A real-time spin state detection method based on diamond NV color centers

Abstract

A real-time spin state detection method based on diamond NV color centers uses the Bayesian estimation theorem and fully utilizes the noisy fluorescence intensity obtained during diamond NV color center detection to achieve real-time updated detection of the first energy level population of the electron spin state ground state. This calculated first energy level population value is used as the final spin state estimation result until it stops changing. This method suppresses photon shot noise and achieves real-time spin state detection, while being simple to operate and easy to implement.

Description

Technical Field

[0001] The present invention relates to the field of quantum precision measurement technology, and more particularly to a real-time spin state detection method based on diamond NV color centers. Based on the Bayesian estimation theorem, the method fully utilizes the noisy fluorescence intensity obtained during diamond NV color center detection to achieve real-time updated detection of the first energy level population of the electron spin ground state. When the first energy level population no longer changes, the first energy level population is used as the final spin state estimation result. The present invention suppresses photon shot noise and achieves real-time spin state detection, while being simple to operate and easy to implement. Background Art

[0002] Diamond nitrogen vacancy color centers have become a research hotspot for solid-state quantum magnetic sensing materials due to their high sensitivity, high spatial resolution, and room-temperature manipulation. Magnetic field measurements using diamond nitrogen vacancy color centers primarily involve three processes: spin polarization, manipulation, and detection. Spin detection involves measuring the occupancy ratio of electrons at each energy level in the ground state to determine the measured magnetic field value. Therefore, the accuracy of spin detection determines the accuracy of magnetic field measurement. Compared to traditional photon summation methods, Bayesian estimation can fully utilize known information to rapidly predict the quantity to be estimated, suppress photon shot noise, improve the signal-to-noise ratio, and thus enhance measurement sensitivity. Furthermore, by integrating with hardware, it can achieve real-time detection. Its promising application prospects will attract significant attention. Summary of the Invention

[0003] The present invention addresses the shortcomings of the prior art and provides a real-time spin state detection method based on diamond NV color centers. Based on the Bayesian estimation theorem, the first energy level population of the electron spin ground state is calculated based on the noisy fluorescence intensity obtained by detecting laser light acting on the diamond NV color center. This is updated in real time until the calculated first energy level population no longer changes. This first energy level population is then used as the final spin state estimation result. The present invention suppresses photon shot noise and achieves real-time spin state detection, while being simple to operate and easy to implement.

[0004] The technical solutions of the present invention are as follows:

[0005] A real-time spin state detection method based on diamond NV color centers is characterized by using the Bayesian estimation theorem to calculate the first energy level population of the electron spin state ground state based on the noisy fluorescence intensity obtained by detecting laser light acting on the diamond NV color center, and updating it in real time until the calculated first energy level population no longer changes, and the calculated first energy level population is used as the final spin state estimation result.

[0006] The following steps are involved:

[0007] Step 101: input a first instruction, and the bias magnetic field component generates a bias magnetic field;

[0008] Step 102: input a second instruction, and the pulse generating module generates a pulse sequence;

[0009] Step 103: The fluorescence detection module obtains the fluorescence intensity fn containing noise information at time tn, where n is the sampling time and tn is the sampling time.

[0010] Step 104, combining the Bayesian estimation theorem, using fn to solve the spin state β1, where the spin state β1 refers to the population of the ground state electron in the spin 0 state, i.e., the electron in the ground state ms=0 energy level, where ms is the spin magnetic quantum number;

[0011] Step 105 , obtaining the fluorescence intensity fn+1 at the next moment to update the spin state β1 until the spin state no longer changes. At this moment, β1 is the final estimation result.

[0012] The bias magnetic field component can generate a directional bias magnetic field with adjustable size and direction and can maintain a stable output.

[0013] The pulse generation sequence generated by the pulse generation module includes laser polarization pulses, microwave manipulation pulses, and laser detection pulses, wherein the laser polarization pulses are used to polarize the electronic state of the NV color center to the spin 0 state of the ground state, the microwave manipulation pulses are used to flip and manipulate the NV color center electron spin, and the laser detection pulses are used to read the fluorescence intensity of the NV color center electron spin state.

[0014] The electronic energy levels of the diamond NV color center include the ground state, excited state, and singlet state. Assume that the ground state ms = 0 (denoted as the first energy level) has a population of β1 and ms = 1 (denoted as the second energy level) has a population of β2, ms is the spin magnetic quantum number, the excited state ms = 0 (denoted as the third energy level) has a population of β3 and ms = 1 (denoted as the fourth energy level) has a population of β4, and the singlet state (denoted as the fifth energy level) has a population of β5. Then, the spin state vector form β = (β1, β2, β3, β4, β5). When not sampled, the probability distribution function P2(β|f0) satisfies a known distribution, one choice being a uniform distribution.

[0015] The noise-containing fluorescence intensity of the sampling is recorded as fn, and the expected fluorescence intensity of the sampling is recorded as <f n >, the current sampling time is tn, the last sampling time is t n-1 , the next sampling time is t n+1 , the function of the spin state vector β and time t is β(t), and the collection efficiency is λ. Then, when the spin state is β1, t n Fluorescence intensity measurement result f at time n The likelihood function P1(f n |β1) is:

[0016]

[0017]

[0018] Where exp is the exponential function.

[0019] The noise-containing fluorescence intensity of the current sampling is recorded as fn, the sampling time is tn, and the next sampling time is t n+1 The noise-containing fluorescence intensity of the next sampling is recorded as f n+1 , then the spin state probability distribution function P2(β1|f n+1 ) satisfies: P2(β1|f n+1 )∝P1(f n+1 |β1)·P2(β1|f n )

[0020] P2(β1|f n )=P1(f n |β1).

[0021] The final estimated spin state is the spin state corresponding to the maximum probability in the probability distribution function obtained after the last sampling.

[0022] The technical effects of the present invention are as follows: A real-time spin state detection method based on diamond NV color centers suppresses photon shot noise and enables real-time spin state detection compared to conventional detection methods. This method, based on Bayesian estimation theory, fully utilizes the noisy fluorescence intensity obtained from diamond NV color center detection to achieve real-time spin state update detection. This method is extremely useful when using nitrogen-vacancy color centers for magnetic field detection and temperature detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The figure is a flow chart of a method for real-time spin state detection based on diamond NV color centers according to the present invention. NV stands for nitrogen vacancy. Figure 1 The process between the start and end of measurement includes step 101, inputting a first instruction, and the bias magnetic field component generates a bias magnetic field; step 102, inputting a second instruction, and the pulse generation module generates a pulse sequence; step 103, the fluorescence detection module obtains the fluorescence intensity fn containing noise information at time tn, where n is the current sampling in the sampling, the previous sampling is recorded as n-1, the next sampling is recorded as n+1, and tn is the current sampling time; step 104, combining the Bayesian estimation theorem, using fn to solve the spin state β1; (spin state β1 refers to the population of ground state electrons in the spin 0 state, that is, the electrons in the ground state ms=0 energy level, and ms is the spin magnetic quantum number) step 105, obtaining the fluorescence intensity fn+1 at the next moment, and updating the spin state β1 until the spin state no longer changes, at which point β1 is the final estimation result.

[0024] Figure 2 1 is an energy level diagram of a negatively charged NV color center in diamond involved in the implementation of the present invention. Figure 2 There are three energy levels, namely the ground state (involving the ground state ms = 0 energy level population β1 or the first energy level population β1, and the ground state ms = 1 energy level population β2 or the second energy level population β2), the excited state (involving the excited state ms = 0 energy level population β3 or the third energy level population β3, and the excited state ms = 1 energy level population β4 or the fourth energy level population β4) and the singlet state (involving the singlet energy level population β5 or the fifth energy level population β5). ① to ⑨ indicate different inter-energy level electron transition paths, ① and ③ represent the electron transition paths in the ground state m s = +1 energy level and m s =0 energy level electrons transition to the excited state corresponding energy level path, the transition rate is Г, its value is related to the laser power irradiated to the diamond. ② and ④ respectively represent the excited state m s = +1 energy level and m s =0 energy level electrons fall back to the corresponding energy level path of the ground state, and its transition rate is k, and the fall process is accompanied by red fluorescence. ⑤ and ⑥ represent the excited state m s = +1 energy level and m s =0 energy level electrons fall back to the singlet state, and the transition rates are recorded as k 35 With k 45 (The subscript 35 of k represents the 3rd to 5th energy levels, and so on), and then falls back to the ground state m through ⑦ and ⑧. s = +1 energy level and m s =0 energy level, the transition rate is recorded as k 52 With k 51 This process is called intersystem crossing, which emits invisible light. Path ⑨ indicates that electrons in the ground state can transition between two energy levels under the action of microwaves, and the transition rate is k 21 By combining the transition rates between different states and the initial fractions of electrons between the states, β (i.e., β1, β2, β3, β4, and β5), a fifth-order equation for the rate of light can be established.

[0025] Figure 3 A schematic diagram of the system structure for implementing a real-time spin state detection method based on diamond NV color centers of the present invention. Figure 3The optical path includes a polarization optical path, a microwave manipulation optical path, and a detection optical path. The components arranged on the polarization optical path include a 532nm laser 1, an optical isolator 2, a polarizer 3, a beam splitter 4, a first lens 5, an acousto-optic modulator 6, and a second lens 7. The components arranged on the microwave manipulation optical path include a bias magnetic field component 8, a microwave antenna 9, an NV color center diamond sample 10, and a microscope objective lens 11. The components arranged on the detection optical path include a dichroic mirror 12, a plane mirror 13, a pinhole 14, a filter 15, an avalanche diode detector 16, and an FPGA board host computer system 17. DETAILED DESCRIPTION

[0026] Below is the attached figure ( Figure 1-Figure 3 ) and Examples illustrate the present invention.

[0027] Figure 1 It is a flow chart of a method for real-time detection of spin states based on diamond NV color centers according to the present invention. Figure 2 1 is an energy level diagram of a negatively charged NV color center in diamond involved in the implementation of the present invention. Figure 3 A schematic diagram of the system structure for implementing a real-time spin state detection method based on diamond NV color centers in the present invention. Figures 1 to 3 As shown, a real-time detection method for spin states based on diamond NV color centers is characterized by using the Bayesian estimation theorem to calculate the first energy level population of the electron spin state ground state according to the noisy fluorescence intensity obtained by detecting the laser acting on the diamond NV color center and update it in real time until the calculated value of the first energy level population no longer changes, and the calculated value of the first energy level population is used as the final spin state estimation result. The method comprises the following steps: step 101, inputting a first instruction, and causing a bias magnetic field component to generate a bias magnetic field; step 102, inputting a second instruction, and causing a pulse generation module to generate a pulse sequence; step 103, causing a fluorescence detection module to obtain a fluorescence intensity fn containing noise information at time tn, where n is the current sampling in the sampling, and tn is the current sampling time; step 104, combining the Bayesian estimation theorem, and using fn to solve the spin state β1, where the spin state β1 refers to the population of ground state electrons in the spin 0 state, that is, the electrons in the ground state ms=0, and ms is the spin magnetic quantum number; step 105, obtaining the fluorescence intensity fn+1 at the next time to update the spin state β1, until the spin state no longer changes, at which time β1 is the final estimation result.

[0028] The bias magnetic field assembly can generate a directional bias magnetic field with adjustable magnitude and direction, and can maintain a stable output. The pulse generation sequence generated by the pulse generation module includes a laser polarization pulse, a microwave manipulation pulse, and a laser detection pulse. The laser polarization pulse is used to polarize the electronic state of the NV color center to the ground state of spin 0, the microwave manipulation pulse is used to flip the NV color center electron spin, and the laser detection pulse is used to read the fluorescence intensity of the NV color center electron spin state. The electronic energy level states of the diamond NV color center include the ground state, the excited state, and the singlet state. Assume that the ground state ms=0 (denoted as the first energy level) has an occupation number of β1 and ms=1 (denoted as the second energy level) has an occupation number of β2, ms is the spin magnetic quantum number, the excited state ms=0 (denoted as the third energy level) has an occupation number of β3 and ms=1 (denoted as the fourth energy level) has an occupation number of β4, and the singlet state (denoted as the fifth energy level) has an occupation number of β5. Then the spin state vector form β=(β1, β2, β3, β4, β5). When not sampled, the probability distribution function P2(β|f0) satisfies a known distribution, and one choice is uniform distribution. When the noise-containing fluorescence intensity of the subsample is denoted as fn, when the expected fluorescence intensity of the subsample is denoted as <f n >, the current sampling time is tn, the last sampling time is t n-1 , the next sampling time is t n+1 , the function of the spin state vector β and time t is β(t), and the collection efficiency is λ. Then, when the spin state is β1, t n Fluorescence intensity measurement result f at time n The likelihood function P1(f n |β1) is:

[0029]

[0030]

[0031] Where exp is the exponential function.

[0032] The noise-containing fluorescence intensity of the current sampling is recorded as fn, the sampling time is tn, and the next sampling time is t n+1 The noise-containing fluorescence intensity of the next sampling is recorded as f n+1 , then the spin state probability distribution function P2(β1|f n+1 ) satisfies: P2(β1|f n+1 )∝P1(f n+1 |β1)·P2(β1|f n )

[0033] P2(β1|f n )=P1(f n |β1).

[0034] The final estimated spin state is the spin state corresponding to the maximum probability in the probability distribution function obtained after the last sampling.

[0035] The present invention discloses a real-time spin state detection method based on diamond nitrogen-vacancy (NV) color centers. Based on estimation theory, this method fully utilizes the noisy fluorescence intensity obtained during diamond NV color center detection to achieve real-time spin state update detection. This scheme suppresses photon shot noise, improves the signal-to-noise ratio of spin state detection, and can also achieve real-time spin state detection when combined with hardware. The method is simple to operate and easy to implement.

[0036] A real-time spin state detection method based on diamond NV color centers fully utilizes the fluorescence intensity obtained in the detection of diamond NV color centers and realizes real-time update detection of the spin state based on estimation theory until the final estimated spin state is obtained.

[0037] The spin state β1 refers to the population of ground state electrons in the ground state spin 0 state.

[0038] The energy level structure of the diamond NV color center can be expressed by five levels when there is an external magnetic field, including the ground state m s =0 energy level, ground state m s = +1 energy level, excited state m s =0 energy level, excited state m s = +1 energy level and singlet energy level (m s is the spin magnetic quantum number), the population of each energy level is represented by β1, β2, β3, β4, and β5, respectively, and the vector form of the spin state is recorded as β = (β1, β2, β3, β4, β5).

[0039] The fluorescence intensity of a single NV color center in a certain time interval t n -t n-1 (n is the current time, n-1 is the previous time) the theoretical fluorescence intensity and excited state m s =0 energy level, excited state m s = proportional to the number of occupants of the +1 energy level, that is, t n The expected (theoretical) intensity of the fluorescence collected at each moment <f n > can be expressed as:

[0040]

[0041] Where λ is the collection efficiency, and β(t) is the function of the vector form β of the spin state and time t.

[0042] The fluorescence intensity satisfies the Poisson distribution under the influence of shot noise, and the expected value of the Poisson distribution is equal to the variance. n Fluorescence intensity measurement result f at timen The likelihood function P1 is:

[0043]

[0044] Where exp is the exponential function.

[0045] The estimation theory, taking Bayesian estimation as an example, is that the probability distribution function P2(β|f0) when no sampling is performed satisfies a certain known distribution, and one choice is uniform distribution.

[0046] The estimation theory mentioned above, taking Bayesian estimation as an example, the t n+1 The spin state probability distribution function P2(β1|f n+1 )satisfy:

[0047] P2(β1|f n+1 )∝P1(f n+1 |β1)·P2(β1|f n )

[0048] The final estimated spin state is the spin state corresponding to the maximum probability in the probability distribution function obtained after the last sampling.

[0049] The t n The probability distribution function of the spin state β1 at time t n+1 Under the condition of time, the spin state distribution function P2(β1|f n )for:

[0050] P2(β1|f n )=P1(f n |β1)

[0051] refer to Figure 1 As shown, the operation flow of a real-time spin state detection method based on diamond nitrogen vacancy color center includes the following steps: Step 101, the user inputs a first instruction, and the bias magnetic field component generates a bias magnetic field; Step 102, the user inputs a second instruction, and the pulse generation module generates a pulse sequence; Step 103, the fluorescence detection module obtains t n The fluorescence intensity f containing noise information at the moment n ; Step 104, combining the Bayesian estimation principle, using the fluorescence intensity f n Solve for the spin state β n Step 105, repeat steps 103 and 104 to obtain the fluorescence information f at the next moment n+1 , and update the spin state β n+1 , until the spin state solution value no longer changes, at which point β1 is the final estimated result.

[0052] The bias magnetic field component in step 101 can generate a directional bias magnetic field with adjustable size and direction and can maintain a stable output.

[0053] The pulse generation sequence in step 102 is characterized in that: the pulse generation module includes a laser polarization pulse, a microwave manipulation pulse, and a laser detection pulse, wherein the laser polarization pulse is used to polarize the electronic state of the NV color center to the spin 0 state of the ground state, the microwave manipulation pulse is used to flip and manipulate the NV color center electron spin, and the laser detection pulse is used to read the fluorescence intensity containing the NV color center electron spin state.

[0054] The spin state β1 refers to the population of ground state electrons in the ground state spin 0 state.

[0055] When there is an external magnetic field, the energy level structure of the NV color center can be expressed by five levels, including the ground state |m s =0>Energy level, ground state|m s =+1>energy level, excited state|m s =0>Energy level, excited state|m s =+1> energy level and singlet energy level, the population of each energy level is represented by β1, β2, β3, β4, β5, and the vector form of the spin state is recorded as β=(β1,β2,β3,β4,β5).

[0056] refer to Figure 2 As shown in the figure, after the laser excites the ground state electrons of the diamond NV color center to the excited state, some of the electrons fall back to the ground state directly from the excited state via paths ②④, emitting red fluorescence; the other part releases 1042nm infrared light through the metastable intersystem crossing (ISC) process ⑤⑥⑦⑧. s = +1 energy level, the probability of transition to the ground state through the ISC process is greater than the probability of the electron in the excited state m s = the probability of the 0 energy level, that is, when the electron is in the ground state m s = When the +1 energy level has a population, after the electron is pumped to the excited state, the fluorescence intensity generated when the electron falls back to the ground state will be less than that of the electron only in the ground state m s =0 energy level. Using an avalanche photodiode (APD) to detect the intensity of the NV color center fluorescence can be used to detect the population of the spin 0 state. By combining the transition rates between different states and the electrons in different states of β1, β2, β3, β4, and β5, a fifth-order light rate equation can be established. The light rate equation is used to construct the following mathematical model:

[0057]

[0058]

[0059]

[0060]

[0061]

[0062] Where Г represents the laser pumping rate, k represents the rate at which electrons fall back to the ground state via paths ② and ④, and k 51 It represents the rate at which electrons transition from a singlet energy level to the first energy level, and so on. Arranged, β′(t)=Aβ(t), where β′(t) is the derivative form of β(t) and is an intermediate variable. A is a coefficient, and

[0063]

[0064] At the initial moment, the electron spin state vector is β(0) = (β1,β2,0,0,0), then the rate equation can be written as

[0065] β(t)=e At β(0)

[0066] Where e is a natural constant and β(t) is the function of the vector form β of the spin state and time t.

[0067] When the electrons fall back to the ground state through processes ② and ④, they emit red fluorescence of 600-800nm, which can be absorbed and read by the avalanche diode. n -t n-1 (n is the number of sampling times, which is an integer greater than 0) The theoretical fluorescence intensity and excited state |m s =0>Energy level, excited state|m s =+1> is proportional to the number of energy level occupancy, that is, t n The expected (theoretical) intensity of the fluorescence collected at each moment <f n > can be expressed as:

[0068]

[0069] Where λ is the collection efficiency, and β(t) is the function of the vector form β of the spin state and time t.

[0070] The fluorescence intensity satisfies the Poisson distribution under the influence of shot noise, and the expected value of the Poisson distribution is equal to the variance. n The measurement result at time f n The likelihood function P1 is:

[0071]

[0072] Taking Bayesian estimation as an example, the probability distribution function P2(β|f0) when no sampling occurs satisfies a known distribution, and one choice is uniform distribution.

[0073] Taking Bayesian estimation as an example, the t n+1 The spin state probability distribution function P2(β1|f n+1 )satisfy:

[0074] P2(β1|f n+1 )∝P1(f n+1 |β1)·P2(β1|f n )

[0075] The final estimated spin state is the spin state corresponding to the maximum probability in the probability distribution function obtained after the last sampling.

[0076] In t n+1 Under the condition of time, the spin state distribution function P2(β1|f n )for:

[0077] P2(β1|f n )=P1(f n |β1)

[0078] refer to Figure 3 As shown, the real-time spin detection method based on diamond nitrogen vacancy color centers consists of three main stages: polarization, manipulation, and detection. A 532nm laser 1 passes through an optical isolator 2, a polarizer 3, and a beam splitter prism 4 to reach an acousto-optic modulator 6. Objective lenses 5 and 7 before and after the acousto-optic modulator 6 focus the laser light. The laser light is then reflected by a dichroic mirror 11 to a microwave antenna 9 carrying a diamond sample 10. The microwave antenna 9 and the diamond sample 10 are placed in the measured magnetic field generated by a bias magnetic field 8. Fluorescence carrying spin information passes through objective lens 11, dichroic mirror 12, reflector 13, aperture 14, and filter 15 to reach an avalanche diode detector 16. Hardware system 17 detects the voltage signal converted by the avalanche diode 16, converts it into fluorescence intensity, and performs Bayesian estimation to achieve real-time detection of the spin state.

[0079] 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 real-time spin state detection method based on diamond NV color centers, characterized in that: This includes using the Bayesian estimation theorem to calculate the first energy level population of the electron spin ground state based on the noisy fluorescence intensity obtained by detecting the laser acting on the diamond NV color center, and updating it in real time until the calculated first energy level population no longer changes, and then using the calculated first energy level population population as the final spin state estimation result; The electronic energy levels of the diamond NV color center include the ground state, the excited state, and the singlet state. The ground state ms = 0 is recorded as the first energy level population β1 and ms = 1 is recorded as the second energy level population β2. ms is the spin magnetic quantum number. The excited state ms = 0 is recorded as the third energy level population β3 and ms = 1 is recorded as the fourth energy level population β4. The singlet state is recorded as the fifth energy level population β5. The spin state vector form β = (β1, β2, β3, β4, β5); The noise-containing fluorescence intensity of the sample is recorded as f n , when the expected fluorescence intensity of the sampling is recorded as <f n >, when the sampling time is t n , the last sampling time is t n-1 , the next sampling time is t n+1 , the function of the spin state vector β and time t is β(t), and the collection efficiency is λ. Then, when the spin state is β1, t n Fluorescence intensity measurement result f at time n The likelihood function P1(f n |β1) is: Where exp is the exponential function; The following steps are involved: Step 101: input a first instruction, and the bias magnetic field component generates a bias magnetic field; Step 102: input a second instruction, and the pulse generating module generates a pulse sequence; Step 103: The fluorescence detection module obtains t n The fluorescence intensity f containing noise information at the moment n , n is the sampling time, t n is the sampling moment; Step 104: Combine the Bayesian estimation theorem and use the fluorescence intensity f n Solve for the spin state β1, which refers to the population of the ground state electron in the spin 0 state, i.e., the electron in the ground state ms=0 energy level, where ms is the spin magnetic quantum number; Step 105: Obtain the fluorescence intensity f at the next moment n+1 , to update the spin state β1 until the spin state no longer changes. At this moment, β1 is the final estimated result; The noise-containing fluorescence intensity of the sample is recorded as f n , when the sampling time is t n , the next sampling time is t n+1 The noise-containing fluorescence intensity of the next sampling is recorded as f n+1 , then the spin state probability distribution function P2(β1|f n+1 ) satisfies: P2(β1|f n+1 )∝P1(f n+1 |β1)·P2(β1|f n ) P2(β1|f n )=P1(f n |β1).

2. The method for real-time detection of spin states based on diamond NV color centers according to claim 1, characterized in that: The bias magnetic field component can generate a directional bias magnetic field with adjustable size and direction and can maintain a stable output.

3. The real-time detection method for spin states based on diamond NV color centers according to claim 1, characterized in that: The pulse generation sequence generated by the pulse generation module includes laser polarization pulses, microwave manipulation pulses, and laser detection pulses, wherein the laser polarization pulses are used to polarize the electronic state of the NV color center to the spin 0 state of the ground state, the microwave manipulation pulses are used to flip and manipulate the NV color center electron spin, and the laser detection pulses are used to read the fluorescence intensity of the NV color center electron spin state.

4. The method for real-time detection of spin states based on diamond NV color centers according to claim 1, characterized in that: When no sampling occurs, the probability distribution function P2(β|f0) satisfies the uniform distribution.

5. The method for real-time detection of spin states based on diamond NV color centers according to claim 1, characterized in that: The final estimated spin state is the spin state corresponding to the maximum probability in the probability distribution function obtained after the last sampling.

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