Diamond nv color center comprehensive performance detection platform

Abstract

The application relates to the technical field of quantum precision measurement, and relates to a kind of diamond NV color center comprehensive performance detection platform, which comprises a front-end detection unit, a dichroic mirror, a micro-unit, a laser unit, a system color center fluorescence acquisition unit, a single color center fluorescence acquisition unit, a first optical path switch, a second optical path switch and a data processing and driving unit.The detection platform of the application simultaneously supports two detection modes of system NV color center and single NV color center on a set of equipment, can be flexibly switched between the two modes through optical path switching, does not need to replace the detection equipment, effectively solves the problem that there is no platform simultaneously supporting the two detection modes in the prior art, significantly improves the detection efficiency, and ensures the comparability of measurement results under different modes when detecting on the same platform.

Description

Technical Field

[0001] This invention relates to the field of quantum precision measurement technology, specifically to a comprehensive performance testing platform for ensemble NV center diamond and single NV center diamond. Background Technology

[0002] NV centers (nitrogen-vacancy color centers) are point defects in diamond formed by nitrogen atoms replacing carbon atoms and creating adjacent vacancies. Due to their excellent optically readable spin properties, they have significant application value in fields such as quantum sensing and quantum computing. Accurate measurement of the performance parameters of NV centers is fundamental to evaluating their quality and application potential.

[0003] Currently, detection technologies based on NV centers mainly employ two approaches: the ensemble NV center scheme and the single NV center scheme. The ensemble NV center scheme uses large-sized diamond particles containing numerous NV centers as the sensing medium, exhibiting high fluorescence signal intensity and has become a mature solution in fields such as magnetic field detection. The single NV center scheme uses diamond microparticles containing a single NV center, possessing a defined crystal orientation and a uniform local environment. It avoids the non-uniform broadening problem caused by inconsistent local strain among NV centers in the ensemble scheme, and can accurately resolve minute shifts in spin resonance frequencies caused by the Stark effect, making it suitable for applications such as high spatial resolution and high-precision electric field detection.

[0004] The intrinsic properties of diamond NV centers directly affect their measurement results, so it is of great significance to fully characterize their intrinsic properties. However, in the existing technology, there is a lack of platforms for testing the intrinsic properties of diamond NV centers, especially a lack of equipment that can simultaneously test the properties of ensemble NV centers and individual NV centers.

[0005] Therefore, how to simultaneously meet the detection requirements of ensemble NV color centers and single NV color centers on a single detection platform and achieve multi-mode detection capability is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] The present invention aims to solve the technical problems mentioned in the background section.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A comprehensive performance testing platform for diamond NV color centers, comprising at least: The front-end detection unit includes a microwave radiator, a displacement stage, an objective lens, and a magnetic field generator. During operation, the microwave radiator is placed on the displacement stage and receives external microwave signals to form a microwave field. The diamond sample is placed in the microwave field. The excitation light is focused by the objective lens and irradiates the diamond sample, exciting the NV color centers within it to generate fluorescence. The magnetic field generator is used to generate a bias magnetic field at the diamond sample. A dichroic mirror, located above the objective lens, is used to reflect excitation light into the objective lens and allow fluorescence to pass through; A microwave unit for transmitting microwave signals to the microwave radiator; The laser unit is used to output excitation light to the dichroic mirror; The ensemble color center fluorescence acquisition unit is used to acquire and process the fluorescence generated by diamonds in the ensemble NV color centers; A single-color-center fluorescence acquisition unit is used to acquire and process the fluorescence generated by single-NV color-center diamonds; The first optical path switcher includes at least a first state, which is used to guide the fluorescence transmitted through the dichroic mirror to the ensemble color center fluorescence acquisition unit. The second optical path switcher includes at least a second state, which is used to guide the fluorescence transmitted through the dichroic mirror to the monochromatic center fluorescence acquisition unit. Among them, at least one of the first optical path switcher and the second optical path switcher has an idle state. When it is in an idle state, it does not have the optical path switching function. Data processing and drive unit, which is used for data processing and system device control.

[0008] Preferably, the ensemble color center fluorescence acquisition unit includes a photodetector for acquiring fluorescence generated by the ensemble NV color center, and the single color center fluorescence acquisition unit includes a single-photon detector for acquiring fluorescence generated by a single NV color center.

[0009] Preferably, the laser unit includes a beam splitting module, which is used to guide a portion of the excitation light to the photodetector to achieve differential noise reduction processing of the excitation light and fluorescence.

[0010] Preferably, the laser unit includes a first half-wave plate, which is located in the optical path in front of the light incident end of the beam splitter module.

[0011] Preferably, the laser unit includes a second half-wave plate, which is located in the optical path between the beam splitter and the dichroic mirror.

[0012] Preferably, among the laser unit, the ensemble color center fluorescence acquisition unit, and the monochromatic color center fluorescence acquisition unit, at least the monochromatic color center fluorescence acquisition unit includes an optical collimation and constraint module, and the optical collimation and constraint module includes a collimating lens group and a pinhole constraint device located in the middle of the collimating lens group.

[0013] Preferably, the aperture of the aperture constraint located in the monochromatic center fluorescence acquisition unit is no greater than 30 μm.

[0014] Preferably, at least one of the ensemble color center fluorescence acquisition unit and the monochromatic color center fluorescence acquisition unit includes a spectral measurement module, and the spectral measurement module includes at least a third optical path switcher and a spectrometer, wherein the third optical path switcher is used to direct the fluorescence to the spectrometer.

[0015] Preferably, the ensemble color center fluorescence acquisition unit and the monochromatic color center fluorescence acquisition unit share a single spectral measurement module. The third optical path switcher includes at least a working state one, a working state two, and an idle state without optical path switching function. When in working state one, the third optical path switcher will guide the fluorescence in the ensemble color center fluorescence acquisition unit to the spectrometer; when in working state two, the third optical path switcher will guide the fluorescence in the monochromatic color center fluorescence acquisition unit to the spectrometer.

[0016] Preferably, the laser unit further includes an acousto-optic modulator for optical field electro-modulation of the excitation light.

[0017] Preferably, the monochromatic center fluorescence acquisition unit further includes an adjustable attenuator for controlling the optical power of the fluorescence entering the monochromatic center fluorescence acquisition unit.

[0018] Preferably, the data processing and driving unit includes at least a photoluminescence spectrum plotting module, an ODMR spectral plotting module, a spin polarization scanning spectral plotting module, a Rabi oscillation curve plotting module, a Ramsey interference curve plotting module, a spin echo attenuation curve plotting module, a longitudinal relaxation attenuation curve plotting module, and an NV color center imaging processing module.

[0019] Preferably, it also includes a fourth optical path switcher, a camera, and a display. The fourth optical path switcher is located above the objective lens and has at least a third state and an idle state without optical path switching function. When the fourth optical path switcher is in the third state, the fourth optical path switcher guides the light transmitted from the objective lens side to the camera, and the camera collects light information and images it on the display.

[0020] Compared with the prior art, the beneficial effects of the present invention are: (1) The detection platform of this application is compatible with both ensemble NV color center and single NV color center detection modes on one set of equipment. It can be flexibly switched between the two modes by switching the optical path without changing the detection equipment. This effectively solves the problem of the lack of a platform that is compatible with both detection modes in the prior art, significantly improves the detection efficiency, and ensures the comparability of measurement results under different modes by performing detection on the same platform.

[0021] (2) The detection platform of this application has flexible optical path configuration capability. Through the design of the idle state, the optical path switching has more optional states, which can adapt to different detection scenarios and optical path requirements, and provide a reliable optical path foundation for multi-mode detection. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a system schematic diagram of the comprehensive performance testing platform in Example 1; Figure 2 This is a schematic diagram of the front-end detection unit in Embodiment 1; Figure 3 This is a schematic diagram of the data processing and driving unit in Embodiment 1; Figure 4 This is a system schematic diagram of the comprehensive performance testing platform in Example 2; Figure 5 This is a system schematic diagram of the comprehensive performance testing platform in Example 3. Detailed Implementation

[0024] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, one or more embodiments are now described with reference to the accompanying drawings, wherein similar reference numerals are used throughout the text to refer to similar components. In the following description, numerous specific details are set forth for purposes of explanation in order to provide a more thorough understanding of one or more embodiments. However, it will be apparent that one or more embodiments may be practiced in various circumstances without these specific details, and the various embodiments may be combined with and referenced to each other without contradiction.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. Example 1

[0027] This example introduces a comprehensive performance testing platform for diamond NV color centers, as shown in the attached document. Figure 1 As shown, it includes a front-end detection unit 10, a dichroic mirror 20, a microwave unit 30, a laser unit 40, an ensemble color center fluorescence acquisition unit 50, a single color center fluorescence acquisition unit 60, a first optical path switcher 70, a second optical path switcher 80, and a data processing and driving unit 90.

[0028] In this example, the front-end detection unit 10 is used to carry the diamond sample 101 and provide a microwave excitation, optical focusing, and bias magnetic field environment, so that the excitation light can be focused onto the diamond sample 101 to excite the NV color centers within it to generate fluorescence. (See attached image) Figure 2 As shown, the front-end detection unit 10 includes a displacement stage 102, an objective lens 103, a microwave radiator 104, and a magnetic field generator 105. During operation, the microwave radiator 104 is placed on the displacement stage 102 and receives external microwave signals to form a microwave field. The diamond sample 101 is placed in the microwave field. Excitation light is focused by the objective lens 103 and irradiates the diamond sample 101, exciting the NV color centers within it to produce fluorescence. The magnetic field generator 105 is used to generate a bias magnetic field at the diamond sample 101.

[0029] The displacement stage 102 is used to support the microwave radiator 104 and the diamond sample 101, and to precisely adjust the relative position of the diamond sample 101 and the objective lens 103. Exemplarily, the displacement stage 102 can be a piezoelectric ceramic nanostage, with a resolution down to the nanometer scale. Exemplarily, the travel of the displacement stage 102 can be in the range of approximately 50 μm to 200 μm, enabling XYZ three-axis movement. Preferably, the displacement stage 102 can also have a rotation adjustment function to achieve multi-dimensional alignment between the diamond sample 101 and the objective lens 103. Of course, the specific type and parameters of the displacement stage 102 can be flexibly selected according to actual application requirements.

[0030] Objective lens 103 is used to focus the excitation light onto the diamond sample 101 and collect the fluorescence generated by the diamond sample 101. Exemplarily, objective lens 103 can be a high numerical aperture objective lens to achieve efficient focusing of the excitation light and efficient collection of fluorescence. Preferably, the numerical aperture (NA) of objective lens 103 is not less than 0.8 to balance the focused spot size and fluorescence collection efficiency. Exemplarily, objective lens 103 can be an infinity-corrected objective lens, facilitating the insertion of optical elements such as a dichroic mirror 20 into the optical path. Of course, the specific parameters of objective lens 103 can be flexibly selected according to actual application requirements.

[0031] The microwave radiator 104 is used to radiate a microwave field onto the diamond sample 101 to drive the spin flipping of the NV color center. Exemplarily, the microwave radiator 104 may be a microstrip antenna. (See attached diagram) Figure 2 As shown, the microwave radiator 104 includes a microwave antenna with a central radiation aperture. The diamond sample 101 is placed within this aperture, allowing the microwave field to efficiently act on the NV color centers within the diamond sample 101. For example, the size of the central radiation aperture can be matched to the size of the diamond sample 101 to ensure efficient coupling between the microwave field and the NV color centers. Of course, the specific type and structure of the microwave radiator 104 can be flexibly designed according to actual application requirements.

[0032] The diamond sample 101 is the object to be tested in the front-end detection unit 10. Depending on the detection mode, the diamond sample 101 has two types: one is an ensemble NV center diamond containing a large number of NV centers, suitable for the ensemble NV center detection mode; the other is a diamond microparticle containing a single NV center, suitable for the single NV center detection mode. By replacing the different types of diamond samples 101 and switching the operating state between the first optical path switcher 70 and the second optical path switcher 80, the two detection modes can be switched on the same detection platform.

[0033] The magnetic field generator 105 is used to generate a bias magnetic field at the diamond sample 101 to achieve Zeeman splitting of the spin energy levels of the NV color center. Exemplarily, the magnetic field generator 105 can employ a three-dimensional Helmholtz coil assembly, and by adjusting the coil currents in the three axial directions, a bias magnetic field with adjustable direction and magnitude can be generated at the diamond sample 101. Exemplarily, the strength of the bias magnetic field can be in the range of approximately 1 mT to 20 mT to generate sufficient Zeeman splitting at the spin resonant frequency of the NV color center, facilitating subsequent ODMR measurements.

[0034] In this example, the dichroic mirror 20 is positioned at the intersection of the excitation light path and the fluorescence acquisition light path, above the objective lens 103. It reflects the excitation light into the objective lens 103 while allowing fluorescence to pass through, thus achieving co-path transmission of the excitation light and fluorescence. Exemplarily, the dichroic mirror 20 can be a dichroic mirror with high reflectivity at a wavelength of 532±10 nm and high transmittance in the 600 nm to 800 nm band, to match the output wavelength of the laser 401 and the fluorescence emission band of the NV color center.

[0035] In this example, microwave unit 30 is used to transmit microwave signals to microwave radiator 104. Exemplarily, microwave unit 30 may include microwave source 301, microwave switch 302, and microwave amplifier 303. The microwave source is used to generate a frequency-tunable microwave signal. Exemplarily, the output frequency range of microwave source 301 may cover approximately 2.7 GHz to 3.1 GHz to cover the zero-field splitting frequency (approximately 2.87 GHz) of the NV color center and the linear region of the ODMR spectrum. Exemplarily, microwave source 301 may support frequency modulation (FM) or amplitude modulation (AM) modes, with modulation frequencies exemplarily ranging from hundreds of hertz to thousands of hertz. Microwave switch 302 is used to control the on / off state of the microwave signal to achieve pulsed microwave output. Microwave amplifier 303 is used to amplify the power of the microwave signal to meet the microwave field strength required for spin manipulation of the NV color center. The microwave signal output from microwave source 301 is transmitted to microwave radiator 104 after passing through microwave switch 302 and microwave amplifier 303, and microwave radiator 104 radiates a microwave field onto diamond sample 101. Of course, the specific composition and structure of the microwave unit 30 can be flexibly designed according to the actual application requirements.

[0036] In this example, laser unit 40 is used to output excitation light to dichroic mirror 20. Laser unit 40 includes laser 401. Laser 401 is used to output excitation light to excite the NV color center. Exemplarily, laser 401 can be a 532nm green laser because the NV color center has a strong absorption efficiency for light at a wavelength of 532nm, enabling efficient spin polarization. Exemplarily, the output power of laser 401 can be in the range of approximately 8mW to 15mW to provide sufficient initial excitation light power. Exemplarily, the power stability of laser 401 can be controlled within ±2% to reduce measurement errors caused by laser power fluctuations. Of course, the specific type and parameters of laser 401 can be flexibly selected according to actual application requirements. Exemplarily, laser 401 can also be a laser of other wavelengths, such as lasers of approximately 520nm or approximately 594nm. The selection of laser wavelength needs to comprehensively consider factors such as the absorption efficiency, fluorescence excitation efficiency, and charge state stability of the NV color center.

[0037] In this example, the ensemble color center fluorescence acquisition unit 50 is used to acquire and process the fluorescence generated by the diamond in the ensemble NV color center. Considering the high fluorescence intensity generated by the ensemble NV color center, in a preferred embodiment, the ensemble color center fluorescence acquisition unit 50 includes a photodetector 501. The photodetector 501 is used to acquire the fluorescence generated by the ensemble NV color center and convert it into an electrical signal. Exemplarily, the photodetector 501 can be a silicon photodiode, a photomultiplier tube, or a balanced photodetector, etc.

[0038] In this example, the monochromatic center fluorescence acquisition unit 60 is used to acquire and process the fluorescence generated by the single NV center diamond. Considering the low fluorescence intensity generated by the single NV center, in a preferred embodiment, the monochromatic center fluorescence acquisition unit 60 includes a single-photon detector 601. The single-photon detector 601 is used to detect and count the fluorescence photons generated by the single NV center. Exemplarily, the single-photon detector 601 can be a single-photon counting module based on an avalanche photodiode (APD), capable of achieving single-photon level fluorescence detection. Exemplarily, the maximum detectable photon count rate of the single-photon detector 601 can be in the range of approximately 10 Mcps to 25 Mcps.

[0039] It should be noted that when the incident light intensity is too high, the single-photon detector 601 may experience pulse accumulation, leading to counting distortion. In severe cases, it may even damage the detector due to overload. Therefore, it is necessary to strictly control the incident light flux to ensure that the single-photon detector 601 operates within the linear response range. Based on this, in a preferred embodiment, the monochromatic fluorescence acquisition unit 60 also includes an adjustable attenuator 603. The adjustable attenuator 603 is used to regulate the optical power of the fluorescence entering the monochromatic fluorescence acquisition unit 60. For example, the adjustable attenuator 603 can be a neutral density filter or an adjustable attenuation wheel. By uniformly attenuating light across all wavelengths, it reduces the photon flux incident on the single-photon detector 601 without changing the fluorescence spectral distribution. Of course, the specific type and parameters of the adjustable attenuator 603 can be flexibly selected according to actual application requirements.

[0040] In a preferred embodiment, the monochromatic center fluorescence acquisition unit 60 further includes an optical collimation and constraint module 100. The optical collimation and constraint module 100 includes a collimating lens group and a pinhole constraint device located in the center of the collimating lens group. The collimating lens group is used to collimate the fluorescence; the pinhole constraint device is used to filter out background stray light deviating from the optical axis. Exemplarily, the pinhole constraint device in the monochromatic center fluorescence acquisition unit 60 uses a fixed pinhole instead of an adjustable aperture, because single NV color center detection requires extremely high spatial filtering accuracy, and the minimum aperture of an adjustable aperture usually cannot meet the needs of single NV color center detection. Exemplarily, the aperture diameter is no greater than 30 μm. Within this aperture range, the pinhole can effectively filter out stray light deviating from the optical axis while ensuring sufficient passage of the fluorescence signal from the diamond sample 101. Of course, the specific aperture diameter can be flexibly selected according to actual application requirements. Similarly, the optical collimation and constraint module 100 can also be designed in the ensemble color center fluorescence acquisition unit 50, which can also improve measurement resolution by filtering out stray light. In another approach, an optical collimation and constraint module 100 can be designed in the laser unit 40. Its main functions include collimating the excitation light and reducing the return light from entering the laser and affecting its power stability.

[0041] It should be noted that the combined use of the collimating lens group and the pinhole constraint offers significant technical advantages. The lower convex lens converges the diverging fluorescence to the pinhole constraint, focusing the signal light propagating along the optical axis into a small spot for efficient passage. While ensuring signal transmittance, background stray light deviating from the optical axis is effectively blocked at the focal point of the pinhole constraint after convergence, achieving excellent stray light suppression. Furthermore, the upper convex lens recollides the signal light after passing through the pinhole constraint into a parallel beam incident on the detector, ensuring a good match between the incident light and the detector's sensitive surface, which helps improve detection efficiency and ensures uniform response. Therefore, the combined use of the collimating lens group and the pinhole constraint achieves excellent performance simultaneously in terms of spatial filtering, signal transmittance, and detection efficiency.

[0042] In this example, the first optical path switcher 70 and the second optical path switcher 80 are arranged in series on the fluorescence optical path after the dichroic mirror 20. Both can use mirrors or a combination of mirrors to achieve the optical path switching function. The order of the first optical path switcher 70 and the second optical path switcher 80 can be flexibly determined according to the actual optical path structure. Taking the second optical path switcher 80 located behind the first optical path switcher 70 as an example, the first optical path switcher 70 includes at least a first state and an idle state. When the first optical path switcher 70 is in the first state, it will pass through the fluorescence guiding ensemble color center fluorescence acquisition unit 50 of the dichroic mirror 20. When the first optical path switcher 70 is in an idle state, it does not have an optical path switching function, and the fluorescence continues to propagate along the original optical path to the second optical path switcher 80. The second optical path switcher 80 should include a second state. When the second optical path switcher 80 is in the second state, it guides the fluorescence to the monochromatic fluorescence acquisition unit 60. Of course, the second optical path switcher 80 can also have an idle state, but since it is already at the rear of the optical path, the design of the idle state is unnecessary. For example, for the reflector, the optical path switching is mainly achieved by electric or manual means. Since the positional relationship and light guiding performance of each state are common knowledge, we will not elaborate on the working posture of the optical path switchers at each position under different test requirements.

[0043] In this example, the data processing and driving unit 90 is used for data processing and system device control. Exemplarily, the data processing and driving unit 90 may include a processor, which is used for system timing control, data acquisition and processing, and coordinated control of various devices. Exemplarily, the processor may be implemented using an FPGA (Field-Programmable Gate Array), DSP (Digital Signal Processor), ARM microprocessor, or a high-performance computer. Of course, the specific composition and structure of the data processing and driving unit 90 can be flexibly designed according to actual application requirements.

[0044] In this example, to ensure the functionality of the testing platform, as shown in the attached document... Figure 3 As shown, the data processing and driving unit 90 has at least the following functional modules: The photoluminescence spectrum plotting module is used to plot photoluminescence spectra based on the acquired fluorescence spectrum data. Photoluminescence spectra can be used to characterize the charge state distribution and fluorescence intensity characteristics of NV color centers.

[0045] The ODMR spectral plotting module is used to plot photodetector magnetic resonance spectral lines based on the acquired fluorescence signal and the microwave frequency used. The resonance frequency shift of the ODMR spectral lines can be used to determine the zero-field splitting parameters of the NV centers, and then analyze the influence of electric or magnetic fields on the NV centers.

[0046] The spin polarization scanning spectral plotting module is used to plot the relationship between the degree of spin polarization and the excitation conditions, based on the acquired fluorescence signal and the excitation light power or excitation time used. Spin polarization scanning spectral lines can be used to evaluate the spin polarization efficiency of NV centers.

[0047] The Rabi oscillation curve plotting module is used to plot the oscillation curve of the spin state as a function of the microwave pulse duration, based on the acquired fluorescence signal and the applied microwave pulse duration. The Rabi oscillation curve can be used to determine the Rabi frequency of the NV color center and to calibrate the duration of the microwave-controlled π pulse and π / 2 pulse.

[0048] The Ramsey interferometry plotting module is used to plot the interference curve of the spin state as a function of the interval time based on the acquired fluorescence signal and the interval time between two π / 2 microwave pulses. The Ramsey interferometry curve can be used to measure the decoherence time T2* of the NV color center.

[0049] The spin echo decay curve plotting module is used to plot the decay curve of the spin state as a function of the waiting time, based on the acquired spin echo signal and the applied waiting time. The spin echo decay curve can be used to measure the coherence time T2 of the NV color center.

[0050] The longitudinal relaxation decay curve plotting module is used to plot the decay curve of the spin state as a function of the waiting time, based on the acquired fluorescence signal and the waiting time after spin polarization. The longitudinal relaxation decay curve can be used to measure the longitudinal relaxation time T1 of the NV color center.

[0051] The NV color center imaging processing module is used to output the spatial distribution image of the NV color centers and the spot alignment analysis results based on the image data acquired by the camera.

[0052] The aforementioned functional modules are implemented by the processor through the execution of corresponding algorithm programs. For example, different detection modes can call different combinations of functional modules: in ensemble NV center detection mode, functional modules such as PL spectrum, ODMR, and spin polarization scanning can be used; in single NV center detection mode, functional modules such as Rabi oscillation, Ramsey interferometry, spin echo, and longitudinal relaxation can be used to achieve a comprehensive characterization of the coherence performance of a single NV center.

[0053] In a preferred embodiment, the testing platform further includes a fourth optical path switcher 120, a camera 130, and a display 140. The fourth optical path switcher 120 is positioned above the objective lens 103 and has at least a third state and an idle state without optical path switching functionality. When the fourth optical path switcher 120 is in the third state, it directs the light transmitted from the objective lens 103 to the camera 130, which collects the light information and images it on the display 140. The imaging mode is primarily used in the pre-processing stage of the system. Before performing NV color center performance testing, the operator needs to confirm that the focused spot of the excitation light, the diamond sample 101, and the radiation center aperture of the microwave radiator 104 are aligned. Specifically, the fourth optical path switcher 120 is switched to the third state, the excitation light is focused by the objective lens 103 and irradiates the diamond sample 101, and the reflected and scattered light is collected by the objective lens 103 and directed by the fourth optical path switcher 120 to the camera 130, where it is imaged on the display 140. The operator observes the image on the monitor 140 to determine the alignment of the light spot with the diamond sample 101 and the radiation center hole of the microwave radiator 104. If the three are not aligned, the position of the displacement stage 102 is adjusted to make them aligned. After alignment is completed, the fourth optical path switcher 120 is switched to the idle state, and subsequent fluorescence detection can begin.

[0054] In a preferred embodiment, the laser unit 40 further includes an acousto-optic modulator (AOM) 402 and an AOM driver 403. The acousto-optic modulator 402 is disposed in the output optical path of the laser 401 for electro-modulation of the excitation light, while the AOM driver 403 controls the acousto-optic modulator 402. For example, the typical transmittance of the acousto-optic modulator 402 is approximately 80%, and the transmittance of the excitation light can be continuously adjusted by regulating the radio frequency drive power. The acousto-optic modulator 402 not only provides on / off control of the excitation light but also provides a key means for achieving precise control of the excitation light power reaching the diamond sample 101.

[0055] It is important to note that the acousto-optic modulator 402 and the adjustable attenuator 603 in the monochromatic center fluorescence acquisition unit 60 are linked in a synergistic manner. This linkage is a crucial design element for ensuring the detection accuracy of single NV centers. Specifically, the acousto-optic modulator 402 continuously adjusts the excitation light transmittance by regulating the radio frequency drive power, thereby controlling the excitation light power reaching the diamond sample 101. The excitation light power directly determines the fluorescence emission intensity of the single NV center in the diamond sample 101 and the background scattered light intensity in the optical path, both of which together constitute the total photon flux received by the single-photon detector 601. The adjustable attenuator 603 further modulates the fluorescence photon flux after spatial filtering. Example 2

[0056] This embodiment is a further improvement based on the various solutions proposed in Embodiment 1, as shown in the appendix. Figure 4 As shown, in this example, the laser unit 40 also includes a beam splitting module 405.

[0057] The beam splitter module 405 is located on the excitation light path and is used to guide a portion of the excitation light to the photodetector 501 to achieve differential noise reduction processing of the excitation light and fluorescence. Specifically, the beam splitter module 405 splits the excitation light into two paths: one path passes through the beam splitter module 405 and continues to propagate along the excitation light path for fluorescence excitation, while the other path is reflected by the beam splitter module 405 and guided to the photodetector 501 in the ensemble color center fluorescence acquisition unit 50. For example, the beam splitter module 405 can be a beam splitter with a transmission-to-reflection ratio of 9:1, so that most of the excitation light energy is used for fluorescence excitation, while retaining sufficient reference light intensity for the photodetector 501 to monitor. Regarding the photodetector here, for example, when the system is configured with the beam splitter module 405 for differential noise reduction, the photodetector 501 is preferably a balanced photodetector, which receives the ensemble fluorescence signal at one end and the reference excitation light signal drawn out by the beam splitter module 405 at the other end, and outputs the differential result to eliminate laser fluctuation noise. The use of a balanced photodetector here is based on its own signal differential function, but this differential function can be implemented in a variety of ways. In actual scheme design, different photodetector design schemes can be selected according to the requirements.

[0058] In a preferred embodiment, the laser unit 40 further includes a first half-wave plate 404. The first half-wave plate 404 is located in the optical path before the light incident end of the beam splitter module 405, and is used to adjust the polarization state of the excitation light incident on the beam splitter module 405. Since the beam splitting characteristics of the beam splitter module 405 may be affected by the polarization state of the incident light, the first half-wave plate 404, positioned before the beam splitter module 405, ensures that the two split beams (the transmitted excitation light and the reflected reference light) have a known and consistent polarization state, thereby guaranteeing the accuracy of subsequent differential noise reduction.

[0059] Furthermore, the laser unit 40 also includes a second half-wave plate 406. The second half-wave plate 406 is located in the optical path between the beam-splitting module 405 and the dichroic mirror 20, and is used to correct polarization changes caused by the beam-splitting module 405. The beam-splitting module 405 may introduce changes in polarization state during the beam splitting process (e.g., due to the polarization dependence of the beam-splitting film), causing the polarization state of the transmitted light to deviate from the expected value. The second half-wave plate 406 can compensate for and correct this polarization deviation, ensuring with extremely high accuracy that the excitation light used to excite the NV color center maintains the same polarization state as the reference light. The combined design of the first half-wave plate 404 and the second half-wave plate 406 ensures that the separated reference excitation light and the excitation light used to excite the NV color center are highly consistent in polarization properties, which is beneficial for high-precision differential noise reduction processing based on the same polarization reference and effectively eliminates system errors introduced by polarization inconsistency. For example, both the first half-wave plate 404 and the second half-wave plate 406 are 532nm wavelength half-wave plates. Of course, the specific parameters of the half-wave plate can be flexibly selected according to the laser wavelength.

[0060] During operation, the excitation light is split into two paths by the beam splitter module 405: the transmitted main beam is polarized and corrected by the second half-wave plate 406 before illuminating the dichroic mirror 20, and after being reflected by the dichroic mirror 20, it is focused onto the diamond sample 101 by the objective lens 103; the reflected reference beam is guided to the photodetector 501 for differential noise reduction. Example 3

[0061] This embodiment is a further improvement based on the various schemes proposed in the foregoing embodiments. Specifically, the ensemble color center fluorescence acquisition unit 50 and / or the monochromatic color center fluorescence acquisition unit 60 also include a spectral measurement module 110.

[0062] The spectral measurement module 110 includes at least a third optical path switcher 1101 and a spectrometer 1102. The third optical path switcher 1101 is used to direct fluorescence to the spectrometer 1102. The spectrometer 1102 is used to acquire the fluorescence spectrum of the NV color center and analyze the NV in the fluorescence spectrum. 0 The concentration of NV centers in diamond sample 101 was determined by analyzing the characteristic emission line intensities of neutral nitrogen-vacancy centers (NV⁻) and negatively charged nitrogen-vacancy centers (NV⁻). Center concentration is an important indicator for evaluating the quality of diamond samples and is significant for assessing the application performance of NV centers.

[0063] Regarding the location of the spectral measurement module 110, to ensure the accuracy of the measurement results, it is preferable to place the spectral measurement module 110 near the receiving port of the photodetector 501 or the single-photon detector 601, so that the fluorescence entering the spectrometer 1102 is signal light that has been spatially filtered and stray light suppressed.

[0064] It should be added that the single-color center fluorescence acquisition unit 60 mentioned in this application has a broader function. This unit realizes the analysis of low-intensity photoluminescence based on the principle of weak light acquisition. Although it is mentioned above that its function includes the acquisition of fluorescence for single NV centers, in fact, this unit also has the ability to analyze ensemble NV centers with ultra-low concentrations.

[0065] For example, as shown in the appendix Figure 1 and attached Figure 4 As shown, the ensemble color center fluorescence acquisition unit 50 and the single-color center fluorescence acquisition unit 60 can each be equipped with an independent spectrometer 1102. Since the fluorescence signal of the ensemble NV color center is relatively strong, a spectrometer with a detection sensitivity in the nanowatt range can be used; while the fluorescence signal of the single NV color center is extremely weak, requiring a high-sensitivity spectrometer with a detection sensitivity in the picowatt range. Preferably, the system is configured with two spectrometers 1102: one with nanowatt-level sensitivity for fluorescence spectral acquisition of the ensemble NV color center; and the other with picowatt-level sensitivity for fluorescence spectral acquisition of the single NV color center. Of course, the specific type and parameters of the spectrometer 1102 can be flexibly selected according to actual application requirements.

[0066] In a preferred embodiment, the ensemble color center fluorescence acquisition unit 50 and the monochromatic color center fluorescence acquisition unit 60 share the same spectral measurement module 110. In this case, the third optical path switcher 1101 includes at least one operating state, one operating state, and an idle state without optical path switching functionality. When in operating state one, the third optical path switcher 1101 enters the fluorescence-guided spectrometer 1102 in the ensemble color center fluorescence acquisition unit 50, at which point the photodetector does not collect fluorescence. When in operating state two, the third optical path switcher 1101 enters the fluorescence-guided spectrometer 1102 in the monochromatic color center fluorescence acquisition unit 60, at which point the single-photon detector does not collect fluorescence. When in the idle state, the fluorescence is not guided to the spectrometer 1102 but continues to propagate along the original optical path to the corresponding detector, at which point the photodetector or single-photon detector normally receives the fluorescence. For example, the third optical path switcher 1101 can be composed of several adjustable-angle reflectors. By adjusting the angle of the reflectors, fluorescence from different acquisition units can be flexibly introduced into the same spectrometer 1102, realizing the sharing of the spectrometer and reducing system costs. Specifically, as shown in the attached figure... Figure 5 As shown, the third optical path switcher 1101 is formed by a combination of four mirrors. By adjusting the angle, fluorescence from different optical paths can be directed to the same spectrometer 1102.

[0067] 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.

[0068] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A comprehensive performance testing platform for diamond NV color centers, characterized in that, At least includes: The front-end detection unit includes a microwave radiator, a displacement stage, an objective lens, and a magnetic field generator. During operation, the microwave radiator is placed on the displacement stage and receives external microwave signals to form a microwave field. The diamond sample is placed in the microwave field. The excitation light is focused by the objective lens and irradiates the diamond sample, exciting the NV color centers within it to generate fluorescence. The magnetic field generator is used to generate a bias magnetic field at the diamond sample. A dichroic mirror, located above the objective lens, is used to reflect excitation light into the objective lens and allow fluorescence to pass through; A microwave unit for transmitting microwave signals to the microwave radiator; The laser unit is used to output excitation light to the dichroic mirror; The ensemble color center fluorescence acquisition unit is used to acquire and process the fluorescence generated by diamonds in the ensemble NV color centers; A single-color-center fluorescence acquisition unit is used to acquire and process the fluorescence generated by single-NV color-center diamonds; The first optical path switcher includes at least a first state, which is used to guide the fluorescence transmitted through the dichroic mirror to the ensemble color center fluorescence acquisition unit. The second optical path switcher includes at least a second state, which is used to guide the fluorescence transmitted through the dichroic mirror to the monochromatic center fluorescence acquisition unit. Among them, at least one of the first optical path switcher and the second optical path switcher has an idle state. When it is in an idle state, it does not have the optical path switching function. Data processing and drive unit, which is used for data processing and system device control.

2. The diamond NV color center comprehensive performance testing platform as described in claim 2, characterized in that, The ensemble color center fluorescence acquisition unit includes a photodetector for acquiring fluorescence generated by the ensemble NV color center, and the single color center fluorescence acquisition unit includes a single-photon detector for acquiring fluorescence generated by a single NV color center.

3. The comprehensive performance testing platform for diamond NV color centers as described in claim 3, characterized in that, The laser unit includes a beam splitting module, which is used to extract a portion of the excitation light to the photodetector to achieve differential noise reduction processing of the excitation light and fluorescence.

4. The diamond NV color center comprehensive performance testing platform as described in claim 1, characterized in that, The laser unit includes a first half-wave plate, which is located in the optical path in front of the light incident end of the beam splitter module.

5. The diamond NV color center comprehensive performance testing platform as described in claim 5, characterized in that, The laser unit includes a second half-wave plate, which is located in the optical path between the beam splitter and the dichroic mirror.

6. The diamond NV color center comprehensive performance testing platform as described in claim 1, characterized in that, Among the laser unit, the ensemble color center fluorescence acquisition unit, and the monochromatic color center fluorescence acquisition unit, at least the monochromatic color center fluorescence acquisition unit includes an optical collimation and constraint module, which includes a collimating lens group and a pinhole constraint device located in the middle of the collimating lens group.

7. The diamond NV color center comprehensive performance testing platform as described in claim , characterized in that, The aperture of the small hole constraint located in the monochromatic heart fluorescence acquisition unit is no greater than μm.

8. The diamond NV color center comprehensive performance testing platform as described in claim 1, characterized in that, At least one of the ensemble color center fluorescence acquisition unit and the monochromatic color center fluorescence acquisition unit includes a spectral measurement module. The spectral measurement module includes at least a third optical path switcher and a spectrometer. The third optical path switcher is used to direct fluorescence to the spectrometer.

9. The diamond NV color center comprehensive performance testing platform as described in claim 1, characterized in that, The ensemble color center fluorescence acquisition unit and the monochromatic color center fluorescence acquisition unit share a single spectral measurement module. The third optical path switcher includes at least one working state, one working state, and an idle state without optical path switching function. When in working state one, the third optical path switcher will guide the fluorescence in the ensemble color center fluorescence acquisition unit to the spectrometer; when in working state two, the third optical path switcher will guide the fluorescence in the monochromatic color center fluorescence acquisition unit to the spectrometer.

10. The diamond NV color center comprehensive performance testing platform as described in claim 1, characterized in that, The laser unit also includes an acousto-optic modulator, which is used to electrically modulate the excitation light.

11. The diamond NV color center comprehensive performance testing platform as described in claim 1, characterized in that, The monochromatic center fluorescence acquisition unit also includes an adjustable attenuator, which is used to regulate the optical power of the fluorescence entering the monochromatic center fluorescence acquisition unit.

12. The diamond NV color center comprehensive performance testing platform as described in claim 1, characterized in that, The data processing and driving unit includes at least a photoluminescence spectrum plotting module, an ODMR spectral plotting module, a spin polarization scanning spectral plotting module, a Rabi oscillation curve plotting module, a Ramsey interference curve plotting module, a spin echo attenuation curve plotting module, a longitudinal relaxation attenuation curve plotting module, and an NV color center imaging processing module.

13. The diamond NV color center comprehensive performance testing platform as described in any one of the claims, characterized in that, It also includes a fourth optical path switcher, a camera, and a display. The fourth optical path switcher is located above the objective lens and has at least a third state and an idle state without optical path switching function. When the fourth optical path switcher is in the third state, the fourth optical path switcher guides the light transmitted from the objective lens side to the camera, and the camera collects light information and images it on the display.

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