CN116660809A - SERF state alkali metal atomic polarizability measuring method and device based on transient response - Google Patents
SERF state alkali metal atomic polarizability measuring method and device based on transient response Download PDFInfo
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- 150000001340 alkali metals Chemical class 0.000 title claims abstract description 153
- 229910052783 alkali metal Inorganic materials 0.000 title claims abstract description 106
- 230000001052 transient effect Effects 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 40
- 230000004044 response Effects 0.000 title claims abstract description 36
- 230000005291 magnetic effect Effects 0.000 claims abstract description 70
- 238000005086 pumping Methods 0.000 claims abstract description 56
- 230000010287 polarization Effects 0.000 claims abstract description 48
- 238000001514 detection method Methods 0.000 claims abstract description 45
- 239000007789 gas Substances 0.000 claims description 24
- 238000005259 measurement Methods 0.000 claims description 11
- 229910052701 rubidium Inorganic materials 0.000 claims description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 10
- 239000001307 helium Substances 0.000 claims description 10
- 229910052734 helium Inorganic materials 0.000 claims description 10
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 10
- 230000003287 optical effect Effects 0.000 claims description 10
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- 230000010355 oscillation Effects 0.000 claims description 8
- 230000000694 effects Effects 0.000 claims description 7
- 230000005389 magnetism Effects 0.000 claims description 6
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 5
- 229910052792 caesium Inorganic materials 0.000 claims description 5
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- 229910052700 potassium Inorganic materials 0.000 claims description 5
- 239000011591 potassium Substances 0.000 claims description 5
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- 230000000171 quenching effect Effects 0.000 claims description 5
- IGLNJRXAVVLDKE-UHFFFAOYSA-N rubidium atom Chemical compound [Rb] IGLNJRXAVVLDKE-UHFFFAOYSA-N 0.000 claims description 5
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- 238000005485 electric heating Methods 0.000 claims description 3
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Abstract
The SERF state alkali metal atom polarizability measuring method and device based on transient response is realized by adding a chopper in a pumping light path to modulate pumping light beams at a certain frequency and transversely applying a known magnetic field, wherein the modulation time of the chopper is longer than the polarization time of alkali metal atoms reaching the SERF state, the atoms are fully polarized in an on state, the atoms are fully depolarized in an off state to obtain a more accurate measuring result of the alkali metal atom polarizability, the resonance frequency of a transverse magnetic field is obtained by fitting by establishing an atomic transient response equation, the alkali metal atom polarizability is obtained by solving a slowing factor, and a more accurate parameter measuring means is provided for further developing a SERF magnetometer device with higher sensitivity and a SERF inertia measuring device, and the SERF state measuring method can be applied to the fields of basic physics research and extremely weak magnetic core brain magnetic detection.
Description
Technical Field
The invention relates to the technical field of SERF (Spin-exchange relaxation-Free) atomic magnetometer instrument measurement, in particular to a method and a device for measuring the polarization rate of an alkali metal atom in a SERF state based on transient response.
Background
Spin-Free Spin-exchange relaxation-Free (SERF) atomic Spin magnetic field measurement is a novel magnetic field measurement technology which is produced in the rapid development of quantum science and technology in recent years, and the sensitivity of the magnetic field measurement theory can reach aT (1 at=10) -18 T) magnitude. The atomic SERF effect can be applied to the physical science front fields of Charge Parity and time reversal Symmetry (Charge, parity, and Time Reversal Symmetry: CPT Symmetry) verification experiments, electron electric dipole moment measurement and the like. The high-sensitivity SERF magnetometer has great significance in extremely weak magnetocardiography, magnetoencephalography, high-resolution imaging, substance magnetic field analysis and other applications.
The alkali metal atomic polarizability is taken as one of important parameters of the SERF atomic spin magnetic field measuring device, determines the accuracy limit which can be achieved by the magnetic field measuring device, also determines the application exploring capability, and accurately measures the alkali metal polarizability as a precondition for judging the self performance of an atomic system.
Common methods for detecting the polarizability of alkali metal atoms: electron paramagnetic resonance, pumping light intensity attenuation, near resonance frequency resonance. For an SERF magnetometer, an electron paramagnetic resonance method needs to apply a G-level magnetic field to measure electron polarizability through the distribution probability of electrons on each energy level of atoms, and the existence of a large magnetic field influences the SERF state condition of the atoms so that the device is not in a working state; by using a pumping light transmission attenuation method, the pumping light cannot be completely transmitted in the pumping direction due to the large optical depth of the SERF magnetometer, so that the measurement accuracy is affected; near-resonance light conditions do not meet the SERF state atomic operating conditions. The existing detection method for the atomic polarizability of the alkali metal is difficult to realize the measurement under the working condition of the SERF state, and the measurement accuracy is low.
Disclosure of Invention
Aiming at the defects or shortcomings in the prior art, the invention provides a SERF state alkali metal atomic polarizability measuring method and device based on transient response, which are realized by adding a chopper in a pumping light path to modulate pumping light beams at a certain frequency and transversely applying a known magnetic field, wherein the modulation time of the chopper is longer than the polarization time of alkali metal atoms reaching the SERF state, the atoms are fully polarized in an on state, the atoms are fully depolarized in an off state to obtain a more accurate measuring result of the alkali metal atomic polarizability, the resonance frequency of a transverse magnetic field is obtained by fitting by establishing an atomic transient response equation, the alkali metal atomic polarizability is obtained by solving a slow factor, and a more accurate parameter measuring means is provided for further developing a SERF magnetometer device and a SERF inertia measuring device with higher sensitivity.
The technical scheme of the invention is as follows:
the SERF state alkali metal atomic polarization rate measuring method based on transient response is characterized by comprising the steps of enabling laser output by a pumping laser to sequentially pass through a gram Taylor prism and a 1/4 wave plate and then become circularly polarized light, modulating pumping light intensity of the circularly polarized light by using a chopper, enabling modulation time of the chopper to be longer than that of the alkali metal atoms reaching SERF state, and applying a Y-axis magnetic field B in a Y-axis direction perpendicular to both Z-axis pumping light and X-axis detection light by using a three-axis magnetic field coil y Linear polarization detecting light, Y-axis magnetic field B y And the modulated circularly polarized pumping light acts on alkali metal atoms in the alkali metal air chamber, and the linear polarization detection light is utilized to detect the spin transient precession process of the alkali metal atoms, and the linear polarization detection light penetrates through the alkali metal air chamberThen the light signal is converted into an electric signal by passing through a 1/4 wave plate, a photoelastic modulator and a gram Taylor prism in turn to be input into a signal acquisition system through a multichannel lock-in amplifier, a transient signal y of atomic spin precession is fitted in the signal acquisition system, and an alkali metal atomic spin precession slowing factor q is obtained, so that the SERF state alkali metal atomic polarizability P based on transient response is calculated.
q＝g/γ e ×B y Where g is the fitting parameter or coefficient, γ e Is the gyromagnetic ratio of alkali metal atoms;
g is determined from the following fitting equation:
y＝ae -(bt) [b cos(gt)+d sin(gt)]+h, wherein a, b, d, h are fitting values, e is a natural constant, and t is time;
the relationship between q and P is as follows:
when the alkali metal atom is 85 At Rb, q= (38+52p) 2 +6P 4 )/(3+10P 2 +3P 4 )；
When the alkali metal atom is 87 Rb or Rb 39 At K, q= (6+2p) 2 )/(1+P 2 )；
When the alkali metal atom is 41 At K, q= (6+P) 2 )/(1+P 2 )；
When the alkali metal atom is 133 In Cs, q= (22+70p) 2 +34P 4 +2P 6 )/(1+7P 2 +7P 4 +P 6 )。
Shielding an environmental magnetic field through a magnetic shielding system, further compensating triaxial residual magnetism by utilizing a triaxial magnetic field coil, and applying B with the amplitude not more than 5nT after compensating the residual magnetism y 。
The alkali metal atoms in the alkali metal gas chamber are one of potassium, rubidium and cesium, buffer gas helium and quenching gas nitrogen are filled in the alkali metal gas chamber, and the helium with the atmospheric pressure of more than 1 atmosphere is filled in the alkali metal gas chamber, so that the atomic spin generates a slowing effect.
The polarization time of the alkali metal atoms reaching the SERF state is in the ms order, the modulation frequency of the chopper is 0.5-2Hz, the atoms are fully polarized in the on state, and the atoms are fully depolarized in the off state.
X-axis component Px of alkali metal atom polarizability P and detection optical rotation angle theta pr The proportional relation of (2) is as follows:
wherein l is the path distance of the detection laser passing through the air chamber, r e Is classical electron radius, c is light velocity, n is alkali metal atom density, P x For the projection of the spin polarization of alkali metal atoms in the x-axis direction, f D2 The oscillation intensity of the D2 line is that v is the frequency of the detected light, v D2 Is the center frequency of the D2 line of the alkali metal atom Γ L Is the pressure broadening value of the D2 line of the alkali metal atom.
The relation between the slow down factor and the polarizability oscillation process is as follows:
wherein t is time, e is natural constant, R p For pumping rate, R rel For relaxation rate, k 0 And k is equal to 1 For amplitude parameters, q (P) is a slow down factor, ω y Is of intermediate quantity omega y ＝γ e ×B y ，γ e Is the gyromagnetic ratio of alkali metal atoms, P x (t) represents a function of change of Px with time t, and Px is a projection of spin polarizability of alkali metal atoms in the x-axis direction.
The SERF state alkali metal atomic polarizability measuring device based on transient response is used for implementing the SERF state alkali metal atomic polarizability measuring method based on transient response and is characterized by comprising a pumping laser and a detection laser, wherein the pumping laser is sequentially connected with a pumping light incident end of an alkali metal air chamber through a first gram taylor prism, a 1/4 wave plate, a chopper and a first beam expander, a pumping light emergent end of the alkali metal air chamber is sequentially connected with a signal acquisition system through a first photoelectric detector and a multi-channel lock-in amplifier, the detection laser is sequentially connected with a detection light incident end of the alkali metal air chamber through a 1/2 wave plate, a second beam expander and a second gram taylor prism, and a detection light emergent end of the alkali metal air chamber is sequentially connected with the signal acquisition system through a 1/4 wave plate, a photoelastic modulator, a third gram taylor prism, a second photoelectric detector and a multi-channel lock-in amplifier.
The periphery of the alkali metal air chamber is provided with a non-magnetoelectric heating system, a triaxial magnetic field coil and a magnetic shielding system, and the triaxial magnetic field coil is connected with a signal generator.
The invention has the following technical effects: the SERF state alkali metal atomic polarizability measuring method and device based on transient response provided by the invention have the advantages that the chopper is added in the pumping light path to modulate pumping light beams at a certain frequency and transversely apply a known magnetic field to realize the modulation of atomic spin polarization, the atomic transient response equation is established to perform fitting to obtain the resonance frequency of the transverse magnetic field, the alkali metal atomic polarizability is obtained through the solution of a slowing factor, the operation process is simple and convenient, the measuring time is short, the accuracy is high, a basic parameter measuring means is provided for the performance optimization of the SERF magnetometer, and the SERF state alkali metal atomic polarizability measuring method and device can be applied to the fields of basic physics research and extremely weak magnetic core brain magnetic detection.
Drawings
Fig. 1 is a schematic structural diagram of a device for measuring the polarization ratio of SERF state alkali metal atoms based on transient response, which is used for implementing the invention. SERF (Spin-exchange relaxation-Free) is Spin-Free relaxation.
Fig. 2 is a schematic flow chart of a method for measuring the polarization rate of SERF state alkali metal atoms based on transient response. FIG. 2 includes step 1, SERF magnetic field measurement triaxial in situ magnetic compensation; step 2, applying a magnetic field with a known size on the Y axis, and applying a certain frequency to modulate Z-axis pumping light by using a chopper; step 3, outputting an instant response signal to the magnetometer by using a signal acquisition system, and obtaining a resonance frequency parameter of the transverse magnetic field through matlab fitting; step 4, calculating to obtain an alkali metal slowing factor through a parameter g; and step 5, obtaining the electron polarization rate according to the calculation relation between the slowing factor and the alkali metal electron polarization rate.
The reference numerals are listed below: 1-pumping laser; 2-a first gram taylor prism; 3-1/4 wave plate; 4-chopper; 5-a first beam expander; 6-a first photodetector; 7-a detection laser; an 8-1/2 wave plate; 9-a second beam expander; 10-a second gram taylor prism; 11-1/4 wave plate; 12-photoelastic modulator; 13-a third gram taylor prism; 14-a second photodetector; 15-a signal generator; 16-a magneto-less electric heating system; 17-alkali metal plenum; 18-a triaxial magnetic field coil; a 19-multichannel lock-in amplifier; 20-a signal acquisition system; 21-magnetic shielding system.
Detailed Description
The invention will be described with reference to the accompanying drawings (fig. 1-2).
Fig. 1 is a schematic structural diagram of a device for measuring the polarization ratio of SERF state alkali metal atoms based on transient response, which is used for implementing the invention. Fig. 2 is a schematic flow chart of a method for measuring the polarization rate of SERF state alkali metal atoms based on transient response. Referring to fig. 1 to 2, the method for measuring the polarization rate of the alkali metal atoms in the SERF state based on transient response comprises sequentially passing laser output by a pumping laser through a gram taylor prism and a 1/4 wave plate to be changed into circularly polarized light, modulating the pumping light intensity of the circularly polarized light by using a chopper, wherein the modulation time of the chopper is longer than the polarization time of the alkali metal atoms in the SERF state, and applying a Y-axis magnetic field B in a Y-axis direction perpendicular to both the Z-axis pumping light and the X-axis detection light by using a three-axis magnetic field coil y Linear polarization detecting light, Y-axis magnetic field B y And the modulated circularly polarized pumping light acts on alkali metal atoms in the alkali metal air chamber, the linear polarization detection light is utilized to detect the transient spin precession process of the alkali metal atoms, the linear polarization detection light sequentially passes through a 1/4 wave plate, a photoelastic modulator and a gram taylor prism after passing through the alkali metal air chamber, and then reaches a photoelectric detector to be converted into an electric signal from an optical signal, the electric signal is input into a signal acquisition system through a multichannel lock-in amplifier, a transient signal y of the spin precession of the atoms is fitted in the signal acquisition system, and an alkali metal atom spin precession slowing factor q is obtained, so that the SERF state alkali metal atom polarization rate P based on transient response is calculated.
q＝g/γ e ×B y Where g is the fitting parameter or coefficient, γ e Is the gyromagnetic ratio of alkali metal atoms; g is fitted fromThe formula is defined in: y=ae -(bt) [b cos(gt)+d sin(gt)]+h, wherein a, b, d, h are fitting values, e is a natural constant, and t is time; the relationship between q and P is as follows: when the alkali metal atom is 85 At Rb, q= (38+52p) 2 +6P 4 )/(3+10P 2 +3P 4 ) The method comprises the steps of carrying out a first treatment on the surface of the When the alkali metal atom is 87 Rb or Rb 39 At K, q= (6+2p) 2 )/(1+P 2 ) The method comprises the steps of carrying out a first treatment on the surface of the When the alkali metal atom is 41 At K, q= (6+P) 2 )/(1+P 2 ) The method comprises the steps of carrying out a first treatment on the surface of the When the alkali metal atom is 133 In Cs, q= (22+70p) 2 +34P 4 +2P 6 )/(1+7P 2 +7P 4 +P 6 )。
Shielding an environmental magnetic field through a magnetic shielding system, further compensating triaxial residual magnetism by utilizing a triaxial magnetic field coil, and applying B with the amplitude not more than 5nT after compensating the residual magnetism y . The alkali metal atoms in the alkali metal gas chamber are one of potassium, rubidium and cesium, buffer gas helium and quenching gas nitrogen are filled in the alkali metal gas chamber, and the helium with the atmospheric pressure of more than 1 atmosphere is filled in the alkali metal gas chamber, so that the atomic spin generates a slowing effect. The polarization time of the alkali metal atoms reaching the SERF state is in the ms order, the modulation frequency of the chopper is 0.5-2Hz, the atoms are fully polarized in the on state, and the atoms are fully depolarized in the off state.
X-axis component Px of alkali metal atom polarizability P and detection optical rotation angle theta pr The proportional relation of (2) is as follows:
wherein l is the path distance of the detection laser passing through the air chamber, r e Is classical electron radius, c is light velocity, n is alkali metal atom density, P x For the projection of the spin polarization of alkali metal atoms in the x-axis direction, f D2 The oscillation intensity of the D2 line is that v is the frequency of the detected light, v D2 Is the center frequency of the D2 line of the alkali metal atom Γ L Is the pressure broadening value of the D2 line of the alkali metal atom.
The relation between the slow down factor and the polarizability oscillation process is as follows:
wherein t is time, e is natural constant, R p For pumping rate, R rel For relaxation rate, k 0 And k is equal to 1 For amplitude parameters, q (P) is a slow down factor, ω y Is of intermediate quantity omega y ＝γ e ×B y ，γ e Is the gyromagnetic ratio of alkali metal atoms, P x (t) represents a function of change of Px with time t, and Px is a projection of spin polarizability of alkali metal atoms in the x-axis direction.
The SERF state alkali metal atomic polarizability measuring device based on transient response is used for implementing the SERF state alkali metal atomic polarizability measuring method based on transient response, and comprises a pumping laser 1 and a detection laser 7, wherein the pumping laser 1 is sequentially connected with a pumping light incident end of an alkali metal air chamber 17 through a first gram taylor prism 2, a 1/4 wave plate 3, a chopper 4 and a first beam expander 5, a pumping light emergent end of the alkali metal air chamber 17 is sequentially connected with a signal acquisition system 20 through a first photoelectric detector 6 and a multi-channel lock-in amplifier 19, the detection laser 7 is sequentially connected with a detection light incident end of the alkali metal air chamber 17 through a 1/2 wave plate 8, a second beam expander 9 and a second gram taylor prism 10, and a detection light emergent end of the alkali metal air chamber 17 is sequentially connected with the signal acquisition system 20 through a 1/4 wave plate 11, a photoelastic modulator 12, a third gram taylor prism 13, a second photoelectric detector 14 and a multi-channel lock-in amplifier 19. The outer periphery of the alkali metal gas chamber 17 is provided with a non-magnetic electric heating system 16, a triaxial magnetic field coil 18 and a magnetic shielding system 21, and the triaxial magnetic field coil 18 is connected with the signal generator 15.
A SERF state alkali metal atom polarizability measuring method and device based on transient response, in pumping light propagation direction, pumping laser 1 outputs laser, after passing through gram Taylor prism 2 and 1/4 wave plate 3, it becomes circular polarized light, and chopper 4 is used to modulate pumping light intensity. Applying a magnetic field B in a direction perpendicular to both the pumping light and the detection light using the triaxial magnetic field coil 18 y . The modulated circularly polarized pumping light, the linearly polarized detection light and the transverse magnetic field act simultaneously on the alkali metal atoms in the gas cell. The detection light perpendicular to the pumping light is used for detecting the transient precession process of the electron spin of the alkali metal atom under the action of the modulated pumping light and the magnetic field. The laser emitted by the detection light laser 7 is linearly polarized light after passing through the 1/2 wave plate 8 and the second gram taylor prism 10, the polarization of the light is modulated by the photoelastic modulator 12 after passing through the alkali metal air chamber 17, the second array detector 14 converts the optical signal of the detection light into an electric signal, the electric signal is collected by the signal collecting system 20, and the transient signal of the atomic spin precession is fitted to obtain an alkali metal atomic spin precession slowing factor, so that the electron polarization rate is calculated.
The modulation time of the chopper is longer than the polarization time of the alkali metal atoms reaching the SERF state, and the atoms are fully polarized in the on state and fully depolarized in the off state.
To ensure that the atomic magnetometer operates in the SERF state, the high performance magnetic shielding system 21 is used to shield the ambient magnetic field and the triaxial remanence is further compensated by the triaxial magnetic field coil 18, after the remanence is compensated, a transverse magnetic field B with the amplitude not more than 5nT is applied in the direction perpendicular to the pumping light and the detection light y 。
The alkali metal atoms in the alkali metal gas chamber 17 are one of potassium, rubidium and cesium, buffer gas helium and quenching gas nitrogen are filled in the alkali metal gas chamber, and the helium with the pressure greater than 1 atmosphere is filled in the alkali metal gas chamber to enable atomic spin to generate a slowing effect.
Detecting the optical rotation angle theta of light pr Projection P in the direction of the detection light with atomic spin polarizability x In direct proportion to each other,
wherein l is the path distance of the detection laser passing through the air chamber, r e Is classical atomic radius, c is light velocity, n is alkali metal atomic density, P x Is the projection of the spin polarization of the alkali metal atoms in the x-axis direction. f (f) D2 Strong oscillation of D2 lineDegree, v is the detected light frequency, v D2 Is the center frequency of the D2 line of the alkali metal atom Γ L Is the pressure broadening value of the D2 line of the alkali metal atom.
The slowing factor versus polarizability oscillation process is shown in the following equation:
wherein t is time, e is natural constant, R p For pumping rate, R rel For relaxation rate, k 0 And k is equal to 1 As amplitude parameter omega y ＝γ e ×B y Q (P) is a slow down factor.
The photodetector converts the optical signal of the detected light into a voltage signal and fits the acquired signal y with the signal acquisition system 20,
obtaining fitting coefficients g, e as natural constants, b, d, h as fitting values, according to q (p) =g/gamma e ×B y Wherein B is y For the y-axis magnetic field value, gamma e For the gyromagnetic ratio of alkali metal atoms, a slowing factor q (P) can be obtained, and a fitting formula is as follows:
y＝ae -(bt) [b cos(gt)+d sin(gt)]+h
the relationship between the slowing factor q and the polarization ratio P is used to determine the polarization ratio from the kind of alkali metal atom.
An SERF state alkali metal atom electron polarizability measuring method based on atom transient response comprises the following steps: in the pumping light propagation direction, the pumping laser 1 outputs laser light, the laser light is changed into circularly polarized light after passing through the gram-taylor prism 2 and the 1/4 wave plate 3, the chopper 4 is removed, pumping light and detection light are simultaneously irradiated on the alkali metal air chamber 17, triaxial magnetic compensation is carried out on the SERF atomic magnetometer by using the triaxial magnetic field coil 17, a voltage is applied to the triaxial magnetic field coil 17 through the control signal generator 15 to generate a magnetic field which is in magnetic contact with the outsideThe field counteracts, so that the output of the photoelectric detector is zero, and the alkali metal atoms do not feel an external magnetic field. The pumping light intensity is modulated using a chopper 4. Applying a magnetic field B in a direction perpendicular to both the pumping light and the detection light using the triaxial magnetic field coil 18 y . The modulated circularly polarized pumping light, the linearly polarized detection light and the transverse magnetic field act simultaneously on the alkali metal atoms in the alkali metal cell. The detection light perpendicular to the pumping light is used for detecting the transient precession process of the electron spin of the alkali metal atom under the action of the modulated pumping light and the magnetic field. The laser emitted by the detection light laser 7 is linearly polarized light after passing through the 1/2 wave plate 8 and the second gram taylor prism 10, the polarization of the light is modulated by the photoelastic modulator 12 after passing through the alkali metal air chamber 17, the second array detector 14 converts the optical signal of the detection light into an electric signal, the electric signal is collected by the signal collecting system 20, and the transient signal of the atomic spin precession is fitted to obtain an alkali metal atomic spin precession slowing factor, so that the electron polarization rate is calculated.
An atomic transient response-based SERF state alkali metal atomic electron polarizability measuring method and device, wherein the modulation time of a chopper is longer than the polarization time of an alkali metal atom reaching the SERF state, and the atoms are fully polarized in an on state and fully depolarized in an off state. The polarization time reached by the electrons is in the order of ms and the chopper 4 modulation frequency is in the order of 0.5-2Hz, taking into account the requirements of fast measurement. The alkali metal atoms in the alkali metal gas chamber 17 are one of potassium, rubidium and cesium, and are filled with buffer gas helium and quenching gas nitrogen, and the helium with the pressure greater than 1 atmosphere is filled to cause the atomic spin to generate a slowing effect.
What is not described in detail in the present specification belongs to the prior art known to those skilled in the art. It is noted that the above description is helpful for a person skilled in the art to understand the present invention, but does not limit the scope of the present invention. Any and all such equivalent substitutions, modifications and/or deletions as may be made without departing from the spirit and scope of the invention.
Claims (9)
1. The SERF state alkali metal atomic polarization rate measuring method based on transient response is characterized by comprising the steps of enabling laser output by a pumping laser to sequentially pass through a gram Taylor prism and a 1/4 wave plate and then become circularly polarized light, modulating pumping light intensity of the circularly polarized light by using a chopper, enabling modulation time of the chopper to be longer than that of the alkali metal atoms reaching SERF state, and applying a Y-axis magnetic field B in a Y-axis direction perpendicular to both Z-axis pumping light and X-axis detection light by using a three-axis magnetic field coil y Linear polarization detecting light, Y-axis magnetic field B y And the modulated circularly polarized pumping light acts on alkali metal atoms in the alkali metal air chamber, the linear polarization detection light is utilized to detect the transient spin precession process of the alkali metal atoms, the linear polarization detection light sequentially passes through a 1/4 wave plate, a photoelastic modulator and a gram taylor prism after passing through the alkali metal air chamber, and then reaches a photoelectric detector to be converted into an electric signal from an optical signal, the electric signal is input into a signal acquisition system through a multichannel lock-in amplifier, a transient signal y of the spin precession of the atoms is fitted in the signal acquisition system, and an alkali metal atom spin precession slowing factor q is obtained, so that the SERF state alkali metal atom polarization rate P based on transient response is calculated.
2. The transient response-based SERF state alkali metal atomic polarizability measurement method according to claim 1, wherein q=g/γ e ×B y Where g is the fitting parameter or coefficient, γ e Is the gyromagnetic ratio of alkali metal atoms;
g is determined from the following fitting equation:
y＝ae -(bt) [bcos(gt)+dsin(gt)]+h, wherein a, b, d, h are fitting values, e is a natural constant, and t is time;
the relationship between q and P is as follows:
when the alkali metal atom is 85 At Rb, q= (38+52p) 2 +6P 4 )/(3+10P 2 +3P 4 )；
When the alkali metal atom is 87 Rb or Rb 39 At K, q= (6+2p) 2 )/(1+P 2 )；
When the alkali metal atom is 41 At K, q= (6+P) 2 )/(1+P 2 )；
When the alkali metal atom is 133 In Cs, q= (22+70p) 2 +34P 4 +2P 6 )/(1+7P 2 +7P 4 +P 6 )。
3. The method for measuring the polarization rate of SERF (surface enhanced Raman Scattering) state alkali metal atoms based on transient response according to claim 1, wherein an environmental magnetic field is shielded through a magnetic shielding system, triaxial residual magnetism is further compensated by a triaxial magnetic field coil, and B with the amplitude not more than 5nT is applied after the residual magnetism is compensated y 。
4. The method for measuring the polarization rate of SERF (surface enhanced Raman Scattering) state alkali metal atoms based on transient response according to claim 1, wherein the alkali metal atoms in the alkali metal gas chamber are one of potassium, rubidium and cesium, buffer gas helium and quenching gas nitrogen are filled in the alkali metal gas chamber, and the slow-down effect is generated by atomic spin through helium filled with more than 1 atmosphere pressure.
5. The method for measuring the polarization rate of SERF (surface enhanced Raman Scattering) state alkali metal atoms based on transient response according to claim 1, wherein the polarization time of the alkali metal atoms reaching the SERF state is in the order of ms, the modulation frequency of the chopper is 0.5-2Hz, and the chopper is fully polarized in an on state and fully depolarized in an off state.
6. The method for measuring the polarization rate of SERF (surface enhanced Raman scattering) state alkali metal atoms based on transient response according to claim 1, wherein the X-axis component Px of the polarization rate P of the alkali metal atoms and the optical rotation angle theta of the detection light pr The proportional relation of (2) is as follows:
wherein l is the path distance of the detection laser passing through the air chamber, r e Is classical electron radius, c is light velocity, n is alkali metal sourceSub-density, P x For the projection of the spin polarization of alkali metal atoms in the x-axis direction, f D2 The oscillation intensity of the D2 line is that v is the frequency of the detected light, v D2 Is the center frequency of the D2 line of the alkali metal atom Γ L Is the pressure broadening value of the D2 line of the alkali metal atom.
7. The method for measuring the polarization rate of SERF (surface enhanced Raman Scattering) state alkali metal atoms based on transient response according to claim 1, wherein the relation between a slowing factor and the polarization rate oscillation process is as follows:
wherein t is time, e is natural constant, R p For pumping rate, R rel For relaxation rate, k 0 And k is equal to 1 For amplitude parameters, q (P) is a slow down factor, ω y Is of intermediate quantity omega y ＝γ e ×B y ，γ e Is the gyromagnetic ratio of alkali metal atoms, P x (t) represents a function of change of Px with time t, and Px is a projection of spin polarizability of alkali metal atoms in the x-axis direction.
8. The SERF state alkali metal atomic polarizability measuring device based on transient response is used for implementing the SERF state alkali metal atomic polarizability measuring method based on transient response according to any one of claims 1-7, and is characterized by comprising a pumping laser and a detection laser, wherein the pumping laser is sequentially connected with a pumping light incident end of an alkali metal air chamber through a first gram-taylor prism, a 1/4 wave plate, a chopper and a first beam expander, a pumping light emergent end of the alkali metal air chamber is sequentially connected with a signal acquisition system through a first photoelectric detector and a multi-channel lock-in amplifier, the detection laser is sequentially connected with a detection light incident end of the alkali metal air chamber through a 1/2 wave plate, a second beam expander and a second gram-taylor prism, and a detection light emergent end of the alkali metal air chamber is sequentially connected with the signal acquisition system through a 1/4 wave plate, a photoelastic modulator, a third gram-taylor prism, a second photoelectric detector and a multi-channel lock-in amplifier.
9. The transient response-based SERF state alkali metal atomic polarizability measurement device according to claim 8, wherein a magneto-less electric heating system, a triaxial magnetic field coil and a magnetic shielding system are arranged on the periphery of the alkali metal air chamber, and the triaxial magnetic field coil is connected with a signal generator.
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