Quantum sensor system

Abstract

This invention provides a quantum sensor system that offers a technology capable of suppressing the deterioration of the signal-to-noise ratio. [Solution] The quantum sensor system comprises: a high-frequency substrate having a first main surface and a second main surface, having a through hole formed between the first main surface and the second main surface, with a conductor pattern arranged around the through hole; an excitation light generating unit that irradiates excitation light from the first main surface side of the high-frequency substrate toward the through hole, irradiating excitation light to a sensor portion having a color center positioned to be exposed in the through hole when the high-frequency substrate is viewed in plan; and wiring having a contact portion that electrically connects to an electronic device, with the contact portion positioned to be shielded from excitation light by the high-frequency substrate.

Description

[Technical Field]

[0001] The technology disclosed herein relates to quantum sensor systems. [Background technology]

[0002] Development is underway on quantum sensor systems that detect physical quantities (e.g., magnetic fields, electric fields, temperature, or pressure) using optically detected magnetic resonance (ODMR). These quantum sensor systems detect physical quantities based on fluorescence emitted when a sensor element containing a color center is relaxed to its ground state, after excitation light has been shone onto the sensor element. Patent documents 1-4 disclose this type of quantum sensor system. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-162910 [Patent Document 2] Japanese Patent Publication No. 2020-063960 [Patent Document 3] Japanese Patent Publication No. 2022-098572 [Patent Document 4] Japanese Patent Publication No. 2024-147159 [Overview of the project] [Problems that the invention aims to solve]

[0004] To understand the electrical characteristics of an electronic device, or to monitor an electronic device, it is sometimes necessary to detect physical quantities around or inside the electronic device while it is in operation. To detect such physical quantities, wiring must be connected to electrodes on the top surface of the electronic device to supply power to the device, and the physical quantities must be detected while the electronic device is in operation. In such a configuration, there is a risk that excitation light may be reflected at the contact points of the wiring, causing noise. This specification provides a quantum sensor system for detecting physical quantities around or inside an electronic device while the electronic device is in operation, and a technique that can suppress deterioration of the signal-to-noise ratio. [Means for solving the problem]

[0005] The quantum sensor system disclosed herein may include: a high-frequency substrate having a first main surface and a second main surface, wherein a through hole is formed between the first main surface and the second main surface, and a conductor pattern is arranged around the through hole; an excitation light generating unit that irradiates excitation light from the first main surface side of the high-frequency substrate toward the through hole, and irradiates the excitation light to a sensor portion having a color center positioned to be exposed in the through hole when the high-frequency substrate is viewed in plan; and wiring having a contact portion that electrically connects to the electronic device, wherein the contact portion is positioned to be shielded from the excitation light by the high-frequency substrate. Here, the sensor portion may be separate from the electronic device or integrated with the electronic device.

[0006] In the quantum sensor system described above, the contact points of the wiring are positioned in a location shielded from the excitation light by the high-frequency substrate. As a result, the reflection of excitation light at the wiring contact points is suppressed. Consequently, the quantum sensor system can detect physical quantities around or inside an electronic device while the electronic device is in operation, while suppressing deterioration of the signal-to-noise ratio. [Brief explanation of the drawing]

[0007] [Figure 1] Figure illustrating the working principle for detecting physical quantities using photodetection magnetic resonance. [Figure 2] Figure schematically showing the configuration of a quantum sensor system. [Figure 3] Figure showing the schematic configuration of a quantum sensor according to one embodiment, in which (A) is a diagram schematically illustrating a plan view of the quantum sensor, (B) is a diagram schematically illustrating a cross-sectional view of the quantum sensor corresponding to line B-B in (A), and (C) is a diagram schematically illustrating a cross-sectional view of the quantum sensor corresponding to line C-C in (B). [Figure 4] Figure schematically showing a cross-sectional view of a quantum sensor according to one embodiment, illustrating a state when detecting a physical quantity of an electronic device. [Figure 5] Figure schematically showing a cross-sectional view of a quantum sensor according to a first modification, illustrating a state when detecting a physical quantity of an electronic device. [Figure 6] Figure schematically showing a cross-sectional view of a quantum sensor according to a second modification, illustrating a state when detecting a physical quantity of an electronic device. MODE FOR CARRYING OUT THE INVENTION

[0008] (Working Principle of Photodetection Magnetic Resonance) Before describing the configuration of the quantum sensor disclosed in the present specification, the working principle for detecting physical quantities using photodetection magnetic resonance will be described. Below, a case where the magnetic resonance material is diamond and the physical quantity to be measured is an external magnetic field will be described as an example.

[0009] Figure 1 shows the energy levels of an NV center composed of substitutional nitrogen and a vacancy in diamond. Electrons present in the NV center have m s = 0, +1, -1 electron spin triplet states. Electrons in the ground state are excited by 515 nm green excitation light. Electrons in the excited state are relaxed to the ground state via direct transition accompanied by 637 nm red light emission or indirect transition via a spin singlet state (i.e., a non-radiative process). m sElectrons in the state of =0 relax to the ground state via direct transition with a high probability. Meanwhile, m s =±1, the probability that electrons relax to the ground state via a non-radiative process is m s higher than that of electrons in the state of =0. Therefore, the ground state is m s electrons in the state of =0 have strong luminescence during relaxation, and when the ground state is m s electrons in the state of =±1 have weak luminescence during relaxation.

[0010] Here, when no external magnetic field is applied, as shown in Fig. 1(a), m s the states of =±1 electrons are degenerate. In this case, when the ground state of the electron is m s =0 to m s =±1, the resonance frequency is 2.87 GHz in all cases. Therefore, as shown in Fig. 1(c), f + =f - weak luminescence intensity is observed at this resonance frequency. Meanwhile, when an external magnetic field is applied, as shown in Fig. 1(b), m s =+1 and m s =-1, the degeneracy of the electron states is lifted by Zeeman splitting. In this case, when the ground state of the electron is m s =0 to m s =+1, the resonance frequency f + is higher than 2.87 GHz, and when the ground state of the electron is m s =0 to m s =-1, the resonance frequency f - is lower than 2.87 GHz. Therefore, as shown in Fig. 1(d), two resonance frequencies f + ,f - weak luminescence intensity is observed at each of them. The difference between the two resonance frequencies (f + -f - ) is proportional to the magnitude of the external magnetic field.

[0011] A quantum sensor using optically detected magnetic resonance measures the intensity of an external magnetic field based on the above-described operation principle. The quantum sensor irradiates green excitation light onto the nitrogen-vacancy centers (NV centers) in diamond while an external magnetic field is applied, sweeps microwaves, acquires the optically detected magnetic resonance (ODMR) spectrum of red fluorescence emitted from the NV centers, and measures the intensity of the external magnetic field based on the resonance frequency of the acquired ODMR spectrum. An embodiment of the quantum sensor based on the above operation principle will be described below. Note that even when the magnetic resonance material is a material other than diamond (for example, silicon carbide) and even when the physical quantity to be measured is a physical quantity other than an external magnetic field, the operation principle for detecting the physical quantity is the same. For example, when the physical quantity is temperature, a temperature change causes m s = 0 and m s = ±1, that is, a shift in the resonance frequency, so it can be measured in the same manner as an external magnetic field.

[0012] (Configuration of Quantum Sensor System) As shown in FIG. 2, the quantum sensor system 1 is a system that detects a physical quantity around or inside an electronic device such as a power device, for example, and includes a quantum sensor 10, an excitation light generation unit 20, a high-frequency signal generation unit 30, a light detection unit 40, a drive unit 50, and a control unit 60.

[0013] The quantum sensor 10 is a sensor element including a sensor unit containing a magnetic resonance material having color centers, as will be described later.

[0014] The excitation light generation unit 20 is configured to generate excitation light and irradiate the generated excitation light onto the sensor unit of the quantum sensor 10. The excitation light generation unit 20 may include a light source such as a light-emitting diode, for example.

[0015] The high-frequency signal generation unit 30 is configured to generate a high-frequency current for generating microwaves and supply the generated high-frequency current to the quantum sensor 10. The high-frequency signal generation unit 30 may include a high-frequency signal source or the like, for example.

[0016] The photodetector 40 is configured to detect fluorescence emitted from the color center. The photodetector 40 may include, for example, a photodetector such as a CCD camera.

[0017] The drive unit 50 is configured to supply power to drive the electronic device. The drive unit 50 may supply several hundred volts of power to the electronic device, for example, if the electronic device is a power device. The drive unit 50 may also supply gate signals to the electronic device to control the on / off state of the electronic device.

[0018] The control unit 60 controls the operation of the excitation light generation unit 20, the high-frequency signal generation unit 30, the photodetection unit 40, and the drive unit 50. The control unit 60 may be composed of a computer having, for example, memory and a control device. The memory stores a physical quantity detection program. The control device is composed of a microprocessor including a CPU or the like. The control device performs physical quantity detection processing by executing the physical quantity detection program.

[0019] As shown in Figure 3, the quantum sensor 10 includes a high-frequency substrate 12 and a sensor section 14 having a color center (i.e., an emission point defect).

[0020] The high-frequency substrate 12 is not particularly limited, but may be, for example, a multilayer printed circuit board. The high-frequency substrate 12 has a first main surface 12a and a second main surface 12b. The high-frequency substrate 12 has through holes 13 that penetrate between the first main surface 12a and the second main surface 12b. When the high-frequency substrate 12 is viewed from above, the shape of the through holes 13 is rectangular. Alternatively, the shape of the through holes 13 may be, for example, circular.

[0021] A microstrip antenna consisting of a signal line 15 and a ground line 16 is arranged on the high-frequency substrate 12. The signal line 15 and the ground line 16 are conductor patterns printed on different inner layers of the high-frequency substrate 12 and are embedded in the high-frequency substrate 12. The signal line 15 and the ground line 16 are not particularly limited, but may be metal foils such as copper or aluminum. The signal line 15 and the ground line 16 face each other in the stacking direction of the high-frequency substrate 12 and may be composed of conductor patterns of a common shape, not particularly limited.

[0022] The signal line 15 is located in the inner layer of the high-frequency substrate 12, closer to the first main surface 12a than the ground line 16, and loops around the through hole 13. The shape of the outer edge of the signal line 15, that is, the shape of the contour defining the outer edge of the signal line 15, may be similar in shape to the through hole 13 when the high-frequency substrate 12 is viewed from above. In this example, the through hole 13 is rectangular, and the shape of the outer edge of the signal line 15 is also rectangular. For example, if the through hole 13 is circular, the outer edge shape of the signal line 15 may also be circular. Alternatively, the shape of the through hole 13 and the shape of the outer edge of the signal line 15 may be different. A gap may be formed in the signal line 15 in the circumferential direction of the through hole 13. A high-frequency current generated by the high-frequency signal generation unit 30 is input to the signal line 15. The grounding line 16 is located in the inner layer of the high-frequency substrate 12, closer to the second main surface 12b than the signal line 15, and forms a loop around the through-hole 13. The grounding line 16 is fixed at GND potential. When a high-frequency current is input to the signal line 15, microwaves are irradiated onto the sensor unit 14. By controlling the high-frequency current, microwaves with adjusted frequencies are irradiated onto the sensor unit 14. If the outer edge of the signal line 15 is circular, the microstrip antenna composed of the signal line 15 and the grounding line 16 can generate circularly polarized microwaves within the through-hole 13, with the axial direction of the through-hole 13 as the propagation direction.

[0023] The high-frequency substrate 12 is further provided with positive electrode wiring 17 and negative electrode wiring 18. The positive electrode wiring 17 and negative electrode wiring 18 are conductive patterns printed on the second main surface 12b of the high-frequency substrate 12. Alternatively, the positive electrode wiring 17 and negative electrode wiring 18 may be a wiring board configured to be sandwiched between an electronic device (described later) and the second main surface 12b of the high-frequency substrate 12, and may be configured separately from the high-frequency substrate 12. The positive electrode wiring 17 and negative electrode wiring 18 are not particularly limited, but may be metal foils such as copper or aluminum.

[0024] The positive electrode wiring 17 has a positive electrode contact portion 17a located close to the through hole 13, and extends linearly from this positive electrode contact portion 17a toward the outer edge of the high-frequency substrate 12. The negative electrode wiring 18 also has a negative electrode contact portion 18a located close to the through hole 13, and extends linearly from this negative electrode contact portion 18a toward the outer edge of the high-frequency substrate 12. The direction in which the positive electrode wiring 17 extends toward the outer edge of the high-frequency substrate 12 from the positive electrode contact portion 17a is opposite to the direction in which the negative electrode wiring 18 extends toward the outer edge of the high-frequency substrate 12 from the negative electrode contact portion 18a. The positive electrode contact portion 17a of the positive electrode wiring 17 and the negative electrode contact portion 18a of the negative electrode wiring 18 are the parts that are electrically connected to electrodes on the upper surface of the electronic device, as will be described later. For this reason, the layout of the positive electrode wiring 17 and the negative electrode wiring 18 is appropriately adjusted according to the type of electronic device. Power supplied from the drive unit 50 is applied to the positive electrode wiring 17 and the negative electrode wiring 18.

[0025] The sensor portion 14 is a flat plate-shaped member made of a magnetic resonance material. The magnetic resonance material of the sensor portion 14 is not particularly limited, but may be, for example, diamond, silicon carbide (SiC), or hexagonal boron nitride (h-BN). The sensor portion 14 may be installed on an electronic device and positioned within the through-hole 13 of the high-frequency substrate 12, as will be described later. Alternatively, the sensor portion 14 may be fixed within the through-hole 13 of the high-frequency substrate 12 and be integrally formed with the high-frequency substrate 12. Furthermore, as will be described later, the sensor portion 14 may be a region having a color center formed inside the electronic device. In any case, the sensor portion 14 is positioned so as to be exposed within the through-hole 13 when the high-frequency substrate 12 is viewed from above.

[0026] Figure 4 shows how the quantum sensor system 1 detects a physical quantity of an electronic device 70. In this example, the electronic device 70 is a horizontal power device, and both electrodes 72 and 74 are provided on the upper surface of the electronic device 70. The sensor unit 14 is mounted on the upper surface of the electronic device 70, in an area affected by the magnetic field generated by the current flowing through the electronic device 70.

[0027] In the quantum sensor system 1, excitation light is irradiated from the first main surface 12a side of the high-frequency substrate 12 toward the through-hole 13, and the excitation light is input to the sensor part 14 exposed in the through-hole 13. Fluorescence emitted from the color center of the sensor part 14 also passes through the through-hole 13 of the high-frequency substrate 12. This example shows that both excitation light and fluorescence pass through the through-hole 13 of the high-frequency substrate 12. The optical path leading from the excitation light irradiated from the high-frequency signal generation unit 30 to the sensor part 14 and the optical path leading from the fluorescence emitted from the sensor part 14 to the photodetector 40 may be separated using an optical system such as a beam splitter. Alternatively, the photodetector 40 may be located on the second main surface 12b side of the high-frequency substrate 12 and configured to detect fluorescence that has passed through the electronic device 70.

[0028] The positive contact portion 17a of the positive electrode wiring 17 is electrically connected to the positive electrode 72 of the electronic device 70. The negative contact portion 18a of the negative electrode wiring 18 is electrically connected to the negative electrode 74 of the electronic device 70. These contact portions 17a, 18a and electrodes 72, 74 may be joined by, for example, solder, or they may simply be in contact.

[0029] The positive electrode contact portion 17a of the positive electrode wiring 17 is located on the second main surface 12b of the high-frequency substrate 12. Therefore, the positive electrode contact portion 17a of the positive electrode wiring 17 is positioned in a location that is shielded from excitation light by the high-frequency substrate 12. The negative electrode contact portion 18a of the negative electrode wiring 18 is also located on the second main surface 12b of the high-frequency substrate 12. Therefore, the negative electrode contact portion 18a of the negative electrode wiring 18 is also positioned in a location that is shielded from excitation light by the high-frequency substrate 12. As a result, the reflection of excitation light at the contact portions 17a and 18a of the wirings 17 and 18, which would cause noise, is suppressed.

[0030] The quantum sensor system 1 can determine the electrical characteristics of the electronic device 70 by measuring the magnetic field strength generated based on the current flowing through the electronic device 70. Since the reflection of excitation light at the contact portions 17a and 18a of the wiring 17 and 18 is suppressed, the quantum sensor system 1 can measure the magnetic field strength around the electronic device 70 while the electronic device 70 is in operation, while suppressing deterioration of the signal-to-noise ratio.

[0031] Furthermore, in the quantum sensor system 1, the sensor unit 14 is positioned within a through-hole 13 of the high-frequency substrate 12. Therefore, the distance between the microstrip antenna, composed of a signal line 15 and a ground line 16 arranged around the through-hole 13 of the high-frequency substrate 12, and the sensor unit 14 is short. As a result, microwaves are efficiently applied to the sensor unit 14 in the quantum sensor system 1. Additionally, since the signal line 15 and ground line 16 are embedded in the high-frequency substrate 12, the distance between the microstrip antenna and the sensor unit 14 is shorter compared to the case where they are provided on the first main surface 12a and the second main surface 12b of the high-frequency substrate 12. This allows for efficient application of microwaves to the sensor unit 14 in the quantum sensor system 1. Furthermore, in the quantum sensor system 1, wiring 17 and 18 are printed on the second main surface 12b of the high-frequency substrate 12. Therefore, the thickness of the contact portions 17a and 18a of the wiring 17 and 18 is small, and the sensor portion 14 installed on the upper surface of the electronic device 70 is positioned deep within the through-hole 13 of the high-frequency substrate 12. As a result, microwaves are efficiently applied to the sensor portion 14 in the quantum sensor system 1.

[0032] (First variation) In the example above, both electrodes 72 and 74 of the pair were provided on the upper surface of the electronic device 70. Alternatively, as shown in Figure 5, the electronic device 70 may be a vertical power device in which the positive electrode 72 is located on the lower surface of the electronic device 70 and the negative electrode 74 is located on the upper surface of the electronic device 70. Even in this case, since the negative contact portion 18a of the negative electrode wiring 18 is positioned to be shielded from excitation light by the high-frequency substrate 12, the reflection of excitation light at the negative contact portion 18a of the negative electrode wiring 18, which causes noise, is suppressed.

[0033] (Second variation) In the above example, the sensor unit 14 was installed on the upper surface of the electronic device 70. Alternatively, as shown in Figure 6, the sensor unit 14 may be located within the electronic device 70. For example, if the semiconductor material of the electronic device 70 is diamond or silicon carbide, the sensor unit 14 can be placed in the region of interest within the electronic device 70 by forming a color center within the electronic device 70. Furthermore, even if the semiconductor material of the electronic device 70 is silicon or the like, the sensor unit 14 can be placed in the region of interest within the electronic device 70 by forming a region of diamond or silicon carbide with a color center within the electronic device 70.

[0034] In this example, the high-frequency substrate 12 has a eaves portion 12c that protrudes into the through-hole 13. The eaves portion 12c is formed at the end of the through-hole 13, i.e., on the same plane as the first main surface 12a of the high-frequency substrate 12. Alternatively, the eaves portion 12c may be formed inside the through-hole 13, i.e., at a position on the inner circumferential surface defining the through-hole 13, away from the first main surface 12a and the second main surface 12b, respectively.

[0035] The contact portion 17a of the positive electrode wiring 17 is located on the back surface of the eaves portion 12c, which is shielded from excitation light. The positive electrode wiring 17 further has a positive electrode embedded portion 17b embedded in the high-frequency substrate 12, and is led out to the second main surface 12b of the high-frequency substrate 12 via this positive electrode embedded portion 17b. The contact portion 18a of the negative electrode wiring 18 is also located on the back surface of the eaves portion 12c, which is shielded from excitation light. The negative electrode wiring 18 further has a negative electrode embedded portion 18b embedded in the high-frequency substrate 12, and is led out to the second main surface 12b of the high-frequency substrate 12 via this negative electrode embedded portion 18b.

[0036] In this example, a portion of the electronic device 70 is inserted into the through-hole 13 of the high-frequency substrate 12, and a pair of electrodes 72 and 74 positioned on the upper surface of the electronic device 70 are electrically connected to the contact portions 17a and 18a of the wirings 17 and 18. By inserting a portion of the electronic device 70 into the through-hole 13 of the high-frequency substrate 12, the sensor portion 14 formed within the electronic device 70 can be positioned within the through-hole 13 of the high-frequency substrate 12. This allows microwaves to be efficiently applied to the sensor portion 14. Furthermore, since the contact portions 17a and 18a of the wirings 17 and 18 are positioned to be shielded from excitation light by the overhang portion 12c, the reflection of excitation light at the contact portions 17a and 18a of the wirings 17 and 18 is suppressed.

[0037] The following summarizes the features of the technology disclosed in this specification. Note that each of the technical elements described below is an independent technical element, and exhibits technical usefulness either individually or in various combinations.

[0038] (Aspect 1) It is a quantum sensor system, A high-frequency substrate having a first main surface and a second main surface, wherein a through hole is formed between the first main surface and the second main surface, and a conductor pattern is arranged around the through hole, An excitation light generating unit that irradiates excitation light from the first main surface side of the high-frequency substrate toward the through hole, wherein the excitation light irradiates the sensor portion having a color center positioned so as to be exposed in the through hole when the high-frequency substrate is viewed in plan, A quantum sensor system comprising: wiring having a contact portion that electrically connects to an electronic device, wherein the contact portion is positioned so as to be shielded from the excitation light by the high-frequency substrate.

[0039] (Aspect 2) The quantum sensor system according to embodiment 1, wherein the contact portion of the wiring is fixed to the second main surface of the high-frequency substrate.

[0040] (Aspect 3) The high-frequency substrate has a eaves portion that protrudes toward the through hole, The quantum sensor system according to embodiment 1, wherein the contact portion of the wiring is positioned to be shielded from the excitation light by the overhang portion.

[0041] (Aspect 4) The quantum sensor system according to any one of embodiments 1 to 3, wherein the conductor pattern is a microstrip antenna having a signal line and a ground line.

[0042] (Appendix 5) The conductor pattern is embedded in the high-frequency substrate, wherein the quantum sensor element is according to any one of embodiments 1 to 4.

[0043] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. Furthermore, the technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness. [Explanation of Symbols]

[0044] 1: Quantum sensor system, 10: Quantum sensor, 12: High-frequency substrate, 13: Through hole, 14: Sensor section, 15: Signal line, 16: Ground line, 17: Positive electrode wiring, 17a: Contact section, 18: Negative electrode wiring, 18a: Negative electrode contact section, 20: Excitation light generation section, 30: High-frequency signal generation section, 40: Photodetection section, 50: Drive section, 60: Control section, 70: Electronic device

Claims

1. It is a quantum sensor system, A high-frequency substrate having a first main surface and a second main surface, wherein a through hole is formed between the first main surface and the second main surface, and a conductor pattern is arranged around the through hole, An excitation light generating unit that irradiates excitation light from the first main surface side of the high-frequency substrate toward the through hole, wherein the excitation light irradiates the sensor portion having a color center positioned so as to be exposed in the through hole when the high-frequency substrate is viewed in plan, A quantum sensor system comprising: wiring having a contact portion that electrically connects to an electronic device, wherein the contact portion is positioned so as to be shielded from the excitation light by the high-frequency substrate.

2. The quantum sensor system according to claim 1, wherein the contact portion of the wiring is fixed to the second main surface of the high-frequency substrate.

3. The high-frequency substrate has a eaves portion that protrudes toward the through hole, The quantum sensor system according to claim 1, wherein the contact portion of the wiring is positioned to be shielded from the excitation light by the overhang portion.

4. The quantum sensor system according to claim 1, wherein the conductor pattern is a microstrip antenna having a signal line and a ground line.

5. The quantum sensor element according to any one of claims 1 to 4, wherein the conductor pattern is embedded in the high-frequency substrate.

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