Rapid magnetic field imaging method based on diamond NV color center coherent regulation and control

Abstract

The invention relates to the technical field of magnetic field imaging, in particular to a rapid magnetic field imaging method based on diamond NV color center coherent regulation and control. In order to solve the problem that an existing magnetic field imaging method based on a diamond NV color center is complex in operation, the invention provides a novel rapid magnetic field imaging method based on diamond NV color center coherent regulation and control, and the method comprises the following steps: 1) setting the frequency of pulse microwaves; 2) setting a synchronous control sequence, and collecting fluorescence intensity of different positions of a diamond NV color center two-dimensional space; the method comprises the steps of (1) drawing time-fluorescence intensity Rabi curves corresponding to different positions of a diamond NV color center two-dimensional space, (2) drawing time-fluorescence intensity Rabi curves corresponding to different positions of the diamond NV color center two-dimensional space, (4) obtaining actual angular frequency corresponding to each Rabi curve, (5) calculating and reversely deducing magnetic field intensity variation corresponding to different positions of the diamond NV color center two-dimensional space, and (6) achieving magnetic field imaging.

Description

Technical Field

[0001] This invention relates to the field of magnetic field imaging technology, specifically to a rapid magnetic field imaging method based on coherent modulation of diamond NV color centers. Background Technology

[0002] With the increasing demands of industrial production, new requirements have been placed on magnetic field imaging detection. In recent years, diamond NV centers have become increasingly popular in the field of quantum sensing, forming a highly efficient and stable solid-state platform with advantages such as high spatial resolution, high-precision magnetic field detection, easy integration and operation, and high magnetic sensitivity. Current technologies for magnetic field imaging, such as typical optically probed magnetic resonance imaging, require a microwave frequency sweep process, limiting measurement speed. While coherent manipulation of quantum states using Ramsey interferometry can achieve rapid magnetic field detection, it requires first determining the Ramsey interferometry parameters using Rabi modulation, making the operation complex and demanding on microwave pulse parameters, thus limiting the further promotion of this technology. Summary of the Invention

[0003] In order to solve the problem of complex operation in existing magnetic field imaging methods based on diamond NV centers, this invention provides a new fast magnetic field imaging method based on coherent modulation of diamond NV centers.

[0004] This invention is achieved using the following technical solution:

[0005] A rapid magnetic field imaging method based on coherent modulation of diamond NV centers includes the following steps: 1) First, the resonant frequency of the diamond NV center is determined using optically detected magnetic resonance (ODMR) technology, and then the frequency of the pulsed microwave is set to correspond to the resonant frequency of the diamond NV center; 2) A synchronous control sequence is set, that is, each time the diamond NV center is first polarized by a pulsed laser, then the pulsed microwave is controlled to act on the diamond NV center with a fixed step size, and finally the fluorescence intensity at different positions in the two-dimensional space of the diamond NV center is collected by an sCMOS camera (i.e., a scientific-grade CMOS camera) until the pulsed microwave reaches the set maximum step size; 3) Based on the fluorescence intensity at different positions in the two-dimensional space of the diamond NV center collected in step 2), Rabi curves of time-fluorescence intensity are plotted for different positions in the two-dimensional space of the diamond NV center; 4) According to the formula The actual angular frequencies of the Rabi curves corresponding to different positions of the diamond NV color center in two-dimensional space were obtained. ,in Is the Rabi curve in The fluorescence intensity at time 10:00. For Rabi curve contrast and , The average fluorescence intensity of the Rabi curve and , This represents the fluorescence intensity value corresponding to the highest point of the Rabi curve. This represents the fluorescence intensity value corresponding to the lowest point of the Rabi curve. The duration of pulsed microwave action. The inherent decoherence time for the NV color center of diamond. The stretch index parameter and , 5) By formula The frequency shift of the Rabi curve corresponding to different positions of the diamond NV color center in two-dimensional space was obtained. ,in The reference angular frequency of the Rabi curve is then determined by the formula. Deducing the change in magnetic field strength at different locations in two-dimensional space corresponding to the diamond NV color center. ,in It is the gyrometry ratio and 6) Based on the change in magnetic field strength at different positions in the two-dimensional space corresponding to the NV color center of diamond. To draw a magnetic field intensity distribution map and achieve magnetic field imaging.

[0006] Principle Analysis: The Rabi modulation method is used instead of the Ramsey interferometric modulation method, which reduces the requirements for microwave modulation parameters during magnetic field detection and lowers the difficulty of experimental operation. At the same time, compared with optically probed magnetic resonance technology, the measurement speed can be guaranteed, and further combined with the high-speed acquisition capability of the sCMOS camera, the goal of rapid magnetic field imaging can be achieved.

[0007] Furthermore, in step 2), the polarization time of the pulsed laser is 1 ms, the exposure time of the sCMOS camera to the fluorescence is 500 μs, and the duration of the pulsed microwave starts from 0 ns and is fixed in step 1 ns until it reaches 400 ns.

[0008] The beneficial effects of this invention are as follows: by using the Rabi modulation method to replace the Ramsey interferometric modulation method, the detection steps are simplified and the detection speed is improved. At the same time, combined with the high-speed acquisition capability of the sCMOS camera, the goal of rapid magnetic field imaging is achieved. Attached Figure Description

[0009] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the magnetic field imaging method described in this invention;

[0012] Figure 2 A schematic diagram of the synchronous control sequence for pulsed laser and pulsed microwave.

[0013] Figure 3 A schematic diagram of Rabi curves at a certain location in two-dimensional space of the diamond NV color center under different magnetic field intensities;

[0014] Figure 4 This is a diagram showing the magnetic field strength distribution of the NV color center in diamond. Detailed Implementation

[0015] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0016] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0017] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0018] like Figure 1 As shown, a fast magnetic field imaging method based on coherent modulation of diamond NV centers includes the following steps: 1) First, the resonant frequency of the diamond NV center is determined using optically detected magnetic resonance (ODMR) technology, and then the frequency of the pulsed microwave is set to the frequency corresponding to the resonant frequency of the diamond NV center; 2) A synchronization control sequence is set, such as... Figure 2As shown, each time, a pulsed laser is first used to polarize the diamond NV center, then pulsed microwaves are controlled to act on the diamond NV center at a fixed step size, and finally, an sCMOS camera (sCMOS camera is a scientific-grade CMOS camera) is used to collect the fluorescence intensity at different positions in the two-dimensional space of the diamond NV center until the pulsed microwaves reach the set maximum step size; 3) Based on the fluorescence intensity at different positions in the two-dimensional space of the diamond NV center collected in step 2), a Rabi curve of time-fluorescence intensity corresponding to different positions in the two-dimensional space of the diamond NV center is plotted; 4) According to the formula The actual angular frequencies of the Rabi curves corresponding to different positions of the diamond NV color center in two-dimensional space were obtained. ,in Is the Rabi curve in The fluorescence intensity at time 10:00. For Rabi curve contrast and , The average fluorescence intensity of the Rabi curve and , This represents the fluorescence intensity value corresponding to the highest point of the Rabi curve. This represents the fluorescence intensity value corresponding to the lowest point of the Rabi curve. The duration of pulsed microwave action. The inherent decoherence time for the NV color center of diamond. The stretch index parameter and , 5) By formula The frequency shift of the Rabi curve corresponding to different positions of the diamond NV color center in two-dimensional space was obtained. ,in The reference angular frequency of the Rabi curve is then determined by the formula. Deducing the change in magnetic field strength at different locations in two-dimensional space corresponding to the diamond NV color center. ,in It is the gyrometry ratio and 6) Based on the change in magnetic field strength at different positions in the two-dimensional space corresponding to the NV color center of diamond. To draw a magnetic field intensity distribution map and achieve magnetic field imaging, such as... Figure 4 As shown.

[0019] Principle Analysis: The Rabi modulation method is used instead of the Ramsey interferometric modulation method, which reduces the requirements for microwave modulation parameters during magnetic field detection and lowers the difficulty of experimental operation. At the same time, compared with optically probed magnetic resonance technology, the measurement speed can be guaranteed, and further combined with the high-speed acquisition capability of the sCMOS camera, the goal of rapid magnetic field imaging can be achieved.

[0020] In specific implementation, in step 2), the polarization time of the pulsed laser is 1ms, the exposure time of the sCMOS camera to the fluorescence is 500μs, and the duration of the pulsed microwave starts from 0ns, with a fixed step size of 1ns, up to 400ns.

[0021] To verify the feasibility of the above method, we conducted the following test: Two permanent magnets were placed on the left and right sides of the horizontal NV color center of a diamond, respectively. Then, a verification experiment was performed. Steps 1) to 3) of the method described in this invention were used to collect the fluorescence intensity at a certain location in the two-dimensional space of the diamond NV color center and plot the corresponding Rabi curve. Subsequently, the permanent magnets were moved to change the external magnetic field, and steps 1) to 3) of the method described in this invention were used again to collect the fluorescence intensity at a certain location in the two-dimensional space of the diamond NV color center and plot the corresponding Rabi curve. Furthermore, to fully verify the feasibility of the method described in this invention, the permanent magnets were moved multiple times, obtaining Rabi curves of a certain location in the two-dimensional space of the diamond NV color center under different magnetic field intensities, as shown below. Figure 3 As shown, at the same time, by Figure 3 It can also be seen that the Rabi curve shifts overall with the change of magnetic field strength, and the corresponding fluorescence intensity also changes, indicating that the NV color center responds to the external magnetic field. Then, the actual angular frequency corresponding to the Rabi curve is calculated. And from the actual angular frequency The change in magnetic field strength at that location was deduced, and it was found to match the actual change in magnetic field strength, proving that the method is feasible.

[0022] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A rapid magnetic field imaging method based on coherent modulation of diamond NV color centers, characterized in that, 1) First, the resonant frequency of the diamond NV center is determined using photodetector magnetic resonance (PDMR) technology. Then, the frequency of the pulsed microwave is set to correspond to the resonant frequency of the diamond NV center. 2) A synchronous control sequence is set up, i.e., the diamond NV center is first polarized by a pulsed laser, then the pulsed microwave is controlled to act on the diamond NV center with a fixed step size, and finally, the fluorescence intensity at different positions in the two-dimensional space of the diamond NV center is collected by an sCMOS camera until the pulsed microwave reaches the set maximum step size. 3) Based on the fluorescence intensity at different positions in the two-dimensional space of the diamond NV center collected in step 2), Rabi curves of time-fluorescence intensity are plotted for different positions in the two-dimensional space of the diamond NV center. 4) According to the formula... The actual angular frequencies of the Rabi curves corresponding to different positions of the diamond NV color center in two-dimensional space were obtained. ,in Is the Rabi curve in The fluorescence intensity at time 10:

00. For Rabi curve contrast and , The average fluorescence intensity of the Rabi curve and , This represents the fluorescence intensity value corresponding to the highest point of the Rabi curve. This represents the fluorescence intensity value corresponding to the lowest point of the Rabi curve. The duration of pulsed microwave action. The inherent decoherence time for the NV color center of diamond. The stretch index parameter and , 5) By formula The frequency shift of the Rabi curve corresponding to different positions of the diamond NV color center in two-dimensional space was obtained. ,in The reference angular frequency of the Rabi curve is then determined by the formula. Deducing the change in magnetic field strength at different locations in two-dimensional space corresponding to the diamond NV color center. ,in It is the gyrometry ratio and 6) Based on the change in magnetic field strength at different positions in the two-dimensional space corresponding to the NV color center of diamond. To draw a magnetic field intensity distribution map and achieve magnetic field imaging.

2. The rapid magnetic field imaging method based on coherent modulation of diamond NV color centers according to claim 1, characterized in that, In step 2), the polarization time of the pulsed laser is 1 ms, the exposure time of the sCMOS camera to the fluorescence is 500 μs, and the duration of the pulsed microwave starts from 0 ns with a fixed step size of 1 ns until it reaches 400 ns.

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