A stable control method for polarizability of alkali metal atoms based on data fusion

Abstract

A data fusion-based method for stabilizing the polarizability of alkali metal atoms is provided. By using an additional photodetector on the basis of the original optical pumping system, an anti-interference and strong robustness are achieved. The method is characterized in that it comprises the following steps: 1. An NPBS is provided on the optical path of the pump light input side of a glass atom gas chamber in an optical pumping device, the reflection side of the NPBS is connected to PD1, and the transmission side of the NPBS is connected to PD2 via the glass atom gas chamber, PD1 and PD2 are respectively connected to a host computer via data acquisition modules, and the host computer is connected to an LCVR; 2. Reflected light information is collected via PD1, and transmitted light information is collected via PD2; 3. A system transfer equation containing random terms is constructed to fuse data at different spaces; 4. Data at different times are fused; and 5. Error information of the pumping rate sensed by the alkali metal atoms is used to adjust the control voltage of the LCVR via the host computer, thereby stabilizing the atomic pumping rate in real time and thereby stabilizing the polarizability.

Description

Technical Field

[0001] The present invention relates to the field of quantum measurement technology, and in particular to a method for stabilizing polarizability of alkali metal atoms based on data fusion. Background Art

[0002] With the development of new theories and technologies in the quantum field, various scientific instruments based on quantum effects are continuously and significantly breaking through the measurement limits of traditional instruments. As a new generation of precision measurement instruments, quantum instruments based on optical pumping processes offer unparalleled performance advantages over traditional instruments and are an important development direction for future high-precision measurement.

[0003] Stable atomic polarizability is a prerequisite for precise atomic spin measurement. Fluctuations in atomic polarizability are significantly affected by optical power and are a key factor influencing polarizability fluctuations. Traditional power stabilization solutions based on optical splitters cannot distinguish between laser fluctuations and temperature-dependent changes in the splitting ratio over long periods of use. The solution of the present invention leverages the existing optical pumping system and employs an additional photodetector, offering the advantages of strong interference resistance and robustness. Summary of the Invention

[0004] In response to the need for long-term anti-interference and stable control of the polarizability of alkali metal atoms, the present invention proposes a stable control method for the polarizability of alkali metal atoms based on data fusion. By using an additional photodetector on the basis of the original optical pumping system, it is beneficial to bring the advantages of strong anti-interference and robustness.

[0005] The technical solutions of the present invention are as follows:

[0006] A method for stabilizing polarizability of alkali metal atoms based on data fusion, characterized by comprising the following steps:

[0007] Step 1: A depolarizing beam splitter prism NPBS is provided on the optical path of the pump light input side of the glass atom gas cell in the optical pumping device. The reflective side of the depolarizing beam splitter prism NPBS is connected to a first photodetector PD1, and the transmissive side of the depolarizing beam splitter prism NPBS is connected to a second photodetector PD2 via the glass atom gas cell. PD1 and PD2 are respectively connected to a host computer via a data acquisition module, and the host computer is connected to a liquid crystal variable phase retarder LCVR.

[0008] Step 2: Using the data acquisition module, the reflected light information from the NPBS is collected through PD1, and the transmitted light information from the glass atomic gas cell is collected through PD2;

[0009] Step 3: Construct a system transfer equation containing random terms, and use a host computer to perform different spatial data fusion on the reflected light information and the transmitted light information. The system transfer equation containing random terms is as follows:

[0010] X k =H k x k +G k υ k ,

[0011]

[0012] x k =[P pd1 , P pd2 ,ΔI] T ,

[0013] where X k is the pump rate vector, H k is the first transfer matrix, x k is the optical power vector, G k is the second transfer matrix, υ k is a random noise vector, k is the time, is the optical power information after data fusion at different optical detection points k, C k is the matrix used to estimate the fusion information at time k, P pd1 is the optical power information detected by PD1, P pd2 is the optical power information detected by PD2, ΔI is the pump rate loss caused by atomic absorption, and T is the transposition operator;

[0014] Step 4: Fusion of data at different times is performed using the following equation:

[0015]

[0016] in is the pump rate or corresponding optical power obtained at time k, is the pump rate or corresponding optical power estimated at time k-1, A k It is the matrix used to estimate the fusion information at time k, namely the data fusion factor;

[0017] In step 5, the error information of the pumping rate sensed by the alkali metal atoms is used to adjust the control voltage of the LCVR through the PID module of the host computer, so as to achieve the purpose of stabilizing the atomic pumping rate in real time when the optical pumping system is operating, and then stabilizing the polarizability.

[0018] Step 5 includes the following formula:

[0019]

[0020]

[0021] where e k is the error at time k, R p is the reference value of the pumping rate felt by the atoms, u k is the control voltage applied to the LCVR at time k, K P Is the proportional coefficient in PID, K I is the integral coefficient in PID, i is the serial number, e i is the i-th error value, K D is the differential coefficient in PID, e k-1 is the error at time k-1, u k-1 is the control voltage applied to the LCVR at time k-1.

[0022] Step 3 includes the following formula:

[0023]

[0024] C k =[1-κ,κ,0],

[0025] Where α is the conversion coefficient between optical power and pump rate, β is the transmittance of the glass cell, which is defined as the ratio of the outgoing light power to the incident light power, and γ is the splitting ratio of the optical splitter, which is defined as the ratio of the main light power to the branch light power.

[0026] The technical effects of the present invention are as follows: The present invention provides a method for stabilizing the polarizability of alkali metal atoms based on data fusion, which can bring advantages of strong anti-interference and robustness.

[0027] The advantages of the present invention compared with the prior art are:

[0028] The present invention constructs a system transfer model and then obtains the pumping rate felt by the alkali metal atoms in real time through a real-time recursive relationship, thereby adjusting the control voltage of the LCVR. This can achieve long-term stability of the polarizability of the alkali metal atoms and has the advantages of small size and online non-destructive measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a schematic structural diagram of an optical pumping device involved in a method for stabilizing the polarizability of alkali metal atoms based on data fusion. Figure 1It includes a laser (such as a distributed feedback laser, Distributed Feedback Laser, DFB), a polarizing beamsplitter prism PBS, a liquid crystal variable phase retarder LCVR (Liquid Crystal Variable Retarder), a depolarizing beamsplitter prism NPBS (Non-polarizing Beamsplitter), a first photoelectric detector PD1 (Photoelectric Detector), a second photodetector PD2, a three-axis magnetic field coil located between NPBS and PD2, and a glass atomic gas chamber located in the three-axis magnetic field coil, PD1 is connected to a data acquisition module, and the data acquisition module is connected to the LCVR through a host computer (the host computer has a built-in PID module, PID, Proportional Integral Derivative, proportional, integral, differential).

[0030] Figure 2 The present invention is a schematic diagram of an atomic polarizability estimation process based on data fusion involved in implementing a method for stabilizing the polarizability of alkali metal atoms based on data fusion. Figure 2 The method includes step 1, the data acquisition module collects the reflected light information from the NPBS through PD1, and collects the transmitted light information from the glass atomic gas chamber through PD2; step 2, the host computer performs different spatial data fusion on the reflected light information and the transmitted light information, X k =H k x k +G k υ k , X k is the pump rate vector, H k is the first transfer matrix, x k is the optical power vector, x k =[P pd1 , P pd2 ,ΔI] T , P pd1 is the optical power information detected by PD1, P pd2 is the optical power information detected by PD2, ΔI is the pump rate loss caused by atomic absorption, T is the transposition operator, G k is the second transfer matrix, υ k is a random noise vector, k is the time, is the optical power information after data fusion at different optical detection points k, C k is the matrix used to estimate the fusion information at time k; Step 3, the host computer fuses the reflected light information and the transmitted light information at different times, is the pump rate or corresponding optical power obtained at time k, is the pump rate or corresponding optical power estimated at time k-1, A k It is the matrix used to estimate the fusion information at time k, namely the data fusion factor.

[0031] Figure 3 The present invention is a flow chart of a method for stabilizing the polarizability of alkali metal atoms based on data fusion. Figure 3 The process includes step 1, the data acquisition module collects the reflected light information from the NPBS through PD1, and collects the transmitted light information from the glass atomic gas cell through PD2; step 2, calculates Step 3, calculate e k , e k is the error at time k; Step 4, calculate u k ,u k is the control voltage applied to the LCVR; u k After applying to LCVR, return to step 1 and repeat the cycle. DETAILED DESCRIPTION

[0032] Below is the attached figure ( Figure 1-Figure 3 ) and Examples illustrate the present invention.

[0033] Figure 1 The present invention is a schematic structural diagram of an optical pumping device involved in a method for stabilizing the polarizability of alkali metal atoms based on data fusion. Figure 2 The present invention is a schematic diagram of an atomic polarizability estimation process based on data fusion involved in implementing a method for stabilizing the polarizability of alkali metal atoms based on data fusion. Figure 3 This is a flow chart of a method for stabilizing the polarizability of alkali metal atoms based on data fusion according to the present invention. Figures 1 to 3 As shown, a method for stabilizing the polarizability of alkali metal atoms based on data fusion is provided, comprising the following steps: Step 1, setting a depolarizing beam splitter prism NPBS on the optical path of the pump light input side of the glass atom gas chamber in the optical pumping device, the reflection side of the depolarizing beam splitter prism NPBS being connected to a first photodetector PD1, and the transmission side of the depolarizing beam splitter prism NPBS being connected to a second photodetector PD2 through the glass atom gas chamber, PD1 and PD2 being connected to a host computer via a data acquisition module, respectively, and the host computer being connected to a liquid crystal variable phase retarder LCVR; Step 2, using the data acquisition module to collect reflected light information from the NPBS via PD1, and to collect transmitted light information from the glass atom gas chamber via PD2; Step 3, constructing a system transfer equation containing random terms, and using the host computer to perform different spatial data fusion on the reflected light information and the transmitted light information, wherein the system transfer equation containing random terms is as follows:

[0034] X k =H k x k +G k υ k ,

[0035]

[0036] x k =[P pd1 , P pd2 ,ΔI] T ,

[0037] where X k is the pump rate vector, H k is the first transfer matrix, x k is the optical power vector, G k is the second transfer matrix, υ k is a random noise vector, k is the time, is the optical power information after data fusion at different optical detection points k, C k is the matrix used to estimate the fusion information at time k, P pd1 is the optical power information detected by PD1, P pd2 is the optical power information detected by PD2, ΔI is the pump rate loss caused by atomic absorption, and T is the transposition operator;

[0038] Step 4: Fusion of data at different times is performed using the following equation:

[0039]

[0040] in is the pump rate or corresponding optical power obtained at time k, is the pump rate or corresponding optical power estimated at time k-1, A k It is the matrix used to estimate the fusion information at time k, namely the data fusion factor;

[0041] In step 5, the error information of the pumping rate sensed by the alkali metal atoms is used to adjust the control voltage of the LCVR through the PID module of the host computer, so as to achieve the purpose of stabilizing the atomic pumping rate in real time when the optical pumping system is operating, and then stabilizing the polarizability.

[0042] Step 5 includes the following formula:

[0043]

[0044] where e k is the error at time k, R p is the reference value of the pumping rate felt by the atoms, uk is the control voltage applied to the LCVR at time k, K P Is the proportional coefficient in PID, K I is the integral coefficient in PID, i is the serial number, e i is the i-th error value, K D is the differential coefficient in PID, e k-1 is the error at time k-1, u k-1 is the control voltage applied to the LCVR at time k-1.

[0045] Step 3 includes the following formula:

[0046]

[0047] C k =[1-κ,κ,0],

[0048] Where α is the conversion coefficient between optical power and pump rate, β is the transmittance of the glass cell, which is defined as the ratio of the outgoing light power to the incident light power, and γ is the splitting ratio of the optical splitter, which is defined as the ratio of the main light power to the branch light power.

[0049] The present invention discloses a method for stabilizing the polarizability of alkali metal atoms based on data fusion, providing a feasible solution for real-time stabilization of the polarizability of alkali metal atoms in the direction of the pumping laser in an optically pumped system. The present invention takes the polarizability of alkali metal atoms in an optically pumped system as the research object. In view of the long-term stability requirement of the polarizability of alkali metal atoms in an atomic chamber, a system transfer equation containing random terms is first established for different optical power detection points. Then, using a data fusion method, the data from the past and present moments of different detection points are fused to obtain the final optical power information. Because the pump rate felt by the atoms is functionally related to the optical power, the atomic relaxation rate remains almost unchanged when the temperature is stable. The atomic polarizability can be estimated in real time based on the optical power information after data fusion. The obtained real-time atomic polarizability is compared with a polarizability reference value to obtain an error. Using a PID method to control the driving voltage of a liquid crystal variable phase retarder (LCVR) can stabilize the optical pump rate and, therefore, the polarizability of the alkali metal atoms. The stabilization method of the present invention is a real-time non-destructive polarizability stabilization control method, which ensures the long-term stability and anti-interference performance of the polarizability of the alkali metal atoms.

[0050] A data fusion-based method for stabilizing the polarizability of alkali metal atoms includes a distributed feedback laser (DFB), a liquid crystal variable retarder (LCVR), a polarizing beamsplitter (PBS), a depolarizing beamsplitter (NPBS), a quarter-wave plate, an oven device, a glass atom gas chamber, a photoelectric detector (PD), a three-axis magnetic field coil, a data acquisition module, a host computer module, and a function generator.

[0051] Step 1: Construct a system transfer equation containing random terms, and measure and identify the parameters. Adjust the frequency of the DFB pump laser to the operating frequency, use an oven and heating film to heat the atomic gas chamber to the working state, and give appropriate excitation to the three-dimensional magnetic compensation coil to prevent the atomic gas chamber from being disturbed by the external magnetic field. Based on the composition of the pumping system, according to factors such as the refraction of the gas chamber and the characteristics of the spectrometer, deduce the relationship between different light detection points and the pump rate, and write it as a transfer equation with random noise terms to facilitate data processing in step 2;

[0052] Step 2: Based on the data fusion method, the pump rate felt by the atoms is estimated in real time. Based on step 1, the pump rate information at different time and space points is integrated using covariance prediction and recursive algorithms to estimate the actual pump rate felt by the atoms in real time.

[0053] Step 3: Utilize the real-time alkali metal atom pumping rate from step 2 and subtract it from the set alkali metal atom pumping rate value to obtain the pumping rate error information felt by the alkali metal atoms. Adjust the control voltage of the LCVR through the PID module of the host computer to achieve the goal of stabilizing the atomic pumping rate in real time when the optical pumping system is operating, and thus stabilizing the polarizability.

[0054] The atomic gas cell is a glass cell widely used in the field of quantum measurement. Taking into account optical losses caused by the atomic gas cell walls and optical power loss due to light absorption, the first photodetector, designated PD1, detects the branch optical power information obtained by the spectrometer before the pump light enters the cell. After the pump light exits the cell, the photodetector designated PD2 detects the output optical power information.

[0055] In the above step 1, based on the system parameter measurement and identification, the transfer equation X of the optical pumping rate actually felt by the atoms at different measurement points is obtained. k =H k x k +Gk υ k Among them, X k is the pump rate vector and k refers to the time instant. Define the k moment, and deduce the pumping rates from the detection information of PD1 and PD2 as is the pump rate from PD1 and PD2, ΔI is the pump rate loss caused by atomic absorption, α is the conversion coefficient between optical power and pump rate, from optical power to pump. β is the transmittance of the glass cell, that is, the ratio of the output light power to the incident light power. γ is the splitting ratio of the optical splitter, defined as the ratio of the main light power to the branch light power. H k and G k Is the transfer matrix, containing the above three parameters. k is the optical power vector, P pd1 and P pd2 are the optical power information detected by PD1 and PD2, x k =[P pd1 , P pd2 , ΔI] T υ k is a random noise vector.

[0056] The optical power information after data fusion at different light detection points k is: The k in the upper right corner represents the k moment, Where k is the data fusion factor, which is obtained in real time according to the recursive algorithm. The pump rate obtained at time k is The pump rate estimated at time k-1 is Among them A k is the data fusion factor.

[0057] refer to Figure 1 The optical pumping device structure uses a distributed feedback laser. Light from the laser passes through a power stabilization module consisting of a PBS and LCVR. The NPBS then splits the light into two beams. One beam is detected by PD1, while the other, linearly polarized light, passes through a quarter-wave plate and becomes circularly polarized pump light, which then enters the atomic gas chamber. The optical power of the light exiting the atomic gas chamber is detected by PD2. The incident and output power levels pass through a data acquisition module and are processed by a host computer. The host computer calculates the pump rate fluctuations felt by the atoms within the gas chamber and adjusts the liquid crystal control voltage using the PID method to stabilize the polarization.

[0058] refer to Figure 2 Atomic polarizability estimation process based on data fusion, P pd1 is the optical power detected by PD1, and the pump rate information inferred from PD1 is

[0059]

[0060] Where Rp1(t) represents the real-time pump rate information, α is the conversion coefficient between optical power and pump rate. β is the transmittance of the glass cell, defined as the ratio of the outgoing light power to the incident light power. γ is the splitting ratio of the optical splitter, defined as the ratio of the main light power to the branch light power. ω1(t) is the noise of the measured PD detector, Indicates the average optical power sensed by detector PD1 during the system identification process.

[0061] The pump rate information inferred from PD2 is as follows:

[0062]

[0063] Where Rp2(t) represents the real-time pump rate information. Ψ(I) is the noise introduced by light absorption, Indicates the average optical power sensed by detector PD1 during the system identification process.

[0064] The transfer equation X contains random terms k =H k x k +G k υ k .in

[0065]

[0066] X k is the pump rate vector, x k is the optical power vector x k =[P pd1 , P pd2 , ΔI] T υ k is a random noise vector, and are the discrete forms of ω1(t) and Ψ(I), respectively. Define Q k It is k The variance matrix of E(υ T υ)=Q k .

[0067] The optical power information after position data fusion is Combining the system equations, we can get the following formula:

[0068] X k =H k x k +G k υ k ,

[0069]

[0070] Among them, C k =[1-κ,κ,0]. The optical power after time data fusion is

[0071] In the actual estimation process,

[0072]

[0073] P k =(1-A k )P k-1

[0074]

[0075] Among them, A k , P k , C k It is the matrix used to estimate the fusion information at time k. k-1 is the matrix at time k-1, used to update P k and A k .

[0076] refer to Figure 3 The atomic polarizability stabilization control process uses the system parameters obtained by system identification and measurement as prior information, and integrates the real-time PD1 and PD2 information to obtain The error at time k is defined as e k , R p is the reference value of the pump rate felt by the atoms. u k is the control voltage applied to the LCVR, e k-1 is the error at time k-1, K P , K I , K D is the PID parameter, K P is the proportionality coefficient, K I is the differential coefficient, K D is the differential coefficient.

[0077]

[0078] Any content not described in detail in this specification is prior art known to those skilled in the art. It should be noted that the above description is intended to help those skilled in the art understand the present invention, but does not limit the scope of protection of the present invention. Any equivalent substitution, modification, improvement, and / or simplification of the above description that does not depart from the essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for stabilizing the polarizability of alkali metal atoms based on data fusion, characterized in that: The following steps are involved: Step 1: A depolarizing beam splitter prism NPBS is provided on the optical path of the pump light input side of the glass atom gas cell in the optical pumping device, wherein the reflective side of the depolarizing beam splitter prism NPBS is connected to a first photodetector PD1, and the transmissive side of the depolarizing beam splitter prism NPBS is connected to a second photodetector PD2 via the glass atom gas cell. PD1 and PD2 are respectively connected to a host computer via a data acquisition module, and the host computer is connected to a liquid crystal variable phase retarder LCVR. Step 2: Using the data acquisition module, the reflected light information from the NPBS is collected through PD1, and the transmitted light information from the glass atomic gas cell is collected through PD2; Step 3: Construct a system transfer equation containing random terms, and use a host computer to perform different spatial data fusion on the reflected light information and the transmitted light information. The system transfer equation containing random terms is as follows: X k =H k x k +G k υ k , x k =[P pd1 ,P pd2 ,ΔI] T , where X k is the pump rate vector, H k is the first transfer matrix, x k is the optical power vector, G k is the second transfer matrix, υ k is a random noise vector, k is the time, is the optical power information after data fusion at different optical detection points k, C k is the matrix used to estimate the fusion information at time k, P pd1 is the optical power information detected by PD1, P pd2 is the optical power information detected by PD2, ΔI is the pump rate loss caused by atomic absorption, and T is the transposition operator; Step 4: Fusion of data at different times is performed using the following equation: in is the pump rate or corresponding optical power obtained at time k, is the pump rate or corresponding optical power estimated at time k-1, A k It is the matrix used to estimate the fusion information at time k, namely the data fusion factor; In step 5, the error information of the pumping rate sensed by the alkali metal atoms is used to adjust the control voltage of the LCVR through the PID module of the host computer, so as to achieve the purpose of stabilizing the atomic pumping rate in real time when the optical pumping system is operating, and then stabilizing the polarizability.

2. The method for stabilizing polarizability of alkali metal atoms based on data fusion according to claim 1, characterized in that: Step 5 includes the following formula: where e k is the error at time k, R p is the reference value of the pumping rate felt by the atoms, u k is the control voltage applied to the LCVR at time k, K P Is the proportional coefficient in PID, K I is the integral coefficient in PID, i is the serial number, e i is the i-th error value, K D is the differential coefficient in PID, e k-1 is the error at time k-1, u k-1 is the control voltage applied to the LCVR at time k-1.

3. The method for stabilizing polarizability of alkali metal atoms based on data fusion according to claim 1, characterized in that: Step 3 includes the following formula: C k =[1-k,k,0], Where α is the conversion coefficient between optical power and pump rate, β is the transmittance of the glass cell, which is defined as the ratio of the outgoing light power to the incident light power, and γ is the splitting ratio of the optical splitter, which is defined as the ratio of the main light power to the branch light power.

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