A method and device for stabilizing static magnetic field of atomic beam clock based on two atoms

Abstract

The present application relates to the field of atomic frequency standards and provides a method and device for stabilizing the static magnetic field of an atomic beam clock based on two atoms. By introducing a second atom on the basis of a traditional atomic beam clock, the two atoms work together in the same path and magnetic field. The first atom is responsible for generating clock transitions as the main frequency reference; while the second atom is specifically used for static magnetic field stabilization. By periodically scanning the Ramsey pattern of the second atom, the changes in the static magnetic field are detected and compensated accordingly to ensure that the static magnetic field remains constant. Since the two atoms are in the same static magnetic field environment, when the static magnetic field of the second atom is stable, the static magnetic field of the first atom also remains stable, effectively eliminating the magnetic field frequency shift. Throughout the process, the locking loop of the first atom is always in a closed state, avoiding the adverse effects on long-term stability caused by the open loop in the traditional method, and improving the long-term stability of the atomic beam clock.

Description

Technical Field

[0001] The present application relates to the field of atomic frequency standards, and in particular to a method and device for stabilizing the static magnetic field of a diatomic atomic beam clock based on diatomic frequencies. Background Art

[0002] The contents of this section merely provide background information related to this application and may not constitute prior art.

[0003] Atomic hyperfine level transitions, due to their high precision and stability, are ideal for constructing reference signals, particularly in atomic clock applications. The operating principle of an atomic clock is based on the atomic hyperfine level transition spectrum. A servo circuit precisely locks the output frequency of a voltage-controlled crystal oscillator to this spectrum, thereby achieving a high-precision and stable signal output with the same atomic transition frequency. However, although atomic hyperfine level transitions are highly resistant to external interference, they are still affected by fluctuations in the temperature, magnetic, optical, and microwave fields surrounding the atoms, causing atomic energy levels to shift (frequency shift), a key factor affecting the frequency accuracy and long-term stability of atomic clocks.

[0004] To improve the performance of atomic clocks, reducing frequency shift is a key approach. Common types of frequency shift include collision frequency shift, Doppler frequency shift, magnetic field frequency shift, and optical frequency shift. Compared to atomic clocks using "storage bubble" technology, "atomic beam clocks" using "atomic beam" technology have significant advantages in reducing frequency shift. The atoms in an atomic beam clock move freely in a straight line in a vacuum, avoiding collisions between atoms and thus eliminating collision frequency shift. At the same time, the direction of atomic movement is perpendicular to the propagation direction of the external electromagnetic wave, effectively avoiding the Doppler effect and thus eliminating Doppler frequency shift. Therefore, atomic beam clocks excel in frequency accuracy and have become a first-class frequency standard.

[0005] Magnetic field frequency shift originates from the slow changes in the magnetic field surrounding atoms. To reduce magnetic field frequency shift and improve the accuracy and medium- to long-term stability of atomic beam clocks, two methods are commonly used to stabilize the static magnetic field: one is to use a high-stability constant current source. This has the advantage of not interfering with the frequency control loop of the atomic beam clock, but the disadvantage is that it places extremely high demands on the stability of the constant current source's output current, resulting in a complex and costly design and susceptibility to minor changes in the environment, temperature, magnetic shielding, and other factors. The other is to use dynamic servo technology, which uses periodic open-loop scanning to dynamically adjust the output current of the magnetic field constant current source, utilizing the relationship between the magnetic field strength felt by the atoms and the difference in the Ramsey transition frequency, thereby maintaining a constant magnetic field strength. The advantage of this method is that it fundamentally ensures the stability of the magnetic field strength and reduces the requirements for the magnetic field constant current source. However, the disadvantage is that the open-loop process can affect the long-term stability of the atomic clock and introduce uncontrollable factors. Summary of the Invention

[0006] In order to solve the above technical problems, the purpose of this application is to provide a method and device for stabilizing the static magnetic field of an atomic beam clock based on two atoms, by using two atoms to realize the atomic beam clock, so that the first atom is used to generate clock transitions, and the second atom is used to stabilize the static magnetic field. Then, by scanning the Ramsey pattern of the second atom, the static magnetic field changes are detected and compensated, thereby keeping the static magnetic field unchanged; utilizing the characteristics that the two atoms are in the same static magnetic field environment, the static magnetic field of the first atom also remains unchanged, thereby eliminating the magnetic field frequency shift.

[0007] The purpose of this application is achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a method for stabilizing a static magnetic field of an atomic beam clock based on a diatomic structure, comprising:

[0009] Two types of atoms are selected, wherein the first type of atom is used as the first atom for generating clock transition, and the second type of atom is used as the second atom for static magnetic field stabilization;

[0010] generating a collinear diatomic beam comprising a first atom and a second atom in a heating furnace under the same path;

[0011] Atomic state preparation is performed on the diatomic beam by emitting two pumping lights of different frequencies through a frequency-stabilized semiconductor laser light source. The two pumping lights are set to pass through the diatomic beam perpendicularly, so that the two pumping lights respectively generate electric dipole resonance with the first atom and the second atom, so that the first atom and the second atom are respectively in their specific ground state hyperfine energy levels;

[0012] The diatomic beam is injected into a dual-mode zero-phase Ramsey cavity. Under the action of a static magnetic field, the first atom and the second atom are excited by a microwave field at the corresponding frequency of the ground state 0-0 hyperfine level transition, so that the first atom and the second atom complete their respective microwave transitions.

[0013] Two probe lights of different frequencies are emitted by a frequency-stabilized semiconductor laser light source, and the two probe lights vertically pass through the diatomic beam after microwave transition and respectively generate electric dipole resonance with the first atom and the second atom;

[0014] A Ramsey resonance transition signal after microwave transition and electric dipole resonance of the first atom and the second atom is received through a fluorescence collector, and the Ramsey resonance transition signal of the first atom is used as a clock transition signal; the clock transition signal is used as a reference signal of the atomic beam clock, and in a servo control system, a phase detector is used to compare the phase of the clock transition signal and the voltage-controlled crystal oscillator signal to obtain an error signal of the voltage-controlled crystal oscillator; the error signal is amplified and filtered by a loop filter to obtain a smooth control signal, and the voltage of the voltage-controlled crystal oscillator is controlled according to the control signal to adjust the frequency of the voltage-controlled crystal oscillator so that the frequency of the voltage-controlled crystal oscillator is consistent with the frequency of the clock transition signal;

[0015] During the operation of the atomic beam clock, the Ramsey resonance transition signal of the second atom is scanned periodically. Taking advantage of the fact that the static magnetic field intensity is proportional to the difference between the two transition frequencies of the second atom, the static magnetic field current value is adjusted to ensure that the difference between the two transition frequencies of the second atom remains unchanged, thereby achieving stability of the static magnetic field.

[0016] Furthermore, the first atom is 87 Rb, the second atom is 133 Cs.

[0017] In a second aspect, the present invention provides a diatomic atomic beam clock static magnetic field stabilization device, which is applied to a diatomic atomic beam clock static magnetic field stabilization method as described in the first aspect. The stabilization device includes:

[0018] A cesium beam tube is provided with a first optical window located between the heating furnace and the dual-mode 0-phase-difference Ramsey cavity, and a second optical window located between the dual-mode 0-phase-difference Ramsey cavity and the fluorescence collector; the first optical window is used to transmit pump light, and the second optical window is used to transmit detection light;

[0019] A heating furnace is provided in the cesium beam tube, and an output port of the heating furnace is provided with a collimating channel, so that a collinear diatomic beam containing a first atom and a second atom is generated in the heating furnace, and the collinear diatomic beam is perpendicular to the pumping light;

[0020] A dual-mode 0-phase-difference Ramsey cavity is provided in a cesium beam tube. The heating furnace, the dual-mode 0-phase-difference Ramsey cavity, and the fluorescence collector are collinearly arranged in sequence. The collinear diatomic beam passes through the dual-mode 0-phase-difference Ramsey cavity and reaches the fluorescence collector. A magnetic shield is provided outside the dual-mode 0-phase-difference Ramsey cavity, and a magnetic field coil is provided inside the magnetic shield.

[0021] An electronics system, the electronics system includes a dual-frequency microwave source, a voltage-controlled crystal oscillator, a constant current source and a servo control system; a dual-mode 0-phase-difference Ramsey cavity, a dual-frequency microwave source, a voltage-controlled crystal oscillator, a servo control system and a fluorescence collector are connected in sequence; the Ramsey resonance transition signal generated by the interaction between the diatomic beam after microwave transition and the detection laser is received through the fluorescence collector, and the Ramsey resonance transition signal of the first atom is used as the clock transition signal; in the servo control system, the clock transition signal is phase-sensitively detected to obtain the error signal of the voltage-controlled crystal oscillator; the dual-mode 0-phase-difference Ramsey cavity is used to generate microwave fields of two frequencies; a magnetic shielding cover is provided outside the dual-mode 0-phase-difference Ramsey cavity, and a magnetic field coil is provided inside the magnetic shielding cover, and the magnetic field coil is used to generate a static magnetic field, which covers the collinear diatomic beam and causes the first atom and the second atom in the collinear diatomic beam to undergo a ground state 0-0 hyperfine energy level transition according to the corresponding microwave frequency;

[0022] A laser system comprising a first frequency-stabilized semiconductor laser light source, a first half-glass slide + PBS combination, a first semi-transparent and semi-reflective mirror, a second half-glass slide + PBS combination, and a second semi-transparent and semi-reflective mirror; the first frequency-stabilized semiconductor laser light source emits laser light that is incident on the first half-glass slide + PBS combination, and the first half-glass slide + PBS combination can continuously adjust the light intensity of the first frequency-stabilized semiconductor laser; the laser light after passing through the first half-glass slide + PBS combination is incident on the first semi-transparent and semi-reflective mirror, and is divided into a first light ray and a second light ray; the first light ray serves as a first pumping light and passes through a first light window to perpendicularly intersect a diatomic beam; the second light ray enters the second half-glass slide + PBS combination, and the second half-glass slide + PBS combination can continuously adjust the light intensity of the second light ray; the laser light after passing through the second half-glass slide + PBS combination is incident on the second semi-transparent and semi-reflective mirror as a first detection light and passes through the second light window to perpendicularly intersect the diatomic beam;

[0023] The laser system also includes a second frequency-stabilized semiconductor laser, a third half glass slide + PBS combination, a third semi-transparent semi-reflective mirror, a fourth half glass slide + PBS combination, and a 45-degree reflective mirror; the laser light emitted by the second frequency-stabilized semiconductor laser is incident on the third half glass slide + PBS combination, and the third half glass slide + PBS combination can continuously adjust the light intensity of the second frequency-stabilized semiconductor laser; the laser light after passing through the third half glass slide + PBS combination is incident on the third semi-transparent semi-reflective mirror, and is divided into a third light ray and a fourth light ray; the third light ray serves as the second pumping light and passes through the first light window to perpendicularly intersect the diatomic beam; the fourth light ray enters the fourth half glass slide + PBS combination, and the fourth half glass slide + PBS combination can continuously adjust the light intensity of the fourth light ray; the laser light after passing through the fourth half glass slide + PBS combination is incident on the 45-degree reflective mirror, serves as the second detection light, and passes through the second light window to perpendicularly intersect the diatomic beam.

[0024] Furthermore, the invention further comprises a graphite block, wherein the diatomic beam passes through the fluorescence collector and is injected into the graphite block.

[0025] Furthermore, the first pumping light and the first detection light have the same laser frequency, and the second pumping light and the second detection light have the same laser frequency.

[0026] Furthermore, the first pumping light and the second pumping light are collinear, and the first detection light and the second detection light are collinear.

[0027] In a third aspect, the present invention provides an electronic device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps corresponding to the method in the first aspect are implemented.

[0028] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps corresponding to the method in the first aspect.

[0029] In summary, the technical solutions of the embodiments of the present application have at least the following advantages and beneficial effects:

[0030] The present invention introduces a second atom by adopting a dual-atom atomic beam clock scheme, which works in conjunction with the first atom originally used to generate clock transitions in the same path and magnetic field environment. The first atom generates clock transitions, while the second atom is used to stabilize the static magnetic field. By scanning the Ramsey pattern of the second atom, changes in the static magnetic field can be accurately detected, and real-time compensation can be performed accordingly to ensure that the static magnetic field remains constant. Since the two atoms are in exactly the same static magnetic field environment, the influence of the static magnetic field on the first atom remains unchanged, thereby effectively eliminating the magnetic field frequency shift, an important factor affecting the accuracy of the atomic beam clock. The atomic beam clock using this dual-atom design allows the locking loop of the first atom to remain closed throughout the entire working process, successfully solving the problem of the loop possibly opening when detecting changes in the static magnetic field in the traditional scheme. The long-term stability of the atomic beam clock is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A flowchart of a diatomic atomic beam clock static magnetic field stabilization method provided by the present invention;

[0032] Figure 2 A schematic structural diagram of a diatomic atomic beam clock static magnetic field stabilization device provided by the present invention;

[0033] Figure 3 For atoms 87 Atomic energy level diagram of Rb;

[0034] Figure 4 For atoms 133 Atomic energy level diagram of Cs;

[0035] Figure 5 is m F = ±1 corresponding Ramsey pattern diagram.

[0036] Icons: 1. Cesium beam tube; 11. First optical window; 12. Second optical window; 2. Heating furnace; 21. Collimation channel; 3. Dual-mode 0-phase difference Ramsey cavity; 31. Magnetic shielding cover; 32. Magnetic field coil; 4. Control system; 41. Dual-frequency microwave source; 42. Voltage-controlled crystal oscillator; 43. Constant current source; 44. Servo control system; 5. Fluorescence collector; 6. Graphite block; 7. Laser system; 71. First frequency-stabilized semiconductor laser light source; 711. Second frequency-stabilized semiconductor laser; 72. First half glass slide + PBS combination; 73. First semi-transparent semi-reflective mirror; 74. Second half glass slide + PBS combination; 75. Second semi-transparent semi-reflective mirror; 76. 45° reflective mirror; 77. Fourth half glass slide + PBS combination; 78. Third semi-transparent semi-reflective mirror; 79. Third half glass slide + PBS combination. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0038] Example 1:

[0039] like Figure 1 As shown, the embodiment of the present application proposes a method for stabilizing the static magnetic field of a diatomic atomic beam clock, including:

[0040] S101, two atoms are selected, wherein the first atom is used as the first atom to generate clock transition, and the second atom is used as the second atom for static magnetic field stabilization. The first atom and the second atom can be used in various combinations. In this embodiment, the first atom is used as 87 Rb and the second atom are 133 Cs is used as an example to illustrate; if the first atom is 133 Cs, the second atom is 87 Rb; the first atom is 133 Cs, the second atom is 85 Rb, this patent also applies. 87 Rb atomic energy level diagram Figure 3 As shown, its clock transition frequency f1 is 6.8346875GHz. 133 Cs, atomic energy level diagram Figure 3 As shown, the static magnetic field is stabilized by Figure 5 The frequency difference is shown.

[0041] Specifically, the first atom and the second atom play different roles in the subsequent process: the first atom is selected as the first atom to produce the clock transition, while the second atom is used to stabilize the static magnetic field. The setting of this step is based on the characteristics of atomic hyperfine level transitions. The atomic clock uses the atomic hyperfine level transition spectrum as a reference signal, and locks the output frequency of the voltage-controlled crystal oscillator to the atomic hyperfine level transition spectrum through a servo circuit, thereby achieving high-precision and high-stability signal output. However, this transition is still affected by the external environment, especially the magnetic field, resulting in frequency shift, which in turn affects the frequency accuracy and long-term stability of the atomic clock. In order to solve this problem, the present invention proposes an innovative method, namely introducing a second atom to stabilize the static magnetic field.

[0042] S102 , generating a collinear diatomic beam containing a first atom and a second atom in the heating furnace 2 on the same path.

[0043] Specifically, by loading the two atoms into the same heating furnace 2 and ejecting them through the same collimation channel 21, it is ensured that they travel along the same path to form a collinear diatomic beam. This enables the two atoms to be processed and detected in the same magnetic field environment, which facilitates the subsequent realization of static magnetic field stabilization and clock transition locking. Secondly, this method of generating a collinear diatomic beam not only simplifies the device structure, but also helps to improve the stability and accuracy of the atomic beam clock. Because the two atoms are in the same physical environment, the interference and influence they are subject to are also the same, which can be compensated and corrected through subsequent signal processing, thereby further improving the performance of the atomic beam clock.

[0044] S103, preparing the atomic state of the diatomic beam, emitting two pumping lights of different frequencies through a frequency-stabilized semiconductor laser light source, setting the two pumping lights to pass through the diatomic beam vertically, so that the two pumping lights respectively generate electric dipole resonance with the first atom and the second atom, so as to achieve the first atom and the second atom being in their specific ground state hyperfine energy levels respectively.

[0045] Specifically, a frequency-stabilized semiconductor laser light source is used to emit two pumping lights of different frequencies, which are set to pass perpendicularly through the formed collinear diatomic beam. 87 Rb and 133 The two atoms of Cs have different energy level structures (such as Figure 3 and 4 Therefore, by precisely adjusting the frequencies of the two pump lights, they can be made to 87 Rb and 133The Cs atoms undergo electric dipole resonance. Electric dipole resonance is an effective method for atomic state preparation, capable of exciting atoms from their initial state to a specific excited state, and then returning to a specific ground state hyperfine energy level through processes such as spontaneous emission. Furthermore, since both atoms are prepared to specific energy levels, their responses to the external environment become more consistent and predictable, which facilitates subsequent signal processing and error correction, further improving the stability and accuracy of the atomic beam clock.

[0046] S104, injecting the diatomic beam into the dual-mode 0 phase difference Ramsey cavity 3, and under the action of the static magnetic field, respectively exciting the first atom and the second atom with a microwave field at the corresponding frequency of the ground state 0-0 hyperfine level transition, so that the first atom and the second atom complete their respective microwave transitions. 87 Rb completes microwave transition under the excitation of microwave magnetic field at the clock transition frequency f1≈6.8346875GHz; 133 Cs completes microwave transition under the excitation of microwave magnetic field at the clock transition frequency f2≈9.192631770.

[0047] Specifically, after the preparation of the diatomic beam and the precise control of the atomic state are completed, step S104 further advances the realization process of the atomic beam clock, which specifically involves introducing the diatomic beam into the dual-mode zero-phase difference Ramsey cavity 3 for microwave field excitation. First, the diatomic beam (including 87 Rb and 133 Cs atoms) are injected into a dual-mode zero-phase Ramsey cavity 3. This cavity is designed to accommodate and process the two atoms while ensuring that they can transition under the same static magnetic field environment.

[0048] In the Ramsey cavity, 87 Rb and 1 33 Two atoms, Cs, are excited by microwave fields at their respective corresponding frequencies. The frequencies of these microwave fields are precisely controlled to match the frequencies of the 0-0 hyperfine energy level transitions in the ground state of the two atoms. The microwave field excites the atoms from their ground state to a short-lived excited state, after which the atoms spontaneously radiate back to the other ground state, forming so-called Ramsey interference fringes. This enables high-precision measurement of the transition frequencies of the two atoms, providing an accurate reference signal for frequency locking of the atomic clock. At the same time, because both atoms undergo transitions in the same static magnetic field environment, their transition frequencies become consistent in their dependence on the magnetic field. This facilitates subsequent monitoring and stabilization of the static magnetic field by comparing the transition frequencies of the two atoms, thereby further improving the long-term stability and frequency accuracy of the atomic beam clock.

[0049] S105 , emitting two probe lights of different frequencies through a frequency-stabilized semiconductor laser light source, wherein the two probe lights vertically pass through the diatomic beam after microwave transition and generate electric dipole resonance with the first atom and the second atom respectively.

[0050] Specifically, a frequency-stabilized semiconductor laser light source emits two probe lights of different frequencies, which are set to pass perpendicularly through the diatomic beam that has completed the microwave transition. The frequency of the probe light can be precisely adjusted by modulating the frequency-stabilized semiconductor laser light source to produce electric dipole resonance with the atomic energy level after the transition. When the probe light resonates with the atom, the atom absorbs the photon and transitions from its current energy level to a higher energy level. This process causes the intensity of the probe light to change. By monitoring the changes in the intensity of the probe light, we can indirectly understand the state and number of atomic transitions, and further analyze and obtain the frequency information of the atomic clock.

[0051] S106, the Ramsey resonance transition signal after the microwave transition and electric dipole resonance of the first atom and the second atom are obtained through the fluorescence collector 5, and the Ramsey resonance transition signal of the first atom is used as the clock transition signal; the clock transition signal is used as the reference signal of the atomic beam clock; in the servo control system 44, a phase detector is used to compare the phase of the clock transition signal and the voltage-controlled crystal oscillator 42 signal to obtain an error signal of the voltage-controlled crystal oscillator 42; the error signal is amplified and filtered by a loop filter to obtain a smooth control signal, and the voltage of the voltage-controlled crystal oscillator 42 is controlled according to the control signal to adjust the frequency of the voltage-controlled crystal oscillator 42 so that the frequency of the voltage-controlled crystal oscillator 42 is consistent with the frequency of the clock transition signal.

[0052] Specifically, a fluorescence collector 5 receives the diatomic beam after microwave transitions and electric dipole resonance. During this process, the fluorescence collector 5 captures the fluorescence signals emitted by the atoms during the transitions, which contain key information about the atomic clock's transitions. The system then extracts the clock transition signal from these fluorescence signals. This signal serves as the reference signal for the atomic beam clock, boasting extremely high frequency stability and accuracy.

[0053] To convert this reference signal into an actual clock output, a phase detector in the servo control system 44 is further utilized to perform a phase comparison between the clock transition signal and the signal generated by the voltage-controlled crystal oscillator 42. This comparison process accurately measures the phase difference between the voltage-controlled crystal oscillator 42 signal and the clock transition signal, i.e., the error signal. The magnitude and direction of the error signal reflect the deviation between the frequency of the voltage-controlled crystal oscillator 42 and the frequency of the clock transition signal. To precisely adjust the frequency of the voltage-controlled crystal oscillator 42, the error signal is fed into a loop filter for amplification and filtering. The loop filter smoothes the error signal to eliminate noise and interference while maintaining signal accuracy. The filtered control signal is used to adjust the control voltage of the voltage-controlled crystal oscillator 42, thereby achieving precise adjustment of the frequency of the voltage-controlled crystal oscillator 42.

[0054] Finally, by continuously adjusting the control voltage of the voltage-controlled crystal oscillator 42 , the frequency of the voltage-controlled crystal oscillator 42 gradually approaches the frequency of the clock transition signal, thereby achieving high stability and high-precision output of the atomic beam clock.

[0055] S107, during the operation of the atomic beam clock, periodically scan the Ramsey resonance transition signal of the second atom, and utilize the characteristic that the static magnetic field strength is proportional to the difference between the two transition frequencies of the second atom. By adjusting the static magnetic field current value, the difference between the two transition frequencies of the second atom remains unchanged, so as to achieve the stability of the static magnetic field.

[0056] Specifically, the Ramsey resonance transition signal of the second atom is used as a tool to monitor the stability of the static magnetic field. The Ramsey resonance transition signal is generated when an atom undergoes hyperfine energy level transition in a specific magnetic field environment, and its frequency is very sensitive to the magnetic field strength. By periodically scanning the Ramsey resonance transition signal of the second atom, the change in magnetic field strength can be monitored in real time. Secondly, there is a proportional relationship between the static magnetic field strength and the difference between the two specific transition frequencies of the second atom. This means that when the magnetic field strength changes, the difference between the two transition frequencies of the second atom will also change accordingly. Therefore, the change in magnetic field strength is indirectly monitored by monitoring the change in the two transition frequency differences.

[0057] To stabilize the static magnetic field, the difference between the two transition frequencies of the second atom must remain constant. To achieve this, the static magnetic field current is adjusted to alter the magnetic field strength, thereby offsetting the effects of external interference on the magnetic field. Specifically, when a change in the difference between the two transition frequencies of the second atom is detected, the control system automatically adjusts the static magnetic field current to restore the magnetic field strength to the original set value, thus ensuring that the difference between the two transition frequencies remains constant.

[0058] In detail, according to 133 The relationship between Cs atomic transition frequency and magnetic field strength:

[0059]

[0060] Among them, v0 is f1≈6.8346875GHz; v (0,0) is the frequency of the microwave excitation signal that causes the atom to transition; H0 is the static magnetic field strength, in Gauss.

[0061] For ΔF=±1,Δm F =0, the transition frequency is:

[0062]

[0063] in, represent 133 Cs atom F=4,m F With F = 3, m F The frequency of transitions between two Zeeman sublevels.

[0064] For m F = ±1, the frequency difference between the two transitions is (see Figure 5 ):

[0065]

[0066] Where Δv is m F = ±1, the difference between the two transition frequencies, for 133 Cs atom F=4,m F =1 and F=3,m F =1The transition frequency between two Zeeman sublevels, for 133 Cs atom F=4,m F =-1 and F=3,m F =-1The transition frequency between two Zeeman sublevels.

[0067] From formula (3), we can know that the static magnetic field intensity H0 is related to m F = ±1 is proportional to the difference in the two transition frequencies, that is, m F = ±1 reflects the change of static magnetic field. F =±1 is used as a reference signal to dynamically adjust the current value of the constant current source 43 to achieve static magnetic field stability.

[0068] And get m F = ±1, the difference between the two transition frequencies is in the first atom 87 After Rb achieves atomic beam clock frequency locking, it scans f2 between 9192666770Hz and 9192681770Hz to obtain the second atomic 133 Cs m F =Frequency value of +1 peak f2+ ; Scan f2 between 9192581770 and 9192596770 to obtain the second atom 133 Cs m F =-1 peak frequency f 2- ; with f 2+ -f 2- The constant current source 43 is dynamically adjusted based on the fixed value, thereby achieving magnetic field stability.

[0069] Example 2:

[0070] Based on the same inventive concept, Figure 2 As shown, the present invention provides a diatomic atomic beam clock static magnetic field stabilization device, which uses a diatomic atomic beam clock static magnetic field stabilization method in Example 1. The stabilization device includes:

[0071] A cesium beam tube 1 is provided with a first light window 11 located between the heating furnace 2 and the dual-mode 0 phase difference Ramsey cavity 3, and a second light window 12 located between the dual-mode 0 phase difference Ramsey cavity 3 and the fluorescence collector 5; the first light window 11 is used to transmit pumping light, and the second light window 12 is used to transmit detection light.

[0072] Specifically, the design of the cesium beam tube 1 not only ensures the effective generation, transmission and processing of the atomic beam, but also realizes the precise control and detection of the atomic beam by the laser through the optical window structure thereon. It includes a heating furnace 2, a dual-mode 0 phase difference Ramsey cavity 3 and a fluorescence collector 5, etc., which are arranged in a collinear manner to ensure that the atomic beam is efficiently and stably transmitted in a straight line. The heating furnace 2 is located at the starting part of the cesium beam tube 1, and is loaded with the first atom (such as 87 Rb) and the second atom (such as 133 Cs). Under the heating effect of heating furnace 2, the two atoms are evaporated and form a collinear diatomic beam, which is precisely emitted through collimation channel 21. This design ensures that the two atoms can be processed and detected under the same physical conditions, providing a solid foundation for subsequent static magnetic field stabilization and clock transition locking.

[0073] Two optical windows are specially provided on the cesium beam tube 1, namely the first optical window 11 and the second optical window 12, which are respectively located between the heating furnace 2 and the dual-mode 0 phase difference Ramsey cavity 3, and between the dual-mode 0 phase difference Ramsey cavity 3 and the fluorescence collector 5. They allow light of specific frequencies (such as pump light and detection light) to penetrate the cesium beam tube 1 and interact with the atomic beam, and also ensure the vertical intersection of the light and the atomic beam, thereby realizing the precise preparation and detection of the atomic state.

[0074] Specifically, the first optical window 11 is mainly used to transmit the pumping light. In the atomic state preparation stage, the frequency-stabilized semiconductor laser light source emits two pumping lights of different frequencies, which are respectively 87 Rb and 133 The two pump beams are set to transition to specific energy levels of Cs atoms. These two pump beams pass perpendicularly through the collinear diatomic beam via the first optical window 11, generating electric dipole resonance with the atoms, exciting them to a specific excited state. The atoms then return to a specific ground-state hyperfine energy level through processes such as spontaneous emission. This process enables precise control of the atomic state, providing reliable support for subsequent microwave transitions and signal detection.

[0075] The second optical window 12 is primarily used to transmit probe light. After the microwave transition and electric dipole resonance, the frequency-stabilized semiconductor laser light source emits two more probe lights of different frequencies. These light beams pass perpendicularly through the diatomic beam, which has already completed the microwave transition, through the second optical window 12. When the probe light resonates with the atoms, the atoms absorb the photons and transition from their current energy level to a higher one, causing the intensity of the probe light to change. By monitoring the changes in the probe light intensity, the state and number of atomic transitions can be indirectly understood, allowing for further analysis to determine the frequency information of the atomic clock.

[0076] A dual-mode 0-phase Ramsey cavity 3 is located within a cesium beam tube 1. The heating furnace 2, dual-mode 0-phase Ramsey cavity 3, and fluorescence collector 5 are collinearly arranged. The collinear diatomic beam passes through the dual-mode 0-phase Ramsey cavity 3 and reaches the fluorescence collector 5. A magnetic shield 31 is located outside the dual-mode 0-phase Ramsey cavity 3, and a magnetic field coil 32 is located within the magnetic shield 31. Specifically, the magnetic shield 31 is a device designed to reduce or eliminate the effects of external magnetic fields on electronic equipment or precision instruments within a specific area. Its design is based on Faraday's law of electromagnetic induction and the principle of magnetic field shielding. It is typically made of high-permeability materials that effectively guide and disperse external magnetic field lines, thereby protecting the space within the shield from interference from external magnetic fields. One or more magnetic field coils 32 are located within the magnetic shield 31. These coils are excited by current to generate an internal magnetic field, which is used to further control or adjust the magnetic field environment within the shield. The operating principle of the magnetic field coil 32 is based on Ampere's circuit law, which states that when current passes through a conductor, a magnetic field is generated around it. By precisely controlling the magnitude and direction of the current in the coil, a magnetic field of desired strength can be generated.

[0077] Electronics system 4, which includes a dual-frequency microwave source 41, a voltage-controlled crystal oscillator 42, a constant current source 43 and a servo control system 44; a dual-mode zero-phase difference Ramsey cavity 3, a dual-frequency microwave source 41, a voltage-controlled crystal oscillator 42, a servo control system 44 and a fluorescence collector 5 are connected in sequence; the fluorescence collector 5 receives the Ramsey resonance transition signal generated by the interaction between the diatomic beam after microwave transition and the detection laser, and obtains the clock transition signal; the clock transition signal is used as the reference signal of the atomic beam clock, and in the servo control system 44, the phase The detector compares the phase of the clock transition signal and the voltage-controlled crystal oscillator 42 signal to obtain the error signal of the voltage-controlled crystal oscillator 42; the dual-mode 0 phase difference Ramsey cavity 3 is used to generate microwaves of two frequencies, and a magnetic shielding cover 31 is provided outside the dual-mode 0 phase difference Ramsey cavity 3, and a magnetic field coil 32 is provided inside the magnetic shielding cover 31. The magnetic field coil 32 is used to generate a static magnetic field, which covers the collinear diatomic beam and enables the first atom and the second atom in the collinear diatomic beam to perform microwave field excitation of the ground state 0-0 hyperfine energy level transition frequency according to the corresponding microwave frequency.

[0078] Specifically, the dual-frequency microwave source 41 is responsible for generating two microwave signals of different frequencies, the frequencies of which are precisely controlled to match 87 Rb and 133 The frequencies of the 0-0 hyperfine energy level transitions between the two atomic ground states of Cs. Within a dual-mode, zero-phase-difference Ramsey cavity, these two microwave signals act on the two atoms, causing them to complete their respective microwave transitions. This step is fundamental to achieving high-precision atomic clock measurements.

[0079] The voltage-controlled crystal oscillator 42 is intended to generate a signal as the initial frequency reference of the atomic beam clock. However, due to the influence of the external environment (especially the magnetic field), the frequency of the voltage-controlled crystal oscillator 42 will shift, thereby affecting the frequency accuracy and long-term stability. In order to solve this problem, the present invention introduces a servo control system 44. The servo control system 44 receives the diatomic beam after microwave transition through the fluorescence collector 5, and extracts the clock transition signal from it. This signal serves as the reference signal of the atomic beam clock and has extremely high frequency stability and accuracy. Then, the servo control system 44 uses a phase detector to compare the phase of the clock transition signal with the signal generated by the voltage-controlled crystal oscillator 42, thereby accurately measuring the phase difference between the voltage-controlled crystal oscillator 42 signal and the clock transition signal, that is, the error signal.

[0080] The magnitude and direction of the error signal reflect the deviation between the frequency of the VCO 42 and the frequency of the clock transition signal. To precisely adjust the frequency of the VCO 42, the error signal is fed into a loop filter for amplification and filtering. The loop filter smoothes the error signal to eliminate noise and interference while maintaining signal accuracy. The filtered control signal is then used to adjust the control voltage of the VCO 42, thereby achieving precise frequency adjustment of the VCO 42.

[0081] In addition, the control system also includes a constant current source 43, which is used to provide a stable current to the magnetic field coil 32. The magnetic field coil 32 is located in a magnetic shield 31 outside the dual-mode zero-phase difference Ramsey cavity 3, and generates an internal static magnetic field through current excitation. This static magnetic field covers the collinear diatomic beam and allows the two types of atoms to transition under the same magnetic field environment. Since both atoms transition under the same static magnetic field environment, their transition frequencies become consistent in their dependence on the magnetic field, which is conducive to subsequent monitoring and stabilization of the static magnetic field by comparing the transition frequencies of the two atoms.

[0082] The laser system 7 is designed to vertically inject pump light and probe light into a preset position. The specific implementation method is as follows: the laser system 7 includes a first frequency-stabilized semiconductor laser light source 71, a first half-glass slide + PBS combination 72, a first semi-transparent semi-reflective mirror 73, a second half-glass slide + PBS combination 74, and a second semi-transparent semi-reflective mirror 75; the first frequency-stabilized semiconductor laser light source 71 emits laser light and injects it into the first half-glass slide + PBS combination 72, and the first half-glass slide + PBS combination 72 can continuously adjust the light intensity of the first frequency-stabilized semiconductor laser; the laser light after passing through the first half-glass slide + PBS combination 72 is injected into the first semi-transparent semi-reflective mirror 73, and the laser light is divided into a first light and a second light; the first light serves as the first pump light and passes through the first light window to intersect the diatomic beam vertically; the second light enters the second half-glass slide + PBS combination 74, and the second half-glass slide + PBS combination 74 can continuously adjust the light intensity of the second light; the laser light after passing through the second half-glass slide + PBS combination 74 is injected into the second semi-transparent semi-reflective mirror 75 as the first probe light, and passes through the second light window to intersect the diatomic beam vertically;

[0083] The laser system 7 also includes a second frequency-stabilized semiconductor laser 711, a third half-slide + PBS combination 79, a third semi-transparent semi-reflective mirror 78, a fourth half-slide + PBS combination 77, and a 45-degree reflective mirror 76. The laser light emitted by the second frequency-stabilized semiconductor laser 711 is incident on the third half-slide + PBS combination 79, which can continuously adjust the light intensity of the second frequency-stabilized semiconductor laser 711. The laser light passing through the third half-slide + PBS combination 79 is incident on the third semi-transparent semi-reflective mirror 78, which divides the laser light into a third light and a fourth light. The third light serves as the second pumping light and passes through the first light window to perpendicularly intersect the diatomic beam. The fourth light serves as the fourth half-slide + PBS combination 77, which can continuously adjust the light intensity of the fourth light. The laser light passes through the fourth half-slide + PBS combination 77 and enters the 45-degree reflective mirror 76 as the second detection light, which passes through the second light window and perpendicularly intersects the diatomic beam.

[0084] Among them, the laser frequency of the first pumping light and the first detection light are the same, both 87 The D2 line of Rb is 780nm. The laser frequencies of the second pumping light and the second detection light are the same, both 133 The D2 line of Cs is 852 nm. In order to simplify the device, the first pumping light and the second pumping light can be collinear, and the first detection light and the second detection light can be collinear.

[0085] Furthermore, a graphite block 6 is included, and the diatomic beam passes through the fluorescence collector 5 and is emitted into the graphite block 6 .

[0086] Specifically, graphite block 6 is designed to be placed at the rear end of fluorescence collector 5. After completing microwave transition and electric dipole resonance, the diatomic beam passes through fluorescence collector 5 and is received there, then continues onward and enters graphite block 6. Graphite block 6 plays two key roles here: first, it serves as a termination absorber for the atomic beam, and second, its unique physical properties help further stabilize the performance of the atomic beam clock.

[0087] First, as the atomic beam's final absorber, graphite block 6 effectively absorbs the remaining atomic beam, preventing it from further scattering or interfering with the normal operation of other components. This ensures the overall stability and accuracy of the atomic beam clock system and avoids errors caused by incomplete atomic beam processing.

[0088] Secondly, graphite block 6, with its high thermal conductivity and excellent thermal stability, helps maintain a stable temperature in the atomic beam clock's operating environment. During the precision measurements of an atomic beam clock, temperature fluctuations can significantly affect the atomic energy level structure and transition frequencies, leading to measurement errors. As a heat conduction medium, graphite block 6 effectively absorbs and dissipates the heat generated during the operation of the atomic beam clock, maintaining a constant system temperature and further improving the frequency accuracy and long-term stability of the atomic beam clock.

[0089] Furthermore, the laser system 7 also includes a second frequency-stabilized semiconductor laser light source 78 , which emits a supplementary laser that enters the second semi-transparent and semi-reflective mirror 75 , and the second semi-transparent and semi-reflective mirror 75 reflects the supplementary laser to the acousto-optic modulator 76 .

[0090] Based on the same inventive concept, the present invention provides an electronic device comprising: a memory, a processor, and a computer program stored on the memory and runnable on the processor. When the processor executes the computer program, a method for stabilizing the static magnetic field of a diatomic atomic beam clock is implemented.

[0091] Based on the same inventive concept, the present invention provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, a static magnetic field stabilization method for an atomic beam clock based on diatoms is implemented.

[0092] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for stabilizing the static magnetic field of an atomic beam clock based on diatomic atoms, characterized in that: Two types of atoms are selected, wherein the first type of atom is used as the first atom for generating clock transition, and the second type of atom is used as the second atom for static magnetic field stabilization; generating a collinear diatomic beam comprising the first and second atoms in a heating furnace under the same path; Performing atomic state preparation on the diatomic beam, emitting two pumping lights of different frequencies through a frequency-stabilized semiconductor laser light source, setting the two pumping lights to vertically pass through the diatomic beam, so that the two pumping lights respectively generate electric dipole resonance with the first atom and the second atom, so as to achieve that the first atom and the second atom are respectively in their specific ground state hyperfine energy levels; Injecting the diatomic beam into a dual-mode zero-phase-difference Ramsey cavity, and subjecting the first atom and the second atom to microwave field excitation at corresponding frequencies of the ground state 0-0 hyperfine level transition under the action of a static magnetic field, so that the first atom and the second atom complete their respective microwave transitions; Two probe lights of different frequencies are emitted by a frequency-stabilized semiconductor laser light source, and the two probe lights vertically pass through the diatomic beam after microwave transition and respectively generate electric dipole resonance with the first atom and the second atom; A Ramsey resonance transition signal after microwave transition and electric dipole resonance of the first atom and the second atom is received through a fluorescence collector, and the Ramsey resonance transition signal of the first atom is used as a clock transition signal; the clock transition signal is used as a reference signal of the atomic beam clock, and in a servo control system, a phase detector is used to compare the phase of the clock transition signal and the voltage-controlled crystal oscillator signal to obtain an error signal of the voltage-controlled crystal oscillator; the error signal is amplified and filtered by a loop filter to obtain a smooth control signal, and the voltage of the voltage-controlled crystal oscillator is controlled according to the control signal to adjust the frequency of the voltage-controlled crystal oscillator so that the frequency of the voltage-controlled crystal oscillator is consistent with the frequency of the clock transition signal; During the operation of the atomic beam clock, the Ramsey resonance transition signal of the second atom is scanned periodically. Taking advantage of the fact that the static magnetic field intensity is proportional to the difference between the two transition frequencies of the second atom, the static magnetic field current value is adjusted to ensure that the difference between the two transition frequencies of the second atom remains unchanged, thereby achieving stability of the static magnetic field.

2. The method for stabilizing the static magnetic field of a diatomic atomic beam clock according to claim 1, characterized in that: The first atom is 87 Rb, the second atom is 133 Cs; or the first atom is 133 Cs, the second atom is 87 Rb; or the first atom is 133 Cs, the second atom is 85 Rb.

3. A static magnetic field stabilization device for an atomic beam clock based on a diatomic structure, characterized in that: The method for stabilizing the static magnetic field of a diatomic atomic beam clock according to any one of claims 1 to 2, wherein the stabilizing device comprises: A cesium beam tube, wherein the cesium beam tube is provided with a first light window located between the heating furnace and the dual-mode 0-phase-difference Ramsey cavity, and a second light window located between the dual-mode 0-phase-difference Ramsey cavity and the fluorescence collector; the first light window is used to transmit pump light, and the second light window is used to transmit detection light; a heating furnace, wherein the heating furnace is disposed in the cesium beam tube, and an output port of the heating furnace is provided with a collimating channel, so that a collinear diatomic beam containing the first atom and the second atom is generated in the heating furnace, and the collinear diatomic beam is perpendicular to the pumping light; A dual-mode 0-phase-difference Ramsey cavity, wherein the dual-mode 0-phase-difference Ramsey cavity is disposed in the cesium beam tube, the heating furnace, the dual-mode 0-phase-difference Ramsey cavity, and the fluorescence collector are collinearly disposed in sequence, and the collinear diatomic beam passes through the dual-mode 0-phase-difference Ramsey cavity to reach the fluorescence collector; a magnetic shielding cover is provided outside the dual-mode 0-phase-difference Ramsey cavity, and a magnetic field coil is provided inside the magnetic shielding cover; An electronics system, comprising a dual-frequency microwave source, a voltage-controlled crystal oscillator, a constant current source and a servo control system; the dual-mode 0-phase-difference Ramsey cavity, the dual-frequency microwave source, the voltage-controlled crystal oscillator, the servo control system and the fluorescence collector are connected in sequence; the Ramsey resonance transition signal generated by the interaction of the diatomic beam after microwave transition and the detection laser is received by the fluorescence collector, and the Ramsey resonance transition signal of the first atom is used as the clock transition signal; in the servo control system, the clock transition signal is subjected to phase-sensitive detection to obtain an error signal of the voltage-controlled crystal oscillator; the dual-mode 0-phase-difference Ramsey cavity is used to generate microwave fields of two frequencies; a magnetic shielding cover is provided outside the dual-mode 0-phase-difference Ramsey cavity, a magnetic field coil is provided inside the magnetic shielding cover, the magnetic field coil is used to generate a static magnetic field, the static magnetic field covers the collinear diatomic beam, and causes the first atom and the second atom in the collinear diatomic beam to undergo a ground state 0-0 hyperfine level transition according to the corresponding microwave frequency; A laser system comprising a first frequency-stabilized semiconductor laser light source, a first half-glass slide + PBS combination, a first semi-transparent and semi-reflective mirror, a second half-glass slide + PBS combination, and a second semi-transparent and semi-reflective mirror; the first frequency-stabilized semiconductor laser light source emits laser light that is incident on the first half-glass slide + PBS combination, and the first half-glass slide + PBS combination can continuously adjust the light intensity of the first frequency-stabilized semiconductor laser; the laser light after passing through the first half-glass slide + PBS combination is incident on the first semi-transparent and semi-reflective mirror, and is divided into a first light ray and a second light ray; the first light ray serves as a first pumping light and passes through a first light window to perpendicularly intersect a diatomic beam; the second light ray enters the second half-glass slide + PBS combination, and the second half-glass slide + PBS combination can continuously adjust the light intensity of the second light ray; the laser light after passing through the second half-glass slide + PBS combination is incident on the second semi-transparent and semi-reflective mirror as a first detection light and passes through the second light window to perpendicularly intersect the diatomic beam; The laser system also includes a second frequency-stabilized semiconductor laser, a third half glass slide + PBS combination, a third semi-transparent semi-reflective mirror, a fourth half glass slide + PBS combination, and a 45-degree reflective mirror; the laser light emitted by the second frequency-stabilized semiconductor laser is incident on the third half glass slide + PBS combination, and the third half glass slide + PBS combination can continuously adjust the light intensity of the second frequency-stabilized semiconductor laser; the laser light after passing through the third half glass slide + PBS combination is incident on the third semi-transparent semi-reflective mirror, and the laser light is divided into a third light and a fourth light; the third light serves as the second pumping light and passes through the first light window to perpendicularly intersect the diatomic beam; the fourth light serves as the fourth half glass slide + PBS combination and the fourth half glass slide + PBS combination is used to continuously adjust the light intensity of the fourth light; the laser light after passing through the fourth half glass slide + PBS combination is incident on the 45-degree reflective mirror, serves as the second detection light, and passes through the second light window to perpendicularly intersect the diatomic beam.

4. The diatomic atomic beam clock static magnetic field stabilization device according to claim 3, characterized in that: Also included is a graphite block, wherein the diatomic beam passes through the fluorescence collector and is incident into the graphite block.

5. The diatomic atomic beam clock static magnetic field stabilization device according to claim 3, characterized in that: The first pumping light and the first detection light have the same laser frequency, and the second pumping light and the second detection light have the same laser frequency.

6. The diatomic atomic beam clock static magnetic field stabilization device according to claim 3, characterized in that: The first pumping light and the second pumping light are collinear, and the first detection light and the second detection light are collinear.

7. An electronic device, characterized in that: The electronic device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps corresponding to the method according to any one of claims 1 to 2 are implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps corresponding to the method according to any one of claims 1 to 2 are implemented.

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