Continuous measurement atom interferometer control method and system

Abstract

The invention belongs to the technical field of atomic inertial measurement, and discloses a continuous measurement atomic interferometer control method and system. The method comprises the steps that atoms are sequentially subjected to N times of stimulated Raman transition, the time difference between the stimulated Raman transition is T, atom interference is achieved, in the same vacuum cavity, a plurality of atomic groups are sequentially subjected to atom interference, when the Kth atomic group is subjected to the nth time of stimulated Raman transition, the (K + 1) th atomic group and the Kth atomic group share Raman laser, and the Kth atomic group and the (K + 1) th atomic group share Raman laser. And the first stimulated Raman transition of the (K + 1) th atomic group is synchronously carried out, so that the atomic interference of the atomic group in the vacuum cavity at each moment can be ensured, the output result of the interferometer covers the working time of the whole interferometer, the continuous measurement of the atomic interferometer is realized, and n is less than or equal to N.

Description

Technical Field

[0001] The invention belongs to the technical field of atomic inertial measurement, and discloses a continuous measurement atomic interferometer control method and system. Background Art

[0002] As a new type of quantum sensor, the atomic interferometer can be transformed into an atomic absolute gravimeter, an atomic interferometer gyroscope, an atomic interferometer accelerometer, etc., according to different interference types and system structures. All of them can be sensitive to inertial physical quantities and have the advantages of ultra-high precision and long life. However, when the atomic interferometer is applied to inertial navigation scenarios, it cannot achieve true continuous measurement due to the dead time caused by the atoms it carries. When applied to the field of inertial navigation, it will further affect the real-time performance of the inertial navigation system and increase the navigation error.

[0003] There are some solutions to eliminate the dead zone of atomic interferometers. A gravimeter based on the interferometric effect of two-component atoms. This method eliminates the dead zone by using two-component atoms for interference, but its optical system and electrical system need to meet the requirements of two-component atoms, which is equivalent to doubling the requirements of the optical system and electrical system, greatly increasing the complexity of the system and reducing the reliability of the system. A superposition-type dead-zone-free atomic interferometer gyroscope. This system uses two vacuum cavities to realize the interference of two groups of atoms. By controlling the interference timing in the two vacuum cavities, there are always atoms performing atomic interference, thereby eliminating the dead zone. However, this design requires the use of two vacuum cavities, 24 trapped light beams, two configuration preparation lights, two groups of detection lights, and one group of Raman lasers, which significantly increases the complexity of the system and is difficult to implement, which is not conducive to the miniaturization of the device. Summary of the invention

[0004] Purpose of the invention: To provide a continuous measurement atom interferometer control method and system, eliminate dead time, achieve continuous measurement, broaden the use scenarios of atom interferometers, and further apply them to inertial navigation scenarios.

[0005] Technical solution:

[0006] A method for controlling a continuous-measurement atomic interferometer comprises: atoms successively perform N stimulated Raman transitions, the time difference between each stimulated Raman transition is T, and atomic interference is realized; in the same vacuum cavity, multiple atomic groups are made to successively perform atomic interference; when the Kth atomic group performs the nth stimulated Raman transition, the K+1th atomic group shares the Raman laser with it, and synchronously performs the first stimulated Raman transition of the K+1th atomic group, so that it can be ensured that an atomic group performs atomic interference at every moment in the vacuum cavity, the interferometer output result covers the entire interferometer working time, and the continuous measurement of the atomic interferometer is realized, wherein n is less than or equal to N.

[0007] Furthermore, for an atomic group, the control method is divided into the following steps:

[0008] Step S1: Atom cooling and trapping: Prepare cold atom clusters by controlling the MOT coil, cooling light and re-pumping light 1;

[0009] Step S2: Select the atomic state of the prepared atomic group: by controlling the blow-off light and the state-selected electromagnetic field generator, the internal state is prepared to be |F=1,m F =0>atomic group;

[0010] Step S3: For the internal state |F=1,m F =0> atomic group to perform atomic interference: by controlling the optical system parameters and timing, N stimulated Raman transitions are completed to achieve atomic interference;

[0011] Step S4: Perform final state detection on the atomic group that has completed atomic interference: by controlling the detection light and the re-pumping light 2, the number of atoms in the F=1 state and the F=2 state is obtained, and the atomic population number P of the F=2 state is obtained. F＝2 =N 2 / (N 1 +N 2 ), F = 2-state atomic population, the interference phase satisfies: Among them, N1 is the number of atoms in the F=1 state, N2 is the number of atoms in the F=2 state, and the interference phase

[0012] Furthermore, for any atomic group that performs interference, a total of N stimulated Raman transitions are performed in the vacuum cavity, and the time interval between two adjacent stimulated Raman transitions is T. Then, when it falls freely in the vacuum cavity, the position of each interference is h(N)=g[(N-1)T+T 0 ] 2 / 2, where T 0 is the time taken for the atom group to start falling and to make the first stimulated Raman transition.

[0013] Assume that the time points of the Kth interfering atomic group's N stimulated Raman transitions are {t 1 ,t 2 ,…,t N}, then the time points at which the K+1th interfering atomic group undergoes N stimulated Raman transitions are {t 1 +nT,t 2 +nT,…,t N +nT}, and so on, the time points at which the K+mth interfering atomic group undergoes N stimulated Raman transitions are {t 1 +nmT,t 2 +nmT,…,t N+nmT}, in space, when the Kth interfering atomic group is at h = gt 2 / 2, the position of the K+mth interfering atomic group is h=g(t-nmT) 2 / 2.

[0014] Further, step S1 is specifically:

[0015] First, the MOT coil generates a gradient magnetic field. The three groups of cooling light reflectors are located in six directions of the three-dimensional rectangular coordinate system. The center of the light field coincides with the zero point of the gradient magnetic field. The cooling light in each direction produces a damping force on the oncoming atoms. At the same time, the gradient magnetic field combines with the polarization of the laser to produce a restoring force on the atoms, which ultimately traps the atoms in the center of the light field. At the same time, the re-pumping light 1 acts to suppress the optical pumping effect, allowing the cooling process to continue.

[0016] Furthermore, step S2 is specifically as follows:

[0017] Turn off the MOT coil, cooling light and re-pumping light used in step S1. First, remove the atoms in the F=1 state in the atomic cluster by blowing out the light. Then, apply an electromagnetic field to the position of the atomic cluster to reverse the population number, so that |F=2,m F =0> transfers the atom to F=1,m F =0> energy level, and then blow out the light again to remove the atoms in the F=2 state, and you can get pure |F=1,m F =0> state atomic group, complete step S2.

[0018] Furthermore, step S3 is specifically as follows:

[0019] Control the start time of the Raman laser to achieve N stimulated Raman transitions. The action time sequence is {t 1 ,t 2 ,…,t N}, each time the Raman laser is turned on, the Raman laser opening time length τ and the Raman laser intensity I are controlled to achieve a 50% or 100% flip of the atomic internal state. By configuring the action time sequence {t 1 ,t 2 ,…,t N}, τ and I, to achieve different types of atomic interference and measure different physical quantities.

[0020] Furthermore, step S4 is specifically as follows:

[0021] The detection light is used to detect atoms in the F=2 state, and the fluorescence generated by the detection is collected by the photodetector, which outputs a corresponding fluorescence signal, and the intensity of the fluorescence signal is linearly related to the number of atoms in the F=2 state; then the atoms in the F=1 state are detected by re-pumping light 2 and the detection light, and their fluorescence signals are recorded by the photodetector. The intensity of the fluorescence signal is linearly related to the number of atoms in the F=2 state, thereby realizing the detection of the number of dual-state atoms.

[0022] A control system for a continuous-measurement atom interferometer, the system is a vacuum chamber, the vacuum chamber comprises: an atom preparation area, an atom interference area, and an atom detection area, wherein the atom preparation area comprises an MOT coil, a re-pumping light 1, a cooling light, three groups of cooling light reflectors, a blow-out light, and a state-selected electromagnetic field generator, the MOT coil, the cooling light, and the three groups of cooling light reflectors constitute a magneto-optical trap, the three groups of cooling light reflectors are respectively located in six directions of a three-dimensional rectangular coordinate system, the magnetic field intensity zero point position of the MOT coil coincides with the geometric center of the three groups of reflectors; the direction of the re-pumping light 1 points to the light field center of the cooling light; the state-selected electromagnetic field generator and the blow-out light are located at the bottom of the atom preparation area;

[0023] The atomic interference region includes a Raman laser, a Raman laser reflector, and a quarter wave plate. The Raman laser reflector and the quarter wave plate are used to generate a pair of Raman lasers for reverse Raman transition. The Raman laser is located at the top of the entire vacuum cavity, and its direction is the direction of gravity. The Raman light reflector is located at the bottom of the entire vacuum cavity, and the mirror surface is perpendicular to the direction of the Raman light. The quarter wave plate is located directly above the Raman light reflector.

[0024] The atom detection area includes detection light, detection light reflector, re-pumping light 2, and photoelectric detector; the detection light is located at the top of the atom detection area and is divided into two beams, and the direction of the light is perpendicular to the direction of gravity; the re-pumping light 2 is located in the middle of the two detection light beams, and the direction is parallel to the detection light; the detection light reflector and the photoelectric detector are located on the other side facing the detection light;

[0025] The atom preparation area is located at the top of the vacuum chamber. After completing steps S1 and S2, the atom cluster is released, and the atom cluster begins to fall freely and enters the atomic interference area. The Raman laser used in the interference area coincides with the free-falling trajectory of the atom cluster. After completing step S3, when the atom cluster reaches the atomic detection area, step S4 is completed.

[0026] Beneficial effects:

[0027] 1. The present invention controls the timing of the atom interferometer so that the interfering atomic groups share the Raman laser, thereby eliminating the dead zone of the atom interferometer and realizing continuous measurement of the atom interferometer. The atom interferometer can be better used as an inertial sensor in the field of inertial navigation.

[0028] 2. The system complexity of the present invention is not significantly increased compared to the traditional atomic interferometer gravimeter solution. Only the timing of each sub-module of the system needs to be reconfigured to achieve continuous absolute gravity measurement. Compared with other existing dead zone elimination solutions, it has a simpler system and control solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flowchart of the atomic interferometer for continuous measurement provided by the present invention;

[0030] Figure 2 A schematic diagram of the control timing of each controlled object by a control method of a continuous-measurement atomic interferometer gravimeter provided by the present invention;

[0031] Figure 3 A schematic diagram of the relationship between the position of an atomic group and time when the dual-pulse continuous measurement atom interferometer provided by the present invention is working;

[0032] Figure 4 This is a schematic diagram of the relationship between the position of atomic clusters and time when the three-pulse continuous measurement atomic interferometer gravimeter provided by the present invention is working. DETAILED DESCRIPTION

[0033] Compared with the traditional atomic interferometer gravimeter, the present invention improves the utilization rate of the atomic interferometer timing, and synchronizes the atomic cooling and trapping and state preparation steps with the atomic interference step. When the Kth atomic group performs the nth stimulated Raman transition, the K+1th atomic group shares the Raman laser with it and synchronously performs the first stimulated Raman transition of the K+1th atomic group.

[0034] An embodiment of the present invention provides a continuous measurement atomic interferometer gravimeter control system, the system is a vacuum chamber, and the vacuum chamber includes: an atom preparation area, an atom interference area, and an atom detection area.

[0035] Among them, the vacuum chamber is filled with alkali metal vapor, and the atomic group is located in the vacuum chamber during the entire gravity measurement process;

[0036] The atom preparation area includes the MOT coil, re-pumping light 1, cooling light, three sets of cooling light mirrors, blowing light, and state-selective electromagnetic field generator. The MOT coil, cooling light, and three sets of cooling light mirrors constitute a magneto-optical trap. The three sets of cooling light mirrors are located in six directions of the three-dimensional rectangular coordinate system. The zero point position of the magnetic field intensity of the MOT coil coincides with the geometric center of the three sets of mirrors. The damping force generated by the cooling light on the oncoming atoms and the restoring force on the atoms generated by the combination of the gradient magnetic field and the polarization of the laser eventually trap the atoms in the center of the magneto-optical trap. Turning on the re-pumping light 1 while cooling can increase the number of atoms trapped by cooling. After the atoms are captured, turn off the cooling light, re-pumping light 1, and the MOT coil, and the atoms fall freely. After the action of the blowing light and the state-selective electromagnetic field generator, the internal states can be obtained to be all |F=1,m F =0>state atomic group. The MOT coil is a pair of anti-Helmholtz coils, which generates a gradient magnetic field. The farther away from the center position, the greater the magnetic field strength. The cooling light is a circularly polarized light that is negatively detuned to the transition of atoms to the excited state. The two work together to achieve the cooling and trapping of atoms. The state-selected electromagnetic field generator can generate an electromagnetic field with a frequency difference between F=1 and F=2, which can achieve a periodic change in the atomic population. By controlling its time length, the change of the atomic internal state can be achieved. The re-pumping light 1 and 2 are lasers that excite F=1 state atoms to a high energy level. During their on-state, atoms that fall back from the excited state to the F=1 state will be excited again, and finally the ground state atoms are all in the F=2 state. The blown-out light is a laser that transitions F=1 and F=2 atoms to the excited state. According to the law of conservation of momentum, the motion trajectory of F=1 or F=2 atoms can be changed and deviate from the original trajectory.

[0037] The atomic interference zone includes Raman laser, Raman laser reflector and quarter wave plate. Raman laser reflector and quarter wave plate are used to generate a pair of Raman lasers for reverse Raman transition. Reverse Raman transition refers to the two Raman laser wave vectors felt by atoms in opposite directions. Under this condition, the total Raman laser wave vector is larger, and the phase obtained by interference is more sensitive to gravitational acceleration. By controlling the opening time of Raman laser, π / 2 and π pulse Raman lasers can be realized, and finally the "beam splitting-reflection-combination" of atomic groups can be realized. Raman laser can realize periodic changes in atomic population and atomic momentum at the same time. By controlling its opening time, π / 2 pulse Raman laser and π pulse Raman laser can be realized. Both the π / 2 pulse Raman laser and the π pulse Raman laser can realize changes in the internal state and momentum of atoms, and the difference between the π pulse Raman laser and the π / 2 pulse Raman laser is the different intensity or duration.

[0038] Under ideal conditions, a π / 2 pulse Raman laser can convert atoms in the F=1 state (or F=2 state) into 50% F=1 state and 50% F=2 state. The momentum of the atoms whose internal state changes will also change, and their motion trajectories will be offset to a certain extent. The effect is analogous to a beam splitter in optics, which can achieve "beam splitting" or "beam combining".

[0039] Under ideal conditions, π-pulse Raman laser can completely convert atoms in the F=1 (or F=2) state into atoms in the F=2 (or F=1) state. At the same time, the momentum also changes, and the trajectory of the entire atomic group shifts. Its effect can be compared to a mirror in optics, which can achieve "reflection".

[0040] The atomic detection area includes detection light, detection light reflector, re-pumping light 2, and photodetector. The detection light first detects atoms in the F=2 state. The detection light reflector is used to generate reverse detection light to prevent the atomic trajectory from being offset by the detection light. The fluorescence generated by the detection is collected by the photodetector, and the corresponding fluorescence signal is output. Then, the atoms in the F=1 state are detected by re-pumping light and detection light, and their fluorescence signals are recorded by the photodetector to obtain the results of atomic interference. The detection light can excite the F=2 state atoms to a high energy level. After the atoms absorb the detection light, the intensity of the detection light will change. The number of atoms in the F=2 state can be determined by this change.

[0041] The re-pumping lights 1 and 2 are lasers that excite the F=1 state atoms to a high energy level. During their on-state, the atoms that fall back from the excited state to the F=1 state will be excited again, and finally all the ground state atoms will be in the F=2 state.

[0042] like Figure 1 and 2 As shown, a continuous measurement atomic interferometer control method of the present invention includes: atoms perform N stimulated Raman transitions successively, and the time difference between each stimulated Raman transition is T, so as to realize atomic interference. In the same vacuum cavity, multiple atomic groups are allowed to perform atomic interference successively. When the Kth atomic group performs the nth stimulated Raman transition, the K+1th atomic group shares the Raman laser with it, and synchronously performs the first stimulated Raman transition of the K+1th atomic group. In this way, it can be ensured that there are atomic groups performing atomic interference at every moment in the vacuum cavity, and the interferometer output results cover the entire interferometer working time, so as to realize continuous measurement of the atomic interferometer, wherein n is less than or equal to N.

[0043] For any atomic group that performs interference, a total of N stimulated Raman transitions are performed in the vacuum cavity, and the time interval between two adjacent stimulated Raman transitions is T. When it falls freely in the vacuum cavity, the position of each interference is h(N)=g[(N-1)T+T 0 ] 2 / 2, where T0 is the time taken for the atom group to start falling and to make the first stimulated Raman transition.

[0044] Assume that the time points of the Kth interfering atomic group's N stimulated Raman transitions are {t 1 ,t 2 ,…,t N}, then the time points at which the K+1th interfering atomic group undergoes N stimulated Raman transitions are {t 1 +nT,t 2 +nT,…,t N +nT}, and so on, the time points at which the K+mth interfering atomic group undergoes N stimulated Raman transitions are {t 1 +nmT,t 2 +nmT,…,t N +nmT}, in space, when the Kth interfering atomic group is at h = gt 2 / 2, the position of the K+mth interfering atomic group is h=g(t-nmT) 2 / 2.

[0045] For an atomic group, the control method is divided into the following steps:

[0046] Step S1: Atom cooling and trapping: The preparation of cold atom clusters is completed by controlling the MOT coil, cooling light and re-pumping light 1; Step S1 is specifically as follows:

[0047] First, the MOT coil generates a gradient magnetic field. The three groups of cooling light reflectors are located in six directions of the three-dimensional rectangular coordinate system. The center of the light field coincides with the zero point of the gradient magnetic field. The cooling light in each direction produces a damping force on the oncoming atoms. At the same time, the gradient magnetic field combines with the polarization of the laser to produce a restoring force on the atoms, which ultimately traps the atoms in the center of the light field. At the same time, the re-pumping light 1 acts to suppress the optical pumping effect, allowing the cooling process to continue.

[0048] Step S2: Select the atomic state of the prepared atomic group: by controlling the blow-off light and the state-selected electromagnetic field generator, the internal state is prepared to be |F=1,m F =0> atomic group; step S2 is specifically:

[0049] Turn off the MOT coil, cooling light and re-pumping light used in step S1. First, remove the atoms in the F=1 state in the atomic cluster by blowing out the light. Then, apply an electromagnetic field to the position of the atomic cluster to reverse the population number, so that |F=2,m F =0> transfers the atom to F=1,m F =0> energy level, and then blow out the light again to remove the atoms in the F=2 state, and you can get pure |F=1,mF =0> state atomic group, complete step S2.

[0050] Step S3: For the internal state |F=1,m F =0> atomic group performs atomic interference: by controlling the optical system parameters and timing, N stimulated Raman transitions are completed to achieve atomic interference; step S3 is specifically:

[0051] Control the start time of the Raman laser to achieve N stimulated Raman transitions. The action time sequence is {t 1 ,t 2 ,…,t N}, each time the Raman laser is turned on, the Raman laser opening time length τ and the Raman laser intensity I are controlled to achieve a 50% or 100% flip of the atomic internal state. By configuring the action time sequence {t 1 ,t 2 ,…,t N}, τ and I, to achieve different types of atomic interference and measure different physical quantities.

[0052] Step S4: Perform final state detection on the atomic group that has completed atomic interference: by controlling the detection light and the re-pumping light 2, the number of atoms in the F=1 state and the F=2 state is obtained, and the atomic population number P of the F=2 state is obtained. F＝2 =N 2 / (N 1 +N 2 ), F = 2-state atomic population, the interference phase satisfies: The interference phase of the atomic group can be obtained by this formula, where N1 is the number of atoms in the F=1 state, N2 is the number of atoms in the F=2 state, and the interference phase Step S4 is specifically as follows:

[0053] The detection light is used to detect atoms in the F=2 state, and the fluorescence generated by the detection is collected by the photodetector, which outputs a corresponding fluorescence signal, and the intensity of the fluorescence signal is linearly related to the number of atoms in the F=2 state; then the atoms in the F=1 state are detected by re-pumping light 2 and the detection light, and their fluorescence signals are recorded by the photodetector. The intensity of the fluorescence signal is linearly related to the number of atoms in the F=2 state, thereby realizing the detection of the number of dual-state atoms.

[0054] Embodiment 1

[0055] The total number of interferences in the configured atom interferometer is 3, and the interference sequence is π / 2-π-π / 2. When the Kth atomic group undergoes the third stimulated Raman transition, the K+1th atomic group shares the Raman laser with it and synchronously undergoes the first stimulated Raman transition of the K+1th atomic group, thus realizing a three-pulse atomic interferometer gravimeter. The schematic diagram of the relationship between the time and position of the atomic groups is shown in Figure 4 The following are the implementation steps.

[0056] S1, turn on the MOT coil to generate a gradient magnetic field. The farther away from its center, the stronger the magnetic field strength. Turn on the cooling light, and the zero point of the magnetic field coincides with the center of the light field. The negatively detuned laser produces a damping force on the oncoming atoms. The gradient magnetic field combined with the polarization of the laser produces a restoring force on the atoms, thus creating a potential well at its center, and the atoms are cooled and trapped at the center. At the same time, turn on the re-pumping light 1, so that the atoms that fall back from the excited state to the F=1 state during the cooling process are excited again, suppressing the optical pumping effect and maintaining the continuous cooling process.

[0057] S2, turn off the cooling light, re-pumping light and MOT coil. Turn on the blow-off light to remove the atoms in the F=1 state in the atomic group, control the state-selected electromagnetic field generator to apply a microwave pulse with a time length that makes the population inversion, so that |F=2,m F =0> transfers the atom to |F=1,m F =0 energy level, and then blow out the light again to remove the atoms in the F=2 state, and you can get pure F=1,m F =0> state atomic group, completing the atomic state selection.

[0058] S3, control the Raman laser on and on length, realize π / 2-π-π / 2 Raman pulse sequence, the atom group will interact with these three pulses in the falling process. After the first π / 2 pulse Raman laser, 50% of the prepared F=1 state atom group will become F=2 state atom, and its motion trajectory will have a fixed offset.

[0059] S4, after the free evolution time T, the two-state atomic clusters are simultaneously acted upon by the π-pulse Raman laser, the internal state of the atoms is flipped, and the trajectories are deflected at the same angle.

[0060] S5, after the free evolution time T, the atomic state and motion trajectory change again with the second π / 2 pulse Raman laser, thus completing the atomic interference process. At the same time, the S1 and S2 steps of the next measurement are completed. At the end of the S2 step, the position of the atomic group should be the position with the first π / 2 pulse, eliminating the measurement dead zone and achieving continuous measurement.

[0061] S6, after a short time of completing the atomic interference, the atomic group reaches the detection area, the detection light is turned on, and the atoms in the F=2 state are detected first. The fluorescence signal generated by the atomic group is collected by the photodetector. Then, the F=1 state atoms are pumped to the F=2 state by re-pumping light 2, and the detection light is turned on to complete the detection of the F=1 state atoms. The generated fluorescence signal is collected by the photodetector. Finally, the number of atoms in the two states is obtained, and the atomic population number P of the F=2 state is calculated. F＝2 =N 2 / (N 1 +N 2 ). Its relationship with the acceleration due to gravity is P F＝2 =(1-cos((k eff ·g-α)T 2 )) / 2, k on the right side of the equation eff is the Raman laser wave vector; α is the Raman laser chirp; T is the free evolution time, that is, the time interval between Raman pulses. If these three are all known quantities, the gravitational acceleration g can be solved.

[0062] Embodiment 2

[0063] The total number of interferences in the configured atom interferometer is 2, and the interference sequence is π / 2-π / 2. When the Kth atomic group undergoes the second stimulated Raman transition, the K+1th atomic group shares the Raman laser with it and synchronously undergoes the first stimulated Raman transition of the K+1th atomic group, thus realizing the continuous measurement of the two-pulse atom interferometer. The schematic diagram of the relationship between the time and position of the atomic groups is shown in Figure 3 The following are the implementation steps.

[0064] S1, turn on the MOT coil to generate a gradient magnetic field. The farther away from its center, the stronger the magnetic field strength. Turn on the cooling light, and the zero point of the magnetic field coincides with the center of the light field. The negatively detuned laser produces a damping force on the oncoming atoms. The gradient magnetic field combined with the polarization of the laser produces a restoring force on the atoms, thus creating a potential well at its center, and the atoms are cooled and trapped at the center. At the same time, turn on the re-pumping light 1, so that the atoms that fall back from the excited state to the F=1 state during the cooling process are excited again, suppressing the optical pumping effect and maintaining the continuous cooling process.

[0065] S2, turn off the cooling light, re-pumping light and MOT coil. Turn on the blow-off light to remove the atoms in the F=1 state in the atomic group, control the state-selected electromagnetic field generator to apply a microwave pulse with a time length that makes the population inversion, so that |F=2,m F =0> transfers the atom to |F=1,m F =0 energy level, and then blow out the light again to remove the atoms in the F=2 state, and you can get pure F=1,m F =0> state atomic group, completing the atomic state selection.

[0066] S3, control the Raman laser on and on length, realize π / 2-π / 2 Raman pulse sequence, the atom group will interact with these three pulses in the falling process. After the first π / 2 pulse Raman laser, 50% of the prepared F=1 state atom group will become F=2 state atom, and its motion trajectory will have a fixed offset.

[0067] S4, after the free evolution time T, the second π / 2 pulse Raman laser is reacted, and the atomic state and motion trajectory change again, thus completing the atomic interference process. At the same time, the S1 and S2 steps of the next measurement are completed. At the end of the S2 step, the position of the atomic group should be the position of the first π / 2 pulse, eliminating the measurement dead zone and achieving continuous measurement.

[0068] S5, after a short time of completing atomic interference, the atomic group reaches the detection area, the detection light is turned on, and the atoms in the F=2 state are detected first, and the fluorescence signal generated by the atomic group is collected by the photodetector. Then, through the re-pumping light 2, the F=1 state atoms are pumped to the F=2 state, and the detection light is turned on to complete the detection of the F=1 state atoms, and the generated fluorescence signal is collected by the photodetector. Finally, the number of atoms in the two states is obtained, and the atomic interference fringes are obtained.

Claims

1. A continuous measurement atomic interferometer control method, characterized in that: include: Atoms undergo N stimulated Raman transitions successively, and the time difference between each stimulated Raman transition is T, to achieve atomic interference. In the same vacuum cavity, multiple atomic groups are allowed to undergo atomic interference successively. When the Kth atomic group undergoes the nth stimulated Raman transition, the K+1th atomic group shares the Raman laser with it and synchronously performs the first stimulated Raman transition of the K+1th atomic group. This ensures that there are atomic groups performing atomic interference at every moment in the vacuum cavity. The interferometer output results cover the entire interferometer working time, thus achieving continuous measurement of the atomic interferometer, where n is less than or equal to N.

2. The method for controlling a continuous-measurement atomic interferometer according to claim 1, characterized in that: For an atomic group, the control method is divided into the following steps: Step S1: Atom cooling and trapping: Prepare cold atom clusters by controlling the MOT coil, cooling light and re-pumping light 1; Step S2: Select the atomic state of the prepared atomic group: by controlling the blow-off light and the state-selected electromagnetic field generator, the internal state is prepared to be |F=1,m F =0> atomic group; Step S3: For the internal state |F=1,m F =0> atomic group to perform atomic interference: by controlling the optical system parameters and timing, N stimulated Raman transitions are completed to achieve atomic interference; Step S4: Perform final state detection on the atomic group that has completed atomic interference: by controlling the detection light and the re-pumping light 2, the number of atoms in the F=1 state and the F=2 state is obtained, and the atomic population number P of the F=2 state is obtained. F＝2 =N2 / (N1+N2), F=2-state atomic population, interference phase satisfies: Among them, N1 is the number of atoms in the F=1 state, N2 is the number of atoms in the F=2 state, and the interference phase 3. The continuous measurement atomic interferometer control method according to claim 1, characterized in that: For any atomic group that performs interference, a total of N stimulated Raman transitions are performed in the vacuum cavity, and the time interval between two adjacent stimulated Raman transitions is T. When it falls freely in the vacuum cavity, the position of each interference is h(N)=g[(N-1)T+T0] 2 / 2, where T0 is the time taken for the atomic group to fall and make the first stimulated Raman transition. Assume that the time points of the Kth interfering atomic group's N stimulated Raman transitions are {t1, t2, ..., t N }, then the time points of the N stimulated Raman transitions of the K+1th interfering atomic group are {t1+nT, t2+nT, …, t N +nT}, and so on. The time points at which the K+mth interfering atomic group undergoes N stimulated Raman transitions are {t1+nmT, t2+nmT, …, t N +nmT}, in space, when the Kth interfering atomic group is at h = gt 2 / 2, the position of the K+mth interfering atomic group is h=g(t-nmT) 2 / 2.

4. The continuous measurement atom interferometer control method according to claim 2, characterized in that: Step S1 is specifically: First, the MOT coil generates a gradient magnetic field. The three groups of cooling light reflectors are located in six directions of the three-dimensional rectangular coordinate system. The center of the light field coincides with the zero point of the gradient magnetic field. The cooling light in each direction produces a damping force on the oncoming atoms. At the same time, the gradient magnetic field combines with the polarization of the laser to produce a restoring force on the atoms, which ultimately traps the atoms in the center of the light field. At the same time, the re-pumping light 1 acts to suppress the optical pumping effect, allowing the cooling process to continue.

5. The continuous measurement atomic interferometer control method according to claim 2, characterized in that: Step S2 is specifically as follows: Turn off the MOT coil, cooling light and re-pumping light used in step S1. First, remove the atoms in the F=1 state in the atomic cluster by blowing out the light. Then, apply an electromagnetic field to the position of the atomic cluster to reverse the population number, so that |F=2,m F =0> transfers the atom to F=1,m F =0> energy level, and then blow out the light again to remove the atoms in the F=2 state, and you can get pure |F=1,m F =0>state atomic group, complete step S2.

6. The continuous measurement atom interferometer control method according to claim 2, characterized in that: Step S3 is specifically as follows: Control the start time of the Raman laser to achieve N stimulated Raman transitions. The action time sequence is {t1, t2, …, t N }, each time the Raman laser is turned on, the Raman laser opening time length τ and the Raman laser intensity I are controlled to achieve a 50% or 100% flip of the atomic internal state. By configuring the action time sequence {t1, t2, …, t N }, τ and I, to achieve different types of atomic interference and measure different physical quantities.

7. The continuous measurement atom interferometer control method according to claim 2, characterized in that: Step S4 is specifically as follows: The detection light is used to detect atoms in the F=2 state, and the fluorescence generated by the detection is collected by the photodetector, which outputs a corresponding fluorescence signal, and the intensity of the fluorescence signal is linearly related to the number of atoms in the F=2 state; then the atoms in the F=1 state are detected by re-pumping light 2 and the detection light, and their fluorescence signals are recorded by the photodetector. The intensity of the fluorescence signal is linearly related to the number of atoms in the F=2 state, thereby realizing the detection of the number of dual-state atoms.

8. A continuous measurement atomic interferometer control system, characterized in that: The system is a vacuum chamber, which includes: an atom preparation area, an atom interference area, and an atom detection area, wherein the atom preparation area includes a MOT coil, a re-pumping light 1, a cooling light, three groups of cooling light reflectors, a blow-out light, and a state-selective electromagnetic field generator, the MOT coil, the cooling light, and the three groups of cooling light reflectors constitute a magneto-optical trap, the three groups of cooling light reflectors are respectively located in six directions of a three-dimensional rectangular coordinate system, the zero point position of the magnetic field intensity of the MOT coil coincides with the geometric center of the three groups of reflectors; the direction of the re-pumping light 1 points to the light field center of the cooling light; the state-selective electromagnetic field generator and the blow-out light are located at the bottom of the atom preparation area; The atomic interference region includes a Raman laser, a Raman laser reflector, and a quarter wave plate. The Raman laser reflector and the quarter wave plate are used to generate a pair of Raman lasers for reverse Raman transition. The Raman laser is located at the top of the entire vacuum cavity, and its direction is the direction of gravity. The Raman light reflector is located at the bottom of the entire vacuum cavity, and the mirror surface is perpendicular to the direction of the Raman light. The quarter wave plate is located directly above the Raman light reflector. The atom detection area includes detection light, detection light reflector, re-pumping light 2, and photoelectric detector; the detection light is located at the top of the atom detection area and is divided into two beams, and the direction of the light is perpendicular to the direction of gravity; the re-pumping light 2 is located in the middle of the two detection light beams, and the direction is parallel to the detection light; the detection light reflector and the photoelectric detector are located on the other side facing the detection light; The atom preparation area is located at the top of the vacuum chamber. After completing steps S1 and S2, the atom cluster is released, and the atom cluster begins to fall freely and enters the atomic interference area. The Raman laser used in the interference area coincides with the free-falling trajectory of the atom cluster. After completing step S3, when the atom cluster reaches the atomic detection area, step S4 is completed.

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