Method and device for compensating horizontal acceleration motion error of movable atomic interferometer gravimeter

Abstract

The present invention provides a method and device for compensating for horizontal acceleration errors in a mobile atomic interferometer gravimeter. Within a single measurement cycle, the method obtains the gravitational phase shift based on the interference loop formed by the interaction between a Raman light pulse sequence and a cold atomic cluster. The method also obtains information on the relative position change of the cold atomic cluster within the horizontal cross-section of the Raman light pulse sequence. Based on this relative position information and pre-acquired characterization information, the method obtains the effective Rabi frequency under the action of horizontal acceleration. The effective Rabi frequency is then compensated to reduce the impact of horizontal acceleration on the atomic interferometer gravity measurement process. Based on the relative position change information and the characterization information, the method obtains the wavefront phase shift introduced by the horizontal acceleration. Based on the wavefront phase shift and the gravitational phase shift, the method obtains a corrected gravitational phase shift. The method then obtains the single-cycle gravitational acceleration based on the corrected gravitational phase shift. This method improves the measurement accuracy of the atomic interferometer gravimeter.

Description

Technical Field

[0001] The present invention relates to the technical field of atomic interferometric precision measurement, and in particular to a method and device for compensating for horizontal acceleration motion errors of a movable atomic interferometric gravimeter. Background Art

[0002] Atom interferometry gravimeters use lasers to manipulate cold atomic clusters in a gravitational field, thereby achieving precise measurements of gravitational acceleration. Cold atoms possess a short de Broglie wavelength, long free evolution time, large static mass, minimal velocity distribution, stable internal structure and energy level distribution, and no mechanical friction. Therefore, these cold atoms enable highly sensitive, high-precision gravity measurements without long-term drift. Currently, the measurement performance of atom interferometry gravimeters approaches or even surpasses that of classical gravimeters. The instrument is developing towards miniaturization and portability, and commercial products have already appeared, demonstrating its promising future.

[0003] The movable atomic interferometer gravimeter is expected to realize dynamic gravity measurement during the movement of the carrier platform. It is an important application direction of quantum gravimeters, but it also faces the influence of dynamic errors introduced by the complex movement of the carrier. Existing technologies pay much attention to the role of factors such as vertical vibration and gravimeter attitude rotation, and propose corresponding technical solutions such as vibration isolation, vibration compensation, and attitude stabilization. However, there is little treatment for the influence of horizontal acceleration. From theoretical analysis and experimental verification, it can be seen that due to the limitations of the carrier platform's functional tasks, path planning requirements, motion control accuracy, horizontal vibration, etc., it is difficult for the moving carrier to maintain a constant horizontal speed. For the atomic interferometer gravimeter carried on it, the accelerated motion will cause the relative position of the atomic cluster in the laser cross section to change, resulting in a decrease in measurement accuracy.

[0004] Therefore, how to improve the measurement accuracy of atomic interferometer gravimeters is an important issue that needs to be urgently addressed in the industry. Summary of the Invention

[0005] The present invention provides a method and device for compensating horizontal acceleration motion errors of a movable atomic interferometer gravimeter, which are used to solve the problems existing in the prior art and improve the measurement accuracy of the atomic interferometer gravimeter.

[0006] The present invention provides a method for compensating horizontal acceleration motion errors of a movable atomic interferometer gravimeter, the method comprising:

[0007] In a single measurement cycle, the gravitational phase shift is obtained based on an interference loop formed by the interaction between a Raman light pulse sequence and a cold atomic cluster, wherein the Raman light pulse sequence includes multiple Raman light pulses;

[0008] Acquiring relative position change information of the cold atomic group in a horizontal cross section of the Raman light pulse sequence, wherein the relative position change information includes relative position information corresponding to multiple Raman light pulses respectively;

[0009] Based on the relative position information and pre-acquired characterization information, an effective Rabi frequency under the action of horizontal acceleration is obtained, and the effective Rabi frequency is compensated to reduce the influence of the horizontal acceleration on the atomic interferometry gravity measurement process, wherein the characterization information includes the intensity distribution of Raman light, the wavefront distribution of Raman light, the initial density distribution of the cold atomic cluster, and the lateral temperature;

[0010] Based on the relative position change information and the characterization information, the wavefront phase shift introduced by the horizontal acceleration motion is obtained, and based on the wavefront phase shift and the gravity phase shift, the corrected gravity phase shift is obtained, and based on the corrected gravity phase shift, the single-cycle gravity acceleration is obtained.

[0011] According to a method for compensating for horizontal acceleration motion errors of a movable atom interferometer gravimeter provided by the present invention, the step of obtaining information on relative position changes of the cold atomic clusters within the horizontal cross section of each of the Raman light pulses comprises:

[0012] Obtain information on the horizontal acceleration of the atomic interferometer gravimeter;

[0013] Relative position change information is acquired based on the horizontal acceleration motion information.

[0014] According to a method for compensating for horizontal acceleration motion errors of a movable atomic interferometer gravimeter provided by the present invention, the steps of obtaining an effective Rabi frequency under the action of horizontal acceleration motion based on the relative position information and pre-acquired characterization information, and compensating the effective Rabi frequency include:

[0015] For each moment when a Raman light pulse interacts with the cold atomic cluster, based on the relative position information corresponding to the Raman light pulse and the characterization information, a current effective Rabi frequency under the current horizontal accelerated motion is obtained;

[0016] Based on the current effective Rabi frequency, the Raman light pulse is adjusted to compensate for the current effective Rabi frequency, so as to reduce the influence of the horizontal acceleration operation on the atomic interferometry gravity measurement process.

[0017] According to a method for compensating for horizontal acceleration motion errors of a movable atomic interferometer gravimeter provided by the present invention, the step of adjusting the Raman light pulse comprises:

[0018] Adjusting the intensity of the Raman light corresponding to the Raman light pulse; or

[0019] Adjust the pulse width of the Raman light pulse.

[0020] According to the present invention, a method for compensating for horizontal acceleration motion errors of a movable atomic interferometer gravimeter is provided.

[0021] The step of obtaining the current effective Rabi frequency under the current horizontal accelerated motion based on the relative position information corresponding to the Raman light pulse and the characterization information includes:

[0022] Obtaining a current density distribution of cold atomic clusters based on the relative position information corresponding to the Raman light pulse, the initial density distribution of the cold atomic clusters, and the lateral temperature;

[0023] Based on the current cold atomic cluster density distribution and the light intensity distribution corresponding to the Raman light pulse, the current effective Rabi frequency of the Raman light pulse is obtained.

[0024] According to a method for compensating for horizontal acceleration motion errors of a movable atom interferometer gravimeter provided by the present invention, before the step of obtaining the gravitational phase shift based on the interference loop formed by the interaction between the Raman light pulse sequence and the cold atomic cluster, the method further includes:

[0025] Characterizing the intensity distribution of the Raman light to obtain the intensity distribution of the Raman light;

[0026] Characterizing the wavefront phase distribution of the Raman light to obtain the wavefront distribution of the Raman light;

[0027] Characterizing the initial density distribution of the cold atomic clusters to obtain the initial density distribution of the cold atomic clusters;

[0028] The transverse temperature of the cold atomic cluster is characterized to obtain the transverse temperature.

[0029] According to a method for compensating for horizontal acceleration motion errors of a movable atom interferometer gravimeter provided by the present invention, the step of characterizing the wavefront phase distribution of Raman light to obtain the wavefront distribution of Raman light includes:

[0030] Zernike polynomials are used to fit the wavefront phase distribution of Raman light;

[0031] Adjusting parameters to be adjusted and constructing a set of equations, wherein the parameters to be adjusted may at least include: information on the initial transverse velocity and horizontal accelerated motion of the atom;

[0032] Based on the equation group, the coefficients of Zernike polynomials of various orders are obtained to obtain the wavefront distribution of the Raman light.

[0033] The present invention also provides a device for compensating for horizontal acceleration motion errors of a movable atomic interferometer gravimeter, the device comprising:

[0034] A gravitational phase shift acquisition module, configured to acquire the gravitational phase shift within a single measurement cycle based on an interference loop formed by the interaction of a Raman light pulse sequence with a cold atomic cluster, wherein the Raman light pulse sequence includes multiple Raman light pulses;

[0035] a relative position change information acquisition module, configured to acquire relative position change information of the cold atomic group within a horizontal cross section of the Raman light pulse sequence, wherein the relative position change information includes relative position information corresponding to multiple Raman light pulses;

[0036] an effective Rabi frequency calculation and compensation module, configured to obtain an effective Rabi frequency under horizontal acceleration based on the relative position information and pre-acquired characterization information, and to compensate for the effective Rabi frequency to reduce the impact of horizontal acceleration on the atomic interferometry gravity measurement process, wherein the characterization information includes the intensity distribution of Raman light, the wavefront distribution of Raman light, the initial density distribution of the cold atomic cluster, and the lateral temperature;

[0037] The wavefront phase shift and gravitational acceleration calculation module is used to obtain the wavefront phase shift introduced by the horizontal acceleration motion based on the relative position change information and the characterization information, and to obtain the corrected gravitational phase shift based on the wavefront phase shift and the gravitational phase shift, and to obtain the single-cycle gravitational acceleration based on the corrected gravitational phase shift.

[0038] According to the present invention, a device for compensating for horizontal acceleration motion errors of a movable atomic interferometer gravimeter, the relative position change information acquisition module includes:

[0039] A horizontal acceleration motion information acquisition unit, used for acquiring horizontal acceleration motion information of the atomic interferometer gravimeter;

[0040] The position change information acquiring unit is configured to acquire relative position change information based on the horizontal acceleration motion information.

[0041] According to the present invention, a device for compensating for horizontal acceleration motion errors of a movable atomic interferometer gravimeter is provided, the device further comprising:

[0042] A characterization module is used to characterize the intensity distribution of the Raman light before obtaining the gravitational phase shift based on the interference loop formed by the interaction between the Raman light pulse sequence and the cold atomic cluster, so as to obtain the intensity distribution of the Raman light;

[0043] Characterizing the wavefront phase distribution of the Raman light to obtain the wavefront distribution of the Raman light;

[0044] Characterizing the initial density distribution of the cold atomic clusters to obtain the initial density distribution of the cold atomic clusters;

[0045] The transverse temperature of the cold atomic cluster is characterized to obtain the transverse temperature.

[0046] The present invention provides a method and device for compensating for horizontal acceleration errors in a movable atomic interferometer gravimeter. The method obtains a gravitational phase shift within a single measurement cycle based on an interference loop formed by a Raman light pulse sequence and a cold atomic cluster. The Raman light pulse sequence includes multiple Raman light pulses, and relative position change information of the cold atomic cluster within a horizontal cross-section of the Raman light pulse sequence is obtained. The relative position change information includes relative position information corresponding to each of the multiple Raman light pulses. Based on the relative position information and pre-acquired characterization information, the effective Rabi frequency under the action of horizontal acceleration is obtained, and the effective Rabi frequency is compensated to reduce the impact of horizontal acceleration on the atomic interferometer gravity measurement process. The characterization information includes the intensity distribution of Raman light, the wavefront distribution of Raman light, the initial density distribution of the cold atomic cluster, and the lateral temperature. Based on the relative position change information and the characterization information, the wavefront phase shift introduced by the horizontal acceleration is obtained, and based on the wavefront phase shift and the gravitational phase shift, a corrected gravitational phase shift is obtained. Based on the corrected gravitational phase shift, a single-cycle gravitational acceleration is obtained. In this way, the effective Rabi frequency can be compensated in real time, the problem of reduced fringe contrast caused by horizontal acceleration motion can be suppressed, and the error compensation of horizontal acceleration motion can be achieved based on the wavefront phase shift introduced by horizontal acceleration motion, thereby improving the measurement accuracy of the atomic interferometer gravimeter. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0048] Figure 1 This is one of the flow charts of the method for compensating the horizontal acceleration motion error of the movable atomic interferometer gravimeter provided by the present invention;

[0049] Figure 2 This is the second flow chart of the method for compensating the horizontal acceleration motion error of the movable atomic interferometer gravimeter provided by the present invention;

[0050] Figure 3 This is the third flow chart of the method for compensating the horizontal acceleration motion error of the movable atomic interferometer gravimeter provided by the present invention;

[0051] Figure 4 This is one of the structural schematic diagrams of the horizontal acceleration motion error compensation device of the movable atomic interferometer gravimeter provided by the present invention;

[0052] Figure 5 This is the second structural schematic diagram of the horizontal acceleration motion error compensation device of the movable atomic interferometer gravimeter provided by the present invention. DETAILED DESCRIPTION

[0053] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0054] In order to improve the measurement accuracy of the atomic interferometer gravimeter, the present invention provides a method and device for compensating the horizontal acceleration motion error of a movable atomic interferometer gravimeter. Figure 1 The present invention describes a method for compensating for horizontal acceleration motion errors of a movable atom interferometer gravimeter.

[0055] like Figure 1 As shown, the present invention discloses a method for compensating horizontal acceleration motion error of a movable atomic interferometer gravimeter, the method comprising:

[0056] S101, within a single measurement cycle, the gravitational phase shift is obtained based on the interference loop formed by the interaction between the Raman light pulse sequence and the cold atomic cluster.

[0057] In order to obtain the gravitational phase shift, cold atomic clusters can be prepared and speed selected within a single measurement cycle, and then the atomic final state measurement can be performed based on the interference loop formed by the interaction between the Raman light pulse sequence and the cold atomic cluster, and the gravitational phase shift can be obtained.

[0058] Among them, the Raman light pulse sequence can include multiple Raman light pulses, and the process of the Raman light pulse sequence interacting with the cold atomic cluster can include multiple Raman light pulses interacting with the cold atomic cluster separately, which can be called multiple Raman light pulse interactions, and the time information corresponding to each Raman light pulse interaction is different.

[0059] S102 , obtaining relative position change information of the cold atomic cluster in a horizontal cross section of the Raman light pulse sequence.

[0060] To obtain the effective Rabi frequency change and wavefront phase shift, the relative position change information of the cold atom cluster within the horizontal cross-section of the Raman light pulse sequence can be obtained. The relative position change information can include relative position information corresponding to multiple Raman light pulses. In other words, the position change information can include multiple relative position information. Corresponding relative position information exists for each interaction between a Raman light pulse and the cold atom cluster.

[0061] For example, a Raman light pulse sequence may include three Raman light pulses, namely, a π / 2 Raman light pulse (Raman light pulse 1), a π Raman light pulse (Raman light pulse 2), and a π / 2 Raman light pulse (Raman light pulse 3). The relative position change information may include: relative position information 1 corresponding to Raman light pulse 1, relative position information 2 corresponding to Raman light pulse 2, and relative position information 3 corresponding to Raman light pulse 3.

[0062] S103, based on the relative position information and the pre-acquired characterization information, obtaining the effective Rabi frequency under the horizontal acceleration motion, and compensating the effective Rabi frequency to reduce the influence of the horizontal acceleration motion on the atomic interferometry gravity measurement process.

[0063] At the moment of each Raman light pulse, since Raman light has the characteristics of Gaussian non-uniform light intensity distribution, and under the action of horizontal acceleration, the relative position of the cold atom cluster in the horizontal cross-section of the Raman light pulse sequence is constantly changing. This will cause the intensity of the Raman light interacting with the atoms of the cold atom cluster to change with the change of relative position information at the moment of different Raman light pulses.

[0064] The effective Rabi frequency of a Raman light pulse interacting with a cold atom cluster is proportional to the intensity of the Raman light interacting with the cold atom cluster. When the pulse width of the Raman light pulse is fixed, the effective Rabi frequency determines the efficiency of each Raman light pulse interacting with the cold atom cluster. Changes in the effective Rabi frequency will reduce the efficiency of the Raman light pulse interacting with the cold atom cluster, thereby reducing the contrast of the atomic interference fringes.

[0065] Therefore, each time relative position information is obtained, the effective Rabi frequency under the action of horizontal accelerated motion can be obtained based on the relative position information and the pre-acquired characterization information.

[0066] The characterization information includes the intensity distribution of the Raman light, the wavefront distribution of the Raman light, the initial density distribution of the cold atom cluster, and the lateral temperature. There are multiple effective Rabi frequencies, each of which has a unique corresponding relative position information and a unique corresponding Raman light pulse. In other words, the Raman light pulse corresponding to each effective Rabi frequency interacts with the cold atom cluster at a different time.

[0067] After obtaining each effective Rabi frequency, the current effective Rabi frequency change can be obtained based on the difference between the effective Rabi frequency and the initially set effective Rabi frequency. Similarly, the current effective Rabi frequency change has unique corresponding relative position information and a unique corresponding Raman light pulse.

[0068] For each Raman light pulse, when the Raman light pulse interacts with the cold atomic cluster, the effective Rabi frequency corresponding to the Raman light pulse can be compensated in real time to reduce the impact of horizontal acceleration operation on the atomic interferometry gravity measurement process.

[0069] In other words, during the interaction between the Raman light pulse sequence and the cold atomic cluster, the effective Rabi frequency will be compensated in real time according to the moment when different Raman light pulses interact with the cold atomic cluster, so as to reduce the impact of horizontal acceleration operation on the atomic interferometry gravity measurement process.

[0070] S104: Based on the relative position change information and the characterization information, a wavefront phase shift introduced by the horizontal acceleration motion is obtained, and based on the wavefront phase shift and the gravity phase shift, a corrected gravity phase shift is obtained, and based on the corrected gravity phase shift, a single-cycle gravity acceleration is obtained.

[0071] After the cold atom cluster interacts with each Raman light pulse, that is, after the atomic interference in the current test cycle is completed, the wavefront phase shift introduced by the horizontal acceleration information can be obtained based on the relative position change information and the previously acquired characterization information. In other words, the wavefront phase shift introduced by the horizontal acceleration information is obtained based on the relative position change information, the wavefront distribution of the Raman light, the initial density distribution of the cold atom cluster, and the lateral temperature.

[0072] The wavefront phase shift introduced by the horizontal acceleration information is the overall wavefront phase shift of the atomic interference fringes after the cold atomic cluster interacts with the Raman light pulse sequence. The horizontal acceleration information can include horizontal acceleration, horizontal velocity, horizontal displacement, and so on. These are all reasonable and are not specifically limited here.

[0073] After obtaining the gravitational phase shift and the wavefront phase shift of the entire cold atomic cluster, the corrected gravitational phase shift can be obtained based on the wavefront phase shift and the gravitational phase shift, and the single-cycle gravitational acceleration can be obtained based on the corrected gravitational phase shift.

[0074] In this way, the effective Rabi frequency can be compensated in real time, the problem of reduced fringe contrast caused by horizontal acceleration motion can be suppressed, and the error compensation of horizontal acceleration motion can be achieved based on the wavefront phase shift introduced by horizontal acceleration motion, thereby improving the measurement accuracy of the atomic interferometer gravimeter.

[0075] As an embodiment of the present invention, the step of obtaining the relative position change information of the cold atomic clusters in the horizontal cross section of each of the Raman light pulses may include:

[0076] Acquiring information about the horizontal acceleration of the atomic interferometer gravimeter. In one embodiment, the time information corresponding to each Raman light pulse is different. During the interaction of the Raman light pulse sequence with the cold atom cluster, the horizontal acceleration information of the atomic interferometer gravimeter is monitored in real time, that is, the horizontal acceleration information corresponding to different time information is acquired.

[0077] As one embodiment, an accelerometer rigidly connected to an atomic interferometer gravimeter can be used to measure horizontal acceleration information in real time. As another embodiment, non-destructive imaging methods can be used to monitor the horizontal motion of a free-falling cold atom cluster relative to an atomic interferometer gravimeter or Raman ray after release, thereby obtaining information on horizontal acceleration. All of these are reasonable and are not specifically limited here.

[0078] Relative position change information is acquired based on the horizontal acceleration motion information.

[0079] After acquiring the horizontal acceleration information, the relative position change information of the cold atom cluster in the horizontal cross section of the Raman light pulse sequence can be calculated in real time based on the horizontal acceleration information. The relative position change information includes multiple relative position information.

[0080] In one embodiment, after the horizontal accelerated motion information is acquired, the horizontal accelerated motion information may be filtered, integrated, denoised, and processed to obtain more accurate relative position change information.

[0081] In this way, the relative position change information of the cold atomic cluster in the horizontal cross section of the Raman light pulse sequence can be calculated, so as to subsequently calculate the effective specific frequency and wavefront phase shift introduced by the horizontal accelerated motion information.

[0082] As an embodiment of the present invention, the step of obtaining the effective Rabi frequency under the horizontal acceleration motion based on the relative position information and the pre-acquired characterization information and compensating the effective Rabi frequency may include:

[0083] At each moment when a Raman light pulse interacts with the cold atomic cluster, the current effective Rabi frequency under the current horizontal accelerated motion is obtained based on the relative position information corresponding to the Raman light pulse and the characterization information.

[0084] For each moment when a Raman light pulse interacts with a cold atom cluster, the relative position information of the cold atom cluster in the horizontal section of the Raman light pulse can be obtained, that is, the relative position information corresponding to the moment when the Raman light pulse interacts.

[0085] In one embodiment, the relative position information corresponding to the moment of the Raman light pulse action, that is, the relative position information corresponding to the Raman light pulse, can be obtained based on the current horizontal acceleration information of the atomic interferometer corresponding to the moment of the Raman light pulse action.

[0086] Based on the relative position information corresponding to the Raman light pulse, the light intensity distribution corresponding to the Raman light pulse, the initial density distribution of the cold atomic clusters and the lateral temperature, the current effective Rabi frequency under the current horizontal accelerated motion is obtained.

[0087] The intensity distribution of the Raman light pulse can be obtained by pre-measurement, for example, using a laser spot analyzer. In one embodiment, for an already constructed atomic interferometer gravimeter, the wavefront distribution of the Raman light corresponding to the instrument is already fixed and can be obtained through pre-characterization, eliminating the need for multiple measurements.

[0088] Based on the current effective Rabi frequency, the Raman light pulse is adjusted to compensate for the effective Rabi frequency, so as to reduce the influence of the horizontal acceleration operation on the atomic interferometry gravity measurement process.

[0089] After obtaining the current effective Rabi frequency, the current effective Rabi frequency change, that is, the effective Rabi frequency change corresponding to the Raman light pulse, can be obtained based on the difference between the current effective Rabi frequency and the initially set effective Rabi frequency. The Raman light pulse can then be adjusted to ensure the efficiency of the Raman light pulse and compensate for the effect of horizontal acceleration on the contrast of interference fringes, thereby reducing the impact of horizontal acceleration on the atomic interferometry gravity measurement process.

[0090] As an embodiment of the present invention, the step of adjusting the Raman light pulse may include:

[0091] Adjusting the intensity of the Raman light corresponding to the Raman light pulse; or

[0092] Adjust the pulse width of the Raman light pulse.

[0093] That is, the Raman light pulse can be adjusted in any of the following ways:

[0094] The first method is to adjust the intensity of the Raman light corresponding to the Raman light pulse.

[0095] In the first manner described above, a corresponding adjustment device may be provided based on the difference in the laser system providing laser (Raman light) for the atomic interferometer gravimeter, and the specific setting may be made according to actual conditions.

[0096] For example, the intensity of the Raman light corresponding to the Raman light pulse can be adjusted by devices such as an acousto-optic modulator, an electro-optic modulator or an adjustable optical attenuator, thereby suppressing the problem of decreased contrast of interference fringes caused by horizontal acceleration.

[0097] As an implementation manner, after adjusting the intensity of the Raman light corresponding to the Raman light pulse, the adjusted intensity distribution may be recorded to facilitate subsequent calculation of the change in the effective Rabi frequency corresponding to the next Raman light pulse.

[0098] The second method is to adjust the pulse width of the Raman light pulse.

[0099] In the second method described above, a digital signal can be used to drive an acousto-optic modulator to adjust the pulse width of the Raman light pulse, thereby achieving precise switching and timing of pulse width adjustment. This allows the Raman light pulse to be quickly and accurately adjusted according to the moment of action of different Raman light pulses, thereby quickly and accurately ensuring the efficiency of the Raman light pulse, compensating for the effect of horizontal acceleration on the contrast of interference fringes, and reducing the impact of horizontal acceleration on the atomic interferometric gravity measurement process.

[0100] The present invention can compensate for the effective Rabi frequency in real time, suppress the problem of reduced fringe contrast caused by horizontal acceleration motion, and realize error compensation for horizontal acceleration motion together with the wavefront phase shift introduced based on the horizontal acceleration motion, thereby realizing joint compensation and further improving the measurement accuracy of the movable atom interferometer gravimeter.

[0101] As an embodiment of the present invention, Figure 2 As shown, the step of obtaining the current effective Rabi frequency under the current horizontal accelerated motion based on the relative position information corresponding to the Raman light pulse and the characterization information may include:

[0102] S201 , obtaining a current density distribution of cold atom clusters based on the relative position information corresponding to the Raman light pulse, the initial density distribution of the cold atom clusters, and the transverse temperature.

[0103] Since the cold atomic clusters can interact with a Raman light pulse sequence including multiple Raman light pulses, the relative position information corresponding to each Raman light pulse is inconsistent. In order to determine the current effective Rabi frequency of the Raman light pulse, the current cold atomic cluster density distribution can be obtained based on the relative position information corresponding to the Raman light pulse, the initial density distribution of the cold atomic clusters, and the lateral temperature.

[0104] For example, in the case of three Raman light pulses, including π / 2 Raman light pulse (Raman light pulse 1), π Raman light pulse (Raman light pulse 2), and π / 2 Raman light pulse (Raman light pulse 3), the density distribution of cold atomic clusters corresponding to the moment of Raman light pulse 1, the density distribution of cold atomic clusters corresponding to the moment of Raman light pulse 2, and the density distribution of cold atomic clusters corresponding to the moment of Raman light pulse 3, that is, the current density distribution of cold atomic clusters, can be obtained based on the relative position information 1 corresponding to Raman light pulse 1, the relative position information 2 corresponding to Raman light pulse 2, and the relative position information 3 corresponding to Raman light pulse 3 and the initial density distribution of cold atomic clusters and the lateral temperature.

[0105] S202 : Acquire a current effective Rabi frequency of the Raman light pulse based on the current cold atomic cluster density distribution and the light intensity distribution corresponding to the Raman light pulse.

[0106] After obtaining the current cold cluster density distribution, the current effective Rabi frequency of the Raman light pulse can be obtained by integrating the current cold cluster density distribution with the light intensity distribution corresponding to the Raman light pulse, that is, the current effective Rabi frequency corresponding to the moment when the Raman light pulse acts.

[0107] In this way, the current effective Rabi frequency corresponding to different moments can be obtained, that is, the current effective Rabi frequency corresponding to different Raman light pulses, so that the Raman light pulses can be subsequently adjusted so that the influence of the horizontal acceleration information at each moment on the interference fringes can be compensated. Without the need for complex fitting calculations, the coupling between horizontal acceleration and the effective Rabi frequency can be dynamically evaluated. This method is fast and direct, can ensure the real-time performance of error compensation, and can further improve the measurement accuracy of the mobile atom interferometer gravimeter.

[0108] As an embodiment of the present invention, before the step of obtaining the gravitational phase shift based on the interference loop formed by the interaction between the Raman light pulse sequence and the cold atomic cluster, the method may further include:

[0109] The intensity distribution of the Raman light is characterized to obtain the intensity distribution of the Raman light.

[0110] The wavefront phase distribution of the Raman light is characterized to obtain the wavefront distribution of the Raman light. As an embodiment, the wavefront phase of the Raman light can be fitted by scanning the atomic interferometer experiment parameters to obtain the wavefront distribution of the Raman light.

[0111] The initial density distribution of the cold atomic clusters is characterized to obtain the initial density distribution of the cold atomic clusters, and the transverse temperature of the cold atomic clusters is characterized to obtain the transverse temperature. In one embodiment, after the cold atomic clusters are prepared, they can be characterized using absorption imaging, cohesive cluster expansion, or Raman optical frequency scanning to obtain the density distribution and transverse temperature of the atomic clusters. These are all reasonable and are not specifically limited here.

[0112] Through the above method, the wavefront distribution of Raman light can be accurately characterized in advance. In the subsequent atomic interferometry gravity measurement process, only the information of horizontal acceleration motion needs to be monitored in real time, making the atomic interferometry gravity measurement process faster and more direct.

[0113] As an embodiment of the present invention, Figure 3 As shown, the above step of characterizing the wavefront phase distribution of the Raman light to obtain the wavefront distribution of the Raman light may include:

[0114] S301, using Zernike polynomials to fit the wavefront phase distribution of the Raman light.

[0115] S302, adjusting the parameters to be adjusted and constructing a set of equations.

[0116] The parameters to be adjusted may include at least: information on the initial transverse velocity and horizontal accelerated motion of the atom;

[0117] S303 , based on the equation group, obtaining coefficients of Zernike polynomials of various orders, and obtaining the wavefront distribution of the Raman light.

[0118] The Zernike polynomial is used to fit the wavefront phase distribution of Raman light. The wavefront distribution of any shape can be expressed as the following formula (1):

[0119]

[0120] in, is the wavefront distribution of arbitrary shape, Z j (x, y) is the jth order Zernike polynomial, k is the total order of the Zernike polynomial used to fit the wavefront distribution, x and y are the horizontal and vertical coordinates of any atom in the Raman light spot, respectively, a j are the coefficients of the j-th order Zernike polynomial.

[0121] Since the final phase of atomic interference is the average phase of all atoms in the cold atomic cluster, during the atomic interference process, the lateral expansion of the cold atomic cluster causes atoms with different speeds to experience different falling trajectories, and interact with Raman light at different lateral positions. Since the wavefront of Raman light is not uniform, there will be relative phase shifts between atoms. Therefore, the final interference phase shift is the integral within the density distribution of the atomic cluster, which is shown in the following formula (2):

[0122] ΔΦ wf =ΔΦ wf,1 -2ΔΦ wf,2 +ΔΦ wf,3

[0123]

[0124] Among them, f r (x, y) is the initial density distribution of the cold atom cluster, (x1, y1) is the position coordinate of the atom within the Raman light spot when a single cold atom interacts with the first Raman light pulse (π / 2 Raman light pulse), (x2, y2) is the position coordinate of the atom within the Raman light spot when a single cold atom interacts with the second Raman light pulse (π Raman light pulse), (x3, y3) is the position coordinate of the atom within the Raman light spot when a single cold atom interacts with the third Raman light pulse (π / 2 Raman light pulse), and S is the integration interval, that is, the coverage range of the Raman light.

[0125] Since the initial density distribution of the cold atomic clusters has been pre-characterized, the above formula (2) can be rewritten as formula (3)

[0126]

[0127] Where t0 is the waiting time from the release of the cold atom to the first Raman pulse, T is the atomic free evolution time between each Raman light pulse, (x0, y0) is the initial position of the atom, (v x ,v y ) is the atomic horizontal velocity.

[0128] in, The expansion of is shown in formula (4):

[0129]

[0130] Substituting the above formula (4) into formula (1), we can get formula (5)

[0131]

[0132] Since the laser system corresponding to the Raman light used to manipulate atoms is rigidly connected to the gravimeter probe, and the cold atom group is free-falling only under the action of gravity during the atomic interferometric gravity measurement process, when the gravimeter is stationary or in horizontal uniform motion, the free-falling cold atom group will not move relative to the center of the Raman light spot in the horizontal plane. Therefore, the existing technology generally only considers the non-single symmetric Zernike terms when characterizing the Raman light wavefront. When only the first 55 Zernike polynomials, including Z4, Z 11 、Z 22 and Z 37 terms, while the integral of the odd symmetric terms is approximately 0.

[0133] However, when the atomic interferometer gravimeter is horizontally accelerated, from the release of the cold atom cluster to the completion of the atomic final state detection, the horizontal acceleration will cause the position of the Raman light rigidly connected to the atomic interferometer gravimeter probe to move relative to the cold atom cluster, making the contribution of the neglected odd-symmetric Zernike term non-negligible. In terms of specific implementation methods, the horizontal acceleration factor can be introduced into the wavefront phase shift formula, as shown in the following formula (6):

[0134]

[0135] By controlling laser parameters and simulating the motion process, the information of the initial transverse velocity of the atoms and the horizontal acceleration motion of the gravimeter is scanned. Combined with the scanning of parameters such as the initial density distribution, transverse temperature, and interference time of the cold atomic cluster, the corresponding fringe phase shift is measured, and a set of equations under horizontal acceleration motion parameters of different directions and magnitudes is constructed. The coefficients of each order Zernike polynomial containing odd symmetry terms are solved, and the wavefront distribution of the Raman light is reconstructed based on the coefficients of each order Zernike polynomial.

[0136] It can be seen that the present invention adds consideration of the odd-symmetric Zernike term in the wavefront phase shift, which is beneficial to further improve the measurement accuracy of the movable atom interferometer gravimeter.

[0137] The following describes a horizontal acceleration motion error compensation device for a movable atom interferometer gravimeter provided by the present invention. The horizontal acceleration motion error compensation device for a movable atom interferometer gravimeter described below and the horizontal acceleration motion error compensation method for a movable atom interferometer gravimeter described above can be referred to each other.

[0138] like Figure 4 As shown, a device for compensating horizontal acceleration motion errors of a movable atomic interferometer gravimeter comprises:

[0139] The gravity phase shift acquisition module 410 is used to acquire the gravity phase shift based on the interference loop formed by the Raman light pulse sequence and the cold atomic cluster within a single measurement cycle.

[0140] Wherein, the Raman light pulse sequence includes multiple Raman light pulses.

[0141] The relative position change information acquisition module 420 is used to acquire the relative position change information of the cold atomic group in the horizontal cross section of the Raman light pulse sequence.

[0142] The relative position change information includes relative position information corresponding to multiple Raman light pulses.

[0143] The effective Rabi frequency calculation and compensation module 430 is used to obtain the effective Rabi frequency under the action of horizontal acceleration based on the relative position information and the pre-acquired characterization information, and compensate for the effective Rabi frequency to reduce the impact of horizontal acceleration on the atomic interferometry gravity measurement process.

[0144] The characterization information includes the intensity distribution of Raman light, the wavefront distribution of Raman light, the initial density distribution of the cold atomic clusters, and the lateral temperature.

[0145] The wavefront phase shift and gravitational acceleration calculation module 440 is used to obtain the wavefront phase shift introduced by the horizontal acceleration motion based on the relative position change information and the characterization information, and to obtain the corrected gravitational phase shift based on the wavefront phase shift and the gravitational phase shift, and to obtain the single-cycle gravitational acceleration based on the corrected gravitational phase shift.

[0146] As an embodiment of the present invention, the relative position change information acquisition module 420 may include:

[0147] A horizontal acceleration motion information acquisition unit, used for acquiring horizontal acceleration motion information of the atomic interferometer gravimeter;

[0148] The position change information acquiring unit is configured to acquire relative position change information based on the horizontal acceleration motion information.

[0149] As an embodiment of the present invention, the effective Rabi frequency calculation and compensation module 430 may include:

[0150] The effective Rabi frequency calculation unit is used to obtain the current effective Rabi frequency under the current horizontal acceleration motion based on the relative position information corresponding to each Raman light pulse and the characterization information at the moment when the Raman light pulse interacts with the cold atomic cluster.

[0151] The effective Rabi frequency compensation unit is used to adjust the Raman light pulse based on the current effective Rabi frequency, and compensate for the current effective Rabi frequency to reduce the influence of the horizontal acceleration operation on the atomic interferometry gravity measurement process.

[0152] As an embodiment of the present invention, the effective Rabi frequency compensation unit may include:

[0153] The first regulating subunit is used to regulate the intensity of the Raman light corresponding to the Raman light pulse. Or,

[0154] The second regulating subunit is used to regulate the pulse width of the Raman light pulse.

[0155] As an embodiment of the present invention, the effective Rabi frequency calculation unit may include:

[0156] a first acquiring subunit, configured to acquire a current density distribution based on the current relative position information, the initial density distribution, and the lateral temperature;

[0157] The second acquisition subunit is configured to acquire the effective Rabi frequency of the Raman light pulse based on the current density distribution and the light intensity distribution corresponding to the Raman light pulse.

[0158] As an embodiment of the present invention, the above device may further include:

[0159] The characterization module is used to characterize the intensity distribution of the Raman light before obtaining the gravitational phase shift based on the interference loop formed by the interaction between the Raman light pulse sequence and the cold atomic group, so as to obtain the intensity distribution of the Raman light.

[0160] The wavefront phase distribution of the Raman light is characterized to obtain the wavefront distribution of the Raman light.

[0161] The initial density distribution of the cold atomic clusters is characterized to obtain the initial density distribution of the cold atomic clusters.

[0162] The transverse temperature of the cold atomic cluster is characterized to obtain the transverse temperature.

[0163] As an embodiment of the present invention, the characterization module can be specifically used to fit the wavefront phase distribution of Raman light using Zernike polynomials.

[0164] Adjust the parameters to be adjusted and construct a set of equations.

[0165] The parameters to be adjusted may at least include information on the initial transverse velocity and horizontal accelerated motion of the atom.

[0166] Based on the equation group, the coefficients of Zernike polynomials of various orders are obtained to obtain the wavefront distribution of the Raman light.

[0167] In order to make it easier to understand the horizontal acceleration motion error compensation device of the movable atomic interferometer gravimeter provided by the present invention, the following is combined with Figure 5The horizontal acceleration motion error compensation device of the movable atomic interferometer gravimeter provided by the present invention is introduced by way of example:

[0168] like Figure 5 As shown, the movable atomic interferometer gravimeter horizontal acceleration motion error compensation device may include an atomic interferometer gravimeter probe and a gravity phase shift calculation unit consisting of a gravity phase shift acquisition module 410, a horizontal acceleration motion information acquisition unit 501, a position change information acquisition unit 502, a characterization module 503, a wavefront phase shift and gravity acceleration calculation module 440, an effective Rabi frequency calculation unit 504, and an effective Rabi frequency compensation unit 505.

[0169] The gravity phase shift acquisition module 410 is rigidly connected to the horizontal acceleration information acquisition unit 501 to ensure that the horizontal measurement axis is orthogonal to the direction of gravity. The horizontal acceleration information acquisition unit 501 is connected to the effective Rabi frequency calculation unit 504 and the position change information acquisition unit 502. The effective Rabi frequency calculation unit 504 is connected to the effective Rabi frequency compensation unit 505. The effective Rabi frequency compensation unit 505 is connected to the gravity phase shift acquisition module 410 and the characterization module 503. The position change information acquisition unit 502 is connected to the wavefront phase shift calculation module 440. The wavefront phase shift and gravity acceleration calculation module 440 is connected to the characterization module 503.

[0170] The characterization module 503 can characterize the light intensity distribution within the horizontal cross section of the Raman light pulse to obtain the light intensity distribution of the Raman light. It can also characterize the wavefront phase distribution of the Raman light to obtain the wavefront distribution of the Raman light, characterize the initial density distribution of the cold atomic clusters to obtain the initial density distribution of the cold atomic clusters, and characterize the transverse temperature of the cold atomic clusters to obtain the transverse temperature. The above-described characterization information can also be retrieved and stored.

[0171] In one embodiment, the wavefront phase shift and gravitational acceleration calculation module can be composed of a wavefront phase shift calculation unit and a gravitational acceleration calculation unit. The horizontal acceleration motion information acquisition unit can also be called a horizontal motion monitoring unit. The above-mentioned atomic interferometer gravimeter can also include a laser parameter control unit for adjusting the intensity of the Raman light or the pulse width of the Raman light pulse. This is all reasonable.

[0172] The movable atomic interferometer gravimeter horizontal acceleration motion error compensation device provided by the present invention has a simple structure. The horizontal acceleration motion information acquisition unit can utilize the three-axis speedometer widely used in the existing vertical vibration compensation technology, and the corresponding calculation does not require the addition of an additional high-speed processor, which is beneficial to reducing the complexity and cost of the system.

[0173] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for compensating horizontal acceleration motion error of a movable atomic interferometer gravimeter, characterized in that: The method comprises: In a single measurement cycle, the gravitational phase shift is obtained based on an interference loop formed by the interaction between a Raman light pulse sequence and a cold atomic cluster, wherein the Raman light pulse sequence includes multiple Raman light pulses; Acquiring relative position change information of the cold atomic group in a horizontal cross section of the Raman light pulse sequence, wherein the relative position change information includes relative position information corresponding to multiple Raman light pulses respectively; Based on the relative position information and pre-acquired characterization information, an effective Rabi frequency under the action of horizontal acceleration is obtained, and the effective Rabi frequency is compensated to reduce the influence of the horizontal acceleration on the atomic interferometry gravity measurement process, wherein the characterization information includes the intensity distribution of Raman light, the wavefront distribution of Raman light, the initial density distribution of the cold atomic cluster, and the lateral temperature; Based on the relative position change information and the characterization information, the wavefront phase shift introduced by the horizontal acceleration motion is obtained, and based on the wavefront phase shift and the gravity phase shift, the corrected gravity phase shift is obtained, and based on the corrected gravity phase shift, the single-cycle gravity acceleration is obtained.

2. The method for compensating horizontal acceleration motion error of a movable atomic interferometer gravimeter according to claim 1, characterized in that: The step of obtaining the relative position change information of the cold atomic clusters in the horizontal cross section of each of the Raman light pulses comprises: Obtain information on the horizontal acceleration of the atomic interferometer gravimeter; Relative position change information is acquired based on the horizontal acceleration motion information.

3. The method for compensating horizontal acceleration motion error of a movable atomic interferometer gravimeter according to claim 1, characterized in that: The step of obtaining the effective Rabi frequency under the action of horizontal accelerated motion based on the relative position information and the pre-acquired characterization information, and compensating the effective Rabi frequency includes: For each moment when a Raman light pulse interacts with the cold atomic cluster, based on the relative position information corresponding to the Raman light pulse and the characterization information, a current effective Rabi frequency under the current horizontal accelerated motion is obtained; Based on the current effective Rabi frequency, the Raman light pulse is adjusted to compensate for the current effective Rabi frequency, so as to reduce the influence of the horizontal acceleration operation on the atomic interferometry gravity measurement process.

4. The method for compensating horizontal acceleration motion error of a movable atomic interferometer gravimeter according to claim 3, characterized in that: The step of adjusting the Raman light pulse comprises: Adjusting the intensity of the Raman light corresponding to the Raman light pulse; or Adjust the pulse width of the Raman light pulse.

5. The method for compensating horizontal acceleration motion error of a movable atomic interferometer gravimeter according to claim 3, characterized in that: The step of obtaining the current effective Rabi frequency under the current horizontal accelerated motion based on the relative position information corresponding to the Raman light pulse and the characterization information includes: Obtaining a current density distribution of cold atomic clusters based on the relative position information corresponding to the Raman light pulse, the initial density distribution of the cold atomic clusters, and the lateral temperature; Based on the current cold atomic cluster density distribution and the light intensity distribution corresponding to the Raman light pulse, the current effective Rabi frequency of the Raman light pulse is obtained.

6. The method for compensating horizontal acceleration motion error of a movable atomic interferometer gravimeter according to any one of claims 1 to 5, characterized in that: Before the step of obtaining the gravitational phase shift based on the interference loop formed by the interaction between the Raman light pulse sequence and the cold atomic cluster, the method further includes: Characterizing the intensity distribution of the Raman light to obtain the intensity distribution of the Raman light; Characterizing the wavefront phase distribution of the Raman light to obtain the wavefront distribution of the Raman light; Characterizing the initial density distribution of the cold atomic clusters to obtain the initial density distribution of the cold atomic clusters; The transverse temperature of the cold atomic cluster is characterized to obtain the transverse temperature.

7. The method for compensating horizontal acceleration motion error of a movable atomic interferometer gravimeter according to claim 6, characterized in that: The step of characterizing the wavefront phase distribution of the Raman light to obtain the wavefront distribution of the Raman light includes: Zernike polynomials are used to fit the wavefront phase distribution of Raman light; Adjusting the parameters to be adjusted and constructing a set of equations, wherein the parameters to be adjusted include: information of the initial transverse velocity and horizontal accelerated motion of the atom; Based on the equation group, the coefficients of Zernike polynomials of various orders are obtained to obtain the wavefront distribution of the Raman light.

8. A device for compensating horizontal acceleration motion errors of a movable atomic interferometer gravimeter, characterized in that: The device comprises: A gravitational phase shift acquisition module, configured to acquire the gravitational phase shift within a single measurement cycle based on an interference loop formed by the interaction of a Raman light pulse sequence with a cold atomic cluster, wherein the Raman light pulse sequence includes multiple Raman light pulses; a relative position change information acquisition module, configured to acquire relative position change information of the cold atomic group within a horizontal cross section of the Raman light pulse sequence, wherein the relative position change information includes relative position information corresponding to multiple Raman light pulses; an effective Rabi frequency calculation and compensation module, configured to obtain an effective Rabi frequency under horizontal acceleration based on the relative position information and pre-acquired characterization information, and to compensate for the effective Rabi frequency to reduce the impact of horizontal acceleration on the atomic interferometry gravity measurement process, wherein the characterization information includes the intensity distribution of Raman light, the wavefront distribution of Raman light, the initial density distribution of the cold atomic cluster, and the lateral temperature; The wavefront phase shift and gravitational acceleration calculation module is used to obtain the wavefront phase shift introduced by the horizontal acceleration motion based on the relative position change information and the characterization information, and to obtain the corrected gravitational phase shift based on the wavefront phase shift and the gravitational phase shift, and to obtain the single-cycle gravitational acceleration based on the corrected gravitational phase shift.

9. The horizontal acceleration motion error compensation device of the movable atomic interferometer gravimeter according to claim 8, characterized in that: The relative position change information acquisition module includes: A horizontal acceleration motion information acquisition unit, used for acquiring horizontal acceleration motion information of the atomic interferometer gravimeter; The position change information acquiring unit is configured to acquire relative position change information based on the horizontal acceleration motion information.

10. The horizontal acceleration motion error compensation device of the movable atomic interferometer gravimeter according to claim 8, characterized in that: The above device also includes: A characterization module is used to characterize the intensity distribution of the Raman light before obtaining the gravitational phase shift based on the interference loop formed by the interaction between the Raman light pulse sequence and the cold atomic cluster, so as to obtain the intensity distribution of the Raman light; Characterizing the wavefront phase distribution of the Raman light to obtain the wavefront distribution of the Raman light; Characterizing the initial density distribution of the cold atomic clusters to obtain the initial density distribution of the cold atomic clusters; The transverse temperature of the cold atomic cluster is characterized to obtain the transverse temperature.

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