Quantum sensor based on optical fiber type diamond NV color center and preparation method thereof

Abstract

The invention discloses a quantum sensor based on an optical fiber type diamond NV color center and a preparation method of the quantum sensor. The quantum sensor comprises diamond particles used for generating the diamond NV color center emitting fluorescence; the multimode optical fiber is used for bearing diamond particles and transmitting optical signals; the diamond particles and the multimode optical fiber form a metal microcavity through silver plating on the surfaces, the metal microcavity is used for binding light to circulate and converge in the cavity, the diamond particles and the multimode optical fiber are coupled, the metal Ag film is plated on the surfaces of the diamond particles and the multimode optical fiber to form a metal microcavity structure, the binding light continuously circulates and converges in the cavity, and therefore the binding light can be effectively restrained. The laser excitation efficiency and the fluorescence collection efficiency are effectively improved, the signal intensity detected by the photoelectric detector is enhanced, and high-precision quantum information detection of NV color center spin characteristics and the like is realized, so that ultra-high spatial resolution detection of a physical field is effectively served.

Description

Technical Field

[0001] The present invention relates to the field of quantum sensing technology, and in particular to a quantum sensor based on optical fiber diamond NV color center and a preparation method thereof. Background Art

[0002] The defect site in the crystal that selectively absorbs visible light is called a color center. Diamond NV color centers are formed when two adjacent carbon atoms in diamond are replaced by a nitrogen atom and a vacancy, and then an electron is captured. Sensing technology based on diamond NV color centers is a quantum sensing technology that has rapidly emerged in recent years and has many advantages in sensing performance. The atomic scale of the electron spin of the diamond NV color center enables sensing detection to achieve very high spatial resolution, and its electron spin can interact with a variety of physical quantities, and is mostly used for the measurement of magnetic fields, electric fields, temperature and pressure. When affected by an external magnetic field, the optical detection magnetic resonance (ODMR) spectrum of the NV color center will produce Zeeman splitting. When affected by an external electric field, the energy level change caused by the Stark effect causes the ODMR spectrum peak to change. The measurement of temperature and pressure is mainly carried out by studying the changes in the zero-field splitting of the ground state of the NV color center. Compared with quantum measurement systems such as atomic vapor and superconductivity, NV color centers are optically stable, thermally stable and non-toxic, allowing NV color centers to work in a variety of experimental environments. The spin state of the NV center can be read out by fluorescence, which allows experimenters to easily obtain its spin information by fluorescence reading. Therefore, quantum sensing technology based on diamond NV center will promote the development of a new generation of measurement technology.

[0003] In the prior art, an objective lens is usually used to focus the laser onto the diamond NV color center, which generates fluorescence, which is then collected by the objective lens, transmitted to the colored filter through a dichroic mirror, and finally received by the photodetector. However, the laser excitation efficiency and fluorescence collection efficiency in the above method are low, which makes the signal detected by the photodetector weak, and high-precision quantum information such as the spin characteristics of the NV color center is difficult to detect, affecting the ultra-high spatial resolution detection of the physical field. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the quantum sensor based on fiber-type diamond NV color center and the preparation method thereof provided by the present invention solve the problem that the laser excitation efficiency is low and the fluorescence collection efficiency is low, resulting in weak signals detected by the photodetector.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: a quantum sensor based on fiber-type diamond NV color center, comprising:

[0006] Diamond particles: used to generate diamond NV color centers that emit fluorescence;

[0007] Multimode optical fiber: used to carry diamond particles and transmit optical signals;

[0008] The diamond particles and the multimode optical fiber are silver-plated on the surface to form a metal microcavity, and the metal microcavity is used to confine light to circulate and converge in the cavity.

[0009] Furthermore: the particle size of the diamond particles is 1-100 μm.

[0010] Furthermore, the coating diameter of the multimode optical fiber is 200-1000 μm, and the core diameter is 50-800 μm.

[0011] The present application also provides a method for preparing a quantum sensor based on an optical fiber-type diamond NV color center, comprising:

[0012] S1. Cut the end face of the multimode optical fiber flatly, remove the multimode optical fiber coating layer 1-3 mm away from the end face to expose the fiber core, and use anhydrous ethanol to remove the residual coating layer on the surface of the fiber core;

[0013] S2, applying UV curing glue to the end face of the multimode optical fiber, and placing diamond particles at the center of the end face of the multimode optical fiber;

[0014] S3, use ultraviolet lamp to irradiate the end face of multimode optical fiber until the ultraviolet curing glue is completely cured;

[0015] S4. The exposed fiber core and the surface of the diamond particles are coated with a metal Ag film to form a metal microcavity.

[0016] Furthermore: in S2, the UV curing adhesive is any one of acrylate UV curing adhesive, silicone UV curing adhesive and epoxy UV curing adhesive.

[0017] Further: S4 includes:

[0018] S41, adding ammonia water dropwise to the AgNO3 solution until the precipitate is completely dissolved and becomes clear to obtain a silver ammonia solution;

[0019] S42, hydrophilically modifying the multimode optical fiber having diamond particles fixed on the end face to obtain a modified multimode optical fiber;

[0020] S43, placing the modified multimode optical fiber in a silver ammonia solution, and adding a reducing solution to the silver ammonia solution;

[0021] S44. Let it stand until the surface of the multimode optical fiber has a metallic luster. Take out the multimode optical fiber and place it in an oven for drying. Then, coat the exposed fiber core and diamond surface with a metal Ag film.

[0022] Further: the S42 includes:

[0023] S421, placing a multimode optical fiber with diamond particles fixed on the end face in a chamber of a plasma cleaning machine;

[0024] S422. Close the three-way valve of the plasma cleaning machine and turn on the vacuum pump to put the chamber in a negative pressure state;

[0025] S423, opening the needle valve of the plasma cleaning machine to allow gas to flow in, and starting the plasma generator to clean the multimode optical fiber with diamond particles fixed on the end surface;

[0026] S424, turn off the plasma generator, needle valve and vacuum pump in sequence, and evacuate the chamber to normal pressure to obtain the modified multimode optical fiber.

[0027] Further: in S43, the reducing solution is any one of 0.05 mL of a formaldehyde solution with a mass fraction of 40%, 0.15 mL of an acetaldehyde solution with a mass fraction of 20%, and 1 mL of a glucose solution with a mass fraction of 10%.

[0028] The beneficial effects of the present invention are:

[0029] The use of a metal microcavity structure effectively improves the laser excitation efficiency and fluorescence collection efficiency, enhances the signal intensity detected by the photodetector, and realizes high-precision quantum information detection such as the spin properties of NV color centers, thereby effectively serving the ultra-high spatial resolution detection of physical fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of a quantum sensor based on fiber-type diamond NV color centers according to an embodiment of the present disclosure;

[0031] Figure 2 A schematic diagram of a sensing system device designed in an embodiment of the present disclosure based on a quantum sensor of optical fiber-type diamond NV color center;

[0032] Figure 3 ODMR spectra of diamond NV color centers without metal film coating on the surface and ODMR spectra of diamond NV color centers with metal Ag film coating on the surface within the acquisition period of the embodiment of the present disclosure.

[0033] Figure 4 In the embodiment of the present disclosure, under the alternating action of laser pulses and microwave pulses, the ODMR spectrum of the diamond NV color center without metal film coating on the surface is obtained within the collection period. DETAILED DESCRIPTION

[0034] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0035] like Figure 1 As shown, in one embodiment of the present invention, a quantum sensor based on fiber-type diamond NV color center is provided, comprising:

[0036] Diamond particles: used to generate diamond NV color centers that emit fluorescence;

[0037] Multimode optical fiber: used to carry diamond particles and transmit optical signals;

[0038] The diamond particles and the multimode optical fiber are silver-plated on the surface to form a metal microcavity, and the metal microcavity is used to confine light to circulate and converge in the cavity.

[0039] The diamond particles have a particle size of 1-100 μm.

[0040] The coating diameter of the multimode optical fiber is 200-1000 μm, and the core diameter is 50-800 μm.

[0041] Preferably, in this embodiment, the coating diameter of the multimode optical fiber is 243 μm, the core diameter is 105 μm, and the particle size of the diamond particles is 50 μm.

[0042] In one embodiment of the present application, a method for preparing a quantum sensor based on an optical fiber diamond NV color center comprises:

[0043] S1. Cut the end face of the multimode optical fiber flatly, remove the multimode optical fiber coating layer 1-3 mm away from the end face to expose the fiber core, and use anhydrous ethanol to remove the residual coating layer on the surface of the fiber core;

[0044] S2, applying UV curing glue to the end face of the multimode optical fiber, and placing diamond particles at the center of the end face of the multimode optical fiber;

[0045] S3, use ultraviolet lamp to irradiate the end face of multimode optical fiber until the ultraviolet curing glue is completely cured;

[0046] S4, coating the exposed fiber core and the surface of the diamond particles with a metal Ag film to form a metal microcavity;

[0047] In S2, the UV curing adhesive is any one of an acrylate UV curing adhesive, a silicone UV curing adhesive and an epoxy UV curing adhesive;

[0048] Preferably, in this embodiment, the UV curing adhesive is an epoxy UV curing adhesive.

[0049] The S4 includes:

[0050] S41, adding ammonia water dropwise to the AgNO3 solution until the precipitate is completely dissolved and becomes clear to obtain a silver ammonia solution;

[0051] S42, hydrophilically modifying the multimode optical fiber having diamond particles fixed on the end face to obtain a modified multimode optical fiber;

[0052] S43, placing the modified multimode optical fiber in a silver ammonia solution, and adding a reducing solution to the silver ammonia solution;

[0053] S44. Let it stand until the surface of the multimode optical fiber has a metallic luster. Take out the multimode optical fiber and place it in an oven for drying. Then, coat the exposed fiber core and diamond surface with a metal Ag film.

[0054] Preferably, in this embodiment, in S41, the silver ammonia solution is prepared by adding 2% ammonia water to 1 mL of 2% AgNO3 solution;

[0055] In the S43, the reducing solution is any one of 0.05 mL of a formaldehyde solution with a mass fraction of 40%, 0.15 mL of an acetaldehyde solution with a mass fraction of 20%, and 1 mL of a glucose solution with a mass fraction of 10%.

[0056] Preferably, in this embodiment, in S44, the time for placing in the oven for drying is 1 hour;

[0057] The S42 includes:

[0058] S421, placing a multimode optical fiber with diamond particles fixed on the end face in a chamber of a plasma cleaning machine;

[0059] S422. Close the three-way valve of the plasma cleaning machine and turn on the vacuum pump to put the chamber in a negative pressure state;

[0060] S423, opening the needle valve of the plasma cleaning machine to allow gas to flow in, and starting the plasma generator to clean the multimode optical fiber with diamond particles fixed on the end surface;

[0061] S424, turn off the plasma generator, needle valve and vacuum pump in sequence, and evacuate the chamber to normal pressure to obtain the modified multimode optical fiber.

[0062] In the above-mentioned S423, cleaning relies on the glow discharge phenomenon.

[0063] The quantum sensor based on fiber-type diamond NV color center and its preparation method described in the present application are used for quantum signal enhancement of fiber-type diamond NV color center. By coupling diamond particles with multimode optical fiber and coating a metal Ag film on its surface to form a metal microcavity structure, the laser excitation efficiency and fluorescence collection efficiency are effectively improved, the signal intensity detected by the photodetector is enhanced, and high-precision quantum information detection such as the spin characteristics of the NV color center is achieved, thereby effectively serving the ultra-high spatial resolution detection of the physical field.

[0064] Preferably, a specific embodiment is cited for illustration. Figure 2 The schematic diagram of the sensing system device of a quantum sensor based on fiber-type diamond NV color center designed in the embodiment of the present disclosure is as follows: the laser source emits a 532nm laser. To ensure that the laser can be injected into the optical device behind in parallel, the angle of the incident light must be adjusted by two reflectors. Then, the laser is focused by a lens and then converted into linearly polarized light by a polarization beam splitter prism. The laser signal can be stabilized by a laser amplitude stabilizer to reduce noise.

[0065] After that, Bragg diffraction occurs through the acousto-optic modulator. After multiple diffraction spots appear, the first-order diffraction spot is screened out by the aperture, and the rest of the diffraction spots are filtered out. Then, the laser is reflected to the objective lens through the lens, reflector, and dichroic mirror for focusing. The converged laser is directly injected into the end of the multimode optical fiber. Diamond particles are glued to the other end of the multimode optical fiber, and the multimode optical fiber is fixed on the platform. Finally, the laser is transmitted by the multimode optical fiber to stimulate the evolution of the quantum state of the diamond NV color center.

[0066] Furthermore, an internal modulation pulse signal is set on the microwave source, and a microwave pulse signal is generated by the microwave source. The microwave pulse signal is then transmitted to the microwave switch, and amplitude modulation is performed by setting the switching ratio. A power amplifier is connected after the microwave switch to enhance the signal size, and finally the microwave pulse signal is transmitted to the antenna to radiate the microwave pulse signal to modulate the quantum state of the diamond NV color center.

[0067] Furthermore, under the alternating action of laser pulses and microwave pulses, the fluorescence signal emitted by the diamond NV color center is transmitted to the objective lens through a multimode optical fiber for focusing, and then transmits red light through a dichroic mirror, and then the fluorescence signal is collected by a photodetector. The curve of the fluorescence signal intensity obtained by the photodetector as a function of microwave frequency is called the optical detection magnetic resonance (ODMR) spectrum;

[0068] In order to prevent other light from entering, a colored filter was installed in front of it during the experiment to ensure that the collected signal was the fluorescence signal.

[0069] Figure 3Under the alternating action of laser pulses and microwave pulses, the ODMR spectra of diamond NV color centers without metal film on the surface and the ODMR spectra of diamond NV color centers with metal Ag film on the surface are obtained within the acquisition period. The ODMR spectrum shows that the fluorescence intensity of the diamond NV color center with metal microcavity structure detected by the photodetector is 2.86 times that of the diamond NV color center without metal microcavity structure;

[0070] like Figure 4 As shown, in this embodiment, the coating diameter of the multimode optical fiber is 243 μm, the core diameter is 105 μm, and the particle size of the diamond particles is 100 nm. Figure 4 In the experiment, compared with diamond particles with a particle size of micron, the coupling effect between diamond particles with a particle size of nanometer and optical fiber is average, the laser excitation efficiency is low and the fluorescence collection efficiency is low. The fluorescence intensity of the diamond NV color center with a particle size of micron detected by the photodetector is 5 times that of the diamond NV color center with a particle size of nanometer.

[0071] This shows that the present application significantly enhances the signal intensity detected by the photodetector. In addition, the contrast of the diamond NV color center ODMR spectrum with a metal microcavity structure is 1.02 times that of the diamond NV color center ODMR spectrum without a metal microcavity structure, and the half-maximum full width is 0.54 times that of the diamond NV color center ODMR spectrum without a metal microcavity structure, which shows that the present application realizes high-precision quantum information detection such as the spin characteristics of the NV color center, thereby effectively serving the ultra-high spatial resolution detection of the physical field.

[0072] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A quantum sensor based on fiber-type diamond NV color centers, characterized in that: include: Diamond particles: used to generate diamond NV color centers that emit fluorescence; Multimode optical fiber: used to carry diamond particles and transmit optical signals; The diamond particles and the multimode optical fiber are silver-plated on the surface to form a metal microcavity, and the metal microcavity is used to constrain light to circulate and converge in the cavity.

2. The quantum sensor based on fiber-type diamond NV color center according to claim 1, characterized in that: The diamond particles have a particle size of 1-100 μm.

3. The quantum sensor based on fiber-type diamond NV color center according to claim 1, characterized in that: The coating diameter of the multimode optical fiber is 200-1000 μm, and the core diameter is 50-800 μm.

4. A method for preparing a quantum sensor based on fiber-type diamond NV color center as claimed in any one of claims 1 to 3, characterized in that: include: S1. Cut the end face of the multimode optical fiber flatly, remove the coating layer of the multimode optical fiber 1-3 mm away from the end face to expose the fiber core, and use anhydrous ethanol to remove the residual coating layer on the surface of the fiber core; S2, applying UV curing glue to the end face of the multimode optical fiber, and placing diamond particles at the center of the end face of the multimode optical fiber; S3, use ultraviolet lamp to irradiate the end face of multimode optical fiber until the ultraviolet curing glue is completely cured; S4. The exposed fiber core and the surface of the diamond particles are coated with a metal Ag film to form a metal microcavity.

5. The method for preparing a quantum sensor based on fiber-type diamond NV color center according to claim 4, characterized in that: In S2, the UV curing adhesive is any one of acrylate UV curing adhesive, silicone UV curing adhesive and epoxy UV curing adhesive.

6. The method for preparing a quantum sensor based on fiber-type diamond NV color center according to claim 4, characterized in that: The S4 includes: S41, adding ammonia water dropwise to the AgNO3 solution until the precipitate is completely dissolved and becomes clear to obtain a silver ammonia solution; S42, hydrophilically modifying the multimode optical fiber having diamond particles fixed on the end face to obtain a modified multimode optical fiber; S43, placing the modified multimode optical fiber in a silver ammonia solution, and adding a reducing solution to the silver ammonia solution; S44. Let it stand until the surface of the multimode optical fiber has a metallic luster. Take out the multimode optical fiber and place it in an oven for drying. Then, coat the exposed fiber core and diamond surface with a metal Ag film.

7. The method for preparing a quantum sensor based on fiber-type diamond NV color center according to claim 6, characterized in that: The S42 includes: S421, placing a multimode optical fiber with diamond particles fixed on the end face in a chamber of a plasma cleaning machine; S422. Close the three-way valve of the plasma cleaning machine and turn on the vacuum pump to put the chamber in a negative pressure state; S423, opening the needle valve of the plasma cleaning machine to allow gas to flow in, and starting the plasma generator to clean the multimode optical fiber with diamond particles fixed on the end surface; S424, turn off the plasma generator, needle valve and vacuum pump in sequence, and evacuate the chamber to normal pressure to obtain the modified multimode optical fiber.

8. The method for preparing a quantum sensor based on fiber-type diamond NV color center according to claim 6, characterized in that: In the S43, the reducing solution is any one of 0.05 mL of a formaldehyde solution with a mass fraction of 40%, 0.15 mL of an acetaldehyde solution with a mass fraction of 20%, and 1 mL of a glucose solution with a mass fraction of 10%.

Images