Superconducting resonant circuit and measuring method

Abstract

To provide a superconducting resonant circuit that requires little time for the analysis of a dielectric loss, and a measuring method.SOLUTION: A superconducting resonant circuit comprises: a first superconducting circuit chip that has a readout waveguide, a concentrated constant-type inductor and a first concentrated constant-type capacitor electrode; a second superconducting circuit chip that has a second concentrated constant-type capacitor electrode facing the first concentrated constant-type capacitor electrode; and a motion mechanism capable of changing a between-electrodes distance between the first and second concentrated constant-type capacitor electrodes.SELECTED DRAWING: Figure 28

Description

[Technical field]

[0001] The present disclosure relates to superconducting resonant circuits and measurement methods. [Background technology]

[0002] It is known that superconducting resonant circuits are used in quantum devices. For example, Non-Patent Document 1 discloses a coplanar type superconducting resonator circuit. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] W. Woods, G. Calusine, A. Melville, A. Sevi, E. Golden, DK Kim, D. Rosenberg, JL Yoder, and WD Oliver Phys. Rev. Applied 12, 014012 ,Published 8 July 2019 Summary of the Invention [Problem to be solved by the invention]

[0004] In the superconducting resonant circuit disclosed in Non-Patent Document 1, the amount of loss in each insulating part, including the dielectric loss between the superconducting metal and air, is analyzed. However, the analysis method disclosed in Non-Patent Document 1 may require, for example, fabricating a large number of prototype superconducting resonant circuits, and the analysis of dielectric loss may take a long time.

[0005] An object of the present disclosure is to provide a superconducting resonant circuit that solves the above-mentioned problems. [Means for solving the problem]

[0006] A superconducting resonant circuit according to one embodiment of the present disclosure includes a first superconducting circuit chip having a readout waveguide, a lumped inductor, and a first lumped capacitor electrode, a second superconducting circuit chip having a second lumped capacitor electrode facing the first lumped capacitor electrode, and an operating mechanism capable of changing the inter-electrode distance between the first lumped capacitor electrode and the second lumped capacitor electrode.

[0007] A measurement method according to one aspect of the present disclosure includes a superconducting resonant circuit including a first superconducting circuit chip having a readout waveguide, a lumped inductor, and a first lumped capacitor electrode, and a second superconducting circuit chip having a second lumped capacitor electrode facing the first lumped capacitor electrode, and changes the inter-electrode distance between the first lumped capacitor electrode and the second lumped capacitor electrode, and measures the high-frequency response characteristics of the superconducting resonant circuit.

[0008] A superconducting resonant circuit according to one embodiment of the present disclosure includes a first superconducting circuit chip having a readout waveguide and a first lumped capacitor electrode, a second superconducting circuit chip having a lumped inductor and a second lumped capacitor electrode facing the first lumped capacitor electrode, and an operating mechanism capable of changing the inter-electrode distance between the first lumped capacitor electrode and the second lumped capacitor electrode.

[0009] A measurement method according to one aspect of the present disclosure includes a superconducting resonant circuit including a first superconducting circuit chip having a readout waveguide and a first lumped capacitor electrode, and a second superconducting circuit chip having a lumped inductor and a second lumped capacitor electrode facing the first lumped capacitor electrode, and changes the inter-electrode distance between the first lumped capacitor electrode and the second lumped capacitor electrode of the superconducting resonant circuit, and measures the high-frequency response characteristics of the superconducting resonant circuit. Effect of the Invention

[0010] According to the above aspect, the analysis of the dielectric loss does not take much time. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a partial cross-sectional front view illustrating an example of a superconducting resonant circuit according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a view taken along the line II-II in FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 2 is a view taken along line IV-IV in FIG. [Diagram 5] 5 is a cross-sectional view taken along line VV in FIG. 4. [Figure 6] FIG. 2 is a diagram illustrating an example of the operation of a superconducting resonant circuit according to the present disclosure. [Figure 7] 1 is a flowchart illustrating an example of a measurement method according to the present disclosure. [Figure 8] 1 is an equivalent circuit diagram showing an example of a superconducting resonant circuit according to the present disclosure. [Figure 9] 1 is a partial cross-sectional front view of an example of a superconducting resonant circuit according to the present disclosure. [Figure 10] FIG. 10 is a view taken along line XX in FIG. [Figure 11] 11 is a cross-sectional view taken along line XI-XI of FIG. 10. [Figure 12] 10 is a view taken along the line XII-XII in FIG. 9. [Figure 13] 13 is a cross-sectional view taken along line XIII-XIII in FIG. 12. [Figure 14] 1 is an equivalent circuit diagram showing an example of a superconducting resonant circuit according to the present disclosure. [Figure 15] 1 is a partial cross-sectional front view of an example of a superconducting resonant circuit according to the present disclosure. [Figure 16] 16 is a view taken along line XVI-XVI in FIG. 15. [Figure 17] FIG. 17 is a view taken along line XVII-XVII in FIG. 15. [Figure 18] 1 is an equivalent circuit diagram showing an example of a superconducting resonant circuit according to the present disclosure. [Figure 19]1 is a partial cross-sectional front view of an example of a superconducting resonant circuit according to the present disclosure. [Figure 20] This is a view taken along the line XX-XX in Figure 19. [Figure 21] FIG. 20 is a view taken along the line XXI-XXI of FIG. 19. [Figure 22] 1 is an equivalent circuit diagram showing an example of a superconducting resonant circuit according to the present disclosure. [Diagram 23] 1 is a partial cross-sectional front view of an example of a superconducting resonant circuit according to the present disclosure. [Figure 24] This is a view taken along the line XXIV-XXIV of Figure 23. [Diagram 25] This is a view taken along the line XXV-XXV of Figure 23. [Figure 26] 1 is an equivalent circuit diagram showing an example of a superconducting resonant circuit according to the present disclosure. [Figure 27] FIG. 27 is an enlarged view of part XXVII in FIG. 26. [Figure 28] 1 is a partial cross-sectional front view of an example of a superconducting resonant circuit according to the present disclosure. [Figure 29] 1 is a partial cross-sectional front view of an example of a superconducting resonant circuit according to the present disclosure. [Diagram 30] 1 is a flowchart illustrating an example of a measurement method according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Various embodiments according to the present disclosure will be described below with reference to the drawings.

[0013] <Embodiment> Hereinafter, an embodiment according to the present disclosure will be described with reference to FIGS.

[0014] (Configuration of superconducting resonant circuit) As shown in FIG. 1, a superconducting resonant circuit 9 includes a first superconducting circuit chip 1, a second superconducting circuit chip 2, and an operating mechanism 3. The first superconducting circuit chip 1 is a first superconducting circuit chip. The first superconducting circuit chip 1 and the second superconducting circuit chip 2 face each other in a facing direction Df. The superconducting resonant circuit 9 can move the first superconducting circuit chip 1 and the second superconducting circuit chip 2 closer to or farther away from each other by the operating mechanism 3 . For example, the superconducting resonant circuit 9 is an LC resonant circuit.

[0015] In the following, one of the opposing directions Df will also be referred to as the +Z direction, and the other as the -Z direction. Moreover, one of the first directions in a plane perpendicular to the facing direction Df is referred to as the +X direction, and the other is referred to as the -X direction. Moreover, one of the second directions in a plane perpendicular to the facing direction Df is referred to as a +Y direction, and the other is referred to as a -Y direction. For example, the ±Z directions, the ±X directions, and the ±Y directions may be perpendicular to each other. For example, the ±Z directions may be the up and down directions, and the XY plane may be the horizontal plane.

[0016] (Configuration of the first superconducting circuit chip) As shown in FIGS. 2 and 3, the first superconducting circuit chip 1 includes a readout waveguide 11, a lumped inductor 12, a first lumped capacitor electrode 13, a ground pattern 14, and a first substrate 15. The first superconducting circuit chip 1 includes a readout waveguide 11, a lumped inductor 12, a first lumped capacitor electrode 13, a ground pattern 14, and a first substrate 15.

[0017] The first substrate 15 has a first surface 15s on the +Z direction side as one of a pair of plate surfaces along the XY plane. For example, the first surface 15s is a plane. For example, the first substrate 15 may be made of an insulator. For example, the first substrate 15 may be a silicon substrate or a sapphire substrate.

[0018] For example, each of the readout waveguide 11, the lumped inductor 12, the first lumped capacitor electrode 13, and the ground pattern 14 may be configured as a thin film pattern along the XY plane. The readout waveguide 11, the lumped inductor 12, the first lumped capacitor electrode 13, and the ground pattern 14 are each provided on a first surface 15s of the first substrate 15. For example, each of the readout waveguide 11, the lumped inductor 12, the first lumped capacitor electrode 13, and the ground pattern 14 may be made of a superconducting metal. These superconducting metals may be materials that function as superconductors at cryogenic temperatures. These superconducting metals may be any of aluminum (Al), niobium (Nb), titanium nitride (TiN), and tantalum (Ta).

[0019] The readout waveguide 11 and the lumped inductor 12 are coupled to each other with respect to microwaves. For example, the readout waveguide 11 is a coplanar waveguide.

[0020] (Configuration of the second superconducting circuit chip) As shown in FIGS. 4 and 5, the second superconducting circuit chip 2 includes a second lumped capacitor electrode 23 and a second substrate 25. The first lumped capacitor electrode 13 and the second lumped capacitor electrode 23 face each other in a facing direction Df.

[0021] The second substrate 25 has, as a pair of plate surfaces along the XY plane, a second surface 25s on the -Z direction side and a third surface 25r on the +Z direction side. The second surface 25s faces the first surface 15s. For example, each of the second surface 25s and the third surface 25r is a plane. For example, the second substrate 25 may be made of an insulator. For example, the second substrate 25 may be a silicon substrate or a sapphire substrate.

[0022] The second lumped capacitor electrode 23 may be configured as a thin film pattern along the XY plane. A second lumped capacitor electrode 23 is provided on the second surface 25s. For example, the second lumped capacitor electrode 23 may be composed of a superconducting metal. These superconducting metals may be materials that function as superconductors at cryogenic temperatures. These superconducting metals may be any of aluminum (Al), niobium (Nb), titanium nitride (TiN), and tantalum (Ta).

[0023] (Configuration of Operation Mechanism 3) The operating mechanism 3 is capable of changing the inter-electrode distance AA between the first lumped capacitor electrode 13 and the second lumped capacitor electrode 23. For example, the operating mechanism 3 changes the inter-electrode distance AA by moving the second superconducting circuit chip 2 relative to the first superconducting circuit chip 1 in the facing direction Df.

[0024] As shown in FIG. 1, the operating mechanism 3 includes an actuator 31 and a fixing jig 32. The actuator 31 includes a rod 311 . The rods 311 extend in a counter direction Df. For example, the actuator 31 may be a piezoelectric actuator. The fixing jig 32 is fixed to the third surface 25 r of the second substrate 25 . For example, fixture 32 may be a copper plate attached to third surface 25r. The fixing jig 32 is fixed to the tip of the rod 311 . As a result, the actuator 31 can move the second superconducting circuit chip 2 in the facing direction Df via the fixing jig 32 by driving the rod 311 back and forth in the facing direction Df. Therefore, the actuator 31 can move the second superconducting circuit chip 2 closer to or farther away from the first superconducting circuit chip 1.

[0025] (Operation of superconducting resonant circuit) 6, the superconducting resonator circuit 9 can move the first superconducting circuit chip 1 and the second superconducting circuit chip 2 closer to or farther away from each other by the operating mechanism 3. This allows the inter-electrode distance AA between the first lumped capacitor electrode 13 and the second lumped capacitor electrode 23 to be changed. For example, by bringing the first superconducting circuit chip 1 and the second superconducting circuit chip 2 close to each other, a capacitor is formed between the first lumped capacitor electrode 13 and the second lumped capacitor electrode 23, and a resonance mode is created together with the inductor formed on the first superconducting circuit chip 1. The loss resulting from TLS, which will be described later, is defined as the sum of the loss tangent (tan δ) of each loss source multiplied by a value representing the weight and a participation ratio.

[0026] (Measurement method) The measurement method of this embodiment will be described below. The measurement method of this embodiment is a method for measuring the high-frequency response characteristics of the superconducting resonant circuit 9.

[0027] As shown in FIG. 7, first, the measurer installs the superconducting resonant circuit 9 in the dilution refrigerator (ST01).

[0028] Following execution of ST01, the measurer drives the actuator 31 to change the inter-electrode distance AA between the first lumped capacitor electrode 13 and the second lumped capacitor electrode 23 (ST02). At that time, the measurer may measure, as an initial value, the high-frequency transmission characteristics of the superconducting resonant circuit 9 before changing the inter-electrode distance AA.

[0029] Following the execution of ST02, the measurer measures the high-frequency transmission characteristics of the superconducting resonant circuit 9 at the changed inter-electrode distance AA (ST03). In addition, the measurer determines the Q TLS Identify. After performing ST03, the measurer returns to ST02, thereby repeatedly performing ST02 and ST03 multiple times.

[0030] On the other hand, the measurer calculates the participation ratio (described later) for different inter-electrode distances AA by electromagnetic field simulation (ST04).

[0031] After repeating ST02 and ST03 and performing ST04, the examiner performs the Q TLS From the participation ratio and the number of measurements repeated, the amount of loss is calculated (ST05).

[0032] Following the implementation of ST05, the examiner measures the Q TLS and fitting is performed using the participation ratio. The multiple loss quantities extracted in ST04 include Q TLS Since there is variation due to measurement errors, by performing such fitting, the loss amount of the MA loss source described later can be calculated with high accuracy.

[0033] (Action and Effects) According to the superconducting resonator circuit 9 of the present embodiment, the inter-electrode distance AA can be changed, and therefore the capacitance of the capacitor formed by the first lumped capacitor electrode 13 and the second lumped capacitor electrode 23 can be changed. Therefore, the high frequency response characteristics of the superconducting resonator circuit 9 can be measured by changing the capacitance value. Therefore, when the superconducting resonant circuit 9 is used, analysis of the dielectric loss does not take much time.

[0034] According to an example of the superconducting resonant circuit 9 of this embodiment, the measurer can extract the amount of loss with high accuracy as follows.

[0035] The coherence (energy relaxation time, internal Q value) of superconducting quantum circuits is largely due to the dielectric loss called the Two level system (TLS). On the other hand, a method called Surface loss extraction (SLE) makes it possible to quantitatively extract the loss of superconducting resonant circuits. The power dependence of the internal Q of coplanar resonators with different cross sections shows that the TLS loss (Fδ TLS ) can be obtained. As a comparative example, there is a method in which the shape of a measured resonator is reproduced in CAD (Computer Aided Design) based on a cross-section of the measured resonator taken with a SEM (Scanning Electron Microscope), and possible loss sources that may exist on the device are embedded in the CAD design. Here, it is believed that there are four possible sources of loss: between the superconducting metal and substrate (MS), between the substrate and air (SA), between the superconducting metal and air (MA), and within the bulk substrate (Sub). Therefore, according to the method of this comparative example, the amount of loss in each insulating part can be extracted from the ratio of energy stored in each insulating part obtained from the electromagnetic field simulation and the internal Q value derived from the TLS obtained from the measurement. However, in order to extract the loss of a prototype superconducting resonator using the analysis method of this comparative example, there are problems in that it is necessary to measure a large number of resonators and that it takes a long time to prototype the device. The main reason is that the Q value obtained from this loss extraction experiment has fluctuations. Another reason is that the loss is obtained from the participation ratio, which represents the weight of how much electrostatic energy is stored in the insulating part obtained from the electromagnetic field simulation, but due to the structure of the device, it is a big challenge to calculate the participation ratio with high accuracy. The uncertainty of these Q values ​​and participation ratios greatly affects the uncertainty of the obtained loss.

[0036] In contrast, the superconducting resonant circuit 9 of this embodiment makes it easier to extract with high accuracy only the loss between the superconducting metal and air, which is considered to have the largest contribution among the four losses. This method is expected to improve the accuracy of the electromagnetic field simulation because it simplifies the structure of the resonator. In addition, the use of the actuator 31 makes it possible to change the geometry of a single device, enabling the extraction of the loss amount with high accuracy. Therefore, it is possible to extract the amount of loss with high accuracy. In addition, by being able to extract the amount of loss between the superconducting metal and the air with higher accuracy, the measurer can also accurately calculate the participation ratio between the superconducting metal and the air.

[0037] According to an example of the superconducting resonant circuit 9 of this embodiment, the measurer can easily measure the high-frequency response characteristics over different inter-electrode distances AA, as described below.

[0038] In the loss extraction by SLE, it is necessary to measure many resonators designed to emphasize each insulating part with different cross sections. The reason why many resonator measurements are required is that there is a fluctuation in the internal Q value between each resonator device. As disclosed in Non-Patent Document 1, the inverse of the internal Q value derived from TLS is the participation ratio P determined by the geometry of the device in each insulating part (MS, SA, MA, Sub). i and the loss amount x i The reciprocal of the internal Q value is determined by the sum of the products of (a) and (b). Specifically, the reciprocal of the internal Q value is expressed by the following formula (1).

[0039]

number

[0040] Here, i represents each insulating part (MS, SA, MA, Sub). And the participation ratio is the electrostatic energy U i and the electrostatic energy U stored in the entire device space tot Ratio (U i / U tot ) is defined as follows. A 4 × 4 matrix can be created from the participation ratios of four devices with different cross sections and fabricated so that each insulating part is emphasized. If the devices are fabricated so that each cross section is well emphasized, this participation ratio matrix approaches linear independence. The 1 / Q matrix obtained from the experiment on the left side of equation (1) is TLSBy measuring four resonators with different geometries, a [4 × 1] matrix can be constructed. By solving the inverse problem of the simultaneous equations above, it is possible to extract the amount of loss in each insulating part. However, the TLS-derived Q value Q on the left side of Eq. (1) TLS Since there are fluctuations between devices, it is necessary to measure a large number of resonators with four different cross sections to reflect a more accurate Q value.

[0041] In contrast, according to the superconducting resonant circuit 9 of this embodiment, the inter-electrode distance AA can be changed, so that the measurer can easily measure the high-frequency response characteristics over different inter-electrode distances AA. In addition, by decreasing the interval of the inter-electrode distance AA at which the measurement is performed, the measurer is able to extract the amount of loss at the superconducting metal-air (vacuum) interface with high precision.

[0042] According to an example of the superconducting resonant circuit 9 of this embodiment, the measurer can easily extract the amount of loss in the superconducting metal-air (MA) insulation portion, as described below. For example, in comparison with a two-dimensional coplanar resonator, the electrostatic energy of a resonant circuit using a parallel plate capacitor such as the superconducting resonant circuit 9 of this embodiment is mainly stored in the air and the superconducting metal / air (Metal / Air) interface, while the electrostatic energy stored in the superconducting metal-substrate (MS) interface, substrate-air (SA) interface, and substrate (Sub) can be ignored. If an LC resonant circuit is constructed from two chips, such as the superconducting resonant circuit 9 of this embodiment, the electric field density at the MA interface can be changed by changing the distance between the chips, making it possible to probe the change in the amount of loss at the MA interface using a single device without fabricating elements at multiple levels. For this reason, the superconducting resonant circuit 9 makes it easy for the measurer to extract the amount of loss in the superconducting metal-air (MA) insulation.

[0043] According to an example of the superconducting resonant circuit 9 of this embodiment, the measurer can calculate the internal Q value of the superconducting resonant circuit 9 as follows.

[0044] In the superconducting resonant circuit 9 of this embodiment, the inter-electrode distance AA can be changed by the actuator 31, so that the measurer can change the capacitance between the first lumped capacitor electrode 13 and the second lumped capacitor electrode 23. As a result, the electric field density at the superconducting metal-air (MA) interface changes, and thus the participation ratio changes. In actual measurements, the change in the distance between the electrodes changes the electrostatic energy stored in the insulating layer at the superconducting metal-air (vacuum) interface, which changes the internal Q value of the measurement. In measuring a superconducting resonator, the internal Q value, which represents the loss of the superconducting resonator, cannot be obtained directly because the resonator is connected to the outside world (waveguide). On the other hand, the amplitude and phase of the high-frequency transmission characteristic S21 and high-frequency reflection characteristic S11 of the response of the resonator, whose high-frequency transmission characteristic S21 and high-frequency reflection characteristic S11 are measured, change depending on how strongly the waveguide and the resonator are coupled. The external Q value is defined as an index that represents the strength of the coupling between the waveguide and the resonator.

[0045] In contrast, the superconducting resonant circuit 9 of this embodiment functions as an LC resonant circuit as shown in FIG. Therefore, the readout waveguide 11 and the lumped inductor 12 are connected to the outside of the superconducting resonator circuit 9 via their mutual inductance. Therefore, a measurer can measure the high frequency response characteristics of the superconducting resonator circuit 9 from outside the superconducting resonator circuit 9 by inputting and outputting high frequency waves to and from the readout waveguide 11 . As a result, the person making the measurement can measure the high-frequency response characteristics (e.g., high-frequency transmission characteristics S21) of the superconducting resonant circuit 9 from outside the superconducting resonant circuit 9 and calculate the internal Q value of the superconducting resonant circuit 9 by fitting the measured high-frequency response characteristics.

[0046] The internal Q values ​​of different superconducting resonator circuits 9 may be measured a number of times to enable accurate extraction of the statistical properties (median and variance of the internal Q values) of the measured internal Q values. The amount of loss may also be extracted using the internal Q value between different superconducting resonator circuits 9 and a participation ratio calculated from an electromagnetic field simulation.

[0047] According to one example of the superconducting resonant circuit 9 of this embodiment, the second superconducting circuit chip 2 is moved relative to the first superconducting circuit chip 1 in the facing direction Df, thereby changing the inter-electrode distance AA. As a result, the movement distance of the second superconducting circuit chip 2 corresponds to the change in the inter-electrode distance AA. This makes it easy for the measurer to set the desired inter-electrode distance AA.

[0048] According to one example of the superconducting resonant circuit 9 of this embodiment, the operating mechanism 3 includes a piezoelectric actuator. This makes it easy for the person measuring to set the inter-electrode distance AA in small increments.

[0049] According to one example of the superconducting resonator circuit 9 of this embodiment, the readout waveguide 11 and the lumped inductor 12 are coupled to each other. This allows the person making the measurement to measure the high-frequency response characteristics of the superconducting resonator circuit 9 through the readout waveguide 11 . This makes it easy for the person making the measurements to measure the high-frequency response characteristics of the superconducting resonant circuit 9.

[0050] In one example of this embodiment, the readout waveguide 11 is a coplanar waveguide. This makes it easy for the person making the measurements to measure the high frequency response characteristics of the superconducting resonant circuit 9 to microwaves.

[0051] (First Modification) As a first modification, the superconducting resonant circuit 9 may be configured as a superconducting resonant circuit 9A shown in FIGS. Compared to the superconducting resonator circuit 9, the superconducting resonator circuit 9A differs in that it is coupled to the readout waveguide via a capacitor rather than via an inductor, but has the same configuration as the superconducting resonator circuit 9, operates in the same way, performs the same measurement method, and provides the same effects.

[0052] As shown in FIG. 9, a superconducting resonant circuit 9A includes a first superconducting circuit chip 1A, a second superconducting circuit chip 2A, and an operating mechanism 3. The first superconducting circuit chip 1A is a first superconducting circuit chip, and a second superconducting circuit chip 2A is a second superconducting circuit chip. As shown in FIGS. 10 and 11, the first superconducting circuit chip 1A includes a readout waveguide 11A, a lumped inductor 12A, a first lumped capacitor electrode 13A, a ground pattern 14, and a first substrate 15. As shown in FIG. The readout waveguide 11A and the first lumped capacitor electrode 13A are coupled to each other with respect to microwaves. As shown in FIGS. 12 and 13, the second superconducting circuit chip 2A includes a second lumped constant capacitor electrode 23A and a second substrate 25. The second superconducting circuit chip 2A includes a second lumped constant capacitor electrode 23A and a second substrate 25. As shown in FIG. The first lumped capacitor electrode 13A and the second lumped capacitor electrode 23A face each other in a facing direction Df. The superconducting resonant circuit 9A of this modification functions as an LC resonant circuit as shown in FIG.

[0053] The superconducting resonator circuit 9A of this modification also allows the inter-electrode distance to be changed, making it possible to change the capacitance of the capacitor formed by the first lumped capacitor electrode 13A and the second lumped capacitor electrode 23A. Therefore, the high frequency response characteristics of the superconducting resonator circuit 9A can be measured by changing the capacitance value. Therefore, with the superconducting resonant circuit 9A, analysis of dielectric loss does not take much time.

[0054] (Second Modification) As a second modified example, the superconducting resonant circuit 9 may be configured as a superconducting resonant circuit 9B shown in FIGS. The superconducting resonator circuit 9B is a circuit including a reflection-type waveguide, a lumped-element capacitor electrode, and a lumped-element inductor, and differs from the superconducting resonator circuit 9 in that the magnitude of the coupling measured changes as the distance between the electrodes changes. This allows the superconducting resonator circuit 9B to extract the amount of loss from the change in the external Q value, not the change in the internal Q value. Other than this, the superconducting resonator circuit 9B has the same configuration as the superconducting resonator circuit 9, operates in the same way, is measured in the same way, and provides the same effects.

[0055] As shown in Fig. 15, a superconducting resonant circuit 9B includes a first superconducting circuit chip 1B, a second superconducting circuit chip 2B, and an operating mechanism 3. Here, the first superconducting circuit chip 1B in Fig. 15 shows a cross section taken along line XV-XV in Fig. 16. Moreover, the second superconducting circuit chip 2B in Fig. 15 shows a cross section taken along line XV-XV in Fig. 17. As shown in FIG. 16, the first superconducting circuit chip 1B includes a readout waveguide 11B, a first lumped capacitor electrode 13B, a ground pattern 14, and a first substrate 15. The first superconducting circuit chip 1B includes a readout waveguide 11B, a first lumped capacitor electrode 13B, a ground pattern 14, and a first substrate 15. The readout waveguide 11B and the first lumped capacitor electrode 13B are in a pattern that is continuously connected, whereby the readout waveguide 11B and the first lumped capacitor electrode 13B are coupled to each other with respect to microwaves. For example, the readout waveguide 11B may be a coplanar waveguide as shown in FIG. As shown in FIG. 17, the second superconducting circuit chip 2B includes a lumped inductor 22B, a second lumped capacitor electrode 23B, and a second substrate 25. The second superconducting circuit chip 2B includes a lumped inductor 22B, a second lumped capacitor electrode 23B, and a second substrate 25. The first lumped capacitor electrode 13B and the second lumped capacitor electrode 23B face each other in a facing direction Df. The superconducting resonant circuit 9B of this modification functions as an LC resonant circuit as shown in FIG.

[0056] The superconducting resonator circuit 9B of this modification also allows the inter-electrode distance to be changed, making it possible to change the capacitance of the capacitor formed by the first lumped capacitor electrode 13B and the second lumped capacitor electrode 23B. Therefore, the high frequency response characteristics of the superconducting resonator circuit 9B can be measured by changing the capacitance value. Therefore, with the superconducting resonant circuit 9B, analysis of the dielectric loss does not take much time.

[0057] (Third Modification) As a third modified example, the superconducting resonant circuit 9 may be configured as a superconducting resonant circuit 9C shown in Figs. In contrast to the superconducting resonator circuit 9, the superconducting resonator circuit 9C is a type of circuit in which one of the lumped constant capacitor electrodes is grounded. Apart from this difference, the superconducting resonator circuit 9C has the same configuration as the superconducting resonator circuit 9, operates in the same way, is measured in the same way, and provides the same effects.

[0058] As shown in FIG. 19, a superconducting resonant circuit 9C includes a first superconducting circuit chip 1, a second superconducting circuit chip 2C, and an operating mechanism 3. The first superconducting circuit chip 1C includes a first superconducting circuit chip 1C, a second superconducting circuit chip 2C, and an operating mechanism 3C. As shown in Figure 20, the first superconducting circuit chip 1, similar to the first superconducting circuit chip 1 shown in Figures 2 and 3, comprises a readout waveguide 11, a lumped inductor 12, a first lumped capacitor electrode 13, a ground pattern 14, and a first substrate 15. As shown in FIGS. 19 and 21, the second superconducting circuit chip 2C includes a second lumped constant capacitor electrode 23C and a second substrate 25. The second superconducting circuit chip 2C includes a second lumped constant capacitor electrode 23C and a second substrate 25. As shown in FIG. The first lumped capacitor electrode 13 and the second lumped capacitor electrode 23C face each other in a facing direction Df. The superconducting resonant circuit 9C of this modification functions as an LC resonant circuit as shown in FIG.

[0059] The superconducting resonator circuit 9C of this modified example also allows the inter-electrode distance to be changed, making it possible to change the capacitance of the capacitor formed by the first lumped capacitor electrode 13 and the second lumped capacitor electrode 23C. Therefore, the high frequency response characteristics of the superconducting resonator circuit 9C can be measured by changing the capacitance value. Therefore, with the superconducting resonant circuit 9C, analysis of the dielectric loss does not take much time.

[0060] (Fourth Modification) The superconducting resonant circuit 9 may be configured as a superconducting resonant circuit 9D shown in Figs. 23 to 27 as a fourth modified example. In contrast to the superconducting resonator circuit 9, the superconducting resonator circuit 9D has two electrodes with different potentials as one electrode constituting a capacitor, and two electrodes arranged to be paired with each of the two electrodes as the other electrode constituting a capacitor. With this configuration, by increasing the distance between the electrodes (d in FIG. 27 described later), the capacitor formed between the two electrodes becomes dominant, making it possible to consider only the contribution of the electrostatic energy stored between the superconducting metal and air (vacuum). Apart from these differences, the superconducting resonator circuit 9D has the same configuration as the superconducting resonator circuit 9, operates in the same way, is measured in the same way, and provides the same effects.

[0061] As shown in FIG. 23, a superconducting resonator circuit 9D includes a first superconducting circuit chip 1D, a second superconducting circuit chip 2D, and an operating mechanism 3. The first superconducting circuit chip 1D is a first superconducting circuit chip, and a second superconducting circuit chip 2D is a second superconducting circuit chip. As shown in FIG. 24, the first superconducting circuit chip 1D includes a readout waveguide 11, a lumped inductor 12D, two first lumped capacitor electrodes 13D, a ground pattern 14 as a first ground pattern, and a first substrate 15. One of the two first lumped capacitor electrodes 13D is continuously connected to one of both ends of the pattern of the lumped inductor 12D. The other of the two first lumped capacitor electrodes 13D is continuously connected to the other of both ends of the pattern of the lumped inductor 12D. As shown in FIG. 25, a second superconducting circuit chip 2D includes two second lumped capacitor electrodes 23D, a second ground pattern 24D, and a second substrate 25. The second superconducting circuit chip 2D includes two second lumped capacitor electrodes 23D, a second ground pattern 24D, and a second substrate 25. Each of the first lumped capacitor electrodes 13D faces a corresponding second lumped capacitor electrode 23D in a one-to-one relationship in the facing direction Df. A superconducting resonant circuit 9D of this modified example functions as an LC resonant circuit as shown in FIGS.

[0062] The superconducting resonator circuit 9D of this modification also allows the inter-electrode distance to be changed, making it possible to change the capacitance of the capacitor formed by the first lumped capacitor electrode 13D and the second lumped capacitor electrode 23D. Therefore, the high frequency response characteristics of the superconducting resonator circuit 9D can be measured by changing the capacitance value. Therefore, with the superconducting resonant circuit 9D, analysis of dielectric loss does not take much time.

[0063] (Other variations) In one example and each variant of this embodiment, the operating mechanism moves the second superconducting circuit chip relative to the first superconducting circuit chip, but the operating mechanism may be configured in any manner as long as it is capable of moving one of the first superconducting circuit chip and the second superconducting circuit chip relative to the other. Alternatively, the movement mechanism may change the inter-electrode distance by moving the first superconducting circuit chip relative to the second superconducting circuit chip.

[0064] In this example and each variation of this embodiment, the readout waveguide is a coplanar waveguide, however, the readout waveguide may be configured in any manner that allows transmission of the readout microwaves. Alternatively, the readout waveguide may be a microstrip line, a stripline, or a coaxial line.

[0065] In one example and each variant of this embodiment, the measurer measures the high-frequency transmission characteristics as the high-frequency response characteristics of the superconducting resonant circuit, but the measurer may measure any high-frequency response characteristics as long as the high-frequency response characteristics of the superconducting resonant circuit can be measured. As a modification, the measurer may measure the high-frequency reflection characteristic as the high-frequency response characteristic of the superconducting resonant circuit.

[0066] <Embodiment of the first minimum configuration of the superconducting resonant circuit> Hereinafter, an embodiment of a first minimum configuration of a superconducting resonant circuit according to the present disclosure will be described with reference to FIG.

[0067] (composition) The superconducting resonant circuit 809 includes a first superconducting circuit chip 801 , a second superconducting circuit chip 802 , and an operating mechanism 803 . The first superconducting circuit chip 801 includes a readout waveguide 811 , a lumped inductor 812 , and a first lumped capacitor electrode 813 . The second superconducting circuit chip 802 includes a second lumped capacitor electrode 823 . The second lumped capacitor electrode 823 faces the first lumped capacitor electrode 813 . The operating mechanism 803 is capable of changing the inter-electrode distance between the first lumped capacitor electrode 813 and the second lumped capacitor electrode 823 .

[0068] (Action and Effects) According to the superconducting resonator circuit 809 of this embodiment, the distance between the electrodes can be changed, and therefore the capacitance of the capacitor formed by the first lumped capacitor electrode 813 and the second lumped capacitor electrode 823 can be changed. Therefore, the high frequency response characteristics of the superconducting resonant circuit 809 can be measured by changing the capacitance value. Therefore, with the superconducting resonant circuit 809, analysis of dielectric loss does not take much time.

[0069] <Embodiment of the second minimum configuration of the superconducting resonant circuit> Hereinafter, an embodiment of the second minimum configuration of a superconducting resonant circuit according to the present disclosure will be described with reference to FIG.

[0070] (composition) The superconducting resonant circuit 909 includes a first superconducting circuit chip 901 , a second superconducting circuit chip 902 , and an operating mechanism 903 . The first superconducting circuit chip 901 includes a readout waveguide 911 and a first lumped capacitor electrode 913 . Second superconducting circuit chip 902 includes a lumped inductor 922 and a second lumped capacitor electrode 923 . The second lumped capacitor electrode 923 faces the first lumped capacitor electrode 913 . The operating mechanism 903 is capable of changing the inter-electrode distance between the first lumped capacitor electrode 913 and the second lumped capacitor electrode 923 .

[0071] (Action and Effects) According to the superconducting resonator circuit 909 of this embodiment, the inter-electrode distance can be changed, and therefore the capacitance of the capacitor formed by the first lumped capacitor electrode 913 and the second lumped capacitor electrode 923 can be changed. Therefore, the high frequency response characteristics of the superconducting resonator circuit 909 can be measured by changing the capacitance value. Therefore, when the superconducting resonant circuit 909 is used, analysis of the dielectric loss does not take much time.

[0072] <Embodiment of the first minimum configuration of the measurement method> Hereinafter, an embodiment of a first minimum configuration of the measurement method according to the present disclosure will be described with reference to FIG.

[0073] (composition) The measurement method of this embodiment includes a first superconducting circuit chip having a readout waveguide, a lumped inductor, and a first lumped capacitor electrode, and a second superconducting circuit chip having a second lumped capacitor electrode facing the first lumped capacitor electrode, and the inter-electrode distance between a first lumped capacitor electrode and a second lumped capacitor electrode is changed (ST801), and the high-frequency response characteristics of the superconducting resonant circuit are measured (ST802).

[0074] (Action and Effects) According to the measurement method of this embodiment, the inter-electrode distance can be changed, and therefore the capacitance of the capacitor constituted by the first lumped capacitor electrode and the second lumped capacitor electrode can be changed. Therefore, the high frequency response characteristics of the superconducting resonator circuit can be measured by changing the capacitance value. Therefore, according to the measurement method of this embodiment, the analysis of the dielectric loss does not take much time.

[0075] <Embodiment of the second minimum configuration of the measurement method> Hereinafter, an embodiment of the second minimum configuration of the measurement method according to the present disclosure will be described with reference to FIG.

[0076] (composition) The measurement method of this embodiment includes a first superconducting circuit chip having a readout waveguide and a first lumped capacitor electrode, and a second superconducting circuit chip having a lumped inductor and a second lumped capacitor electrode facing the first lumped capacitor electrode, and changes the inter-electrode distance between a first lumped capacitor electrode and a second lumped capacitor electrode (ST901), and measures the high-frequency response characteristics of the superconducting resonant circuit (ST902).

[0077] (Action and Effects) According to the measurement method of this embodiment, the inter-electrode distance can be changed, and therefore the capacitance of the capacitor constituted by the first lumped capacitor electrode and the second lumped capacitor electrode can be changed. Therefore, the high frequency response characteristics of the superconducting resonator circuit can be measured by changing the capacitance value. Therefore, according to the measurement method of this embodiment, the analysis of the dielectric loss does not take much time.

[0078] Although the embodiment of the present disclosure has been described above, this embodiment is shown as an example and is not intended to limit the scope of the present disclosure. This embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the present disclosure.

[0079] A part or all of the above-described embodiments may be described as, but is not limited to, the following supplementary notes.

[0080] (Appendix 1) a first superconducting circuit chip having a readout waveguide, a lumped inductor, and a first lumped capacitor electrode; a second superconducting circuit chip having a second lumped capacitor electrode facing the first lumped capacitor electrode; an operating mechanism capable of changing an inter-electrode distance between the first lumped capacitor electrode and the second lumped capacitor electrode; Equipped Superconducting resonant circuit.

[0081] (Appendix 2) The operating mechanism changes the inter-electrode distance by moving one of the first superconducting circuit chip and the second superconducting circuit chip relative to the other in a direction in which the first lumped capacitor electrode and the second lumped capacitor electrode face each other. 2. The superconducting resonant circuit of claim 1.

[0082] (Appendix 3) The operating mechanism includes a piezoelectric actuator. 3. The superconducting resonant circuit according to claim 1 or 2.

[0083] (Appendix 4) The readout waveguide and the lumped inductor are coupled together. 4. The superconducting resonant circuit of claim 1.

[0084] (Appendix 5) The readout waveguide and the first lumped capacitor electrode are coupled together. 5. The superconducting resonant circuit of claim 1.

[0085] (Appendix 6) The readout waveguide is a coplanar waveguide. 6. The superconducting resonant circuit of claim 1.

[0086] (Appendix 7) a first superconducting circuit chip having a readout waveguide, a lumped inductor, and a first lumped capacitor electrode, and a second superconducting circuit chip having a second lumped capacitor electrode facing the first lumped capacitor electrode, the inter-electrode distance between the first lumped capacitor electrode and the second lumped capacitor electrode being changed; Measure the high frequency response characteristics of the superconducting resonant circuit Measurement method.

[0087] (Appendix 8) A loss amount of the superconducting resonant circuit is extracted based on the high frequency response characteristic. Measurement method described in Appendix 7.

[0088] (Appendix 9) The inter-electrode distance is changed by moving one of the first superconducting circuit chip and the second superconducting circuit chip relative to the other in a direction in which the first lumped capacitor electrode and the second lumped capacitor electrode face each other. The measurement method described in Appendix 7 or 8.

[0089] (Appendix 10) The readout waveguide and the lumped inductor are coupled together. A measurement method according to any one of appendix 7 to 9.

[0090] (Appendix 11) The readout waveguide and the first lumped capacitor electrode are coupled together. 11. The measurement method according to any one of claims 7 to 10.

[0091] (Appendix 12) The readout waveguide is a coplanar waveguide. 12. The measurement method according to any one of claims 7 to 11.

[0092] (Appendix 13) a first superconducting circuit chip having a readout waveguide and a first lumped capacitor electrode; a second superconducting circuit chip having a lumped inductor and a second lumped capacitor electrode facing the first lumped capacitor electrode; an operating mechanism capable of changing an inter-electrode distance between the first lumped capacitor electrode and the second lumped capacitor electrode; Equipped Superconducting resonant circuit.

[0093] (Appendix 14) The operating mechanism changes the inter-electrode distance by moving one of the first superconducting circuit chip and the second superconducting circuit chip relative to the other in a direction in which the first lumped capacitor electrode and the second lumped capacitor electrode face each other. 14. The superconducting resonant circuit of claim 13.

[0094] (Appendix 15) The operating mechanism includes a piezoelectric actuator. 15. The superconducting resonant circuit according to claim 13 or 14.

[0095] (Appendix 16) The readout waveguide and the first lumped capacitor electrode are coupled together. 16. The superconducting resonant circuit of any one of appendix 13 to 15.

[0096] (Appendix 17) The readout waveguide is a coplanar waveguide. 17. The superconducting resonant circuit of any one of appendix 13 to 16.

[0097] (Appendix 18) a first superconducting circuit chip having a readout waveguide and a first lumped capacitor electrode, and a second superconducting circuit chip having a lumped inductor and a second lumped capacitor electrode facing the first lumped capacitor electrode, the inter-electrode distance between the first lumped capacitor electrode and the second lumped capacitor electrode being changed; Measure the high frequency response characteristics of the superconducting resonant circuit Measurement method.

[0098] (Appendix 19) A loss amount of the superconducting resonant circuit is extracted based on the high frequency response characteristic. Measurement method described in Appendix 18.

[0099] (Appendix 20) The inter-electrode distance is changed by moving one of the first superconducting circuit chip and the second superconducting circuit chip relative to the other in a direction in which the first lumped capacitor electrode and the second lumped capacitor electrode face each other. The measurement method described in Appendix 18 or 19.

[0100] (Appendix 21) The readout waveguide and the first lumped capacitor electrode are coupled together. 21. The measurement method according to any one of claims 18 to 20.

[0101] (Appendix 22) The readout waveguide is a coplanar waveguide. 22. The measurement method according to any one of claims 18 to 21. [Explanation of symbols]

[0102] 1. The first superconducting circuit chip 1A First superconducting circuit chip 1B First superconducting circuit chip 1D First superconducting circuit chip 2. Second superconducting circuit chip 2A Second superconducting circuit chip 2B Second superconducting circuit chip 2C Second superconducting circuit chip 2D second superconducting circuit chip 3 Operating mechanism 9 Superconducting resonant circuits 9A Superconducting Resonant Circuit 9B Superconducting resonant circuit 9C Superconducting resonant circuit 9D Superconducting resonator circuit 11 Readout waveguide 11A Readout waveguide 11B Readout waveguide 12 Lumped-element inductors 12A Lumped Inductor 12D Lumped Inductor 13 First lumped constant capacitor electrode 13A First Lumped Element Capacitor Electrode 13B First lumped constant capacitor electrode 13D First lumped constant capacitor electrode 14 Ground Pattern 15 First board 15s first surface 22B Lumped Inductor 23 Second lumped constant capacitor electrode 23A Second lumped constant capacitor electrode 23B Second lumped constant capacitor electrode 23C Second lumped constant capacitor electrode 23D Second lumped constant capacitor electrode 24D Second ground pattern 25 Second board 25r third surface 25s second surface 31 Actuator 32 Fixture 311 Rod 801 First Superconducting Circuit Chip 802 Second Superconducting Circuit Chip 803 Operating mechanism 809 Superconducting Resonant Circuit 811 Readout Waveguide 812 Lumped constant inductor 813 First lumped constant capacitor electrode 823 Second lumped constant capacitor electrode 901 First Superconducting Circuit Chip 902 Second superconducting circuit chip 903 Operating mechanism 909 Superconducting Resonant Circuit 911 Readout Waveguide 913 First lumped constant capacitor electrode 922 Lumped constant inductor 923 Second lumped constant capacitor electrode Df Opposite direction

Claims

1. a first superconducting circuit chip having a readout waveguide, a lumped inductor, and a first lumped capacitor electrode; a second superconducting circuit chip having a second lumped capacitor electrode facing the first lumped capacitor electrode; an operating mechanism capable of changing an inter-electrode distance between the first lumped capacitor electrode and the second lumped capacitor electrode; Equipped Superconducting resonant circuit.

2. The operating mechanism changes the inter-electrode distance by moving one of the first superconducting circuit chip and the second superconducting circuit chip relative to the other in a direction in which the first lumped capacitor electrode and the second lumped capacitor electrode face each other.

2. The superconducting resonant circuit of claim 1.

3. The operating mechanism includes a piezoelectric actuator.

3. The superconducting resonant circuit according to claim 1 or 2.

4. The readout waveguide and the lumped inductor are coupled together.

3. The superconducting resonant circuit according to claim 1 or 2.

5. The readout waveguide and the first lumped capacitor electrode are coupled together.

3. The superconducting resonant circuit according to claim 1 or 2.

6. The readout waveguide is a coplanar waveguide.

3. The superconducting resonant circuit according to claim 1 or 2.

7. a first superconducting circuit chip having a readout waveguide, a lumped inductor, and a first lumped capacitor electrode, and a second superconducting circuit chip having a second lumped capacitor electrode facing the first lumped capacitor electrode, the inter-electrode distance between the first lumped capacitor electrode and the second lumped capacitor electrode being changed; Measure the high frequency response characteristics of the superconducting resonant circuit Measurement method.

8. A loss amount of the superconducting resonant circuit is extracted based on the high frequency response characteristic. The measurement method according to claim 7.

9. a first superconducting circuit chip having a readout waveguide and a first lumped capacitor electrode; a second superconducting circuit chip having a lumped inductor and a second lumped capacitor electrode facing the first lumped capacitor electrode; an operating mechanism capable of changing an inter-electrode distance between the first lumped capacitor electrode and the second lumped capacitor electrode; Equipped Superconducting resonant circuit.

10. a first superconducting circuit chip having a readout waveguide and a first lumped capacitor electrode, and a second superconducting circuit chip having a lumped inductor and a second lumped capacitor electrode facing the first lumped capacitor electrode, the inter-electrode distance between the first lumped capacitor electrode and the second lumped capacitor electrode being changed; Measure the high frequency response characteristics of the superconducting resonant circuit Measurement method.

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