阅读说明：本技术 基于量子自然基准的正弦交变电流的测量装置及方法 (Measuring device and method of sinusoidal alternating current based on quantum natural reference ) 是由 缪培贤 杨炜 冯浩 史彦超 陈大勇 张金海 廉吉庆 刘志栋 陈江 刘宗鑫 于 2021-07-16 设计创作，主要内容包括：本公开的基于量子自然基准的正弦交变电流的测量装置及方法,其本底磁场产生组件包括恒流源9、标准线圈2和磁屏蔽筒1,磁屏蔽筒1屏蔽地磁场,标准线圈2轴对称地置于磁屏蔽筒1的内部,恒流源9向标准线圈2输入电流以产生本底磁场；抽运-检测型原子磁力仪的探头部分置于标准线圈2的几何中心,包括亥姆霍兹线圈3、铷泡加热模块4、铷泡5、圆偏振抽运光10和线偏振探测光11,铷泡加热模块4使铷泡5保持恒温,圆偏振抽运光10制备铷泡5内铷原子的极化态,线偏振探测光11测量铷泡5内铷原子磁共振塞曼跃迁的内态演化信号；信号源6与亥姆霍兹线圈3、开关7和负载8相连,开关7控制信号源6向亥姆霍兹线圈3和负载8输入的待测正弦交变电流信号。本公开能够表明磁共振塞曼跃迁是有过程的,是确定性的,是可被重复操控的。(The measuring device and the method of the sine alternating current based on the quantum natural reference have the advantages that a background magnetic field generating assembly comprises a constant current source 9, a standard coil 2 and a magnetic shielding cylinder 1, the magnetic shielding cylinder 1 shields a geomagnetic field, the standard coil 2 is axially and symmetrically arranged inside the magnetic shielding cylinder 1, and the constant current source 9 inputs current to the standard coil 2 to generate the background magnetic field; the probe part of the pumping-detection type atomic magnetometer is arranged in the geometric center of a standard coil 2 and comprises a Helmholtz coil 3, a rubidium bubble heating module 4, a rubidium bubble 5, circular polarization pumping light 10 and linear polarization detection light 11, wherein the rubidium bubble heating module 4 keeps the rubidium bubble 5 at a constant temperature, the circular polarization pumping light 10 is used for preparing the polarization state of rubidium atoms in the rubidium bubble 5, and the linear polarization detection light 11 is used for measuring an internal state evolution signal of magnetic resonance Zeeman transition of the rubidium atoms in the rubidium bubble 5; the signal source 6 is connected with the Helmholtz coil 3, the switch 7 and the load 8, and the switch 7 controls the sinusoidal alternating current signal to be detected, which is input to the Helmholtz coil 3 and the load 8 by the signal source 6. The present disclosure can show that magnetic resonance zeeman transitions are procedural, deterministic, and can be manipulated repeatedly.)

1. A device for measuring sinusoidal alternating current based on a quantum natural reference, the device comprising: a background magnetic field generating assembly, a pumping-detection type atomic magnetometer, a signal source 6, a switch 7 and a load 8;

the background magnetic field generating assembly comprises a constant current source 9, a standard coil 2 and a magnetic shielding cylinder 1, wherein the magnetic shielding cylinder 1 is used for shielding a ground magnetic field, the standard coil 2 is axisymmetrically arranged inside the magnetic shielding cylinder 1, and the constant current source 9 is used for inputting current to the standard coil 2 to generate a uniform and stable background magnetic field of a z axis;

the pumping-detection type atomic magnetometer comprises a Helmholtz coil 3, a rubidium bubble heating module 4, a rubidium bubble 5, circular polarization pumping light 10 and linear polarization detection light 11; the rubidium bubble heating module 4 enables the rubidium bubble 5 to keep constant temperature, the circular polarization pumping light 10 is parallel to the z axis and used for preparing the polarization state of a rubidium atom ensemble in the rubidium bubble 5, and the linear polarization detection light 11 is parallel to the x axis and used for measuring an internal state evolution signal of a rubidium atom magnetic resonance Zeeman transition in the rubidium bubble 5;

the signal source 6 is connected to the helmholtz coil 3, the switch 7 and the load 8, and the switch 7 is configured to turn on or off a sinusoidal alternating current signal to be measured, which is input to the helmholtz coil 3 and the load 8 by the signal source 6.

2. Sinusoidal alternating current measuring device according to claim 1, characterized in that a sinusoidal alternating current is passed through the helmholtz coil 3 for generating a linearly polarized magnetic field; based on the classical theory of two-energy-level magnetic resonance Zeeman transition, the linear polarization magnetic field consists of a left-handed field and a right-handed field with the same amplitude, and the left-handed field or the right-handed field acts in the magnetic resonance Zeeman transition in the same precession direction of the atomic magnetic moment around the external magnetic field.

3. Sinusoidal alternating current measuring device according to claim 1, characterized in that the frequency of sinusoidal alternating current is traced to a quantum natural reference represented by cesium atomic clocks.

4. Sinusoidal alternating current measuring device according to claim 1, characterized in that the coil coefficients of the standard coil 2 and the helmholtz coil 3 are traced to three quantum natural references, the josephson effect, the quantized hall effect and the larmor precession effect.

5. Sinusoidal alternating current measuring device according to claim 1, characterized in, that the magnetic shielding cylinder is cylindrical with an internal cylinder diameter of 500mm and an internal cylinder length of greater than or equal to 700 mm.

6. Sinusoidal alternating current measuring device according to claim 1, characterized in, that the magnetic shielding cartridge 1 is replaced by a magnetic shielding coefficient of less than 10^-4The magnetic shield room of (1).

7. A sinusoidal alternating current measuring device according to claim 1, characterised in that the load 8 is a resistive, capacitive or inductive element.

8. Sinusoidal alternating current measuring device according to claim 1, characterized in that the frequency of the circularly polarized pump light 10 of the pump-detection type rubidium atom magnetometer is locked to⁸⁷D1 line transition of Rb atom, said⁸⁷D1 line transition of Rb atom to 5²S_1/2→5²P_1/2The frequency of the linearly polarized probe light 11 is red detuned 3GHz to 10GHz compared to the frequency of the circularly polarized pump light 10.

9. Sinusoidal alternating current measuring device according to claim 1, characterized in that the switch 7 is triggered with TTL level to switch on or off the sinusoidal alternating current signal under test output by the signal source 6.

10. A method for measuring sinusoidal alternating current based on quantum natural reference, which is applied to the apparatus for measuring sinusoidal alternating current based on quantum natural reference of any one of claims 1 to 9, the method comprising:

step 1: strictly controlling the magnetic field environment of the experimental device and keeping the magnetic shielding cylinder 1 at a constant temperature;

step 2: starting a signal source 6, and measuring the frequency f of a sine alternating signal output by the signal source 6;

and step 3: setting control time sequences of the circular polarization pumping light 10 and the switch 7 based on the working principle of the pumping-detection type atomic magnetometer, wherein the time sequence change period is integral multiple of 1/f, so that the repetition of magnetic resonance Zeeman transition signals during repeated measurement is ensured, and the phase of measured sine alternating current is kept stable and unchanged;

and 4, step 4: the current I input to the standard coil 2 by the constant current source 9 is set₉＝2πf₀/(γC₂) Setting the timing of the switch 7 such that the pulse duration of the sinusoidal alternating current signal is L₁So that the pumping-detection type atomic magnetometer can work normally, and the current I input to the standard coil 2 by the constant current source 9 is adjusted₉A magnetic field B is arranged at the center of the standard coil 2₀Corresponding larmor precession frequency f₀Equal to the frequency f of the radio frequency sine alternating current signal to be measured;

and 5: setting the time sequence of the switch 7 to ensure that the pulse duration of the radio-frequency sine alternating current signal to be measured is L₂At the pulse duration L₂Internally collecting a differential amplification signal of the internal state evolution of the magnetic resonance Zeeman transition measured by the linear polarization probe light 11 in the x-axis direction;

step 6: deleting the experimental data of the radio frequency field in the first pi pulse duration and the data of which the signal-to-noise ratio at the tail end does not meet the expectation in the step 5, and according to the expressionFitting A mu and B step by step_rf、f₀δ and T₂Parameter, wherein V_x-singalA is a differential amplification signal output by a pumping-detection type atom magnetometer in the x-axis direction, A is a proportionality coefficient, mu is the atomic magnetic moment of a single atom, gamma is the gyromagnetic ratio of rubidium atoms, and B is_rfIs the amplitude of the rotating field in the x-y plane, f₀Is a constant magnetic field B₀Proportional larmor precession frequency, δ being the angle of the rotating coordinate system relative to the laboratory coordinate system at the initial moment, related to the initial phase of the radio frequency field, T₂Relaxation time, which is the macroscopic magnetization of the atomic ensemble;

and 7: according to the parameter B_rfAnd expression B_rf＝C₃I₀Calculating the amplitude I of the sinusoidal alternating current signal to be measured in the Helmholtz coil 3₀In which C is₃The coil coefficient of the helmholtz coil 3; and analyzing according to the parameter delta, the time sequence control parameter of the pumping-detection type atomic magnetometer and the data interception position to obtain the phase of the sinusoidal alternating current signal to be detected in the Helmholtz coil 3.

Technical Field

The disclosure belongs to the technical field of electromagnetic measurement and quantum information, and particularly relates to a device and a method for measuring sinusoidal alternating current based on quantum natural reference.

Background

Since the 20 th century, the discovery of the josephson effect and the quantized hall effect has driven the establishment of quantum voltage references and quantum resistance references, where units of current can be derived from ohm's law to achieve indirect quantum currents, but efforts to find a more direct quantum current reference have not been stopped { references: zhangzhouhua, expecting the electromagnetic measurement [ J ] of the 21 st century, measurement and control technology, 2002, 21: 17-22}. An atomic magnetometer is utilized to measure a uniform magnetic field generated by a current-carrying standard coil, the magnetic field value and a quantum current value (determined by the ratio of quantum voltage to quantum resistance) in the standard coil are in a linear relation, the coil coefficient can be traced to three quantum natural references of a Josephson effect, a quantized Hall effect and a Larmor precession effect, and the current metering based on the quantum natural references can be realized in principle. The current in the current-carrying standard coil is locked to the Larmor precession frequency corresponding to the alkali metal atom magnetic resonance Zeeman transition, the low-drift constant current source function is realized by strictly controlling the physical environment of the experimental device, and the method is a feasible construction scheme of the quantum current reference device. The above described solution of current metering is limited to constant current only and does not involve alternating current. A stable sinusoidal alternating current has three parameters: amplitude, frequency and phase, wherein the frequency is easily traced to a quantum natural reference represented by a cesium atomic clock, however, there is no literature or patent report that the amplitude and phase of a sinusoidally alternating current are traced to a quantum natural reference.

Since the 20 th century, quantum information technology has been vigorously developed at home and abroad. Quantum information technology is a new discipline of quantum physics and information science, and the physical basis of the technology is considered as the superposition of quantum states, quantum non-locality, quantum unclonable theorem { reference: guo Guang, Zhang Hao, Wang Qin, Quantum information technology development overview [ J ]. Nanjing post and telecommunications university school newspaper (Nature science edition), 2017, 37(3):1-14 }. The magnetic resonance Zeeman transition also belongs to quantum transition, and if the internal state evolution details of the magnetic resonance Zeeman transition can be theoretically and experimentally revealed, the physical basis of the quantum information technology can be verified to a certain extent; the amplitude and phase of the radio frequency field are closely related to the internal state evolution process of the magnetic resonance Zeeman transition, and the radio frequency field can be generated by introducing a sine alternating current into a coil. Therefore, by deeply researching the physical process of magnetic resonance Zeeman transition, the amplitude and the phase of the sine alternating current can be traced to the quantum natural reference, and related theories and experimental techniques are helpful to analyzing and verifying the physical basis of the quantum information technology.

Disclosure of Invention

The present disclosure provides a measuring device and method of sinusoidal alternating current based on quantum natural reference, which can show that magnetic resonance zeeman transition is procedural, deterministic, and can be repeatedly manipulated. In the present disclosure, the frequency of the sinusoidal alternating current is traced to a quantum natural reference represented by a cesium atomic clock, and the amplitude and phase of the sinusoidal alternating current in the helmholtz coil are traced to three quantum natural references of the josephson effect, the quantized hall effect, and the larmor precession effect based on the classical theory of two-level magnetic resonance zeeman transition.

According to an aspect of the present disclosure, there is provided a sinusoidal alternating current measurement device based on a quantum natural reference, the device comprising: a background magnetic field generating assembly, a pumping-detection type atomic magnetometer, a signal source 6, a switch 7 and a load 8;

the background magnetic field generating assembly comprises a constant current source 9, a standard coil 2 and a magnetic shielding cylinder 1, wherein the magnetic shielding cylinder 1 is used for shielding a ground magnetic field, the standard coil 2 is axisymmetrically arranged inside the magnetic shielding cylinder 1, and the constant current source 9 is used for inputting current to the standard coil 2 to generate a uniform and stable background magnetic field of a z axis;

the pumping-detection type atomic magnetometer comprises a Helmholtz coil 3, a rubidium bubble heating module 4, a rubidium bubble 5, circular polarization pumping light 10 and linear polarization detection light 11; the rubidium bubble heating module 4 enables the rubidium bubble 5 to keep constant temperature, the circular polarization pumping light 10 is parallel to the z axis and used for preparing the polarization state of a rubidium atom ensemble in the rubidium bubble 5, and the linear polarization detection light 11 is parallel to the x axis and used for measuring an internal state evolution signal of a rubidium atom magnetic resonance Zeeman transition in the rubidium bubble 5;

the signal source 6 is connected to the helmholtz coil 3, the switch 7 and the load 8, and the switch 7 is configured to turn on or off a sinusoidal alternating current signal to be measured, which is input to the helmholtz coil 3 and the load 8 by the signal source 6.

In a possible implementation manner, a sinusoidal alternating current is passed through the helmholtz coil 3 to generate a linearly polarized magnetic field; based on the classical theory of two-energy-level magnetic resonance Zeeman transition, the linear polarization magnetic field consists of a left-handed field and a right-handed field with the same amplitude, and the left-handed field or the right-handed field acts in the magnetic resonance Zeeman transition in the same precession direction of the atomic magnetic moment around the external magnetic field.

In one possible implementation, the frequency of the sinusoidal alternating current is traced to a quantum natural reference represented by the cesium atomic clock, for example, when the frequency of the sinusoidal alternating current is obtained by acquiring a sinusoidal alternating current signal with a data acquisition card and performing fourier transform, the sampling rate parameter of the data acquisition card is calibrated with the quantum natural reference represented by the cesium atomic clock.

In one possible implementation, the coil coefficients of the standard coil 2 and the helmholtz coil 3 are traced to three quantum natural references, the josephson effect, the quantized hall effect and the larmor precession effect.

In one possible implementation, the magnetic shielding cylinder is cylindrical, the inner diameter of the cylinder is 500mm, and the length of the inner cylinder is greater than or equal to 700 mm.

In a possible realization, the magnetic shielding cartridge 1 can be replaced by a magnetic shielding coefficient of less than 10^-4The magnetic shield room of (1).

In a possible implementation, the load 8 is a resistive, capacitive or inductive element.

In one possible implementation, the frequency of the circularly polarized pump light 10 of the pump-detection type rubidium atom magnetometer is locked to⁸⁷D1 line transition of Rb atom, said⁸⁷D1 line transition of Rb atom to 5²S_1/2→5²P_1/2The frequency of the linearly polarized probe light 11 is red detuned 3GHz to 10GHz compared to the frequency of the circularly polarized pump light 10.

In a possible implementation manner, the switch 7 is triggered by a TTL level to turn on or off the sinusoidal alternating current signal to be measured output by the signal source 6.

According to another aspect of the present disclosure, a quantum natural reference based sinusoidal alternating current method is provided, which is applied to the above quantum natural reference based sinusoidal alternating current measuring apparatus, and the method includes:

step 1: strictly controlling the magnetic field environment of the experimental device and keeping the magnetic shielding cylinder 1 at a constant temperature;

step 2: starting a signal source 6, and measuring the frequency f of a sine alternating signal output by the signal source 6;

and step 3: setting control time sequences of the circular polarization pumping light 10 and the switch 7 based on the working principle of the pumping-detection type atomic magnetometer, wherein the time sequence change period is integral multiple of 1/f, so that the repetition of magnetic resonance Zeeman transition signals during repeated measurement is ensured, and the phase of measured sine alternating current is kept stable and unchanged;

and 4, step 4: the current I input to the standard coil 2 by the constant current source 9 is set₉＝2πf₀/(γC₂) Setting the timing of the switch 7 such that the pulse duration of the sinusoidal alternating current signal is L₁So that the pumping-detection type atomic magnetometer can work normally and constantly by adjustingCurrent I from current source 9 to standard coil 2₉A magnetic field B is arranged at the center of the standard coil 2₀Corresponding larmor precession frequency f₀Equal to the frequency f of the radio frequency sine alternating current signal to be measured;

and 5: setting the time sequence of the switch 7 to ensure that the pulse duration of the radio-frequency sine alternating current signal to be measured is L₂At the pulse duration L₂Internally collecting a differential amplification signal of the internal state evolution of the magnetic resonance Zeeman transition measured by the linear polarization probe light 11 in the x-axis direction;

step 6: deleting the experimental data of the radio frequency field in the first pi pulse duration and the data of which the signal-to-noise ratio at the tail end does not meet the expectation in the step 5, and according to the expressionFitting A mu and B step by step_rf、f₀δ and T₂Parameter, wherein V_x-singalA is a differential amplification signal output by a pumping-detection type atom magnetometer in the x-axis direction, A is a proportionality coefficient, mu is the atomic magnetic moment of a single atom, gamma is the gyromagnetic ratio of rubidium atoms, and B is_rfIs the amplitude of the rotating field in the x-y plane, f₀Is a constant magnetic field B₀Proportional larmor precession frequency, δ being the angle of the rotating coordinate system relative to the laboratory coordinate system at the initial moment, related to the initial phase of the radio frequency field, T₂Relaxation time, which is the macroscopic magnetization of the atomic ensemble;

and 7: according to the parameter B_rfAnd expression B_rf＝C₃I₀Calculating the amplitude I of the sinusoidal alternating current signal to be measured in the Helmholtz coil 3₀In which C is₃The coil coefficient of the helmholtz coil 3; and analyzing according to the parameter delta, the time sequence control parameter of the pumping-detection type atomic magnetometer and the data interception position to obtain the phase of the sinusoidal alternating current signal to be detected in the Helmholtz coil 3.

The measuring device of the sinusoidal alternating current based on the quantum natural reference comprises a background magnetic field generating assembly, a pumping-detection type atomic magnetometer, a signal source 6, a switch 7 and a load 8; the background magnetic field generating assembly comprises a constant current source 9, a standard coil 2 and a magnetic shielding cylinder 1, the magnetic shielding cylinder 1 is used for shielding a ground magnetic field, the standard coil 2 is axisymmetrically arranged inside the magnetic shielding cylinder 1, and the constant current source 9 is used for inputting current to the standard coil 2 to generate a uniform and stable background magnetic field of a z axis; the pumping-detection type atomic magnetometer comprises a Helmholtz coil 3, a rubidium bubble heating module 4, a rubidium bubble 5, circular polarization pumping light 10 and linear polarization detection light 11, wherein the rubidium bubble heating module 4 keeps the rubidium bubble 5 at a constant temperature, the circular polarization pumping light 10 parallel to a z axis prepares a polarization state of a rubidium atom ensemble in the rubidium bubble 5, and the linear polarization detection light 11 parallel to an x axis measures an internal state evolution signal of a rubidium atom magnetic resonance Zeeman transition in the rubidium bubble 5; the function of a radio frequency signal source in the complete pumping-detection type atomic magnetometer is realized by the signal source 6 and the switch 7, and the pumping-detection type atomic magnetometer measures the magnetic field value at the spatial position of the rubidium bubble 5; the signal source 6 is respectively connected with the helmholtz coil 3, the switch 7 and the load 8, and the switch 7 is used for turning on or off a sinusoidal alternating current signal to be detected, which is input to the helmholtz coil 3 and the load 8 by the signal source 6. The present disclosure can show that magnetic resonance zeeman transitions are procedural, deterministic, and can be manipulated repeatedly. In the present disclosure, the frequency of the sinusoidal alternating current is traced to a quantum natural reference represented by a cesium atomic clock, and the amplitude and phase of the sinusoidal alternating current in the helmholtz coil are traced to three quantum natural references of the josephson effect, the quantized hall effect, and the larmor precession effect based on the classical theory of two-level magnetic resonance zeeman transition.

Drawings

The accompanying drawings are included to provide a further understanding of the technology or prior art of the present application and are incorporated in and constitute a part of this specification. The drawings expressing the embodiments of the present application are used for explaining the technical solutions of the present application, and should not be construed as limiting the technical solutions of the present application.

Fig. 1 shows a schematic structural diagram of a sinusoidal alternating current measurement device based on quantum natural reference according to an embodiment of the present disclosure;

FIG. 2a is a schematic diagram illustrating a partial differential amplification signal output by an atomic magnetometer in the x-axis direction when the RF field is applied for 0.5ms after the pump light is turned off according to an embodiment of the present disclosure;

FIG. 2b shows a schematic diagram of a partially amplified signal of an atomic magnetometer output in the x-axis direction at 30ms RF field after pump light is turned off according to an embodiment of the present disclosure;

FIG. 3a shows a schematic of experimental data of a truncated signal for 10 repeated measurements according to an embodiment of the present disclosure;

FIG. 3b illustrates an enlarged schematic view of a portion of the data in FIG. 3a, according to an embodiment of the present disclosure;

FIG. 4a is a graph illustrating the result of peaking the data curve of FIG. 3a according to one embodiment of the present disclosure;

FIG. 4b shows a schematic diagram of the result of peaking the data curve of FIG. 4a, according to an embodiment of the present disclosure;

FIG. 5a shows a schematic diagram of the results of taking peaks and valleys of the data curve in FIG. 3, according to an embodiment of the present disclosure;

FIG. 5b illustrates a graph of the equation in FIG. 5a according to an embodiment of the disclosureThe result of screening the data is shown schematically;

FIG. 5c is a graph illustrating the results of a curve fit to the screening data of FIG. 5b according to one embodiment of the present disclosure;

FIG. 6 is a graph illustrating results from curve fitting the data of FIG. 3 according to one embodiment of the present disclosure;

fig. 7 shows a schematic diagram of a differential amplification signal output in the x-axis direction of the pumping-detection type atomic magnetometer when setting radio frequency pulse signals of different initial phases according to an embodiment of the present disclosure.

Detailed Description

Embodiments of the present disclosure will be described in detail with reference to the accompanying drawings and examples, so that how to apply technical means to solve technical problems and achieve the corresponding technical effects can be fully understood and implemented. The embodiments and various features in the embodiments of the present application can be combined with each other without conflict, and the formed technical solutions are all within the protection scope of the present disclosure.

Fig. 1 shows a schematic structural diagram of a sinusoidal alternating current measurement device based on a quantum natural reference according to an embodiment of the present disclosure.

As shown in fig. 1, the apparatus may include a background magnetic field generating assembly, a pump-detection type atomic magnetometer, a signal source 6, a switch 7, and a load 8;

the background magnetic field generating assembly comprises a constant current source 9, a standard coil 2 and a magnetic shielding cylinder 1. The magnetic shielding cylinder 1 is used for shielding a geomagnetic field, the standard coil 2 is axisymmetrically arranged inside the magnetic shielding cylinder 1, and the constant current source 9 is used for inputting current to the standard coil 2 to generate a background magnetic field with uniform and stable z-axis.

Preferably, the magnetic shield cylinder 1 is cylindrical, and the inner dimension can be selected to be larger than phi 500mm x 700 mm. The magnetic shield cylinder 1 can be replaced with a magnetic shield coefficient of less than 10^-4The magnetic shield room of (1). When the internal size of the magnetic shielding cylinder 1 or the magnetic shielding room is far larger than that of the standard coil 2, the influence of the current-carrying coil on the magnetization state of the magnetic shielding cylinder can be obviously reduced, and further, the influence on the recurring magnetic field is reduced. The standard coil 2 is sized such that the magnetic field gradient in the probe region of the pumping-detection type atomic magnetometer is less than 1% to ensure that the atomic magnetometer measures the magnetic field with high accuracy.

Preferably, the constant current source 9 may employ a 6.5-bit commercial digital current source.

The composition and working principle of the pumping-detection type rubidium atom magnetometer are disclosed in the issued invention patent of 'a rubidium atom magnetometer and a magnetic field measuring method thereof' (the patent number is CN 201710270545.8). Wherein the range of the pumping-detection type rubidium atom magnetometer is 100 nT-100000 nT, and the ultimate sensitivity is 0.2pT/Hz^1/2. As shown in fig. 1, the pumping-detection type rubidium atom magnetometer only shows a probe part, and includes a helmholtz coil 3, a rubidium bubble heating module 4, a rubidium bubble 5, a circularly polarized pumping light 10 and a linearly polarized detection light 11, wherein the rubidium bubble heating module 4 keeps the rubidium bubble 5 at a constant temperature, the circularly polarized pumping light 10 parallel to the z axis prepares a polarization state of a rubidium atom ensemble in the rubidium bubble 5, and the linearly polarized detection light 11 parallel to the x axis measures the rubidium atom ensembleAnd (3) an internal state evolution signal of the magnetic resonance Zeeman transition of rubidium atoms in the bubble 5. The function of a radio frequency signal source in the complete pumping-detection type atomic magnetometer in the patent of the invention is realized by a signal source 6 and a switch 7 in the figure 1, and the pumping-detection type atomic magnetometer measures the magnetic field value at the spatial position of the rubidium bubble 5.

As shown in fig. 1, the signal source 6 is connected to the helmholtz coil 3, the switch 7 and the load 8, respectively, and the switch 7 is used to turn on or off the sinusoidal alternating current signal to be measured, which is input to the helmholtz coil 3 and the load 8 by the signal source 6. In the embodiment of the present disclosure, the signal source 6 is an agilent 33250A signal source, the function of the switch 7 is implemented by using a Trigger function of the 33250A signal source, and the 33250A signal source directly outputs a pulsed sinusoidal alternating current signal to be detected. The load 8 may be an element having resistive, capacitive, inductive properties. Load 8 and helmholtz coil 3 are the research object when this disclosure device specifically applies, and load 8 and helmholtz coil 3 are established ties, can calculate amplitude, frequency and the phase place of sinusoidal alternating current signal in load 8 through measuring amplitude, frequency and the phase place of sinusoidal alternating current signal in helmholtz coil 3.

For example, when the load 8 is set to a resistance of 0 ohm, the stable sinusoidal alternating current signal to be measured can be expressed by the expression (1):

wherein, I₀Is the amplitude of the sinusoidal alternating current to be measured, f is the radio frequency field frequency of the sinusoidal alternating current to be measured,is the initial phase of the sinusoidal alternating current to be measured.

The frequency of the sinusoidal alternating current to be detected can be traced to a quantum natural reference represented by a cesium atomic clock, for example, when a data acquisition card is used for acquiring sinusoidal alternating current signals and performing Fourier transform to obtain the frequency of the sinusoidal alternating current, the sampling rate parameters of the data acquisition card are calibrated by the quantum natural reference represented by the cesium atomic clock.

Larmor precession frequency f corresponding to magnetic field at central position of current-carrying standard coil 2₀When the frequency f of the radio frequency sine alternating current to be detected is equal, the magnetic resonance Zeeman transition internal state evolution signal V differentially detected by the linear polarization detection light 11 in the x-axis direction_x-signalThe expression of (a) is:

wherein A is a proportionality coefficient, mu is an atomic magnetic moment of a single atom, gamma is a gyromagnetic ratio of rubidium atoms, and B_rfIs the amplitude of the rotating field in the x-y plane, f₀Larmor precession frequency for resonance, δ is the angle of the rotating coordinate system with respect to the laboratory coordinate system at the initial time (related to the initial phase of the radio frequency field), T₂Relaxation time of macroscopic magnetization of an ensemble of atoms.

And (3) setting the coil coefficient of the Helmholtz coil as C, inputting the sine alternating current to be measured described by the formula (1) into the Helmholtz coil, and generating a linear polarization magnetic field by the Helmholtz coil on the axis. Based on the classical theory of two-level magnetic resonance zeeman transitions, a linearly polarized magnetic field is believed to consist of a left-handed field and a right-handed field of the same amplitude, which act in the magnetic resonance zeeman transition in the same precession direction of the atomic magnetic moment around the external magnetic field.

The magnetic field generated at the center of the helmholtz coil is:

the larmor precession frequency f corresponding to the magnetic field at the central position of the reference coil 2₀Amplitude B of rotating magnetic field acting in magnetic resonance Zeeman transition at frequency f of sinusoidal alternating current to be measured_rfSatisfies the following conditions:

B_rf＝CI₀[ formula (4) ]2.

Timing sequence when pumping-detecting type atomic magnetometer worksAfter the control process is accurately calibrated by a cesium atomic clock, the phase delta and the phase in the formulas (2) and (3) can be obtained based on physical analysisThe relationship (2) of (c).

Since the magnetic field value measured by the pumping-detection type atomic magnetometer is in a linear relationship with the current value in the standard coil 2, and the ratio of the quantum voltage to the quantum resistance can be defined as the quantum current, which can be linked with the magnetic field value measured by the pumping-detection type atomic magnetometer, the coil coefficient of the standard coil 2 in the present disclosure can be traced to three quantum natural references of the josephson effect, the quantized hall effect, and the larmor precession effect. Similarly, an atomic magnetometer is additionally selected to calibrate the coil coefficient of the helmholtz coil 3, so that the coil coefficient is traced to the three quantum natural references, and therefore the measurement values of the amplitude and the phase of the sinusoidal alternating current to be measured, which are provided by the disclosure, are also traced to the three quantum natural references, namely the josephson effect, the quantized hall effect and the larmor precession effect.

Under stringent magnetic resonance conditions, i.e. with the magnetic field at the geometric centre of the standard coil 2 corresponding to the larmor precession frequency f₀Equal to the frequency f of the sinusoidal alternating current to be measured, the main objective of measuring the amplitude and phase of the sinusoidal alternating current signal to be measured being to obtain the parameter B in equation (2)_rfAnd delta, and then analyzing the amplitude I of the sinusoidal alternating current signal to be measured in equation (1)₀And phase

Since A mu and B are determined when experimental data are fitted according to formula (2)_rf、f₀、δ、T₂The direct fitting is difficult to converge due to the total of 5 fitting parameters, the step-by-step fitting method is provided for fitting, and the formula (2) can be rewritten as follows:

V_x-signal＝μ₁·μ₂·μ₃the compound of the formula (5),

wherein:

μ₂＝sin(γB_rft) formula (7),

μ₃＝sin(2πf₀t-delta) formula (8).

The parameters A mu and T can be fitted from equation (6)₂Then by mu₁·μ₂Fitting out the parameter B_rfFinally by μ₁·μ₂·μ₃Fitting parameter f₀And δ, finally achieving fitting convergence.

In electromagnetism, a helmholtz coil can be considered as a series circuit of a resistance and an inductance, when a sinusoidal voltage excites a radio frequency coil there is a transient process that is related to the resistance, the inductance and the initial phase of the sinusoidal voltage at the turn-on time. In order to eliminate the influence of the transient process on the fitting result of the experimental data, the experimental data within the action duration of the first pi pulse of the radio frequency field is deleted when the experimental result is fitted by using the formula (2) (without considering the phase delay caused by impedance matching of the Helmholtz coil).

In addition, according to the principle of the operation of the pumping-detection type atomic magnetometer, a radio frequency sinusoidal alternating current signal must be pulsed and output in each measurement period, i.e., a radio frequency field pulse train is turned on immediately after the circularly polarized pumping light is turned off. If the sinusoidal alternating current to be measured is continuous, the switch 7 causes the rf field to be pulsed into the helmholtz coil 3, the switch 7 being controlled by the timing of the operation of the pumping-detection type atomic magnetometer.

The present disclosure provides a measuring device and method of sinusoidal alternating current based on quantum natural reference, which can show that magnetic resonance zeeman transition is procedural, deterministic, and can be repeatedly manipulated. In the present disclosure, the frequency of the sinusoidal alternating current is traced to a quantum natural reference represented by a cesium atomic clock, and the amplitude and phase of the sinusoidal alternating current in the helmholtz coil are traced to three quantum natural references of the josephson effect, the quantized hall effect, and the larmor precession effect based on the classical theory of two-level magnetic resonance zeeman transition.

According to another aspect of the present disclosure, a measuring method of sinusoidal alternating current based on quantum natural reference is provided, which is applied to the measuring device of sinusoidal alternating current. The following describes a current metering device and a metering method based on quantum natural reference in the summary of the invention with reference to an embodiment.

The first embodiment is as follows:

step 1: the experimental environment is strictly controlled, the constant temperature of the magnetic shielding cylinder 1 or the magnetic shielding room 1 is kept, no obvious magnetic field fluctuation and magnetic noise source exists around the magnetic shielding cylinder 1 or the magnetic shielding room 1, the influence of the change of the magnetization state of the magnetic shielding material and the environmental magnetic noise on the magnetic field measurement is reduced, and the remanence in the magnetic shielding cylinder 1 or the magnetic shielding room 1 tends to zero after the magnetic shielding cylinder 1 or the magnetic shielding room 1 is strictly demagnetized.

Step 2: the signal source 6 is started and the frequency of the sinusoidal alternating current signal output by the signal source 6 is measured as f.

In this embodiment, the signal source 6 is an agilent 33250A signal source, and directly outputs a sinusoidal alternating current signal with an amplitude of 760mV and a frequency of 10kHz, and the frequency f of the sinusoidal alternating current signal to be measured is 10kHz, where the 33250A signal source product has traced the output frequency to a quantum natural reference represented by a cesium atomic clock when it leaves the factory. In a specific experiment, a high-speed data acquisition card can be used for acquiring a sine alternating current signal and carrying out Fourier transform to obtain the frequency of the sine alternating current signal, wherein the sampling rate parameter of the data acquisition card is calibrated by a quantum natural reference represented by a cesium atomic clock.

And step 3: the control time sequence of the circular polarization pumping light 10 and the switch 7 is set based on the working principle of the pumping-detection type atomic magnetometer, and the time sequence change period is integral multiple of 1/f, so that the repetition of magnetic resonance Zeeman transition signals during repeated measurement is ensured, and the phase of the measured sine alternating current is kept stable and unchanged.

In this embodiment, the 33250A signal source sets the initial phase of the pulse train to zero when outputting the pulsed sinusoidal alternating signal, which can automatically satisfy the requirement that the phase of the sinusoidal alternating current remains stable. In this embodiment, the timing duty cycle is set to 100ms, wherein the pumping light duration is 30 ms. Round (T-shaped)The frequency of the polarized pump light 10 is locked to⁸⁷D1 line transition of Rb atom (i.e., 5)²S_1/2→5²P_1/2) The frequency of the linearly polarized probe light 11 is red detuned by 8GHz compared to the frequency of the circularly polarized pump light 10.

And 4, step 4: the current I input to the standard coil 2 by the constant current source 9 is set₉＝2πf₀/(γC₂) Setting the timing of the switch 7 such that the pulse duration of the sinusoidal alternating current signal is L₁So that the pumping-detection type atomic magnetometer can work normally, and the current I input to the standard coil 2 by the constant current source 9 is adjusted₉A magnetic field B is arranged at the center of the standard coil 2₀Corresponding larmor precession frequency f₀Equal to the frequency f of the radio frequency sinusoidal alternating current signal to be measured.

In this embodiment, the load 8 is selected as a 0 Ω resistor, the constant current source 9 is a B2912A model current source of delta Technology (Keysight Technology), and the coil coefficient C of the standard coil 2₂52.4265nT/mA, the gyromagnetic ratio gamma/2 pi of rubidium atoms is 6.99583Hz/nT, and the current I input to the standard coil 2 by the constant current source 9₉＝2πf/(γC₂) Calculating to obtain current I₉About 27.2653 mA. In the embodiment, the switch 7 is the Trigger function of a 33250A signal source, and the pulse duration L of the sine alternating current signal is controlled by the time sequence of the pumping-detection type atomic magnetometer₁Is 0.5 ms. Inputting 10kHz sine alternating current signal output by a 33250A signal source into a Helmholtz coil 3 in a pulse mode, analyzing the magnetic field at the center of a standard coil 2 by a free relaxation signal according to a method for measuring the magnetic field by a pumping-detection type atomic magnetometer, and properly finely adjusting the current output from a constant current source 9 to the standard coil 2 to ensure that the Larmor precession frequency f is equal to₀Strictly equal to 10kHz, the partial differential amplification signal output by the pumping-detection type atomic magnetometer in the x-axis direction when the radio frequency field acts for 0.5ms after the pumping light is turned off is shown in fig. 2 a.

And 5: setting the time sequence of the switch 7 to ensure that the pulse duration of the radio-frequency sine alternating current signal to be measured is L₂At the pulse duration L₂And internally collecting a differential amplification signal of the internal state evolution of the magnetic resonance Zeeman transition measured by the linear polarization probe light 11 in the x-axis direction.

In the embodiment, the switch 7 is the Trigger function of a 33250A signal source, and the pulse duration L of the sine alternating current signal is controlled by the time sequence of the pumping-detection type atomic magnetometer₂At 30ms, the part of the differential amplification signal output by the pumping-detection type atomic magnetometer in the x-axis direction when the radio frequency field acts for 30ms after the pumping light is turned off is shown in fig. 2 b.

Step 6: deleting the experimental data of the radio frequency field in the first pi pulse duration and the data of which the signal-to-noise ratio at the tail end does not meet the expectation in the step 5, and according to the expressionFitting A mu and B step by step_rf、f₀δ and T₂Parameter, wherein V_x-singalA is a differential amplification signal output by a pumping-detection type atom magnetometer in the x-axis direction, A is a proportionality coefficient, mu is the atomic magnetic moment of a single atom, gamma is the gyromagnetic ratio of rubidium atoms, and B is_rfIs the amplitude of the rotating field in the x-y plane, f₀Is a constant magnetic field B₀The larmor precession frequency is in direct proportion, delta is the angle of the rotating coordinate system relative to the laboratory coordinate system at the initial moment (related to the initial phase of the radio frequency field), and T₂Relaxation time, which is the macroscopic magnetization of the atomic ensemble;

FIG. 3a shows a schematic of experimental data of a truncated signal for 10 repeated measurements according to an embodiment of the present disclosure; FIG. 3b illustrates an enlarged schematic view of a portion of the data in FIG. 3a, according to an embodiment of the disclosure.

In fig. 3, the experimental data (i.e., the first envelope) of the radio frequency field in the first pi pulse action duration and the data with a poor signal-to-noise ratio at the end in fig. 2b are deleted, so that the influence of the transient process of the helmholtz coil on the fitting result can be effectively eliminated.

FIG. 4a is a graph illustrating the result of peaking the data curve of FIG. 3a according to one embodiment of the present disclosure; FIG. 4b shows a schematic diagram of the result of peaking the data curve in FIG. 4a, according to an embodiment of the present disclosure. According to the experimental data of FIG. 4b, fromFitting out the parameters A mu and T₂The value is obtained.

FIGS. 5a-5c show the results of experimental data processing according to the expressionFitting B_rfThe result of (1). FIG. 5a shows the data curve of FIG. 3 after the peaks and valleys are taken; FIG. 5b is a graph showing the equation of FIG. 5aThe result of screening the data of (a) is actually two data curves, the data points of one curve in the graph are black, and the data points of the other curve are gray; FIG. 5c is a graph of black data from FIG. 5B, fitted to a curve to obtain B_rfThe results of (1) were fitted with A μ and T₂The parameters were set to those obtained when fitting the experimental data of fig. 4 b. A. mu.B is known_rfAnd T₂After the parameters, f is fitted according to expression (2)₀The results of δ and δ are shown in FIG. 6, and the results of fitting the experimental curves for all the magnetic resonance Zeeman transition signals are shown in Table 1, where the Larmor precession frequency f is₀The reproducibility of (2) is expressed as relative standard deviation as 5.4X 10^-7The precision of the current source is consistent with that of the 6.5-bit B2912A precision current source.

TABLE 1

Fitting term	Aμ	Brf(nT)	f0(Hz)	δ(rad)	T2(s)
						1	3.5915	85.6137	10000.6749	-1.0188	0.005320
2	3.5839	85.6115	10000.6718	-1.0225	0.005319
						3	3.6148	85.6154	10000.6664	-1.0180	0.005323
4	3.5996	85.6109	10000.6732	-1.0127	0.005327
						5	3.6070	85.6125	10000.6721	-1.0174	0.005317
6	3.6020	85.6109	10000.6674	-1.0147	0.005333
						7	3.6024	85.6150	10000.6563	-1.0178	0.005331
8	3.5862	85.6146	10000.6728	-1.0159	0.005326
						9	3.5893	85.6137	10000.6710	-1.0216	0.005345
10	3.5993	85.6167	10000.6680	-1.0209	0.005317
						Mean value of	3.5976	85.6135	10000.6694	-1.0180	0.005326
Standard deviation of	0.0098	0.0020	0.005359	0.0031	8.8E-06
						Relative Standard Deviation (SD)	0.0027	2.3E-05	5.4E-07	-0.0030	0.0016

And 7: according to the parameter B_rfAnd expression B_rf＝C₃I₀Calculating the amplitude I of the sinusoidal alternating current signal to be measured in the Helmholtz coil 3₀In which C is₃The coil coefficient of the helmholtz coil 3; and analyzing according to the parameter delta, the time sequence control parameter of the pumping-detection type atomic magnetometer and the data interception position to obtain the phase of the sinusoidal alternating current signal to be detected in the Helmholtz coil 3.

In obtaining the parameter B_rfThen, the amplitude of the sinusoidal alternating current in the helmholtz coil 3 is calculated by the formula (4), the coil coefficient of the helmholtz coil 3 is 49.08nT/mA, and the amplitude of the sinusoidal alternating current in the helmholtz coil 3 is 1.74 mA; knowing the parameter delta, from the pumping-detection type atomic magnetic forceThe phase of the sinusoidal alternating current in the helmholtz coil 3 can be analyzed by the timing control parameters of the instrument and the data interception position.

Fig. 7 shows a schematic diagram of a differentially amplified signal output in the x-axis direction of the pumping-detection type atomic magnetometer when setting radio frequency pulse signals of different initial phases. As shown in fig. 7, when the initial phases of the sinusoidal rf pulse train of the agilent 33250A signal source are set to 0 °, 45 °, 90 °, 135 °, and 180 °, the phase of the output signal of the pump-detection type atomic magnetometer in the x-axis direction changes accordingly, and the change can be analyzed from the data curve of the shaded portion in the second envelope, which proves that the apparatus of the present disclosure can measure the phase of the sinusoidal alternating current signal.

The measurement method of the sinusoidal alternating current based on the quantum natural reference of the present disclosure derives the expression (2), most theories are directed to a single atom, and in the book "laser cooling and trapping of atoms" (beijing university press, 2007) written by mr. queens, the first paragraph 5 at page 58 indicates that when the wave function phases of a group of atoms are consistent (or referred to as atomic states are coherent), the group of atoms can be regarded as one. A group of atomic states that are 100% polarized in this disclosure is coherent if the relaxation mechanism is not considered, because the pumping of circularly polarized light and the action of the radio frequency field precess the magnetic moments of these atoms in unison, and thus this group of atoms can be considered as one; it should also be noted that the experimental method of changing the polarization rate of the group of atoms by changing the pumping intensity in the experiment does not affect the experimental conclusion of the embodiments of the present disclosure. The x-axis direction in this disclosure probes this group of atoms with far detuned probe light, with almost negligible disruption of the atomic polarization state by the probe light. The method disclosed by the invention is equivalent to the evolution of a single atomic magnetic moment by the collective evolution of the atomic ensemble macroscopic magnetic moment, proves that the magnetic resonance Zeeman transition in a single atom is procedural, deterministic and can be repeatedly controlled, and indicates the importance of matching the precession phase of the atomic magnetic moment in the magnetic resonance Zeeman transition with the phase of an electromagnetic wave. The measurement method disclosed by the invention has the potential to be used for questioning the quantum state superposition and quantum non-local physical basis of the quantum information technology in the future.

In summary, in the first embodiment, a preliminary test method for sinusoidal alternating current based on quantum natural reference according to the present disclosure, a lot of work is required to be performed when the measurement height of the alternating current rises to the measurement height, and the contribution of various measurement processes, experimental conditions, and load electrical parameters in a current loop to the uncertainty of the amplitude and phase measurement of the alternating current is analyzed. With the development of basic theory of physics and the improvement of measurement level, the limitation of the classical theory of two-level magnetic resonance zeeman transition is discussed in the future, for example, based on the classical theory of two-level magnetic resonance zeeman transition, the amplitude of the rotating magnetic field acting in the expression (4) is half of the amplitude of the linear polarization magnetic field, and whether the conclusion is true or not needs to be strictly proved based on theory and experiment.

The embodiment is merely a preferred embodiment of the disclosure, and is not intended to limit the scope of the disclosure. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.