Method for adjusting spin charge state of solid quantum of diamond by utilizing ultraviolet light and application of method

Abstract

The invention discloses a method for adjusting a diamond solid quantum spin charge state by using ultraviolet light and application thereof, and aims to solve the problem of adjusting two charge states of an NV color center. The method for adjusting the solid quantum spin charge state of the diamond by utilizing ultraviolet light comprises the following steps of: 1, preparing the diamond with a nitrogen vacancy color center; 2, irradiating the diamond with the color center by using laser as an excitation light source; and 3, under the condition of laser irradiation, simultaneously applying an ultraviolet light source for irradiation to increase the content of NV0 in a neutral charge state, thereby completing the method for adjusting the spin charge state of the solid quantum of the diamond by utilizing the ultraviolet light. The NV color center charge state is regulated and controlled in an ultraviolet irradiation mode, compared with a terminal method and a Schottky contact method, the method has the advantages of being non-contact and non-destructive, and the crystal quality can be better guaranteed. The method for adjusting the spin charge state of the solid quantum of the diamond can promote the application of the NV color center in quantum precision measurement and an extensible quantum system.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor materials and quantum technology, and specifically relates to a method for regulating the solid-state quantum spin charge state of diamond using ultraviolet light (UV) and its application. Background Art

[0002] Diamond is a new generation of semiconductor material with high carrier mobility, high thermal conductivity and wide bandgap. When impurity atoms, such as nitrogen atoms or silicon atoms, are doped into the diamond lattice, luminescence centers will be formed in the crystal. These luminescence centers have the characteristics of quantum light sources and can be applied to quantum computing, quantum communication and quantum detection, with very broad application scenarios. Among them, the diamond nitrogen-vacancy center (NV center) has the characteristics of stable fluorescence intensity, long electron spin coherence time and atomic-level characteristic size, making it an excellent nano solid-state quantum spin sensor. The NV center electron spin quantum state also has a coupling relationship with physical quantities such as temperature field and electromagnetic field. Based on these coupling relationships, researchers have experimentally achieved high-sensitivity characterization of related physical quantities with nanoscale spatial resolution, which can be used in quantum sensing technology. NV centers have two states: neutral and negative charge. In a single application, usually only one charge state of NV centers is used, and the other charge state will exist as background fluorescence noise. However, in the excited state, the NV center is always in the neutral charge state (NV 0 ) and negatively charged states (NV - ), which greatly limits the application and reliability of NV. Therefore, the charge state control technology of NV color center makes it possible to realize solid-state quantum information processing with NV color center as experimental carrier, and provides a good theoretical basis and experimental guarantee for improving the performance of room temperature solid-state quantum sensing. The previous control technology of NV color center charge state includes terminal method and Schottky contact method, which are all based on contact as the condition to control the charge state of NV color center, which has certain damage to the quantum sensor itself - diamond. Summary of the invention

[0003] The present invention aims to solve the problem of regulating the two charge states of NV color centers by applying ultraviolet light to diamonds containing NV color centers and observing the NV 0 and NV - The changes in the spectral intensity of the two color centers before and after ultraviolet exposure confirm the change in charge state, providing a method for non-contact optical regulation of diamond solid-state quantum spin charge state and its application.

[0004] The method of regulating the solid-state quantum spin charge state of diamond by ultraviolet light of the present invention is implemented by the following steps:

[0005] 1. Preparation of diamond with nitrogen vacancy color center;

[0006] Second, use laser as the excitation light source to irradiate the diamond with color center;

[0007] 3. Under laser irradiation conditions, ultraviolet light (UV) is applied simultaneously to irradiate the neutral charge state NV 0 The content is increased, thereby completing the method of using ultraviolet light to adjust the solid-state quantum spin charge state of diamond.

[0008] The application of the method of regulating the solid-state quantum spin charge state of diamond by ultraviolet light of the present invention is to prepare a solid-state quantum spin sensor, which includes diamond with nitrogen vacancy color center, an excitation light source and an ultraviolet light source. Laser is used as the excitation light source, and the laser is used to excite the diamond with NV color center. At the same time, an ultraviolet light source (UV) is applied for irradiation. The real-time monitoring of the fluorescence intensity of the characteristic peak of the NV color center is carried out to achieve the regulation of the solid-state quantum spin charge state of the diamond.

[0009] The present invention provides a novel method for regulating the solid-state quantum spin charge state of diamond using ultraviolet light. Compared with previous charge state regulation methods, this method is novel in form and has the advantages of being non-contact and non-destructive. At the same time, it can achieve real-time regulation while ensuring the quality of the crystal.

[0010] The method of using ultraviolet light to adjust the diamond solid-state quantum spin charge state and its application include the following beneficial effects:

[0011] 1. The present invention regulates the solid-state quantum spin charge state of diamond in real time by applying UV. Compared with the terminal method and Schottky contact method, the process is simple and the equipment cost is lower. It can effectively promote the application research based on diamond color center.

[0012] 2. The present invention regulates the charge state of NV color centers by ultraviolet light irradiation. Compared with the terminal method and Schottky contact method, it has the characteristics of non-contact and non-destructiveness, and can better ensure the quality of crystals. The method of regulating the charge state of diamond solid-state quantum spin by ultraviolet light can promote the application of NV color centers in quantum precision measurement and scalable quantum systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a simplified structural diagram of an experimental device for simultaneously applying an ultraviolet light source for irradiation under laser irradiation conditions in the embodiments;

[0014] Figure 2 The test diagram of the relationship between spectral intensity and time under different loading conditions in the embodiment, where the red spectrum is NV - The relationship between the spectral intensity and time before UV loading, during UV loading, and after UV removal. The black spectrum line is NV 0The relationship between the spectral intensity and time before UV loading, during UV loading and after UV removal;

[0015] Figure 3 This is a test diagram of the diamond surface potential scanning result in the embodiment. The position with high potential and brightness is the UV loading moment, and the position with low potential and darkness is the UV off moment. DETAILED DESCRIPTION

[0016] Specific implementation method 1: In this implementation method, the method of using ultraviolet light to adjust the diamond solid-state quantum spin charge state is implemented according to the following steps:

[0017] 1. Preparation of diamond with nitrogen vacancy color center;

[0018] Second, use laser as the excitation light source to irradiate the diamond with color center;

[0019] 3. Under laser irradiation conditions, ultraviolet light (UV) is applied simultaneously to irradiate the neutral charge state NV 0 The content is increased, thereby completing the method of using ultraviolet light to adjust the solid-state quantum spin charge state of diamond.

[0020] This embodiment provides a method for non-contact regulation of the solid-state quantum spin charge state of diamond while ensuring the quality of diamond, which is expected to promote the application of NV color centers in quantum precision measurement and scalable quantum systems.

[0021] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the concentration of the color center in the diamond with nitrogen vacancy color center in step 1 is 400 ppb to 20 ppm.

[0022] Specific embodiment 3: This embodiment is different from specific embodiment 1 or 2 in that the process of preparing diamond with nitrogen vacancy color center in step 1 is as follows:

[0023] 1. Clean the high temperature and high pressure diamond substrate to obtain a clean diamond substrate;

[0024] 2. Preparation of solid-state quantum spin in diamond NV color center:

[0025] a. Place the clean diamond substrate into the CVD growth chamber, evacuate the chamber and introduce hydrogen, adjust the pressure in the CVD growth chamber to 8-12 mbar, start the microwave generator and activate the plasma;

[0026] b. Increase the gas pressure in the CVD growth chamber and the power of the microwave generator to make the temperature of the clean diamond substrate reach 700-1000°C;

[0027] c. Introduce methane and control the methane flow rate to 4-32 sccm;

[0028] d. Introduce nitrogen as doping gas, control the temperature of the diamond substrate to be stable at 700-1000°C, and carry out CVD growth. After the growth, turn off the methane and doping gas, gradually reduce the power of the microwave generator and the air pressure in the CVD growth chamber, close the hydrogen valve, and vent to atmospheric pressure to obtain diamonds with nitrogen vacancy color centers.

[0029] Specific embodiment 4: This embodiment is different from specific embodiment 3 in that the temperature of the clean diamond substrate is made to reach 700-850°C in step b.

[0030] Specific implementation method five: This implementation method is different from specific implementation method three or four in that in step d, during the CVD growth process, the hydrogen flow rate is controlled to be 200-400 sccm, the methane flow rate is 4-32 sccm, and the doping element gas nitrogen flow rate is 0.01-1 sccm.

[0031] Specific implementation method 6: The difference between this implementation method and any one of specific implementation methods 3 to 5 is that the CVD growth time in step d is 1 to 10 hours.

[0032] Specific implementation method 7: The difference between this implementation method and specific implementation method 1 is that the wavelength of the laser in step 2 is 532 nm and the energy is 0.05-5 mW.

[0033] Specific implementation example eight: This implementation example is different from specific implementation example one in that the wavelength of the ultraviolet light emitted by the ultraviolet light source in step three is 200 to 380 nm.

[0034] Specific implementation method 9: The difference between this implementation method and specific implementation method 1 is that the time of applying the ultraviolet light source (UV) for irradiation in step 3 is 100 to 300 seconds.

[0035] Embodiment: The method of using ultraviolet light to adjust the diamond solid-state quantum spin charge state is implemented according to the following steps:

[0036] 1. Diamond cleaning:

[0037] The diamond seed crystal was placed in acetone, deionized water and anhydrous ethanol in turn, and cleaned for 30 minutes respectively under the condition of ultrasonic power of 100W to obtain clean diamond;

[0038] 2. Growing diamonds containing NV color centers:

[0039] S1. Place the clean diamond sample into the CVD growth chamber, close the chamber, and evacuate the chamber to a pressure of 5.0×10 -6 mbar;

[0040] S2, start the program, set the hydrogen flow rate to 200 sccm, adjust the pressure in the growth chamber to 10 mbar, start the microwave generator, activate the plasma; then increase the pressure and power to make the surface temperature of the diamond sample reach 750 ° C;

[0041] S3, adjusting the hydrogen flow rate to 192 sccm, introducing methane, setting the methane flow rate to 8 sccm, introducing nitrogen, setting the nitrogen flow rate to 0.01 sccm;

[0042] S4. Adjust the gas pressure and power to stabilize the surface temperature of the diamond sample at 830°C for 120 min; turn off nitrogen and methane;

[0043] S5. Gradually reduce the pressure in the growth chamber to 10 mbar, close the hydrogen valve, and pump the gas to 10 -3 mbar, then vent to atmospheric pressure, open the chamber door, and take out the diamond with nitrogen vacancy color center;

[0044] 3. UV control and fluorescence spectrum characterization:

[0045] a. Use a 10x microscope to focus on the upper surface of the diamond with nitrogen vacancy color centers and determine the characterization area;

[0046] b. Use a 50x microscope to observe, select a test point in the normal epitaxial area of ​​diamond with nitrogen vacancy color center, and focus again;

[0047] c. The UV light source uses the deuterium lamp of Ocean Optics DH-2000. The UV light is introduced from DH-2000 through optical fiber. The optical fiber head is equipped with a convex lens to collimate the light. The angle is adjusted so that the UV light can fully irradiate the diamond surface with nitrogen vacancy color centers. Figure 1 As shown;

[0048] d. Use 532nm excitation light, 3mW energy, and set the test range to NV 0 The measurement time is set to 20 minutes, and the NV at the normal epitaxial area of ​​the diamond with nitrogen vacancy color center is measured in real time. 0 The fluorescence spectrum of

[0049] e. During the measurement process in step d, turn on the UV light source and remove the UV light after 200 seconds. Measure the NV at the same point as in step d. 0 Changes in fluorescence spectrum intensity after simultaneous laser and UV loading and after UV loading is removed;

[0050] f. Use 532nm excitation light, 3mW energy, and set the test range to NV -The measurement time is set to 20 minutes, and the NV at the same point as step d is measured in real time. - The fluorescence spectrum of

[0051] g. During the measurement process in step f, turn on the UV light source and keep it on for 200 seconds before removing the UV. Measure the NV at the same point as in step f. - Changes in fluorescence spectrum intensity after simultaneous laser and UV loading and after UV loading is removed;

[0052] Comparing the above spectra, Figure 2 As shown. It can be found from the spectrum that when UV is loaded, NV 0 The spectral intensity of NV increases sharply. - The spectral intensity of NV decreases sharply, and after removing the UV loading, 0 and NV - The intensity of both recovered to the state before UV loading at a certain speed, and the recovery time of both was about 600s. This shows that UV loading regulates the two charge states of NV color centers, making NV 0 and NV - The two charge states undergo a transformation into each other.

[0053] Conduct KPFM Kelvin Probe Microscope Test:

[0054] (1) Using KPFM, the diamond surface potential distribution is obtained by moving along the x-axis direction of the diamond surface and scanning back and forth in the y-axis direction. During the scanning process, the UV is turned on and off in real time;

[0055] (2) Select the midpoint of the diamond in the y-axis direction, and also let the KPFM move along the x-axis direction of the diamond. During the scanning process, the UV is turned on and off in real time. The diamond length and the KPFM forward speed are used for conversion to obtain the time-dependent potential distribution diagram, such as Figure 3 shown.

[0056] From the potential distribution diagram, it can be found that the position with high potential and brightness is when the UV is turned on, and the position with low potential and darkness is when the UV is turned off. Since the color center charge state is sensitive to the electrical environment, KPFM confirms that UV loading mainly affects the potential of the diamond surface, thereby regulating the NV color center charge state.

[0057] The present invention provides an innovative non-contact and non-destructive method for the regulation of the two charge states of diamond NV color centers, which can be extended to the experimental research of multi-charge state color centers in other diamonds and other crystal materials. At the same time, it will help promote the theoretical research on the charge state transition dynamics of NV centers and optimize the contrast and other parameters of diamond NV centers in quantum precision measurement and other technologies. In addition, the optical regulation and transformation of the two charge states is also expected to develop optical logic gate research similar to traditional semiconductors.

Claims

1. A method for regulating the solid-state quantum spin charge state of diamond using ultraviolet light, characterized in that The method for adjusting the diamond solid-state quantum spin charge state is implemented according to the following steps:

1. Preparation of diamond with nitrogen vacancy color center; Second, use laser as the excitation light source to irradiate the diamond with color center; 3. Under the condition of laser irradiation, ultraviolet light source is applied to irradiate the neutral charge state NV 0 The content is increased, thereby completing the method of using ultraviolet light to adjust the solid-state quantum spin charge state of diamond.

2. The method for regulating the solid-state quantum spin charge state of diamond using ultraviolet light according to claim 1, characterized in that In step 1, the concentration of the color center in the diamond with nitrogen vacancy color center is 400 ppb to 20 ppm.

3. The method for regulating the solid-state quantum spin charge state of diamond using ultraviolet light according to claim 1, characterized in that The process of preparing diamond with nitrogen vacancy color center in step 1 is as follows:

1. Clean the high temperature and high pressure diamond substrate to obtain a clean diamond substrate; 2. Preparation of solid-state quantum spin in diamond NV color center: a. Place the clean diamond substrate into the CVD growth chamber, evacuate the chamber and introduce hydrogen, adjust the pressure in the CVD growth chamber to 8-12 mbar, start the microwave generator and activate the plasma; b. Increase the gas pressure in the CVD growth chamber and the power of the microwave generator to make the temperature of the clean diamond substrate reach 700-1000°C; c. Introduce methane and control the methane flow rate to 4-32 sccm; d. Introduce nitrogen as doping gas, control the temperature of the diamond substrate to be stable at 700-1000°C, and carry out CVD growth. After the growth, turn off the methane and doping gas, gradually reduce the power of the microwave generator and the air pressure in the CVD growth chamber, close the hydrogen valve, and vent to atmospheric pressure to obtain diamonds with nitrogen vacancy color centers.

4. The method for regulating the solid-state quantum spin charge state of diamond using ultraviolet light according to claim 3, characterized in that In step b, the temperature of the clean diamond substrate is made to reach 700-850°C.

5. The method for regulating the solid-state quantum spin charge state of diamond using ultraviolet light according to claim 3, characterized in that In step d, during the CVD growth process, the hydrogen flow rate is controlled to be 200-400 sccm, the methane flow rate is controlled to be 4-32 sccm, and the doping element gas nitrogen flow rate is controlled to be 0.01-1 sccm.

6. The method for regulating the solid-state quantum spin charge state of diamond using ultraviolet light according to claim 3, characterized in that The CVD growth time in step d is 1 to 10 hours.

7. The method for regulating the solid-state quantum spin charge state of diamond using ultraviolet light according to claim 1, characterized in that In step 2, the wavelength of the laser is 532 nm, and the energy is 0.05-5 mW.

8. The method for regulating the solid-state quantum spin charge state of diamond using ultraviolet light according to claim 1, characterized in that The wavelength of the ultraviolet light emitted by the ultraviolet light source in step 3 is 200-380nm.

9. The method for regulating the solid-state quantum spin charge state of diamond using ultraviolet light according to claim 1, characterized in that In step 3, the ultraviolet light source is applied for irradiation for 100 to 300 seconds.

10. The use of the method for regulating the solid-state quantum spin charge state of diamond using ultraviolet light as claimed in claim 1, characterized in that The application of the method of using ultraviolet light to regulate the solid-state quantum spin charge state of diamond is to prepare a solid-state quantum spin sensor, which includes a diamond with a nitrogen vacancy color center, an excitation light source and an ultraviolet light source. Laser is used as the excitation light source, and the laser is used to excite the diamond with the NV color center. At the same time, an ultraviolet light source is applied for irradiation to regulate the solid-state quantum spin charge state of the diamond.

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