CN-121978767-A - Cold atom gravity meter time sequence control method and device for controlling speed distribution evolution

CN121978767ACN 121978767 ACN121978767 ACN 121978767ACN-121978767-A

Abstract

The application provides a time sequence control method and a time sequence control device for a cold atom gravity meter for controlling the speed distribution evolution, which lead atoms with different instantaneous mass center speeds and different heat speed distributions to be sequentially acted by the radio frequency driving light pulses matched with the instantaneous mass center speeds and the heat speed distributions by introducing the radio frequency driving light pulses matched with the instantaneous mass center speeds and the heat speed distributions in the atom falling process, thereby quickly reducing the heat speed distribution width of the atoms, effectively improving the proportion of the atoms participating in the effective interference or momentum transfer process, enhancing the contrast ratio of atomic signals and the visibility of interference fringes, and having direct effects on measuring the sensitivity and reducing the statistical noise.

Inventors

YANG YANGBO
WU YUELONG
CHEN LIRONG
HE TINGQIANG
ZHENG YAOHUI

Assignees

四川长虹电子科技有限公司
山西大学

Dates

Publication Date: 20260505
Application Date: 20260211

Claims (10)

1. The cold atom gravity meter time sequence control method for controlling the speed distribution evolution is characterized by comprising the following steps of: Acquiring an initial centroid speed, an initial thermal speed and a target thermal speed of an atom cloud; determining a plurality of target initial thermal velocities from the initial thermal velocities of the atom cloud; Determining effective wave vector directions for carrying out Raman cooling on each target initial thermal velocity according to each target initial thermal velocity; Acquiring pulse application time corresponding to each target initial thermal velocity, wherein the pulse application time corresponding to each target initial thermal velocity is determined by the pulse application time, pulse time and pulse interval of the previous pulse, or is the first action time of the pulse, and the first action time of the pulse is the time when the atomic cloud is subjected to Raman cooling; Determining pulse time sequence information of each target initial thermal velocity according to the initial centroid velocity of the atomic cloud, the pulse application time and the effective wave vector direction corresponding to each target initial thermal velocity, wherein the pulse time sequence information comprises an angular frequency difference, pulse time, radio frequency, light intensity and light power of two Raman lasers applied to each target initial thermal velocity; And after the pulse time sequence information of the last target initial thermal speed is determined, acquiring a pulse time sequence information table according to the pulse time sequence information corresponding to each target initial thermal speed.
2. The method of claim 1, wherein prior to the acquiring the pulse application time corresponding to each of the target initial thermal speeds, further comprising: determining a pulse application sequence between the plurality of target initial thermal velocities according to a target thermal velocity of the atomic cloud and each of the target initial thermal velocities; correspondingly, the acquiring the pulse applying time corresponding to each target initial thermal velocity includes: and determining pulse application time corresponding to each target initial thermal speed according to the pulse application sequence among the target initial thermal speeds.
3. The method of claim 2, wherein said determining a pulse application sequence between said plurality of target initial thermal velocities from a target thermal velocity of said atom cloud and each of said target initial thermal velocities comprises: acquiring a distance between a target thermal velocity of the atom cloud and each target initial thermal velocity; the pulse application sequence between the plurality of target initial thermal speeds is determined in order of the pitch from large to small.
4. The method of claim 1, wherein determining a plurality of target initial thermal velocities from the initial thermal velocities of the atom cloud comprises: dividing the distance between the initial thermal velocity of the atom cloud and the target thermal velocity of the atom cloud to obtain a plurality of velocity distributions; for each velocity profile, a corresponding target initial thermal velocity is determined.
5. The method according to claim 1, wherein after determining the pulse timing information of the last target initial thermal velocity, acquiring a pulse timing information table according to the pulse timing information corresponding to each target initial thermal velocity includes: Acquiring the intermediate thermal velocity of the atomic cloud after determining the pulse time sequence information of the last target initial thermal velocity; determining whether to perform Raman cooling on the atom cloud again according to the intermediate thermal speed and the target thermal speed of the atom cloud; If yes, taking the intermediate thermal velocity of the atom cloud as the initial thermal velocity of the atom cloud, and determining a plurality of new target initial thermal velocities; If not, acquiring a pulse time sequence information table according to the pulse time sequence information corresponding to each target initial thermal speed.
6. A radio frequency output device, comprising: An FPGA control module in which the pulse timing information determined by the method of any one of claims 1 to 5 is provided; a constant temperature crystal oscillator for outputting a reference clock signal; The clock buffer is connected with the output end of the constant temperature crystal oscillator and is used for outputting a plurality of clock signals with consistent phases; the phase-locked loop module is connected with the output end of the clock buffer and used for generating a microwave base load signal; the direct digital frequency synthesis module is connected with the output end of the clock buffer and used for generating radio frequency signals under the control of the FPGA control module; the mixer is connected with the output end of the phase-locked loop module and the output end of the direct digital frequency synthesis module and is used for mixing the microwave baseband signal and the radio frequency signal; the band-pass filter is connected with the output end of the mixer and is used for selecting a target frequency band signal from the mixed microwave base-load signal and the radio frequency signal; The low-noise amplifier is connected with the output end of the band-pass filter in sequence and is used for improving the signal power of the target frequency band signal; The radio frequency switch is arranged between the low-noise amplifier and the radio frequency power amplifier, and a control end of the radio frequency switch is connected with the FPGA control module and used for controlling a signal output time window so that the signal output time window corresponds to the pulse time.
7. A cold atom gravity meter according to claim 6, comprising a radio frequency output device.
8. An electronic device is characterized by comprising a processor and a memory; the memory stores computer-executable instructions; A processor executing computer-executable instructions stored in a memory, causing the processor to perform the method of any one of claims 1-5.
9. A readable storage medium comprising a program or instructions which, when run on a computer, performs the method of any of claims 1-5.
10. A computer program product comprising a computer program which, when executed by a processor, implements the method according to any of claims 1-5.

Description

Cold atom gravity meter time sequence control method and device for controlling speed distribution evolution Technical Field The application relates to the technical field of cold atom gravimeters, in particular to a time sequence control method and device for a cold atom gravimeter, which are used for controlling speed distribution evolution. Background Gravitational acceleration is a physical quantity that varies with time and space, and accurate measurement of the magnitude of gravitational acceleration has very wide and important applications in the fields of resource exploration, geodetic measurement, and metrology science. The cold atomic gravimeter is an instrument for acquiring absolute gravitational acceleration, and atoms of the cold atomic gravimeter adopt alkali metal atomic groups such as rubidium-87, wherein the atomic cloud needs to be cooled before absolute gravitational acceleration measurement is carried out, and the cooling process comprises the steps of firstly preparing super-cold in vacuum by utilizing a laser cooling and magneto-optical trap technology, then carrying out free falling motion on the atomic cloud, and carrying out Raman cooling in the free falling motion to obtain the atomic cloud capable of carrying out absolute gravitational acceleration measurement. The core of the raman cooling is that atoms with different speeds (the speeds refer to speeds of the atoms mainly of internal thermal motion and are marked as thermal speeds) are subjected to selective transition through raman laser with specific frequency difference, so that the atoms realize gradual compression of the thermal speed distribution width in the process of multiple actions. In the prior art, a preset frequency scanning strategy or a pulse sequence with fixed time intervals is adopted in the raman cooling process to finish sequential selection of different speed steps, but in the free falling process, the instantaneous speed (the instantaneous speed here comprises the speed corresponding to the free falling body (denoted as centroid speed) and the thermal speed) of atoms continuously changes along with time under the action of gravity, if a fixed or coarse-granularity time sequence control mode is still adopted, the motion phases of all atoms cannot be matched, partial speed components (denoted as thermal speed) atoms are not perfectly excited or transferred because of the action time, the purity of the selected atom cloud speed (denoted as thermal speed) is reduced, the speed (denoted as thermal speed) distribution is widened, the accuracy and the cooling efficiency of speed (denoted as thermal speed) selection are reduced, meanwhile, the speed (denoted as thermal speed) and the position distribution are widened, the 'visibility' of interference fringes is directly reduced, so that the signal contrast is reduced, and if the experimental environment is slowly changed, the fixed time sequence control mode cannot adapt to the change to maintain the optimal cooling and beam splitting effect, the slow contrast and the atom number drift are easily caused, and the signal is required to be reduced. Disclosure of Invention The application provides a cold atom gravity meter time sequence control method and device for controlling speed distribution evolution, which are used for solving the technical problems in the background technology. In a first aspect, the present application provides a method for controlling a time sequence of a cold atom gravity meter for controlling a speed distribution evolution, comprising: Acquiring an initial centroid speed, an initial thermal speed and a target thermal speed of an atom cloud; determining a plurality of target initial thermal velocities from the initial thermal velocities of the atom cloud; Determining effective wave vector directions for carrying out Raman cooling on each target initial thermal velocity according to each target initial thermal velocity; Acquiring pulse application time corresponding to each target initial thermal velocity, wherein the pulse application time corresponding to each target initial thermal velocity is determined by the pulse application time, pulse time and pulse interval of the previous pulse, or is the first action time of the pulse, and the first action time of the pulse is the time when the atomic cloud is subjected to Raman cooling; Determining pulse time sequence information of each target initial thermal velocity according to the initial centroid velocity of the atomic cloud, the pulse application time and the effective wave vector direction corresponding to each target initial thermal velocity, wherein the pulse time sequence information comprises an angular frequency difference, pulse time, radio frequency, light intensity and light power of two Raman lasers applied to each target initial thermal velocity; And after the pulse time sequence information of the last target initial thermal speed is determined, acquiring a pulse time sequence