A Zeeman deceleration optimization method, system, and apparatus for multi-component atoms

Abstract

This invention discloses a Zeeman deceleration optimization method, system, and apparatus for multi-component atoms. The method includes: generating a Zeeman decelerator magnetic field based on a magnetic field coil; setting a first cooling light and a second cooling light, and adjusting the intensity and detuning of the first and second cooling lights, as well as the Zeeman decelerator magnetic field, to decelerate a high-temperature atomic beam, obtaining the parameters of the first and second cooling lights and the Zeeman decelerator magnetic field at the point of highest deceleration efficiency. The system includes a magnetic field generation module, a first cooling light deceleration module, a first deceleration efficiency adjustment module, a second cooling light deceleration module, and a second deceleration efficiency adjustment module. The apparatus includes an atomic furnace, a first differential tube, a second differential tube, a Zeeman decelerator, a magneto-optical trap, and the first and second cooling lights. By using this invention, the deceleration efficiency of multi-component atom Zeeman deceleration can be improved. This invention can be widely applied in the field of atomic laser cooling and trapping technology.

Description

Technical Field

[0001] This invention relates to the field of atomic laser cooling and trapping technology, and in particular to a Zeeman deceleration optimization method, system and apparatus for multi-component atoms. Background Technology

[0002] Atomic laser cooling and trapping technology is a hot topic in physics research. The technique of cooling atomic systems to ultracold temperatures and controlling their quantum states has achieved valuable progress in the field of physics, including research on quantum degenerate Fermi gases, cold atom clocks, and quantum precision measurement. Among these, quantum degenerate Fermi gases are neutral atomic gases that exhibit the Pauli exclusion principle. Due to their unique properties, they are used to study various important physical experiments, such as quantum simulations. Quantum simulations use controllable systems to simulate quantum systems that are difficult to study directly.

[0003] To achieve quantum degenerate Fermi gas, a common laboratory method involves heating atoms in a nuclear furnace to generate a high-temperature atomic beam. This beam is then pre-decelerated using a Zeeman throttle, followed by cooling and trapping using a magneto-optical trap (MOT). Finally, the loaded atoms are rapidly transferred to an optical dipole trap, where evaporative cooling achieves a quantum degenerate state. However, the MOT's trapping velocity is too low to effectively decelerate the high-temperature atomic beam. The Zeeman throttle acts as a pre-decelerator, slowing the beam down to the MOT's trapping velocity, thus enabling its capture. Therefore, improving the Zeeman throttle's deceleration efficiency is crucial.

[0004] Current Zeeman reducers use a single beam of cooling light, which, when matched with a magnetic field, can produce a good deceleration effect on the same atoms. However, to achieve quantum degenerate Fermi gas, fermion isotopes of atoms are required. In a single-beam cooled Zeeman reducer, the ground state energy level of atoms increases, and atoms at different energy levels experience different effective detuning. A single beam of light can only effectively decelerate atoms at one energy level, while the deceleration effect on atoms at other energy levels is poor. Using a traditional Zeeman reducer to decelerate atoms of multiple components will greatly reduce its deceleration efficiency. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a Zeeman deceleration optimization method, system, and apparatus for multi-component atoms, thereby improving the deceleration efficiency of multi-component atom Zeeman deceleration.

[0006] The first technical solution adopted in this invention is: a Zeeman deceleration optimization method for multi-component atoms, comprising the following steps:

[0007] Based on the generation of the Zeeman reducer magnetic field within the range of the magnetic field coil;

[0008] The first cooling light is set to decelerate the high-temperature atomic beam and cover the area from the atomic furnace exit to the magneto-optical trap;

[0009] The light intensity and detuning of the first cooling light and the magnetic field parameters of the Zeeman reducer are adjusted, and the deceleration efficiency of the Zeeman reducer under different parameters is measured to obtain the light intensity, detuning and magnetic field parameters of the first cooling light when the deceleration efficiency is the highest.

[0010] Based on the light intensity, detuning and magnetic field parameters of the first cooling light when the deceleration efficiency is the highest, the second cooling light is set to decelerate the high-temperature atomic beam, and the coverage range is the same as that of the first cooling light.

[0011] The intensity and detuning of the second cooling light were adjusted, and the deceleration efficiency of the Zeeman reducer under different parameters was measured to obtain the intensity and detuning of the second cooling light when the deceleration efficiency was the highest.

[0012] Furthermore, the field strength expression of the Zeeman reducer magnetic field is as follows:

[0013]

[0014] Where B(x) represents the magnetic field strength of the Zeeman reducer, δ0 represents laser detuning, and μ′ represents the effective magnetic moment. Let v(x) represent the reduced Planck constant, k represent the laser wave vector, and v(x) represent the initial velocity v. c The curve showing the change in velocity of atoms in a Zeeman reducer as a function of their path of motion.

[0015] Furthermore, the Zeeman reducer applies acceleration to the high-temperature atomic beam, as expressed below:

[0016]

[0017] Where 'a' represents the acceleration experienced by the atom in the Zeeman decelerator. Let denot be the reduced Planck constant, k be the laser wave vector, Γ be the spontaneous emissivity of the excited state, m be the atomic mass, s be the laser saturation parameter, δ be the effective detuning, δ0 be the laser detuning, μ′ be the effective magnetic moment, B(x) be the field strength of the Zeeman reducer magnetic field, and v be the velocity of the atom.

[0018] Furthermore, the step of adjusting the light intensity and detuning of the first cooling light and the magnetic field parameters of the Zeeman reducer, and measuring the deceleration efficiency of the Zeeman reducer under different parameters to obtain the light intensity, detuning, and magnetic field parameters of the first cooling light when the deceleration efficiency is highest, specifically includes:

[0019] Adjust the light intensity and detuning of the first cooling light and the magnetic field parameters of the Zeeman reducer, and measure the velocity distribution of the high-temperature atomic beam after it is decelerated by the Zeeman reducer under different parameters;

[0020] The trapping velocity of the magneto-optical trap was calculated and compared with the velocity distribution of the high-temperature atomic beam after being decelerated by the Zeeman decelerator under different parameters, and the comparison results under different parameters were obtained.

[0021] The reduction efficiency of the Zeeman reducer is determined based on the comparison results under the different parameters.

[0022] Through this preferred step, the light intensity and detuning of the first cooling light, as well as the magnetic field of the Zeeman reducer, are adjusted to the state with the highest deceleration efficiency.

[0023] Furthermore, the capture velocity of the magneto-optical trap is calculated using the following expression:

[0024]

[0025] Among them, v cap The value represents the trapping velocity of the magneto-optical trap, and m represents the atomic mass. Let Γ denote the reduced Planck constant, k denote the laser wave vector, Γ denote the spontaneous emissivity of the excited state, and ω denote the beam waist radius of the magneto-optical trap.

[0026] The second technical solution adopted in this invention is: a Zeeman deceleration optimization system for multi-component atoms, comprising:

[0027] The magnetic field generation module generates the Zeeman reducer magnetic field within the range of the Zeeman reducer based on the magnetic field coil.

[0028] The first cooling light deceleration module is used to set the first cooling light to decelerate the high-temperature atomic beam and cover the range from the atomic furnace outlet to the magneto-optical trap.

[0029] The first deceleration efficiency adjustment module is used to adjust the light intensity and detuning of the first cooling light and the magnetic field parameters of the Zeeman reducer, and to measure the deceleration efficiency of the Zeeman reducer under different parameters, so as to obtain the light intensity, detuning and magnetic field parameters of the first cooling light when the deceleration efficiency is the highest.

[0030] The second cooling light deceleration module is configured to decelerate the high-temperature atomic beam based on the light intensity, detuning and magnetic field parameters of the first cooling light when the deceleration efficiency is highest, and the coverage range is the same as that of the first cooling light.

[0031] The second deceleration efficiency adjustment module is used to adjust the light intensity and detuning of the second cooling light, and to measure the deceleration efficiency of the Zeeman reducer under different parameters, so as to obtain the light intensity and detuning of the second cooling light when the deceleration efficiency is the highest.

[0032] The third technical solution adopted in this invention is: a Zeeman deceleration optimization device for multi-component atoms, comprising an atomic furnace, a first differential tube, a second differential tube, a Zeeman decelerator, a magneto-optical trap, a first cooling beam, and a second cooling beam, wherein:

[0033] The atomic furnace is used to generate high-temperature atomic beams;

[0034] The high-temperature atomic beam exits the atomic furnace and passes sequentially through the first differential tube, the second differential tube, and the Zeeman reducer before finally reaching the magneto-optical trap.

[0035] The first and second differential tubes are used to collimate the atomic beam.

[0036] The Zeeman reducer is used to pre-decelerate the high-temperature atomic beam;

[0037] The magneto-optical trap is used to capture high-temperature atoms after cooling and deceleration;

[0038] The first and second cooling lights are used to improve and optimize the deceleration efficiency of the Zeeman reducer.

[0039] Furthermore, the coverage area of ​​the first cooling light and the second cooling light extends from the furnace outlet to the magneto-optical trap.

[0040] The beneficial effects of the method and apparatus of this invention are as follows: This invention generates a Zeeman reducer magnetic field with field strength varying with position within the Zeeman reducer range; the intensity and detuning of the first cooling light and the Zeeman reducer magnetic field are set and adjusted to decelerate the high-temperature atomic beam; at the state where the Zeeman reducer has the highest deceleration efficiency, the intensity and detuning of the second cooling light are set and adjusted so that the deceleration efficiency of the Zeeman reducer reaches its maximum under the two cooling lights, which can improve the Zeeman deceleration efficiency of multi-component atoms and provide sufficient atoms for the preparation of quantum degenerate Fermi gas. Attached Figure Description

[0041] Figure 1 This is a flowchart of the Zeeman deceleration optimization method for multi-component atoms according to the present invention;

[0042] Figure 2 This is a structural diagram of a Zeeman deceleration optimization system for multi-component atoms according to the present invention;

[0043] Figure 3 This is a diagram showing the magnetic field distribution curve of a Zeeman reducer based on the Zeeman deceleration optimization method for multi-component atoms according to the present invention.

[0044] Figure 4 This is an atomic energy level transition diagram of a Zeeman deceleration optimization method for multi-component atoms according to the present invention;

[0045] Figure 5 This is a schematic diagram of the structure of a Zeeman deceleration optimization device for multi-component atoms according to the present invention;

[0046] Figure descriptions: 1. First cooling beam; 2. Second cooling beam; 3. First differential tube; 4. Second differential tube; 5. Atomic furnace; 6. Zeeman reducer; 7. Magneto-optical trap. Detailed Implementation

[0047] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

[0048] Reference Figure 1 This invention provides a Zeeman deceleration optimization method for multi-component atoms, the method comprising the following steps:

[0049] S1. Based on the field coil generating a Zeeman reducer magnetic field with varying field strength within the Zeeman reducer range;

[0050] Specifically, refer to Figure 3 The magnetic field strength of the Zeeman reducer increases continuously with the increase of position, and its expression is as follows:

[0051]

[0052] Where B(x) represents the magnetic field strength of the Zeeman reducer, δ0 represents laser detuning, and μ′ represents the effective magnetic moment. Let v(x) represent the reduced Planck constant, also known as the Dirac constant, k represent the laser wave vector, and v(x) represent the initial velocity v. c The curve showing the change in velocity of atoms in a Zeeman reducer as a function of their path of motion.

[0053] S2. Set the first cooling light to decelerate the high-temperature atomic beam and cover the area from the atomic furnace outlet to the magneto-optical trap;

[0054] Specifically, the high-temperature atomic beam is 173 The energy level distribution and transitions of Yb atoms in the Zeeman reducer are as follows: Figure 4 As shown. The Zeeman decelerator applies acceleration to the high-temperature atomic beam, and its expression is as follows:

[0055]

[0056] Where 'a' represents the acceleration experienced by the atom in the Zeeman decelerator. Let denot be the reduced Planck constant, k be the laser wave vector, Γ be the spontaneous emissivity of the excited state, m be the atomic mass, s be the laser saturation parameter, δ be the effective detuning, δ0 be the laser detuning, μ′ be the effective magnetic moment, B(x) be the field strength of the Zeeman reducer magnetic field, and v be the velocity of the atom.

[0057] The first cooling light wavelength is 399 nm; the cooling light 1 is circularly polarized light, whose laser detuning matches the magnetic field distribution, enabling energy level transitions in the Zeeman reducer to |F=5 / 2,m F =5 / 2>→|F=7 / 2,m F Atoms with a ratio of 7 / 2> produce a better deceleration effect.

[0058] S3. Adjust the light intensity and detuning of the first cooling light and the magnetic field parameters of the Zeeman reducer, and measure the deceleration efficiency of the Zeeman reducer under different parameters to obtain the light intensity, detuning and magnetic field parameters of the first cooling light when the deceleration efficiency is the highest.

[0059] Specifically, the light intensity and detuning of the first cooling light and the magnetic field parameters of the Zeeman reducer are adjusted, and the velocity distribution of the high-temperature atomic beam after deceleration by the Zeeman reducer under different parameters is measured.

[0060] Next, the trapping velocity of the magneto-optical trap is calculated, and its calculation expression is as follows:

[0061]

[0062] Among them, v cap The value represents the trapping velocity of the magneto-optical trap, and m represents the atomic mass. Let Γ denote the reduced Planck constant, k denote the laser wave vector, Γ denote the spontaneous emissivity of the excited state, and ω denote the beam waist radius of the magneto-optical trap.

[0063] Then, the velocity distribution of the high-temperature atomic beam after being decelerated by the Zeeman reducer under different parameters is compared with the trapping velocity of the magneto-optical trap to obtain the comparison results under different parameters. Finally, the deceleration efficiency of the Zeeman reducer is determined based on the comparison results under different parameters. If the comparison results under different parameters show that the number of atoms with a velocity lower than the trapping velocity of the magneto-optical trap is more, it indicates that the deceleration efficiency of the Zeeman reducer is higher.

[0064] Because atoms at different energy levels have different effective magnetic moments μ', when using the first cooling light, under the influence of the magnetic field and the cooling light, atoms at a certain energy level can maintain a constant δ value of 0 in the Zeeman decelerator, experiencing the maximum deceleration force. However, atoms at other energy levels, due to their effective magnetic moments μ', cannot maintain a constant effective detuning, resulting in a smaller deceleration force and a poor deceleration effect from a single beam of cooling light. Therefore, this scheme adds a second cooling light to optimize the Zeeman deceleration of the component atoms.

[0065] S4. Based on the light intensity, detuning and magnetic field parameters of the first cooling light when the deceleration efficiency is the highest, the second cooling light is set to decelerate the high-temperature atomic beam, and the coverage range is the same as that of the first cooling light.

[0066] Specifically, the laser detuning of the second cooling light is different from that of the first cooling light. Since the effective magnetic moments μ' of atoms of different components are different, the second cooling light, in conjunction with the first cooling light, can change the effective detuning δ of atoms of different energy levels with the laser, so that more atoms are decelerated.

[0067] S5. Adjust the light intensity and detuning of the second cooling light, and measure the deceleration efficiency of the Zeeman reducer under different parameters to obtain the light intensity and detuning of the second cooling light when the deceleration efficiency is the highest.

[0068] Specifically, the intensity and detuning of the second cooling light are adjusted, and the velocity distribution of the high-temperature atomic beam after deceleration by the Zeeman reducer under different parameters is measured. Then, the velocity distribution of the high-temperature atomic beam after deceleration by the Zeeman reducer under different parameters with the second and first cooling lights is compared with the trapping velocity of the magneto-optical trap. If the comparison results under different parameters show that the number of atoms with a velocity lower than the trapping velocity of the magneto-optical trap is more, it indicates that the deceleration efficiency of the Zeeman reducer is higher.

[0069] Reference Figure 2 This invention provides a Zeeman deceleration optimization system for multi-component atoms, comprising:

[0070] The magnetic field generation module generates the Zeeman reducer magnetic field within the range of the Zeeman reducer based on the magnetic field coil.

[0071] The first cooling light deceleration module is used to set the first cooling light to decelerate the high-temperature atomic beam and cover the range from the atomic furnace outlet to the magneto-optical trap.

[0072] The first deceleration efficiency adjustment module is used to adjust the light intensity and detuning of the first cooling light and the magnetic field parameters of the Zeeman reducer, and to measure the deceleration efficiency of the Zeeman reducer under different parameters, so as to obtain the light intensity, detuning and magnetic field parameters of the first cooling light when the deceleration efficiency is the highest.

[0073] The second cooling light deceleration module is configured to decelerate the high-temperature atomic beam based on the light intensity, detuning and magnetic field parameters of the first cooling light when the deceleration efficiency is highest, and the coverage range is the same as that of the first cooling light.

[0074] The second deceleration efficiency adjustment module is used to adjust the light intensity and detuning of the second cooling light, and to measure the deceleration efficiency of the Zeeman reducer under different parameters, so as to obtain the light intensity and detuning of the second cooling light when the deceleration efficiency is the highest.

[0075] The content of the above method embodiments is applicable to this system embodiment. The specific functions implemented in this system embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0076] Reference Figure 5 This invention provides a Zeeman deceleration optimization device for multi-component atoms, comprising an atomic furnace 5, a first differential tube 3, a second differential tube 4, a Zeeman decelerator 6, a magneto-optical trap 7, a first cooling beam 1, and a second cooling beam 2, wherein:

[0077] The atomic furnace 5 is used to generate high-temperature atomic beams;

[0078] The high-temperature atomic beam is emitted from the outlet of the atomic furnace 5 and passes sequentially through the first differential tube 3, the second differential tube 4, and the Zeeman reducer 6, finally reaching the magneto-optical trap 7;

[0079] Preferably, there are distance gaps between the outlet of the atomic furnace 5 and the first differential tube 3, between the first differential tube 3 and the second differential tube 4, between the second differential tube 4 and the Zeeman reducer 6, and between the Zeeman reducer 6 and the magneto-optical trap 7.

[0080] The first differential tube 3 and the second differential tube 4 have a diameter of 7 mm and a length of 42 mm, and are used to collimate the atomic beam.

[0081] The Zeeman reducer 6 is used to pre-decelerate the high-temperature atomic beam;

[0082] The magneto-optical trap 7 is used to capture high-temperature atoms after cooling and deceleration;

[0083] The first cooling light 1 and the second cooling light 2 are used to improve and optimize the deceleration efficiency of the Zeeman reducer.

[0084] Preferably, the coverage area of ​​the first cooling light 1 and the second cooling light 2 is from the furnace outlet to the magneto-optical trap.

[0085] The content of the above method embodiments is applicable to the device embodiments. The specific functions implemented by the device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0086] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A Zeeman deceleration optimization method for multi-component atoms, characterized in that, Includes the following steps: Based on the generation of the Zeeman reducer magnetic field within the range of the magnetic field coil; The first cooling light is set to decelerate the high-temperature atomic beam and cover the area from the atomic furnace exit to the magneto-optical trap; The light intensity and detuning of the first cooling light and the magnetic field parameters of the Zeeman reducer are adjusted, and the deceleration efficiency of the Zeeman reducer under different parameters is measured to obtain the light intensity, detuning and magnetic field parameters of the first cooling light when the deceleration efficiency is the highest. Based on the light intensity, detuning and magnetic field parameters of the first cooling light when the deceleration efficiency is the highest, the second cooling light is set to decelerate the high-temperature atomic beam, and the coverage range is the same as that of the first cooling light. The intensity and detuning of the second cooling light were adjusted, and the deceleration efficiency of the Zeeman reducer under different parameters was measured to obtain the intensity and detuning of the second cooling light when the deceleration efficiency was the highest.

2. The Zeeman deceleration optimization method for multi-component atoms according to claim 1, characterized in that, The field strength expression of the Zeeman reducer's magnetic field is as follows: in, This indicates the magnetic field strength of the Zeeman reducer. Indicates laser detuning. Indicates the effective magnetic moment, This represents the reduced Planck constant. Represents the laser wave vector. Indicates the initial velocity is The curve showing the change in velocity of atoms in a Zeeman reducer as a function of their path of motion.

3. The Zeeman deceleration optimization method for multi-component atoms according to claim 1, characterized in that, The Zeeman decelerator applies acceleration to the high-temperature atomic beam, as expressed below: in, This represents the acceleration experienced by an atom in a Zeeman decelerator. This represents the reduced Planck constant. Represents the laser wave vector. Represents the spontaneous emission rate of the excited state. Indicates atomic mass, Indicates the laser saturation parameter. Indicates effective mistuning. Indicates laser detuning. Indicates the effective magnetic moment, This indicates the magnetic field strength of the Zeeman reducer. This indicates the velocity of an atom.

4. The Zeeman deceleration optimization method for multi-component atoms according to claim 1, characterized in that, The step of adjusting the light intensity and detuning of the first cooling light and the magnetic field parameters of the Zeeman reducer, and measuring the deceleration efficiency of the Zeeman reducer under different parameters to obtain the light intensity, detuning, and magnetic field parameters of the first cooling light when the deceleration efficiency is highest, specifically includes: Adjust the light intensity and detuning of the first cooling light and the magnetic field parameters of the Zeeman reducer, and measure the velocity distribution of the high-temperature atomic beam after it is decelerated by the Zeeman reducer under different parameters; The trapping velocity of the magneto-optical trap was calculated and compared with the velocity distribution of the high-temperature atomic beam after being decelerated by the Zeeman decelerator under different parameters, and the comparison results under different parameters were obtained. The reduction efficiency of the Zeeman reducer is determined based on the comparison results under the different parameters.

5. The Zeeman deceleration optimization method for multi-component atoms according to claim 4, characterized in that, The capture velocity of the magneto-optical trap is calculated using the following expression: in, This indicates the capture velocity of the magneto-optical trap. Indicates atomic mass, This represents the reduced Planck constant. Represents the laser wave vector. Represents the spontaneous emission rate of the excited state. This indicates the radius of the laser beam waist in the magneto-optical trap.

6. A Zeeman deceleration optimization system for multi-component atoms, characterized in that, include: The magnetic field generation module generates the Zeeman reducer magnetic field within the range of the Zeeman reducer based on the magnetic field coil. The first cooling light deceleration module is used to set the first cooling light to decelerate the high-temperature atomic beam and cover the range from the atomic furnace outlet to the magneto-optical trap. The first deceleration efficiency adjustment module is used to adjust the light intensity and detuning of the first cooling light and the magnetic field parameters of the Zeeman reducer, and to measure the deceleration efficiency of the Zeeman reducer under different parameters, so as to obtain the light intensity, detuning and magnetic field parameters of the first cooling light when the deceleration efficiency is the highest. The second cooling light deceleration module is configured to decelerate the high-temperature atomic beam based on the light intensity, detuning and magnetic field parameters of the first cooling light when the deceleration efficiency is highest, and the coverage range is the same as that of the first cooling light. The second deceleration efficiency adjustment module is used to adjust the light intensity and detuning of the second cooling light, and to measure the deceleration efficiency of the Zeeman reducer under different parameters, so as to obtain the light intensity and detuning of the second cooling light when the deceleration efficiency is the highest.

7. A Zeeman deceleration optimization device for multi-component atoms, used to implement the Zeeman deceleration optimization method for multi-component atoms as described in any one of claims 1-5, characterized in that, It includes a nuclear reactor, a first differential tube, a second differential tube, a Zeeman reducer, a magneto-optical trap, a first cooling beam, and a second cooling beam, wherein: The atomic furnace is used to generate high-temperature atomic beams; The high-temperature atomic beam exits the atomic furnace and passes sequentially through the first differential tube, the second differential tube, and the Zeeman reducer before finally reaching the magneto-optical trap. The first and second differential tubes are used to collimate the atomic beam. The Zeeman reducer is used to pre-decelerate the high-temperature atomic beam; The magneto-optical trap is used to capture high-temperature atoms after cooling and deceleration; The first and second cooling lights are used to improve and optimize the deceleration efficiency of the Zeeman reducer.

8. The Zeeman deceleration optimization device for multi-component atoms according to claim 7, characterized in that, The coverage area of ​​the first cooling light and the second cooling light is from the furnace outlet to the magneto-optical trap.

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