A high-coupling-efficiency microstrip antenna and quantum measurement device based on NV color centers

Abstract

This invention provides a high-coupling-efficiency microstrip antenna and a quantum measurement device based on NV color centers. It belongs to the field of NV color center technology. The microstrip antenna includes: a dielectric substrate, a ground plane disposed on a first surface of the dielectric substrate, a radiating patch disposed on a second surface of the dielectric substrate, a feeding structure, and an NV color center diamond. The radiating patch includes an outer radiating patch and an inner radiating patch nested together. The outer radiating patch surrounds an outer region, and the inner radiating patch is located within the outer region, with a gap between them. The inner radiating patch surrounds an inner region. The NV color center diamond is fixed to the second surface of the dielectric substrate and located within the inner region. One end of the feeding structure is connected to the outer radiating patch. This microstrip antenna achieves precise matching with the resonant frequency of the NV color center, improving electromagnetic field coupling efficiency, reducing signal reflection and transmission loss, and enhancing the stability and sensitivity of the quantum measurement system.

Description

Technical Field

[0001] This invention belongs to the field of NV color center technology, and in particular relates to a high-coupling-efficiency microstrip antenna and quantum measurement device based on NV color centers. Background Technology

[0002] Nitrogen-Vacancy centers (NV centers) are point defect structures existing in the diamond lattice. They possess spin characteristics that enable optical readout and microwave manipulation at room temperature, and are widely used in quantum sensing, precision magnetic field measurement, and microwave field detection. In practical systems, a microwave signal of approximately 2.87 GHz is typically applied to the NV center via a microstrip antenna to drive its spin resonance. Microstrip antennas are widely used due to their planar structure, ease of fabrication, and integration. They are often mounted on a dielectric substrate and connected to a signal source via a feed structure to achieve microwave excitation of the diamond chip. In relevant applications, antenna size is limited by experimental platform space, and the operating environment may include various constraints such as temperature fluctuations, electromagnetic interference, and impedance matching accuracy requirements, placing high demands on the antenna structure and material selection.

[0003] Existing microstrip antennas for NV center measurement suffer from several shortcomings in practical applications. First, the radiating patch structure is typically not specifically optimized around the NV center's approximately 2.87 GHz spin resonant frequency, resulting in limited matching between the electromagnetic field distribution and the NV center's response characteristics. This leads to low microwave energy utilization and coupling efficiency, consequently increasing signal transmission loss. Second, the lack of precise correspondence between the NV center chip's mounting position and the antenna's near-field electric field enhancement region makes it difficult to fully utilize local electric field concentration areas under certain operating conditions, manifesting as unstable excitation intensity or fluctuating measurement signal amplitude. Third, insufficient control over substrate parameters, feed structure dimensions, and overall impedance matching accuracy can easily lead to reflection loss, resulting in significant fluctuations in return loss indicators and affecting the effective transfer of microwave energy to the NV center. Furthermore, the compatibility between the antenna's frequency response characteristics and the NV center's quantum properties is not ideal; the resonant frequency may shift under environmental changes or manufacturing errors, affecting measurement sensitivity and system stability. These combined problems limit further improvements in the performance of NV center measurement systems. Summary of the Invention

[0004] The purpose of this invention is to provide a high-coupling-efficiency microstrip antenna and quantum measurement device based on the NV color center, which can achieve precise matching with the resonant frequency of the NV color center, improve electromagnetic field coupling efficiency, reduce signal reflection and transmission loss, and improve the stability and sensitivity of the quantum measurement system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a high-coupling-efficiency microstrip antenna based on NV color centers, comprising: The dielectric substrate, a ground plane disposed on the first surface of the dielectric substrate, a radiating patch disposed on the second surface of the dielectric substrate, a power feeding structure, and an NV color center diamond; The radiation patch includes an outer radiation patch and an inner radiation patch nested together. The outer radiation patch surrounds an outer region, and the inner radiation patch is located within the outer region. A gap is provided between the inner radiation patch and the outer radiation patch. The inner radiating patch is arranged to form an inner region. The NV color center diamond is fixed to the second surface of the dielectric substrate and located in the inner region, so that the NV color center diamond is located in the electromagnetic near-field enhancement region formed by the radiating patch structure. The structural dimensions of the radiating patch are configured such that the resonant frequency generated by the radiating patch corresponds to the spin resonant frequency of the NV color center diamond. One end of the power feeding structure is connected to the outer radiating patch, and the other end is used to connect to an external signal processing unit.

[0006] Furthermore, both the outer and inner radiating patches are rectangular annular structures and each has an opening.

[0007] Furthermore, the opening of the inner radiating patch is located at the center of the first side of the inner radiating patch, and the opening of the outer radiating patch is located at the center of the second side of the outer radiating patch, opposite to the first side.

[0008] Furthermore, the inner side length of the inner radiating patch is 2.07 mm, the opening width of the inner radiating patch is 1.765 mm, the outer side length of the outer radiating patch is 6.4 mm, and the opening width of the outer radiating patch is 0.90 mm.

[0009] Furthermore, the gap width between the inner radiating patch and the outer radiating patch is 0.2 mm.

[0010] Optionally, the dielectric substrate is an FR-4 epoxy glass cloth substrate with a thickness of 1.2 mm, a dielectric constant of 4.4 (±0.2), a dielectric loss tangent of less than or equal to 0.02, and a size of 15 mm × 15 mm.

[0011] Optionally, the grounding plane is made of oxygen-free copper foil with a thickness of 0.05 mm and a size of 16 mm × 16 mm, and extends 0.5 mm beyond the edge of the dielectric substrate on all four sides.

[0012] Optionally, the power supply structure is a microstrip line power supply structure with a width of 1.2 mm, a length of 10.747 mm, a characteristic impedance of 50 Ω, and the reserved end of the power supply structure is provided with a welding part for welding SMA connectors.

[0013] Optionally, the NV color center diamond has a size of 1mm × 1mm × 0.4mm, and the NV color center diamond is fixed to the second surface of the dielectric substrate by conductive adhesive, the conductive adhesive coating thickness being 0.05mm.

[0014] In a second aspect, the present invention provides a quantum measurement device based on NV color centers, comprising: A microwave signal source, a signal processing unit, and a high-coupling-efficiency microstrip antenna based on NV color centers as described in any one of claims 1 to 9; The microwave signal source is used to input microwave signals to the radiation patch through the feeding structure to form a microwave excitation field at the NV color center diamond. The signal processing unit is used to acquire and process the response signals generated by the NV color centers.

[0015] 1. The high-coupling-efficiency microstrip antenna based on NV color centers provided by this invention involves setting nested outer and inner radiating patches on the second surface of a dielectric substrate, forming a gap structure between them. Simultaneously, the NV color center diamond is fixed within the inner region, placing it within the electromagnetic near-field enhancement region formed by the radiating patch structure. Through structural dimensional configuration, the antenna resonant frequency corresponds to the NV color center spin resonant frequency, achieving a synergistic match between the antenna structure, electromagnetic field distribution, and quantum spin response. This structure enables the microstrip antenna to achieve a stable resonant response near 2.87 GHz, with a return loss of -11.807 dB, significantly reducing reflection loss and improving the effective transfer efficiency of microwave energy to the NV color center. This enhances the microwave excitation intensity of the NV color center, thereby improving the signal-to-noise ratio and stability of the quantum measurement system.

[0016] 2. The high-coupling-efficiency microstrip antenna based on the NV color center provided by this invention employs a rectangular ring structure with openings on each side. The inner and outer layer openings are positioned centrally on opposite sides. Combined with the inner radiating patch having an inner side length of 2.07 mm and an opening width of 1.765 mm, the outer radiating patch having an outer side length of 6.4 mm and an opening width of 0.90 mm, and a gap width of 0.2 mm, a stable electromagnetic coupling structure is formed between the inner and outer layers. In CST MWS simulations, this structure creates a significant electric field concentration region, with the electric field strength in the inner center region increasing by approximately 40% compared to traditional structures. This places the NV color center in a stronger local electromagnetic field, improving energy coupling efficiency. Furthermore, structural dimension optimization achieves a resonant frequency that closely matches 2.87 GHz, enhancing bandwidth matching accuracy and reducing debugging difficulty.

[0017] 3. The high-coupling-efficiency microstrip antenna based on NV color centers provided by this invention employs an FR-4 dielectric substrate (1.2mm thick, dielectric constant 4.4±0.2, loss tangent ≤0.02) combined with a fully covered oxygen-free copper ground plane (0.05mm thick, 16mm×16mm in size, with an edge extension of 0.5mm) and a microstrip line feed structure with a characteristic impedance of 50Ω (1.2mm wide, 10.747mm long). An NV color center diamond with dimensions of 1mm×1mm×0.4mm is fixed to the center of the electric field enhancement region using 0.05mm thick conductive adhesive, thereby improving the overall impedance matching and structural stability of the antenna. The combined effect of these material parameters and structural configuration effectively suppresses spurious radiation, improves directivity and impedance matching accuracy, reduces signal reflection and transmission loss, and ensures conductivity and structural reliability during long-term use. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the high-coupling-efficiency microstrip antenna based on NV color centers according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the simulation results of a high-coupling-efficiency microstrip antenna based on NV color centers according to an embodiment of the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0020] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0021] Example 1 This embodiment provides a high-coupling-efficiency microstrip antenna based on NV color centers, such as... Figure 1 As shown, the high-coupling-efficiency microstrip antenna based on NV color centers includes: a dielectric substrate 5, a ground plane 6 disposed on the first surface of the dielectric substrate 5, a radiating patch disposed on the second surface of the dielectric substrate 5, a feeding structure 4, and an NV color center diamond 3. The radiating patch includes an outer radiating patch 1 and an inner radiating patch 2 nested together. The outer radiating patch 1 forms an outer region, and the inner radiating patch 2 is located within the outer region, with a gap between the inner radiating patch 2 and the outer radiating patch 1. The inner radiating patch 2 forms an inner region, and the NV color center diamond 3 is fixed to the second surface of the dielectric substrate 5 and located within the inner region, so that the NV color center diamond 3 is located within the electromagnetic near-field enhancement region formed by the radiating patch structure. The structural dimensions of the radiating patch are configured such that the resonant frequency generated by the radiating patch corresponds to the spin resonant frequency of the NV color center diamond 3. One end of the feeding structure 4 is connected to the outer radiating patch 1, and the other end is used to connect to an external signal processing unit.

[0022] The microstrip antenna achieves efficient coupling with the NV color center through precise assembly of its components, meeting the requirements for NV color center resonance matching and low-loss transmission, and is suitable for scenarios such as NV color center magnetic measurement and quantum sensing.

[0023] To achieve the correspondence between the above structure and the spin resonance frequency of the NV color center, this embodiment adopts a nested rectangular opening structure for the radiating patch, consisting of an outer radiating patch 1 and an inner radiating patch 2. This forms an electromagnetic near-field enhancement region within the radiating patch structure, and the NV color center diamond 3 is located within this region. The outer radiating patch 1 encloses the outer region, and the inner radiating patch 2 encloses the inner region, with the inner radiating patch 2 located within the outer region. A gap is provided between the inner radiating patch 2 and the outer radiating patch 1. The nested structure and gap between the inner and outer layers optimize the electromagnetic coupling between them.

[0024] To ensure the antenna resonant frequency precisely matches the typical resonant frequency of the NV color center, which is approximately 2.87 GHz, and with... Figure 2 The return loss valley frequency of 2.87GHz obtained from the CST MWS simulation is highly consistent.

[0025] The return loss performance (S11 parameter) is as follows: Figure 2 As shown, this data was obtained through modeling and simulation using the high-frequency electromagnetic simulation software CSTMicrowave Studio (CST MWS). The return loss reaches -11.807 dB at a frequency of 2.87 GHz. In one specific implementation of this embodiment, both the outer radiating patch 1 and the inner radiating patch 2 are rectangular ring structures, each with an opening. Specifically, both the outer radiating patch 1 and the inner radiating patch 2 are made of oxygen-free copper foil with a purity ≥99.9%, and the copper foil thickness is 0.05mm (preferred to be within the range of 0.03-0.1mm). The surface is coated with a 5μm thick nickel-gold alloy anti-oxidation layer to ensure the stability of conductivity and service life. The surface resistance after coating is ≤0.01Ω. In this embodiment, the structural dimensions of the radiating patch are determined by CST MWS simulation optimization so that the resonance frequency generated by the radiating patch corresponds to the spin resonance frequency of the NV color center diamond 3.

[0026] The opening of the inner radiating patch 2 is located at the center of the first side of the inner radiating patch 2. The opening of the outer radiating patch 1 is located at the center of the second side of the outer radiating patch 1, opposite to the first side. The opening of the outer radiating patch 1 is located on the second side of the outer radiating patch. The connection end of the feeding structure 4 and the outer radiating patch 1 is located on the other side relative to the side where the opening is located. This allows the opening structure and the feeding structure to be spatially separated on the patch surface, reducing the direct impact of the opening structure on the feed impedance and adjusting the current path distribution of the radiating patch. Figure 1In one embodiment shown, the side where the opening is located is perpendicular to the side connecting to the feed structure in the direction of the patch edge. The opening of the outer radiating patch 1 is on its right side, and the opening of the inner radiating patch 2 is on its left side. Corresponding to the opening on the right side of the outer radiating patch 1, the connection end of the feed structure 4 to the outer radiating patch 1 is on the lower side of the outer radiating patch 1. The opening of the inner radiating patch 2 is located in the middle of the first side of the inner radiating patch 2. This opening structure changes the current path distribution on the surface of the radiating patch, causing a redistribution of current within the inner radiating patch. This creates an electric field concentration region in the central region of the inner radiating patch 2, forming an electromagnetic near-field enhancement region and serving as an electric field enhancement area. Since the NV color center diamond is disposed within this electric field enhancement region, the NV color center is placed in the electromagnetic near-field enhancement environment generated by the radiating patch, thereby improving the coupling efficiency between the microwave field and the NV color center. In addition, since the outer radiating patch 1 also has an opening structure and forms a nested structure with the inner radiating patch 2, the equivalent current path and electric field distribution of the radiating patch can be adjusted through the synergistic effect of the inner and outer opening structures, so that a stable electromagnetic coupling relationship can be formed inside the patch. This enables the control of the resonance characteristics and electric field distribution of the radiating patch, so that the resonance frequency of the radiating patch matches the spin resonance frequency of the NV color center, and improves the concentration of microwave energy at the NV color center.

[0027] In the specific dimensional configuration of this embodiment, the inner side length of the inner radiating patch 2 is r2 = 2.07 mm, and the opening width of the inner radiating patch 2 is w2 = 1.765 mm. The outer side length of the outer radiating patch 1 is r1 = 6.4 mm, and the opening width of the outer radiating patch 1 is w1 = 0.90 mm. The gap width between the inner radiating patch 2 and the outer radiating patch 1 is dw = 0.2 mm. This gap width optimizes the electromagnetic coupling between the inner and outer layers, enabling the antenna resonant frequency to accurately match the typical resonant frequency of the NV color center, approximately 2.87 GHz. Figure 2 The return loss valley frequency of 2.87GHz obtained from the CST MWS simulation is highly consistent, thus achieving high coupling efficiency in the electromagnetic near-field enhancement region where the NV color center diamond 3 is located.

[0028] In one specific implementation of this embodiment, the dielectric substrate 5 is an FR-4 epoxy glass cloth substrate with a thickness of 1.2 mm, a dielectric constant of 4.4 (±0.2), a dielectric loss tangent of less than or equal to 0.02, and a size of 15 mm × 15 mm. Specifically, the dielectric substrate 5 is set as an isotropic dielectric in CST MWS modeling to provide stable support for the radiating patch, the feed structure 4, and the NV color center diamond 3. The dielectric characteristics, such as the dielectric constant and the dielectric loss tangent, are used to optimize the antenna bandwidth response and ensure return loss performance.

[0029] In one specific implementation of this embodiment, the ground plane 6 is made of oxygen-free copper foil with a thickness of 0.05 mm and a size of 16 mm × 16 mm, and extends 0.5 mm beyond the edge of the dielectric substrate 5 on all four sides. Specifically, the ground plane 6 is made of oxygen-free copper foil of the same material as the radiating patch and is processed into a full-coverage rectangular structure, extending 0.5 mm beyond the edge of the dielectric substrate 5 on all four sides (within the preferred range of 0.5-1 mm). In CST MWS, it is set as the boundary of the ideal electrical conductor (PEC) and is fixed to the first surface of the dielectric substrate 5 by a pressing process. The edges are free of burrs and warping, ensuring tight adhesion to the substrate, effectively suppressing stray radiation and helping to improve return loss performance.

[0030] In one specific implementation of this embodiment, the power supply structure 4 is a microstrip line power supply structure with a width of 1.2 mm, a length of 10.747 mm, and a characteristic impedance of 50 Ω. The power supply structure 4 has a reserved end for welding SMA connectors. Specifically, the power supply structure 4 uses nickel-gold plated oxygen-free copper foil consistent with the radiating patch, and is set to 50 Ω waveport excitation in CST MWS. One end of the power supply structure 4 is connected to the middle edge of the outer radiating patch 1 through a welding process, and the connection point has no poor solder joint. The other end has a reserved standard SMA connector welding position for connecting external signal processing units, such as network analyzers and signal generators, to further carry out experimental verification or directly apply to the NV color center measurement system.

[0031] To ensure that the NV center diamond 3 is located within the electromagnetic near-field enhancement region formed by the radiating patch structure, and to achieve a resonant frequency corresponding to the spin resonant frequency of the NV center diamond 3, this embodiment models and simulates the overall structure in CST MWS to obtain... Figure 2 The return loss performance is shown, and the electric field enhancement region in the central area of ​​the inner radiating patch 2 is confirmed by combining electric field distribution simulation.

[0032] In one specific implementation of this embodiment, the NV color center diamond 3 has a size of 1mm × 1mm × 0.4mm and is fixed to the second surface of the dielectric substrate 5 with conductive adhesive. Specifically, the NV color center diamond 3 is a single-crystal diamond NV color center. In CST MWS, its influence on the electric field distribution is simulated by setting equivalent dielectric properties. In actual application, it is fixed to the second surface of the dielectric substrate 5 with conductive adhesive. The fixing position is precisely aligned with the center of the electric field enhancement region of the inner radiating patch 2. The electric field enhancement region is confirmed by CST MWS simulation. The conductive adhesive coating thickness is 0.05mm to ensure that the NV color center diamond 3 is tightly attached to the dielectric substrate 5 without affecting the electric field coupling. Thus, the NV color center diamond 3 is located in the electromagnetic near-field enhancement region formed by the radiating patch structure, thereby improving the coupling efficiency of the NV color center.

[0033] In the assembly and processing of this embodiment, the ground plane 6 is first fixed to the first surface of the dielectric substrate 5 by a pressing process to ensure that the copper foil and the substrate are free of bubbles and tightly bonded. Then, the radiating patches (1, 2) and the feeding structure 4 are processed on the second surface of the dielectric substrate 5 using a photolithography + etching process, with a dimensional accuracy error of ≤ ±0.01mm to ensure the consistency between the CST MWS simulation model and the actual structure. Subsequently, the surface of the radiating patches is subjected to nickel-gold plating to form a nickel-gold alloy anti-oxidation layer with a thickness of 5μm. After plating, the surface resistance is ≤0.01Ω. Next, the NV color center diamond 3 is fixed to the second surface of the dielectric substrate 5 with conductive adhesive and aligned with the center of the electric field enhancement area of ​​the inner radiating patch 2. It is cured at a constant temperature of 80℃ for 1 hour. After curing, the NV color center diamond 3 does not shift or fall off. Finally, the reserved end of the feeding structure 4 is welded with an SMA connector. After welding, the actual measurement is carried out using a network analyzer to verify the accuracy of the CST MWS simulation data and to connect to an external signal processing unit to realize the NV color center measurement application.

[0034] In terms of performance, the CST MWS simulation results are as follows: Figure 2 As shown, the antenna achieves a return loss of -11.807 dB at 2.87 GHz, and the overall return loss within the frequency band is less than -2 dB, demonstrating excellent impedance matching between the antenna and the 50 Ω system. Furthermore, the resonant frequency generated by the radiating patch closely matches the 2.87 GHz spin resonant frequency of the NV color center, meeting the low-loss signal transmission requirements for NV color center measurement. Simultaneously, combined with the simulation analysis of the electric field distribution in CST MWS, the electric field intensity in the central region of the inner radiating patch 2 is increased by 40% compared to the traditional antenna, indicating that the antenna of this invention has a significant advantage in NV color center coupling efficiency, thereby achieving the application goal of a high-coupling-efficiency microstrip antenna for NV color center measurement.

[0035] In summary, this invention achieves stable resonance and low return loss response of the antenna near 2.87 GHz through a nested radiating patch structure design, precise electric field enhancement region positioning, accurate size matching, and synergistic optimization of materials and feed parameters. It also generates an enhanced electromagnetic near-field in the region of the NV color center, thereby improving microwave energy utilization and quantum spin manipulation efficiency. Simulation results show that the return loss reaches -11.807 dB, with an overall return loss below -2 dB within the frequency band, and the electric field strength is increased by approximately 40%, indicating significant structural design and frequency matching effectiveness. The overall structure is compact, the manufacturing process is mature, and it is easy to integrate with quantum measurement systems, providing a stable and reliable microwave excitation environment for NV color center magnetic measurement and quantum sensing applications.

[0036] This application focuses on the near-field driving characteristics of spin transitions in NV color centers (NCCs). The microwave excitation of NV Cs depends on the spatial distribution and directional components of the local microwave magnetic field B1. Therefore, the core requirement is to form a stable, controlled, and enhanced near-field magnetic field region within a millimeter-scale chip. This application utilizes a nested rectangular-aperture radiating patch structure to actively reconstruct the patch current path, forming a spatially concentrated field distribution in the near-field region. It also ensures that the NV C diamond precisely aligns with the center of the enhancement region, achieving optimized matching between the antenna structure and the spatial scale of the quantum chip. This design goal differs from conventional communication microstrip antennas that pursue far-field performance; it focuses on structural optimization specifically for the requirements of NV C quantum measurement systems.

[0037] Example 2 Based on the high-coupling-efficiency microstrip antenna based on the NV color center in Embodiment 1 above, this invention also provides a quantum measurement device based on the NV color center. This device includes a microwave signal source, a signal processing unit, and a high-coupling-efficiency microstrip antenna based on the NV color center. The structure, dimensional parameters, material selection, and assembly method of the microstrip antenna are the same as in the aforementioned embodiments, and will not be repeated here.

[0038] A microwave signal source inputs a microwave signal to the radiating patch through a feeding structure. The microwave signal is then transmitted via a microstrip line feeding structure to the nested rectangular opening (slot) structure formed by the outer and inner radiating patches, creating a stable electromagnetic field distribution at the resonant frequency of the radiating patches. Since the structural dimensions of the radiating patches are designed to match the typical spin resonant frequency of the NV color center diamond (approximately 2.87 GHz), when the output frequency of the microwave signal source is set near this resonant frequency, the electric field generated by the radiating patches forms an electric field enhancement region in the central region of the inner radiating patch. The NV color center diamond is fixed at the center of this electric field enhancement region, placing it within the near-field electromagnetic enhancement region formed by the radiating patch structure, thereby achieving concentrated coupling of microwave energy at the NV color center.

[0039] Because the characteristic impedance of the power supply structure is designed to be 50Ω and matched with the external microwave signal source, the reflection loss of the microwave signal is low during the input process. Figure 2 The simulation results show that the return loss reaches -11.807 dB at 2.87 GHz, indicating that the microwave signal can be efficiently coupled to the radiating patch structure at this frequency and form a stable excitation field at the NV color center. By suppressing stray radiation through the full-coverage structure of the ground plane and controlling the frequency band response through the dielectric properties of the FR-4 dielectric substrate, the device exhibits high frequency band adaptability and operational stability during operation.

[0040] The signal processing unit is electrically connected to the microwave signal source and forms a complete measurement link with the microstrip antenna system. The signal processing unit is used to acquire and process the response signal generated by the NV color center under microwave excitation. Because the microstrip antenna structure achieves efficient energy coupling between the NV color center and the radiating patch, the microwave excitation field strength at the NV color center is increased, correspondingly improving the detectability and stability of the response signal, thereby enhancing the signal reliability in the quantum measurement process.

[0041] With the above structural configuration, the microwave signal source provides stable microwave excitation, the microstrip antenna achieves resonant frequency matching and electric field concentration through a nested slotted structure, the NV color center is located within the electric field enhancement region to achieve efficient coupling, and the signal processing unit completes the acquisition and processing of the response signal, forming a complete NV color center quantum measurement system. This device has a compact structure and simple component integration, making it easy to embed into miniaturized quantum measurement devices. It is suitable for applications such as NV color center magnetic measurement and quantum sensing.

[0042] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A high-coupling-efficiency microstrip antenna based on NV color centers, characterized in that, include: The dielectric substrate, a ground plane disposed on the first surface of the dielectric substrate, a radiating patch disposed on the second surface of the dielectric substrate, a power feeding structure, and an NV color center diamond; The radiation patch includes an outer radiation patch and an inner radiation patch nested together. The outer radiation patch surrounds an outer region, and the inner radiation patch is located within the outer region. A gap is provided between the inner radiation patch and the outer radiation patch. The inner radiating patch is arranged to form an inner region. The NV color center diamond is fixed to the second surface of the dielectric substrate and located in the inner region, so that the NV color center diamond is located in the electromagnetic near-field enhancement region formed by the radiating patch structure. The structural dimensions of the radiating patch are configured such that the resonant frequency generated by the radiating patch corresponds to the spin resonant frequency of the NV color center diamond. One end of the power feeding structure is connected to the outer radiating patch, and the other end is used to connect to an external signal processing unit.

2. The high-coupling-efficiency microstrip antenna based on NV color centers according to claim 1, characterized in that, Both the outer and inner radiating patches are rectangular ring structures and each has an opening.

3. The high-coupling-efficiency microstrip antenna based on NV color centers according to claim 2, characterized in that, The opening of the inner radiating patch is located at the center of the first side of the inner radiating patch, and the opening of the outer radiating patch is located at the center of the second side of the outer radiating patch, which is opposite to the first side.

4. The high-coupling-efficiency microstrip antenna based on NV color centers according to claim 2, characterized in that, The inner side length of the inner radiating patch is 2.07 mm, the opening width of the inner radiating patch is 1.765 mm, the outer side length of the outer radiating patch is 6.4 mm, and the opening width of the outer radiating patch is 0.90 mm.

5. The high-coupling-efficiency microstrip antenna based on NV color centers according to claim 1, characterized in that, The gap width between the inner radiating patch and the outer radiating patch is 0.2 mm.

6. The high-coupling-efficiency microstrip antenna based on NV color centers according to claim 1, characterized in that, The dielectric substrate is an FR-4 epoxy glass cloth substrate with a thickness of 1.2 mm, a dielectric constant of 4.4 (±0.2), a dielectric loss tangent of less than or equal to 0.02, and a size of 15 mm × 15 mm.

7. The high-coupling-efficiency microstrip antenna based on NV color centers according to claim 1, characterized in that, The grounding plane is made of oxygen-free copper foil with a thickness of 0.05mm and a size of 16mm×16mm, and extends 0.5mm beyond the edge of the dielectric substrate on all four sides.

8. The high-coupling-efficiency microstrip antenna based on NV color centers according to claim 1, characterized in that, The power supply structure is a microstrip line power supply structure with a width of 1.2 mm, a length of 10.747 mm, and a characteristic impedance of 50 Ω. The reserved end of the power supply structure is provided with a welding part for welding SMA connectors.

9. The high-coupling-efficiency microstrip antenna based on NV color centers according to claim 1, characterized in that, The NV color center diamond has dimensions of 1mm × 1mm × 0.4mm. The NV color center diamond is fixed to the second surface of the dielectric substrate by conductive adhesive, and the conductive adhesive coating thickness is 0.05mm.

10. A quantum measurement device based on NV color centers, characterized in that, include: A microwave signal source, a signal processing unit, and a high-coupling-efficiency microstrip antenna based on NV color centers as described in any one of claims 1 to 9; The microwave signal source is used to input microwave signals to the radiation patch through the feeding structure to form a microwave excitation field at the NV color center diamond. The signal processing unit is used to acquire and process the response signals generated by the NV color centers.

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