art will understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the scope of protection of the present invention is defined by the claims.

Claims

1. A device for generating a high-flow-rate integrated low-speed atomic source, characterized in that, The high-flow integrated low-speed atomic source generation device includes: a vacuum chamber, an atomic furnace, an integrated Zeeman magnetic field coil, a cooling laser, an atomic beam switch, and an observation window; wherein, the atomic furnace includes a heating vessel and a capillary tube; the integrated Zeeman magnetic field coil, from the inside out, includes a coaxial differential tube, a sealed cavity, a water-cooled layer, and a magnetic field coil, the differential tube is hollow inside and located at the center of the integrated Zeeman magnetic field coil, the central axis of the differential tube is the geometric center of the integrated Zeeman magnetic field coil, and the magnetic field coil is made by winding a metal wire around the outer wall of the water-cooled layer; an observation window is provided on one side wall of the vacuum chamber, and an atomic transmission port is opened on the other side wall of the vacuum chamber opposite to the observation window; the atomic transmission port is sealed and connected to the end of the integrated Zeeman magnetic field coil; the beginning of the integrated Zeeman magnetic field coil is connected to the end of the capillary tube of the atomic furnace through the atomic beam switch, and a nozzle is provided at the end of the capillary tube; The beginning of the capillary tube of the nuclear furnace is connected to the outlet of the heating tank; the horizontal plane is located in the yz plane, and the vertical direction is the x direction; the central axis of the vacuum chamber is along the z direction, the central axis of the integrated Zeeman magnetic field coil and the capillary tube are located on the same straight line along the z direction, the central axis of the vacuum chamber is parallel to the central axis of the integrated Zeeman magnetic field coil and is offset along the x direction, and the central axis of the vacuum chamber is located outside the outer wall of the differential tube. The metal is located in the heating chamber of the atomic furnace. Heating the metal generates thermal atoms, which are ejected through the nozzle of the atomic furnace's capillary, forming a nearly collimated thermal atom source. The emission direction of the thermal atom source is parallel to the z-axis and has a divergence angle. The beam flow rate of the thermal atom source is adjusted by changing the temperature of the heating chamber, and the divergence angle is adjusted by changing the ratio of the inner diameter to the length of the capillary. The direction of the thermal atom source ejected from the atomic furnace is aligned with the geometric center of the integrated Zeeman magnetic field coil, ensuring that most of the thermal atoms ejected from the atomic furnace can pass through the differential tube at the center of the integrated Zeeman magnetic field coil. The thermal atom source is controlled by an atomic beam switch, passing through the differential tube of the integrated Zeeman magnetic field coil and entering the vacuum cavity through the atomic transmission port. The cooling laser is a circularly polarized laser beam focused at the nozzle of the atomic furnace. The relationship between the polarization direction and the magnetic field direction of the integrated Zeeman magnetic field coil is as follows: with the magnetic field direction, it is a left-handed spiral circularly polarized beam; against the magnetic field direction, it is a right-handed spiral circularly polarized beam. The magnetic field direction is parallel to the central axis of the integrated Zeeman magnetic field coil. Depending on the direction of the coil current, the integrated Zeeman magnetic field coil can be directed from its beginning to its end or from its end to its beginning. The transmission direction of the cooling laser is located in the xz plane with the central axis of the vacuum cavity and forms an angle with the z direction. The cooling laser is obliquely incident into the vacuum cavity through the observation window and converges to the nozzle of the atomic furnace through the differential tube of the integrated Zeeman magnetic field coil. The closer the laser is to the atomic furnace, the higher the optical power density. The cooling laser effectively restricts the beam direction, ensuring the overall efficiency of the hot atoms reaching the vacuum cavity. The cooling laser also acts as an optical waveguide, guiding the hot atoms to the center of the vacuum cavity. Based on the Maxwell-Boltzmann velocity distribution, the initial and final velocities of the hot atoms, the detuning of the Doppler cooling spectral frequency corresponding to the relative atomic isotopes of the cooling laser, and the acceleration applied by the cooling laser, the length of the integrated Zeeman magnetic field coil from its beginning to its end, the end magnetic field, and the magnetic field variation parameters are obtained. Thus, the axial magnetic field distribution on the central axis is obtained. The axial magnetic field distribution on the central axis is used for Zeeman deceleration and is called the Zeeman magnetic field gradient.The Zeeman magnetic field gradient is simulated using the Helmholtz coil magnetic field curve plotting method to obtain the wire winding density, roll number, and coil current required to achieve the Zeeman magnetic field gradient. This allows the integrated Zeeman magnetic field coil to generate a decelerating Zeeman magnetic field that matches the velocity of the hot atoms. The magnitude of the Zeeman magnetic field decreases from the beginning to the end, and the detuning of the cooling laser frequency is proportional to the intercept of the Zeeman magnetic field gradient. By adjusting the intercept of the Zeeman magnetic field gradient through the frequency of the cooling laser, a set Zeeman magnetic field gradient can be obtained under a single current. This Zeeman magnetic field gradient can match the velocity of the hot atoms, enabling a single hot atom to interact with the cooling laser and decelerate at any spatial position throughout its flight. The cooling laser cools the hot atoms, causing their velocity curves to decrease linearly with position. For hot atoms whose initial velocity is no higher than the upper limit of the capture velocity corresponding to the maximum magnetic field of the integrated Zeeman magnetic field coil, their final velocity is lower than the upper limit of the atomic velocity that the magneto-optical trap can capture. After cooling by the laser, the resulting atomic beam enters the vacuum cavity. The central axis of the vacuum cavity is vertically offset from the central axis of the integrated Zeeman magnetic field coil, ensuring that the atomic beam entering the vacuum cavity does not affect the experiment at the center of the vacuum cavity. The atomic beam is captured by the magneto-optical trap of the vacuum cavity, obtaining a low-velocity atomic source. Furthermore, by adjusting the frequency of the cooling laser, low-velocity atomic isotopes are selected to be captured by the magneto-optical trap of the vacuum cavity, obtaining a predetermined low-velocity atomic isotope source.

2. The apparatus for generating a high-flow-rate integrated low-speed atomic source as described in claim 1, characterized in that, The atomic transport port is connected to the end of the integrated Zeeman magnetic field coil via a flange seal.

3. The apparatus for generating a high-flow integrated low-speed atomic source as described in claim 1, characterized in that, The central axis of the vacuum chamber is located 3-5 mm outside the outer wall of the differential tube.

4. The apparatus for generating a high-flow integrated low-speed atomic source as described in claim 1, characterized in that, The angle between the transmission direction of the cooling laser and the horizontal direction is 2.5 to 3 milliradians.

5. The apparatus for generating a high-flow integrated low-speed atomic source as described in claim 1, characterized in that, The divergence angle of the near-collimated thermal atom source is 10–40 milliradians, which is proportional to the ratio of the cross-sectional area to the length of the capillary.

6. The apparatus for generating a high-flow integrated low-speed atomic source as described in claim 1, characterized in that, The cooling laser frequency is at a red detuning of 16 to 24 times the linewidth of the Doppler cooling frequency corresponding to the atomic isotope.

7. The apparatus for generating a high-flow-rate integrated low-speed atomic source as described in claim 1, characterized in that, It also includes a heat shield that surrounds the observation window, controlling the temperature at 25–35°C below the atomic melting point.

8. A method for generating a high-flow integrated low-speed atomic source as described in claim 1, characterized in that, The method described above includes the following steps: 1) The metal is placed in the heating tank of the atomic furnace and heated to generate thermal atoms. The thermal atoms are ejected through the nozzle of the capillary tube of the atomic furnace to form a near-collimated thermal atom source. The emission direction of the thermal atom source is parallel to the z-direction and has a divergence angle. The beam flow rate of the thermal atom source is adjusted by changing the temperature of the heating tank of the atomic furnace and the divergence angle of the thermal atom source is adjusted by changing the ratio of the inner diameter to the length of the capillary tube of the atomic furnace. 2) The direction of the hot atom source ejected from the nuclear furnace is aligned with the geometric center of the integrated Zeeman magnetic field coil to ensure that most of the hot atoms ejected from the nuclear furnace can pass through the differential tube at the center of the integrated Zeeman magnetic field coil; 3) The thermal atom source, controlled by an atomic beam switch, enters the vacuum chamber through the atomic transmission port via the differential tube of the integrated Zeeman magnetic field coil. 4) The cooling laser is a circularly polarized laser beam focused at the nozzle of the atomic furnace. The polarization direction is related to the magnetic field direction of the integrated Zeeman magnetic field coil as follows: with the magnetic field direction, it is a left-handed spiral circularly polarized beam, and against the magnetic field direction, it is a right-handed spiral circularly polarized beam. The magnetic field direction is parallel to the central axis of the integrated Zeeman magnetic field coil. Depending on the direction of the coil current, it points from the beginning to the end of the integrated Zeeman magnetic field coil or from the end to the beginning of the integrated Zeeman magnetic field coil. The transmission direction of the cooling laser is located in the xz plane with the central axis of the vacuum cavity and has an angle with the z direction. The cooling laser is obliquely incident into the vacuum cavity through the observation window and focused at the nozzle of the atomic furnace through the differential tube of the integrated Zeeman magnetic field coil. The closer the position is to the atomic furnace, the higher the optical power density. The cooling laser effectively restricts the beam direction and ensures the overall efficiency of hot atoms reaching the vacuum cavity. The cooling laser also acts as an optical waveguide, guiding hot atoms to the center of the vacuum cavity. 5) Based on the Maxwell-Boltzmann velocity distribution, the initial and final velocities of the hot atoms, the detuning of the Doppler cooling spectral frequency corresponding to the relative atomic isotopes of the cooling laser, and the acceleration applied by the cooling laser, the length of the integrated Zeeman magnetic field coil from the beginning to the end, the end magnetic field, and the magnetic field variation parameters are obtained, thereby obtaining the axial magnetic field distribution on the central axis. The axial magnetic field distribution on the central axis is used for Zeeman deceleration and is called the Zeeman magnetic field gradient. 6) The Zeeman magnetic field gradient is substituted into the Helmholtz coil magnetic field curve plotting method for simulation to obtain the wire winding density and roll number and the coil current required to realize the Zeeman magnetic field gradient. Thus, the integrated Zeeman magnetic field coil generates a decelerating Zeeman magnetic field that matches the velocity of the hot atom. The magnitude of the Zeeman magnetic field decreases from the beginning to the end, and the detuning of the frequency of the cooling laser is proportional to the intercept of the Zeeman magnetic field gradient. By adjusting the intercept of the Zeeman magnetic field gradient through the frequency of the cooling laser, the set Zeeman magnetic field gradient can be obtained under a single current. The Zeeman magnetic field gradient can match the velocity of the hot atom. The Zeeman magnetic field gradient allows a single hot atom to interact with the cooling laser and decelerate at any spatial position during the entire flight process, realizing the cooling of the hot atom by the cooling laser. The velocity curve of the hot atom conforms to the linear decrease with position. For hot atoms whose initial velocity is not higher than the upper limit of the capture velocity corresponding to the maximum magnetic field of the integrated Zeeman magnetic field coil, the final velocity is lower than the upper limit of the atomic velocity that the magneto-optical trap can capture. After being cooled by the cooling laser, the atomic beam enters the vacuum cavity. 7) The central axis of the vacuum cavity is vertically offset from the central axis of the integrated Zeeman magnetic field coil, so that the atomic beam entering the vacuum cavity does not affect the experiment at the center of the vacuum cavity. The atomic beam is captured by the magneto-optical trap of the vacuum cavity to obtain a low-speed atomic source. 8) By adjusting the frequency of the cooling laser, low-speed atomic isotopes are selected to be captured by the magneto-optical trap of the vacuum cavity to obtain the set low-speed atomic isotope source.

9. The method of production as described in claim 8, characterized in that, In step 1), the atomic furnace is placed in a heat shield box and heated in multiple sections: the heating tube is divided into two to three sections for heating, with the temperature decreasing from bottom to top along the direction of gravity, with a decreasing gradient of 5 to 10°C. The temperature at the bottom of the heating tank is the heating reference temperature, which is higher than the melting point of the metal. The higher the temperature, the greater the atomic flow rate. The capillary is divided into three to four sections for heating, with the temperature decreasing from the heating tank to the capillary nozzle, with a decreasing gradient of 10 to 20°C.

10. The method of production as described in claim 8, characterized in that, In step 8), the cooling laser frequency is at a red detuning of 16 to 24 times the linewidth of the Doppler cooling frequency corresponding to the atomic isotope.

Images