Single-molecule magnetic resonance measuring device based on silicon carbide color centers

Abstract

The present disclosure provides a single-molecule magnetic resonance measurement device based on silicon carbide color centers, comprising: a static magnetic field module for applying a static magnetic field to a magnetic sensitive module and a sample to be measured, wherein the magnetic sensitive module comprises silicon carbide color centers, the static magnetic field makes the degenerate energy level of the silicon carbide color centers depolarized to obtain a depolarized energy level, and makes the characteristic frequency of the spin label of the sample to be measured located in the microwave band; a light source module, which applies excitation light in the infrared wavelength range to the silicon carbide color centers, so that the silicon carbide color centers transition from the ground state energy level to the excited state energy level; a control field module, which applies a preset microwave control field to the silicon carbide color centers, so as to control the evolution process of the silicon carbide color centers and the evolution process of the spin label in the sample to be measured; a readout module, which reads the population of each ground state energy level of the silicon carbide color centers after the end of the evolution process; and a data processing module, which obtains the measurement result of the sample to be measured according to the population of each ground state energy level of the silicon carbide color centers.

Description

Technical Field

[0001] This disclosure relates to the field of magnetic resonance measurement technology, and more specifically to a single-molecule magnetic resonance measurement device based on silicon carbide color centers. Background Technology

[0002] When the spin magnetic moment in a substance is not zero, the spin energy levels of electrons in that substance will split under the influence of an external magnetic field. For example, under the influence of an external field, the spin energy level of an electron will split into several energy levels. When the frequency of the applied microwave matches the frequency of the energy level splitting, transitions can occur between the energy levels, absorbing the radiation energy of the electromagnetic field. This is the phenomenon of magnetic resonance. Based on the frequency and intensity of magnetic resonance, the composition and structure of a substance can be inferred, and the frequency and intensity of magnetic resonance can also be used to measure external magnetic fields.

[0003] In realizing the present invention, the inventors discovered at least the following technical problems in the related technology: The magnetic sensing module in the magnetic resonance measurement device generally uses a diamond NV center (nitrogen-vacancy center). In the process of measuring the magnetic resonance phenomenon using the NV center, a 532nm laser in the visible light band is required to initialize and read out the NV center. During the initialization and readout process, the fluorescent material in the medium in which the sample is located may be activated and emit fluorescence. The measurement signal-to-noise ratio in the final readout result of the fluorescence readout scheme will be reduced as a result. At the same time, the spin signal in the sample to be tested, such as the electron paramagnetic signal of the spin tag TEMPO (tetramethylpiperidine oxide, C9HNO), will disappear after being disturbed by light. This means that the spin signal in the sample to be tested is destroyed by the 532nm laser in the visible light band, and thus the intensity of the spin signal in the sample to be tested cannot be guaranteed. Summary of the Invention

[0004] In view of the above problems, this disclosure provides a single-molecule magnetic resonance measurement device based on silicon carbide color centers, in order to at least partially solve the above problems and ensure the intensity of the spin signal in the sample to be measured.

[0005] IB222122 Active Modification

[0006] This disclosure provides a single-molecule magnetic resonance measurement device based on a silicon carbide color center, characterized by comprising: a static magnetic field module for applying a static magnetic field to a magnetically sensitive module and a sample under test, wherein the magnetically sensitive module includes a silicon carbide color center, and the static magnetic field is configured to degenerate the degenerate energy levels of the silicon carbide color center to obtain degenerate energy levels, and to ensure that the characteristic frequency of the spin tag of the sample under test is located in the microwave band; a light source module for applying excitation light in the infrared wavelength range to the silicon carbide color center, wherein the excitation light is configured to cause the silicon carbide color center to transition from a ground state energy level to an excited state energy level when the excitation light is applied; and a manipulation field module for applying a preset microwave manipulation field to the silicon carbide color center and the sample under test to control the quantum state of the whole formed by the silicon carbide color center and the spin tag in the sample under test. The evolution process of the silicon carbide color center; the readout module is used to read out the population of each ground state energy level of the silicon carbide color center after the evolution process is completed; the data processing module is used to obtain the measurement results of the sample under test based on the population of each ground state energy level of the silicon carbide color center after the application of the preset microwave manipulation field, wherein the measurement results include the magnetic resonance spectrum of electron spin in the sample under test and the Rabi oscillation curve of electron spin in the sample under test; wherein the silicon carbide color center and the spin tag of the sample under test have magnetic dipole interaction, and under the influence of the spin tag, the population of each ground state energy level obtained by the silicon carbide color center after the application of the preset microwave manipulation field is different, and the measurement results of the sample under test are obtained based on the population of each ground state energy level obtained after the application of the preset microwave manipulation field.

[0007] According to an embodiment of this disclosure, the control field module includes a control source and a microwave antenna, wherein the control source is configured to be electrically connected to the microwave antenna.

[0008] According to an embodiment of this disclosure, the control source is configured as a microwave source to generate the preset microwave control field.

[0009] According to embodiments of this disclosure, the microwave control field includes any one or more combinations of the following: a single-frequency combined pulse control field, a single-frequency control field, a dual-frequency control field synthesized from a first frequency control field and a second frequency control field, an amplitude-modulated control field, a frequency-modulated control field, a phase-modulated control field, an amplitude shift keying (APS) modulated control field, a frequency shift keying (FSK) modulated control field, and a phase shift keying (PSK) modulated control field.

[0010] According to an embodiment of this disclosure, the microwave antenna is configured to correspond to the magnetic sensing module, wherein the microwave antenna radiates the preset microwave control field of the control source to the magnetic sensing module.

[0011] IB222122 Active Modification

[0012] According to embodiments of this disclosure, the aforementioned static magnetic field is configured as at least one of the following: a geomagnetic field, a magnetic field generated by a magnetic material, or a magnetic field generated by a current-carrying conductor.

[0013] According to embodiments of this disclosure, the light source module includes an excitation light unit and an optical path control unit.

[0014] According to embodiments of this disclosure, the excitation unit is configured as at least one of the following: a laser, a light-emitting diode, or a laser diode.

[0015] According to the embodiments of this disclosure, a single-molecule magnetic resonance measurement device based on silicon carbide color centers applies a static magnetic field to a magnetically sensitive module including the silicon carbide color center and the sample to be measured through a static magnetic field module; excitation light in the infrared wavelength range is applied to the silicon carbide color center; a preset microwave manipulation field is applied to the silicon carbide color center; after the preset microwave manipulation field sequence is applied, the population of each ground state energy level of the silicon carbide color center after the evolution process is completed is read out using a readout module; because there is a magnetic dipole interaction between the silicon carbide color center and the sample to be measured, the measurement result of the sample to be measured can be obtained according to the population of each ground state energy level of the silicon carbide color center. In this method, because silicon carbide color centers are used as magnetic sensing modules, these centers can be excited by infrared light. Therefore, excitation light within the infrared wavelength range can be used to initialize and read out the silicon carbide color centers. Since the photon energy in the infrared wavelength range is lower than that in the visible light wavelength range, background fluorescence excited by visible light from the medium can be avoided. At the same time, for common spin tags such as TEMPO, they hardly absorb photons in the infrared band. The excitation light in the infrared band used by the silicon carbide single-molecule magnetic resonance device will not quench the spin tags in the sample. Therefore, this method at least partially overcomes the technical problem in related technologies where the use of lasers in the visible light band will destroy the spin signal in the sample, causing the spin signal to disappear. This achieves the technical effect of ensuring the intensity of the spin signal in the sample, thus making it possible to study the dynamic behavior of spin tags over a longer period of time. Attached Figure Description

[0016] Figure 1 A schematic diagram of a single-molecule magnetic resonance measurement device based on silicon carbide color centers according to an embodiment of the present disclosure is shown.

[0017] Figure 2 A schematic diagram illustrating the energy level structure of a silicon carbide color center according to an embodiment of the present disclosure is shown.

[0018] Figure 3 A schematic diagram of a light source module according to an embodiment of the present disclosure is shown; and

[0019] Figure 4 A schematic diagram of a light source module and a readout module according to an embodiment of the present disclosure is shown. Detailed Implementation

[0020] IB222122 Active Modification

[0021] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0023] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0024] When using expressions such as "at least one of A, B, and C", they should generally be interpreted in accordance with the meaning that is commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B, and C, etc.).

[0025] In recent years, the rapid development of solid-state spin quantum information processing methods has brought about new technological updates and promoted the development of solid-state spin sensor technology. Solid-state spin quantum information has been applied to the measurement of magnetic resonance spectra of biomolecules and magnetic materials. The specific principle is that when the sample to be measured has a non-zero spin, the spin-spin interaction will affect the quantum state of the solid-state spin sensor. For example, the commonly used solid-state quantum sensor is the NV color center in diamond. When an XY8 pulse sequence is applied to the color center, a microwave pulse is also applied to the electron spin of the sample. By scanning the frequency of the microwave pulse applied to the electron spin of the sample, when the frequency of the microwave pulse matches the characteristic frequency of the energy level splitting of the sample spin, a peak signal will be measured.

[0026] Based on this, in 2015, Shi Fazhan, Zhang Qi, Wang Pengfei, and others used NV centers to measure the first magnetic resonance spectrum of a single protein molecule in an ambient environment at room temperature (Single-protein Spin Resonance Spectroscopy under Ambient Conditions, Science 347, 1135 (2015)). The IB222122 active modification achieved nanoscale single-molecule magnetic resonance detection. However, the measurement process requires initialization and readout using a 532nm laser in the visible light band. This causes the spins in the sample to quench upon laser application, and the spin signal disappears after a certain laser irradiation time. Furthermore, the raw material for NV centers is diamond, and diamond processing and production technologies are relatively immature, making large-scale industrialization more difficult.

[0027] In view of this, this disclosure provides a single-molecule magnetic resonance measurement device based on silicon carbide color centers. By using silicon carbide color centers as magnetic sensing modules, the intensity of the spin signal in the sample under test is ensured. At the same time, the processing and production technology of silicon carbide color centers is more mature than that of diamond NV color centers, and it is easier to realize industrialization. Specifically, the device includes a static magnetic field module for applying a static magnetic field to a magnetically sensitive module and the sample under test. The magnetically sensitive module includes a silicon carbide color center, and the static magnetic field is configured to degenerate the degenerate energy levels of the silicon carbide color center to obtain degenerate energy levels, and to ensure that the characteristic frequency of the spin tag of the sample under test is located in the microwave band. A light source module is used to apply excitation light in the infrared wavelength range to the silicon carbide color center. The excitation light is configured to cause the silicon carbide color center to transition from a ground state energy level to an excited state energy level upon application. A manipulation field module is used to apply a preset microwave manipulation field to the silicon carbide color center and the sample under test to control the evolution of the quantum state of the entire system composed of the silicon carbide color center and the spin tag in the sample under test. A readout module is also included. The first module is used to read the population of each ground state energy level of the silicon carbide color center after the evolution process is completed. The second module is used to obtain the measurement results of the sample under test based on the population of each ground state energy level of the silicon carbide color center after applying a preset microwave manipulation field. The measurement results include the magnetic resonance spectrum of electron spin in the sample under test and the Rabi oscillation curve of electron spin in the sample under test. The silicon carbide color center and the spin tag of the sample under test have magnetic dipole interaction. Under the influence of the spin tag, the population of each ground state energy level of the silicon carbide color center after applying the preset microwave manipulation field is different. The measurement results of the sample under test are obtained based on the population of each ground state energy level after applying the preset microwave manipulation field.

[0028] Figure 1 A schematic diagram of a single-molecule magnetic resonance measurement device based on silicon carbide color centers according to an embodiment of the present disclosure is shown.

[0029] like Figure 1 As shown, a single-molecule magnetic resonance measurement device based on silicon carbide color centers may include a static magnetic field module 1, a magnetic sensing module 2, a light source module 3, a manipulation field module 4, a readout module 5, and a data processing module 6.

[0030] According to embodiments of this disclosure, the static magnetic field module 1 can apply a static magnetic field to the magnetic sensing module 2 and the sample 7 to be tested, wherein the magnetic sensing module 2 may include one or more silicon carbide color centers 8.

[0031] IB222122 Active Modification

[0032] The static magnetic field can degenerate the degenerate energy level of the silicon carbide color center 8 to obtain a degenerate energy level, and cause the energy level of the spin tag of the sample to be tested 7 to split, thereby adjusting the characteristic frequency corresponding to the splitting of the energy level, so that the characteristic frequency is located in the microwave band, which can be the 50MHz to 30GHz band.

[0033] According to embodiments of this disclosure, the static magnetic field module 1 can be implemented using a permanent magnet or a charged coil that is a certain distance away from the sample to be tested 7 and the magnetic sensing module 2. Optionally, the permanent magnet and the charged coil can be fixed or movable.

[0034] According to embodiments of this disclosure, the static magnetic field can be at least one of the following: the Earth's magnetic field, a magnetic field generated by a magnetic material, or a magnetic field generated by a current-carrying conductor. The static magnetic field can also be adaptively adjusted according to actual needs.

[0035] According to embodiments of this disclosure, a sample 7 to be tested can be placed on the magnetic sensing module 2. The magnetic sensing module 2 can be composed of one or more magnetically sensitive defects in silicon carbide. Specifically, the magnetically sensitive defect can be a silicon carbide double-vacancy color center 8, which is formed by a silicon carbide lattice vacancy of one adjacent C atom and one Si atom. The silicon carbide color center 8 can be used to detect spin tags in the sample 7 to be tested, and the spin tags can be unpaired electrons in the sample 7 to be tested.

[0036] According to embodiments of this disclosure, the magnetic sensing module 2 can also be composed of other magnetically sensitive defects. Specifically, the ground state energy level of the magnetically sensitive defect can have a magnetic dipole interaction with the spin signal in the sample under test, and can be excited and read out by infrared light. For example, other magnetically sensitive defects can be NV color centers in silicon carbide, which are composed of a nitrogen atom replacing a C atom or a Si atom in the silicon carbide lattice plus the vacancy of adjacent C or Si atoms.

[0037] Figure 2 A schematic diagram of the energy level structure of a silicon carbide color center according to an embodiment of the present disclosure is shown.

[0038] like Figure 2 As shown, the energy level structure of the silicon carbide color center 8 can include the 0-state energy level 9 without an applied static magnetic field, the degenerate +1-state energy level 10 and -1-state energy level 11 without an applied static magnetic field, the excited state energy level 12 of the silicon carbide color center, the 0-state energy level 13 after applying a static magnetic field, and the -1-state energy level 14 and +1-state energy level 15 that are split after applying a static magnetic field. Figure 2 The diagram not only illustrates the energy level diagram but also the transition process diagram. For example, the transition process of silicon carbide color centers when excitation light is applied 16; the spontaneous emission fluorescence diagram when the silicon carbide color center is in the 0 state 17; the spontaneous emission fluorescence diagram when the silicon carbide color center is in the ±1 state 18; the microwave diagram used to manipulate the transition between the 0 and -1 states after applying a static magnetic field 19; the microwave diagram used to manipulate the transition between the 0 and +1 states after applying a static magnetic field 20; nonradiative transition 21; and spin singlet 22.

[0039] IB222122 Active Modification

[0040] According to embodiments of this disclosure, the +1 state level 10 and -1 state level 11 of the silicon carbide color center are degenerate when no static magnetic field is applied. The degenerate levels obtained after degeneracy can include the -1 state level 14 and the +1 state level 15, which are split after the application of a static magnetic field. The static magnetic field can also cause the spin levels in the sample 7 to split, thereby adjusting the characteristic frequency corresponding to the splitting of the sample's energy levels, so that the adjusted characteristic frequency is located in the microwave band.

[0041] According to embodiments of this disclosure, the ground state energy levels of the silicon carbide color center 8 are state 0 (13), state -1 (14), and state +1 (15) after applying a static magnetic field. The light source module 3 can be used to apply excitation light in the infrared wavelength range to the silicon carbide color center 8. This excitation light can cause the quantum state of the silicon carbide color center 8 to transition from the ground state energy level to the excited state energy level 12 of the silicon carbide color center, thereby completing the initialization process of the silicon carbide color center 8.

[0042] According to embodiments of this disclosure, the excitation light emitted by the light source module 3 can cause the quantum states of the silicon carbide color center 8 to transition between the 0-state energy level 13 and the excited state energy level 12 of the silicon carbide color center after the application of a static magnetic field, between the +1-state energy level 15 and the excited state energy level 12 of the silicon carbide color center after the application of a static magnetic field, and between the -1-state energy level 14 and the excited state energy level 12 of the silicon carbide color center after the application of a static magnetic field. After transitioning to the excited state energy level 12 of the silicon carbide color center, a portion of the population returns to the original energy level through spontaneous emission fluorescence, while another portion of the population relaxes to the 0-state energy level 13 after the application of a static magnetic field through non-radiative transitions. Overall, the entire process causes the populations at the +1-state energy level 15 and the -1-state energy level 14 after the application of a static magnetic field to transfer to the 0-state energy level 13 after the application of a static magnetic field. After applying laser light for a period of time, the quantum states of the silicon carbide color center 8 are initialized to the 0-state energy level 13 after the application of a static magnetic field. Before initialization, the quanta of silicon carbide color center 8 are randomly distributed on energy level 13 (0 state), energy level 15 (+1 state), and energy level 14 (-1 state) after applying a static magnetic field. Initializing the quantum state of silicon carbide color center 8 can obtain a unified initial state.

[0043] According to embodiments of this disclosure, the quantum states of silicon carbide color centers are initialized to ensure that the quantum states of silicon carbide color centers are the same before their evolution. If a uniform initialization is not performed, the initial states before each evolution will be different, and the final evolved states will be randomly distributed, so the spin tag signal will not be detected.

[0044] According to embodiments of this disclosure, the manipulation field module 4 is used to apply a preset microwave manipulation field to the silicon carbide color center 8 and the sample 7 to control the evolution of the quantum state of the whole formed by the spin tags in the silicon carbide color center 8 and the sample 7. The preset microwave manipulation field may include multiple preset microwave pulse sequences, which can also be understood as a magnetic field with a preset waveform. The preset pulse sequence and the preset waveform magnetic field can be adaptively adjusted according to actual conditions. The preset microwave pulse sequence in embodiments of this disclosure can be as follows: Figure 3 As shown.

[0045] According to embodiments of this disclosure, the manipulation field module 4 is used to output a preset pulse sequence and apply the pulse sequence to the spin tags of the silicon carbide color center 8 and the sample 7 under test, that is, to apply a preset waveform magnetic field to the spin tags of the silicon carbide color center 8 and the sample 7 under test. The preset waveform magnetic field will affect the Hamiltonian of the silicon carbide color center 8 and the sample 7 under test as a whole during the evolution process, thereby affecting the quantum state evolution process of the silicon carbide color center 8 and the sample 7 under test as a whole. Therefore, the population of each ground state energy level of the silicon carbide color center 8 obtained after evolution under different microwave pulse sequences is different.

[0046] According to embodiments of this disclosure, the readout module 5 can be used to read out the population of each ground state energy level of the silicon carbide color center 8 after the evolution process is completed. Specifically, the readout method of the silicon carbide color center 8 can be fluorescence readout. The readout process can be based on the difference in the expected number of fluorescent photons emitted by the 0-state energy level 13 after the application of a static magnetic field and the +1-state energy levels 15 and -1-state energy levels 14 after the application of a static magnetic field, after being excited by excitation light for a period of time, to read out the population of the 0-state energy level 13 of the silicon carbide color center 8. The populations of the +1-state energy levels 15 and -1-state energy levels 14 can be exchanged with the 0-state energy level 13 by a pulse, and then the population of the 0-state energy level 13 can be read out. The fluorescence readout process can be that the light source module 3 applies excitation light, the fluorescence emitted by the silicon carbide color center 8 reaches the readout module 5, is collected by the readout module 5 and counted, and the population of the 0-state energy level 13 of the silicon carbide color center can be obtained based on the obtained photon count.

[0047] According to embodiments of this disclosure, the data processing module 6 can be used to obtain the measurement results of the sample under test based on the population of each ground state energy level of the silicon carbide color center 8 after a preset microwave manipulation field is applied. The measurement results may include the magnetic resonance spectrum of electron spin in the sample under test, the Rabi oscillation curve of electron spin in the sample under test, etc. Specifically, the data processing module 6 can be used to obtain the measurement results of the sample under test by causing the silicon carbide color center to undergo an evolution process under different microwave pulse sequences output by the preset microwave manipulation field. Alternatively, the data processing module 6 can be understood as obtaining the measurement results of the sample under test based on the population of each ground state energy level of the silicon carbide color center 8 after applying different pulse sequences.

[0048] According to embodiments of this disclosure, the silicon carbide color center 8 and the spin tag of the sample 7 under test have a magnetic dipole interaction. Under the influence of the spin tag, the population of each ground state energy level obtained by the silicon carbide color center 8 after being actively modified by a preset microwave manipulation field is different. The measurement result of the sample 7 under test is obtained based on the population of each ground state energy level obtained after the preset microwave manipulation field is applied. It can also be understood that when the sample 7 under test has a spin tag, there is a magnetic dipole interaction between the spin tag and the silicon carbide color center 8. This magnetic dipole interaction can affect the evolution of the state of the silicon carbide color center 8. Thus, during the initialization-evolution-readout process of the silicon carbide color center 8 under different microwave pulse sequences, the population of each ground state energy level of the silicon carbide color center 8 is different. The population can be understood as the probability that the silicon carbide color center 8 is in a certain energy level.

[0049] Figure 3 The illustration shows a schematic diagram of a microwave pulse sequence during magnetic resonance measurement according to an embodiment of the present disclosure.

[0050] like Figure 3 As shown, a series of manipulation field sequences can be Figure 3 The sequence shown is obtained by changing the radio frequency field frequency f while keeping the pulse interval τ0 and the radio frequency field pulse time τ fixed. Then, based on the population of different ground state energy levels of the silicon carbide color center obtained through the initialization-evolution-readout process under this last series of manipulation fields, the magnetic resonance spectrum of the sample can be obtained. When the series of manipulation fields applied during the evolution process are... Figure 3 In the sequence shown, the fixed radio frequency is the characteristic frequency of the electron spin of the sample under test, while maintaining the pulse interval time τ0. By changing the radio frequency time τ, the Rabi oscillation curve of the spin tag on the sample under test can be obtained based on the population of different ground state energy levels of silicon carbide color centers obtained by the initialization-evolution-readout process under the last series of manipulation fields.

[0051] like Figure 3 The pulse sequence shown represents the initialization and readout processes, with the initialization and readout blocks representing the initialization and readout processes, and the other blocks representing microwave pulses. These are combinations of microwave pulse fields at two frequencies, one of which matches the energy level splitting of the silicon carbide color center, thus manipulating it. The diagram illustrates these pulses as π pulses of microwave X and microwave Y, as well as blocks π / 2 and 3π / 2. These pulses are single-frequency sinusoidal pulses. The main difference between the pulses is the pulse duration and phase. Microwave X and microwave Y have a 90-degree phase difference. The pulse duration of the π pulse of microwave X must ensure that the color center experiences a π gate after the pulse is applied. The pulse duration of the π pulse of microwave Y must also ensure that the color center experiences a π gate after the pulse is applied. The pulse duration of the π / 2 pulse must ensure that the color center experiences a π / 2 gate after the pulse is applied. The pulse duration of the π / 2 pulse must ensure that the color center experiences a 3π / 2 gate after the pulse is applied. The frequency of the other microwave pulse field can be arbitrarily selected, denoted as f, and the pulse time can also be arbitrarily selected, denoted as τ. The main purpose of setting the pulse time is to actively modify the electron spin in the sample.

[0052] Control. There is a time interval between pulses, such as... Figure 3 In the manipulation sequence of silicon carbide color centers, after the π / 2 pulse is applied, a wait of τ0 / 2 is required before simultaneously applying the π pulse of microwave X and the radio frequency field pulse. The π pulse interval between microwave X and microwave Y, as well as the radio frequency field pulse interval, are both τ0. Additionally... Figure 3 The microwave pulse sequence enclosed in square brackets 31 can be repeated n times. Choosing n appropriately can improve the signal-to-noise ratio of the final signal.

[0053] According to embodiments of this disclosure, a static magnetic field is applied to a magnetically sensitive module including a silicon carbide color center and the sample to be tested via a static magnetic field module; excitation light in the infrared wavelength range is applied to the silicon carbide color center; a preset microwave manipulation field is applied to the silicon carbide color center, causing the silicon carbide color center to evolve; after the evolution process is completed, the population of each ground state energy level of the silicon carbide color center is read out using a readout module; because there is a magnetic dipole interaction between the silicon carbide color center and the sample to be tested, the measurement result of the sample to be tested can be obtained based on the population of each ground state energy level of the silicon carbide color center. In this method, because silicon carbide color centers are used as magnetic sensing modules, silicon carbide can be excited by infrared light. Therefore, excitation light within the infrared wavelength range can be used to initialize and read out the silicon carbide color centers. Since the photon energy in the infrared wavelength range is lower than that in the visible light wavelength range, background fluorescence excited by visible light from the medium can be avoided. Furthermore, for common spin tags such as TEMPO, they absorb almost no photons in the infrared band. The infrared excitation light used in the silicon carbide single-molecule magnetic resonance device will not quench the spin tags in the sample. Therefore, this method at least partially overcomes the technical problem in related technologies where the use of visible light lasers destroys the spin signal in the sample, leading to the disappearance of the spin signal. This achieves the technical effect of ensuring the intensity of the spin signal in the sample. In addition, the magnetic resonance measurement device provided by this disclosure also makes it possible to study the dynamic behavior of spin tags over a longer period of time.

[0054] According to embodiments of this disclosure, the control field module 4 may include a control source 401 and a microwave antenna 402. The control source 401 may be a microwave source used to generate a preset microwave control field, and the control source 401 is electrically connected to the microwave antenna 402. The microwave source 401 may also include a microwave power amplifier component and a switching component, etc. It is understood that the microwave source can be constructed based on components commonly used in the art, and will not be described in detail here.

[0055] According to embodiments of this disclosure, microwave antenna 402 can be configured to correspond to magnetic sensing module 2, with magnetic sensing module 2 corresponding to microwave antenna 402, in order to position magnetic sensing module 2 at a sufficiently strong location within the control field emitted by microwave antenna 402. Microwave antenna 402 can radiate a preset microwave control field generated by control source 401 to magnetic sensing module 2.

[0056] IB222122 Active Modification

[0057] According to embodiments of this disclosure, the microwave control field includes any one or more combinations of the following: a single-frequency combined pulse control field, a single-frequency control field, a dual-frequency control field synthesized from a first frequency control field and a second frequency control field, an amplitude-modulated control field, a frequency-modulated control field, a phase-modulated control field, an amplitude-shift keying (APS) modulated control field, a frequency-shift keying (FSK) modulated control field, and a phase-shift keying (PSK) modulated control field. The control field can also be adaptively adjusted according to actual needs.

[0058] According to embodiments of this disclosure, the manipulation field module 4 can be a microwave source plus a microwave antenna. The microwave source can generate a preset microwave pulse sequence, and the microwave antenna can radiate microwaves, thereby generating an alternating magnetic field with a preset waveform corresponding to the preset microwave pulse sequence at the magnetic sensing module.

[0059] Figure 4 A schematic diagram of a light source module and a readout module according to an embodiment of the present disclosure is shown.

[0060] like Figure 4 As shown, the light source module 3 may include an excitation light unit 301 and an optical path control unit. Specifically, the excitation light unit 301 may be at least one of the following: a laser, a light-emitting diode, or a laser diode. The wavelength emitted by the excitation light unit may be 700nm to 1000nm.

[0061] According to embodiments of this disclosure, the optical path control unit may include a 1 / 2λ waveplate 302, a polarization beam splitter 303, a first plano-convex lens 304, an acousto-optic modulator 305, a second plano-convex lens 306, a 1 / 4λ waveplate 307, a reflector 308, a pinhole 309, a first fiber collimator 310, and a second collimator 311. The optical path control unit is used to control the excitation light emitted by the excitation light unit to be incident on the sample under test. The focal lengths of the first plano-convex lens 304 and the second plano-convex lens 306 can be adaptively adjusted according to actual needs. The acousto-optic modulator 305 is used to switch the laser on and off. When a TTL (Transistor-Transistor Logic) signal is applied to the acousto-optic modulator 305, light can be incident on the optical path after passing through the fiber in the first fiber collimator 310; when no TTL signal is applied to the acousto-optic modulator 305, light cannot be incident on the optical path after passing through the fiber in the first fiber collimator 310.

[0062] According to the embodiments of this disclosure, the light source module 3 can operate as follows: the excitation light unit 301 is incident on the polarization beam splitter 303 through the 1 / 2λ waveplate 302 and then transmitted. After being focused by the first plano-convex lens 304, it is incident on the acousto-optic modulator 305. The diffracted first-order light spot is then collimated by the second plano-convex lens 306 and then reflected by the mirror 308 through a 1 / 4λ waveplate 307. After passing through the second plano-convex lens 306 and the acousto-optic modulator 305, it is diffracted. The diffracted first-order light spot is incident on the polarization beam splitter 303 through the first plano-convex lens 304 and reflected. Then, it is incident on the first fiber collimator 310 through an IB222122 active modification aperture 309. After being transmitted through the optical fiber, it is emitted from the second fiber collimator 311 and incident on the silicon carbide color center 8.

[0063] like Figure 4 As shown, the readout module 5 can count the number of fluorescent photons emitted by the silicon carbide color center 8 and read out the population of each ground state energy level of the silicon carbide color center 8. After the evolution process is completed, the silicon carbide color center 8 is excited by the light source module 3, and the number of fluorescent photons emitted by the silicon carbide color center 8 is counted by the readout module 5. The population of each ground state energy level of the silicon carbide color center 8 can be obtained based on the number of readout fluorescent photons. The readout module 5 may include a long-pass filter 501, a focusing lens 502, a third fiber collimator 503, and a single-photon detector 504. Specifically, the readout process can be that after the fluorescence is emitted from the magnetic sensing module on the sample holder and the displacement stage, it first passes through a long-pass dichroic mirror. The long-pass dichroic mirror allows light with wavelengths greater than a specific wavelength to pass through, while light with wavelengths smaller than a specific wavelength is reflected by the dichroic mirror. The specific wavelength can be adaptively adjusted as needed. The fluorescence passing through the long-pass dichroic mirror will pass through the long-pass filter 501 and the focusing lens 502. After being focused by the focusing lens 502, it will converge onto the third fiber collimator 503, and then be connected to the single-photon detector 504 through the fiber to realize the detection and readout of the fluorescence signal.

[0064] like Figure 4 As shown, the sample holder and displacement stage can be used to place samples, specifically, they can hold magnetic sensing module 2, sample to be tested 7, microwave antenna 402, etc.

[0065] According to embodiments of this disclosure, a method for measuring the magnetic resonance spectrum of a sample to be tested using a single-molecule magnetic resonance measurement device based on silicon carbide color centers according to embodiments of this disclosure is also provided. Specifically, the method includes the following steps.

[0066] During the measurement of the magnetic resonance spectrum, the sample 7 to be measured can be placed on the magnetically sensitive module 2, and a static magnetic field can be applied. For a series of different pulse sequences, the following initialization-evolution-readout operation can be repeated:

[0067] Initialization can be achieved by using light emitted from the light source module 3 to incident on the silicon carbide color center 8 in the magnetic sensing module 2 to initialize the silicon carbide color center 8. When excitation light is applied, it is initialized to the 0-state energy level 13 after the application of a static magnetic field through the ISC (State-selective intersystem crossing) process.

[0068] The evolution process can be achieved by the manipulation field module 4 applying a pulse sequence to the sample 7 and the magnetic sensing module 2. Each applied pulse sequence can be different, and the pulse sequence output by the manipulation field can be as follows: Figure 3 As shown, after the initialization process, the quantum states of the electron spins in the silicon carbide color center 8 and the test sample 7 evolve into actively modified quantum states (IB222122) under the dominance of the system's Hamiltonian. This evolution is achieved by outputting a preset microwave manipulation field to the silicon carbide color center 8 and the test sample 7 through the manipulation field module 4. The microwave manipulation field affects the Hamiltonian of the spin tags in the silicon carbide color center and the test sample during the pulse sequence application time, thus influencing the resulting quantum states.

[0069] like Figure 3 As shown, microwaves X and Y, which are 90 degrees out of phase, are applied to the silicon carbide color center 8 via a microwave antenna using π pulses, 3π / 2 pulses, or π / 2 pulses. At the same time as the microwaves are applied, radio frequency field pulses with frequency f and time τ are applied to the sample under test 7 to manipulate the spin on the sample under test 7. The interval between adjacent π pulses is τ0, the interval between π / 2 pulses is τ0 / 2, and the interval between π pulses and 3π / 2 pulses is also τ0 / 2.

[0070] After the evolution process, the state of the silicon carbide color center 8 can be read out. This can be achieved by using light emitted from the excitation unit 301 of the light source module 3, which is incident on the silicon carbide color center 8 in the magnetic sensing module 2. The readout module counts the number of fluorescent photons emitted by the silicon carbide color center, and the population of each ground state energy level of the silicon carbide color center can be obtained based on the number of readout fluorescent photons. After reading out the evolution process, the evolution state of the silicon carbide color center after applying a preset microwave manipulation field is obtained, yielding the population of each ground state energy level of the silicon carbide color center. Furthermore, based on the population read out under different microwave sequences in different manipulation fields, the measurement results of the sample under test can be determined.

[0071] According to embodiments of this disclosure, if a series of manipulation field sequences are Figure 3The sequence shown, obtained by changing the radio frequency field frequency f while keeping the pulse interval τ0 and the radio frequency field pulse time τ constant, allows us to obtain the magnetic resonance spectrum of the sample by analyzing the populations of different ground state energy levels of the silicon carbide color center obtained from the initialization-evolution-readout process under the last series of manipulation fields. If the series of manipulation fields applied during the evolution process are... Figure 3 The sequence shown is obtained by fixing the radio frequency frequency f, which is the characteristic frequency of the electron spin of the sample under test, while keeping the pulse interval time τ0 and changing the radio frequency time τ. Based on the population of different ground state energy levels of silicon carbide color centers obtained by the initialization-evolution-readout process under the last series of manipulation fields, the Rabi oscillation curve of the spin tag on the sample under test can be obtained.

[0072] According to embodiments of this disclosure, the system Hamiltonian includes the Hamiltonian of the silicon carbide color center itself, the Hamiltonian of the sample to be tested, and the Hamiltonian of the magnetic dipole interaction between the silicon carbide color center and the spin tag of the sample to be tested. Therefore, the properties of the spin tag itself will affect the evolution process of the silicon carbide color center under different microwave manipulation fields, thereby changing the population of the ground state energy level of the silicon carbide color center after different microwave manipulation fields are applied. Therefore, the measurement results of the properties of the sample to be tested can be obtained based on the population of the ground state energy level of the silicon carbide color center after different microwave manipulation fields are applied.

[0073] According to embodiments of this disclosure, for each pulse sequence, the initialization-evolution-readout operation is repeated a certain number of times. During these iterations, the results obtained by the readout module are averaged to obtain an average amplitude. The number of iterations is chosen to ensure that the signal-to-noise ratio of the final average result is sufficiently high. Sufficiently high can be understood as the amplitude of the sample signal being measured being stronger than the amplitude of the noise. Finally, the average value of the readout module results after each pulse sequence undergoes the initialization-evolution-readout operation is obtained. Data processing of the values ​​yields the final measurement result.

[0074] According to embodiments of this disclosure, silicon carbide color centers are used as magnetic sensing modules, thereby enabling the use of silicon carbide instead of diamond as raw materials. Compared to diamond, whose processing and production technologies are not very mature, the use of silicon carbide, whose processing and production technologies are more mature, is more conducive to achieving large-scale industrialization.

[0075] According to embodiments of this disclosure, initialization and readout are performed using an infrared light source. Compared to the 532nm visible light initialization and readout method used in NV color centers, the infrared light source has lower photon energy, is located within the "biological window," and causes less damage to biological materials (e.g., cells) at the same power. Furthermore, using an infrared light source avoids disturbance to visible light-sensitive media. For example, when lens oil is used as the sample-containing medium, fluorescence under 532nm laser irradiation may interfere with readout signals; the lower photon energy of the infrared light source mitigates this issue. Therefore, using silicon carbide instead of diamond as the raw material for the magnetically sensitive unit is easier to industrialize. Additionally, using an infrared light source for initialization and readout, compared to the original 532nm visible light initialization and readout method used in NV color centers, theoretically causes less sample disturbance and damage, ensuring the intensity of the spin signal in the sample under test. Moreover, the magnetic resonance measurement device provided by embodiments of this disclosure also enables the study of the dynamic behavior of spin tags over longer periods.

[0076] It should be noted that, unless it is explicitly stated that there is a sequential order of execution between different operations, or that there is a sequential order of execution between different operations in terms of technical implementation, the execution order between multiple operations may not be significant, and multiple operations may be executed simultaneously.

[0077] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this disclosure.

[0078] IB222122 Active Modification

[0079] Furthermore, the shapes and dimensions of the components in the figures do not reflect actual size and proportion, but are merely illustrative of embodiments of this disclosure. Moreover, the word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0080] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of this disclosure, various features of this disclosure are sometimes grouped together in a single embodiment, figure, or description thereof. However, this inventive approach should not be construed as reflecting an intention that the claimed disclosure requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single embodiment of the foregoing invention. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of this disclosure.

[0081] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A single-molecule magnetic resonance measurement device based on silicon carbide color centers, characterized in that, include: A static magnetic field module is used to apply a static magnetic field to a magnetically sensitive module and a sample to be tested. The magnetically sensitive module includes a silicon carbide color center. The static magnetic field is configured to degenerate the degenerate energy level of the silicon carbide color center to obtain a degenerate energy level, and to make the characteristic frequency of the spin tag of the sample to be tested located in the microwave band. A light source module is used to apply excitation light in the infrared wavelength range to the silicon carbide color center, the excitation light being configured to cause the silicon carbide color center to transition from the ground state energy level to the excited state energy level when the excitation light is applied; The manipulation field module is used to apply a preset microwave manipulation field to the silicon carbide color center and the sample to be tested, so as to control the evolution of the quantum state of the whole formed by the spin tag in the silicon carbide color center and the sample to be tested. The readout module is used to read out the population of each ground state energy level of the silicon carbide color center after the evolution process is completed; The data processing module is used to obtain the measurement results of the sample under test based on the population of each ground state energy level of the silicon carbide color center after the preset microwave manipulation field is applied. The measurement results include the magnetic resonance spectrum of electron spin in the sample under test and the Rabi oscillation curve of electron spin in the sample under test. The silicon carbide color center and the spin tag of the sample under test have magnetic dipole interaction. Under the influence of the spin tag, the population of each ground state energy level obtained by the silicon carbide color center after the application of the preset microwave manipulation field is different. The measurement result of the sample under test is obtained according to the population of each ground state energy level obtained after the application of the preset microwave manipulation field. The control field module includes a control source and a microwave antenna, wherein the control source is configured to be electrically connected to the microwave antenna. The control source is configured as a microwave source to generate the preset microwave control field.

2. The apparatus according to claim 1, characterized in that, The microwave control field includes any one or more combinations of the following: single-frequency combined pulse control field, single-frequency control field, dual-frequency control field synthesized from a first frequency control field and a second frequency control field, amplitude-modulated control field, frequency-modulated control field, phase-modulated control field, amplitude shift keying modulation control field, frequency shift keying modulation control field, and phase shift keying modulation control field.

3. The apparatus according to claim 1, characterized in that, The microwave antenna is configured to correspond to the magnetic sensing module, wherein the microwave antenna radiates the preset microwave control field of the control source to the magnetic sensing module.

4. The apparatus according to claim 1, characterized in that, The static magnetic field is configured as at least one of the following: the Earth's magnetic field, a magnetic field generated by a magnetic material, or a magnetic field generated by a current-carrying conductor.

5. The apparatus according to claim 1, characterized in that, The light source module includes an excitation light unit and an optical path control unit.

6. The apparatus according to claim 4, characterized in that, The excitation unit is configured as at least one of the following: a laser, a light-emitting diode, or a laser diode.

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