High temperature superconducting quantum voltage standard device based on coplanar waveguide and preparation method thereof

Abstract

The application relates to a high-temperature superconducting quantum voltage standard device based on a coplanar waveguide and a preparation method thereof, which comprises a substrate, a coplanar waveguide and a high-temperature superconducting Josephson junction array; the coplanar waveguide comprises a first grounding strip, a second grounding strip and a target central signal strip located between the first grounding strip and the second grounding strip and used for receiving a microwave signal as a microwave transmission structure; the high-temperature superconducting Josephson junction array comprises N Josephson junctions connected in series with the target central signal strip and formed by focusing a helium ion beam technology to pattern an initial central signal strip of a preset area or adopting a meander line to shuttle a twin crystal grain boundary technology, and the remaining initial central signal strip outside the area is used for constituting the target central signal strip. Aiming at the problems existing in the high-temperature superconducting quantum voltage standard device of a three-dimensional resonant cavity, a novel device with compact structure and high stability is provided, efficient and wideband excitation is realized, the preparation method is low in difficulty, high in repeatability and suitable for batch production.

Description

Technical Field

[0001] This application relates to the field of quantum voltage standards, and in particular to a high-temperature superconducting quantum voltage standard device based on a coplanar waveguide and its fabrication method. Background Technology

[0002] Traditional voltage standards, generated by standard batteries, are affected by temperature, vibration, and charging / discharging, causing their values ​​to drift over time and making it difficult to achieve uniformity in the values ​​reproduced by different countries. Quantum voltage standards, based on the Josephson effect, possess extremely high accuracy and stability and are widely used in metrology, electronic instrument calibration, and other fields.

[0003] Traditional low-temperature superconducting (such as niobium-based) quantum voltage standard technologies are mature, but their operating temperature needs to be maintained at liquid helium temperature of 4.2K, resulting in high refrigeration costs. To reduce operating costs, research on high-temperature superconducting (such as yttrium barium copper oxide, YBCO) Josephson arrays has emerged. High-temperature superconducting arrays can operate in the liquid nitrogen temperature range (77K) or higher, offering significant practical advantages.

[0004] However, the high-temperature superconducting quantum voltage standard devices in the relevant mechanism have problems such as poor stability of the quantized voltage step and extremely high requirements for processing and assembly precision. Summary of the Invention

[0005] Therefore, it is necessary to address the technical problems in the existing technology by providing a high-temperature superconducting quantum voltage standard device based on a coplanar waveguide and its fabrication method, which can at least improve the working stability of the high-temperature superconducting quantum voltage standard device and reduce its fabrication difficulty.

[0006] In a first aspect, this application provides a high-temperature superconducting quantum voltage standard device based on a coplanar waveguide, comprising:

[0007] The substrate, and the coplanar waveguide and high-temperature superconducting Josephson array located on the top surface of the substrate;

[0008] The coplanar waveguide includes a first ground band, a second ground band, and a target center signal band located between the first ground band and the second ground band; the target center signal band is used as a microwave transmission structure to receive microwave signals.

[0009] The high-temperature superconducting Josephson junction array consists of N Josephson junctions connected in series with the target center signal band, used to couple with microwave signals to generate quantum voltage; the operating temperature range of the high-temperature superconducting Josephson junction array is 30K-100K.

[0010] The target center signal band and the high-temperature superconducting Josephson array were prepared simultaneously in the same process steps.

[0011] In some embodiments, the material of the target center signal band includes yttrium barium copper oxide, thallium barium calcium copper oxide, bismuth strontium calcium copper oxide, iron-based superconductor, nickel-based superconductor, or a combination thereof;

[0012] N Josephson junctions are formed by the initial center signal band of a graphically preset region, and the remaining initial center signal band outside the region is used to form the target center signal band.

[0013] In some embodiments, the substrate is a single-crystal substrate;

[0014] Josephson nodes within the preset area are arranged at intervals along the target center signal band.

[0015] In some embodiments, the substrate is a bicrystalline substrate;

[0016] The preset area includes N S-shaped high-temperature superconducting thin films connected end to end in sequence. The two ends of the overall pattern are connected to the target center signal band. The spacing between the film and the first ground band and the second ground band remains unchanged and spans across the domain and is perpendicular to the grain boundary line of the bicrystalline substrate.

[0017] N Josephson junctions are located within each S-type high-temperature superconducting thin film, spaced apart at the grain boundaries.

[0018] In some embodiments, the target center signal band includes:

[0019] An impedance matching structure is used to receive microwave signals at one end and is connected to a high-temperature superconducting Josephson junction array at the other end. Its characteristic impedance gradually increases along the direction towards the high-temperature superconducting Josephson junction array.

[0020] In some embodiments, the length of the impedance matching structure is 0.5mm-3mm;

[0021] The width of the signal band at the center of the target is 5μm-100μm;

[0022] The spacing between the target center signal band, the first ground band, and the second ground band ranges from 10μm to 200μm.

[0023] Secondly, this application also provides a method for fabricating a high-temperature superconducting quantum voltage standard device based on a coplanar waveguide, comprising:

[0024] A substrate is provided, on the top surface of which a high-temperature superconducting thin film and a metal thin film are sequentially stacked in a direction away from the substrate;

[0025] A portion of the high-temperature superconducting thin film and the metal thin film are removed to form a coplanar waveguide; the coplanar waveguide includes a first ground band, a second ground band, and an initial center signal band located between the first ground band and the second ground band;

[0026] The initial center signal band is partially patterned to form a high-temperature superconducting Josephson array, and the remaining initial center signal band is used to form the target center signal band. The operating temperature range of the high-temperature superconducting Josephson array is 30K-100K. The target center signal band is used as a microwave transmission structure to receive microwave signals.

[0027] In some embodiments, the substrate is a single-crystal substrate; forming a high-temperature superconducting Josephson junction array includes:

[0028] Within a predetermined region of the initial central signal band, a pattern of a high-temperature superconducting Josephson array is defined using focused helium ion beam technology. The high-temperature superconducting Josephson array comprises N Josephson junctions spaced apart along the extension direction of the target central signal band.

[0029] In some embodiments, the substrate is a bicrystalline substrate;

[0030] Forming a high-temperature superconducting Josephson junction includes:

[0031] In the preset region of the initial central signal band, the pattern of the high-temperature superconducting Josephson array is defined by ultraviolet lithography and argon ion etching technology; the preset region includes N S-shaped high-temperature superconducting thin films connected end to end in sequence, the two ends of the overall pattern are connected to the target central signal band, the spacing between the overall pattern and the first ground band and the second ground band remains unchanged and spans across and is perpendicular to the grain boundary line of the bicrystalline substrate.

[0032] N Josephson junctions are located within each S-type high-temperature superconducting thin film and are spaced apart at the grain boundaries.

[0033] In some embodiments, the high-temperature superconducting Josephson junction array comprises 1-10000 intrinsic high-temperature superconducting Josephson junctions connected in series;

[0034] The materials for the target center signal band include yttrium barium copper oxide, thallium barium calcium copper oxide, bismuth strontium calcium copper oxide, iron-based superconductors, nickel-based superconductors, or combinations thereof;

[0035] The width of the signal band at the center of the target is 5μm-100μm;

[0036] The spacing between the target center signal band, the first ground band, and the second ground band ranges from 10μm to 200μm.

[0037] The high-temperature superconducting quantum voltage standard device and its fabrication method based on coplanar waveguides provided in this application use coplanar waveguides to replace the three-dimensional Fabry-Perot resonator in related technologies. The planar structure of the coplanar waveguide can effectively reduce the processing difficulty and manufacturing cost of the device, making it compatible with standard microelectronic processes. The high-temperature superconducting Josephson junction array is directly integrated on the target center signal band of the coplanar waveguide and connected in series with the target center signal band, so that microwave energy is directly and locally coupled to each high-temperature superconducting Josephson junction in traveling wave mode, ensuring the uniformity and efficiency of microwave energy transmission in the array. Combined with the optimization of the impedance matching structure, the clarity and stability of the quantized voltage step are guaranteed. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the high-temperature superconducting quantum voltage standard device provided in Embodiment 1 of this application;

[0040] Figure 2 for Figure 1 A magnified view of the area corresponding to the dashed box in the middle;

[0041] Figure 3 This is a schematic diagram of the process flow for fabricating a high-temperature superconducting quantum voltage standard device provided in one embodiment;

[0042] Figure 4 This is a schematic cross-sectional view of the structure obtained after step S2 in the preparation method;

[0043] Figure 5 This is a schematic diagram of the high-temperature superconducting quantum voltage standard device provided in Embodiment 2 of this application;

[0044] Figure 6 This is a schematic diagram of the high-temperature superconducting quantum voltage standard device provided in Embodiment 3 of this application;

[0045] Figure 7 This is a comparison chart of test results for quantum voltage standard devices in this application and related technologies.

[0046] Explanation of reference numerals in the attached figures:

[0047] 10. Substrate; 20. Coplanar waveguide; 21. First ground band; 22. Second ground band; 231. Initial center signal band; 23. Target center signal band; 30. High-temperature superconducting Josephson junction array; 301. Josephson junction; 41. High-temperature superconducting thin film; 42. Metal thin film. Detailed Implementation

[0048] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate preferred embodiments of the application. However, this application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0050] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, parts, regions, layers, doping types, and / or portions, these elements, parts, regions, layers, doping types, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, part, region, layer, doping type, or portion from another element, part, region, layer, doping type, or portion. Therefore, without departing from the teachings of this application, the first element, component, region, layer, doping type, or portion discussed below may be represented as a second element, component, region, layer, or portion; for example, the first doping type may be referred to as the second doping type, and similarly, the second doping type may be referred to as the first doping type; the first doping type and the second doping type are different doping types, for example, the first doping type may be P-type and the second doping type may be N-type, or the first doping type may be N-type and the second doping type may be P-type.

[0051] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as “below,” “under,” or “below” will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0052] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that when the terms “comprise” and / or “comprising” are used in this specification, the presence of the stated feature, integer, step, operation, element, and / or part is established, but the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups is not excluded. Meanwhile, when used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0053] Embodiments of the invention are described herein with reference to cross-sectional views illustrating ideal embodiments (and intermediate structures) of this application, thus allowing for variations in the illustrated shapes due to, for example, manufacturing techniques and / or tolerances. Therefore, embodiments of this application should not be limited to the specific shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing techniques. For instance, implantation regions shown as rectangular typically have rounded or curved features at their edges and / or implantation concentration gradients, rather than a binary change from implantation regions to non-implantation regions. Similarly, the buried regions formed by implantation can result in some implantation in the region between the buried region and the surface traversed during implantation. Therefore, the regions shown in the figures are substantially schematic, and their shapes do not represent the actual shapes of regions of the device and do not limit the scope of this application.

[0054] The core of a quantum voltage reference is a large-scale integrated Josephson array chip, which can be used at frequencies of 1000 MHz and 1000 MHz. When a microwave signal irradiates a Josephson junction, a highly precise quantized voltage is generated across the junction:

[0055]

[0056] Where n is a constant, K Jis the Josephson constant. By connecting thousands to tens of thousands of Josephson junctions in series to form an array, a standard voltage on the order of 1V or 10V can be generated. In related technologies, a Fabry-Perot resonant cavity is used as the microwave coupling structure for the Josephson junction array. This structure is a three-dimensional resonant cavity with a high quality factor (a quantitative indicator of the cavity loss rate). Quantized voltages are generated by irradiating the array at the point of maximum standing wave electric field within the cavity.

[0057] However, Fabry-Perot resonators can only operate effectively within a very narrow frequency band, limiting the usable frequency range of the device. They are also extremely sensitive to mechanical vibrations and temperature fluctuations. Small deformations or temperature drifts can cause the resonant frequency to detune, resulting in drastic changes in the microwave power coupled into the array, which ultimately leads to instability or even disappearance of the quantized voltage step.

[0058] In addition, the processing and assembly precision requirements of three-dimensional resonant cavities are extremely high, and the accurate positioning of the array within the cavity is difficult, resulting in poor performance consistency between different devices and making it difficult to achieve standardized mass production.

[0059] Therefore, there is an urgent need in this field for a new scheme that can provide stable and reliable microwave coupling to promote the practical application of high-temperature superconducting quantum voltage standard devices.

[0060] Example 1

[0061] Please see Figure 1 Embodiment 1 of this application provides a high-temperature superconducting quantum voltage standard device based on a coplanar waveguide, comprising:

[0062] Substrate 10, and coplanar waveguide 20 and high-temperature superconducting Josephson array 30 located on the top surface of substrate 10;

[0063] The coplanar waveguide 20 includes a first grounding band 21, a second grounding band 22, and a target center signal band 23 located between the first grounding band 21 and the second grounding band 22; the target center signal band 23 is used as a microwave transmission structure to receive microwave signals.

[0064] The high-temperature superconducting Josephson junction array 30 includes N Josephson junctions 301 connected in series with the signal band at the center of the target, which are used to couple with microwave signals to generate quantum voltage; the operating temperature range of the high-temperature superconducting Josephson junction array 30 is 30K-100K.

[0065] The target center signal band 23 and the high-temperature superconducting Josephson array 30 were prepared simultaneously in the same process steps.

[0066] For example, substrate 10 is selected as a single-crystal substrate with dimensions of 10mm × 5mm × 0.5mm, featuring low microwave loss and high thermal conductivity, such as magnesium oxide (MgO), lanthanum scandate (LaAlO3), sapphire (Al2O3), or strontium titanium-doped lanthanum aluminate (LSAT). The low microwave loss characteristics of such materials can reduce the energy attenuation of microwave signals during transmission, ensuring efficient microwave conduction by the coplanar waveguide. At the same time, the high thermal conductivity can quickly dissipate the heat generated during the operation of the high-temperature superconducting Josephson array, avoiding the impact of local temperature fluctuations on the stability of quantum voltage generation.

[0067] For example, the material of the target center signal band 23 and the high-temperature superconducting Josephson array 30 includes the rare earth barium copper oxide (ReBa2Cu3O4) material of the target center signal band. 7-x (Re represents rare earth elements), such as yttrium barium copper oxide (YBCO), thallium barium calcium copper oxide (TBCCO), bismuth strontium calcium copper oxide (BSCCO), iron-based superconductors, nickel-based superconductors, or combinations thereof.

[0068] Figure 2 It shows Figure 1 The enlarged schematic diagram corresponding to the dashed box in the middle is used to show the connection structure and detailed features of the coplanar waveguide 20 and the high-temperature superconducting Josephson array 30 in this region. For example... Figure 2 As shown, the coplanar waveguide 20 consists of a target center signal band 23 and two sides, namely a first ground band 21 and a second ground band 22. The target center signal band 23 serves as the core microwave transmission structure, with one end set as a microwave signal input terminal for connecting to an external microwave source; the first ground band 21 and the second ground band 22 are both connected to ground (GND).

[0069] For example, the width of the target center signal band 23 is 5μm-100μm, such as 5μm, 25μm, 50μm, 75μm, or 100μm; the spacing between the target center signal band 23, the first ground band 21, and the second ground band 22 ranges from 10μm to 200μm, such as 10μm, 50μm, 100μm, 150μm, or 200μm. In the embodiment mentioned in this application, the width of the target center signal band 23 is 30μm, and the spacing between the target center signal band 23 and the first ground band and the second ground band on both sides is 60μm.

[0070] Please continue reading. Figure 2 The high-temperature superconducting Josephson junction array 30 is composed of N Josephson junctions 301 (N is usually thousands to tens of thousands). These junctions are directly integrated on the target center signal band 23 and connected in series through the target center signal band 23 to form a whole. Their two ends are led out as the output terminals of quantum voltage.

[0071] The above-mentioned method for fabricating high-temperature superconducting quantum voltage standard devices based on coplanar waveguides, such as... Figure 3 As shown, it includes the following steps:

[0072] Step S1: Provide a substrate 10; a high-temperature superconducting thin film 41 and a metal thin film 42 are sequentially stacked on the top surface of the substrate 10 along the direction away from the substrate.

[0073] Specifically, a 10mm×5mm×0.5mm MgO single crystal was used as the dielectric substrate and subjected to rigorous cleaning and polishing. High-quality c-axis oriented YBCO was epitaxially grown on the substrate 10 as a high-temperature superconducting thin film 41, and gold (Au) was used as a metal thin film 42.

[0074] For example, the thickness of the high-temperature superconducting thin film 41 is 280nm-320nm, such as 280nm, 300nm, or 320nm; the thickness of the metal thin film 42 is 28nm-32nm, such as 28nm, 30nm, or 32nm. In this embodiment, the thickness of the YBCO high-temperature superconducting thin film is 300nm, and the thickness of the Au metal thin film is 30nm.

[0075] Step S2: Remove part of the high-temperature superconducting thin film 41 to form a coplanar waveguide 20; the coplanar waveguide 20 includes a first grounding band 21, a second grounding band 22, and an initial center signal band 231 located between the first grounding band 21 and the second grounding band 22;

[0076] For example, the high-temperature superconducting thin film 41 is patterned using ultraviolet lithography and argon ion etching techniques to form the basic structure of a coplanar waveguide, namely the initial central signal band 231, and the first ground band 21 and the second ground band 22 on both sides, as shown. Figure 4 As shown.

[0077] Step S3: Part of the initial center signal band 231 is patterned to form a high-temperature superconducting Josephson array 30, and the remaining initial center signal band 231 is used to form the target center signal band 23; the target center signal band 23 is used as a microwave transmission structure to receive microwave signals.

[0078] For example, within a predetermined region of the initial central signal band 231, a high-temperature superconducting thin film is irradiated by a focused helium ion beam at intervals along the vertical direction, thereby achieving structural and performance alterations in a localized region and defining the pattern of the high-temperature superconducting Josephson array 30. The specific irradiation area is as follows... Figure 2As shown, the width of the specific irradiation area is greater than the target center signal band 23, but smaller than the distance between the first ground band 21 and the second ground band 22. The array consists of 1 to 10,000 intrinsic high-temperature superconducting Josephson junctions connected in series. Specifically, N Josephson junctions 301 are arranged at intervals along the extension direction of the target center signal band 23. It should be understood that... Figure 2 This is just one example of a high-temperature superconducting Josephson array; there are other suitable examples of high-temperature superconducting Josephson arrays formed using this step.

[0079] In some embodiments, after step S3, an electron beam evaporation technique can be used to deposit a gold film at the microwave input end and the voltage output region of the high-temperature superconducting Josephson array, and peel it off to form electrode pads (not shown) to facilitate wire bonding.

[0080] In the above embodiments, a high-performance high-temperature superconducting quantum voltage standard device was successfully constructed by replacing the traditional three-dimensional resonant cavity with a coplanar waveguide. This avoids the problem of poor performance consistency between different devices caused by the extremely high precision requirements for the processing and assembly of the three-dimensional resonant cavity and the difficulty in accurately positioning the array within the cavity. This provides a feasible technical path for the standardization and mass production of high-performance high-temperature superconducting quantum voltage standard devices.

[0081] Example 2

[0082] Please see Figure 5 This embodiment provides a high-temperature superconducting quantum voltage standard device based on a coplanar waveguide. Compared with Embodiment 1, the main difference of this embodiment is at least that: the substrate is a bicrystalline substrate, and the high-temperature superconducting thin film in the preset area shuttles back and forth through the bicrystalline grain boundary like a winding line to form a high-temperature superconducting Josephson junction array, as shown in the figure. N Josephson junctions are located in each S-type high-temperature superconducting thin film and are arranged at intervals on the grain boundary line.

[0083] In the above-described method for fabricating a high-temperature superconducting quantum voltage standard device based on a coplanar waveguide, this embodiment uses LSAT bicrystalline substrates as the substrate. The substrates are formed by sintering two substrates with different orientations together at a certain angle, with the interface between the two substrates being a grain boundary line. After depositing a 300nm YBCO high-temperature thin film and a 30nm Au metal thin film, the YBCO thin film is patterned using ultraviolet lithography and argon ion etching techniques to form a coplanar waveguide 20 and a high-temperature superconducting Josephson array 30.

[0084] The high-temperature superconducting Josephson array 30 formed in Example 2 includes N S-shaped high-temperature superconducting thin films. In a predetermined region, the S-shaped high-temperature superconducting thin films are connected end to end in sequence, that is, the end of one S-shaped high-temperature superconducting thin film is connected to the beginning of the next S-shaped high-temperature superconducting thin film, forming a continuous, bent series arrangement. The spacing between the S-shaped superconducting thin film and the first and second grounding bands located on both sides remains unchanged. The pattern spans the entire region and is perpendicular to the grain boundary line of the bicrystalline substrate.

[0085] Compared to Example 2, this embodiment uses ultraviolet lithography and argon ion etching to simultaneously fabricate a coplanar waveguide 20 and a high-temperature superconducting Josephson junction array 30. This not only combines the technical effects of Example 1 but also simplifies the process flow. In addition, the arc-shaped high-temperature superconducting thin films on both sides of the single junction serve as microwave transmission, which can reduce microwave reflection loss at the corners compared to a rectangular shape.

[0086] Example 3

[0087] Please see Figure 6 This embodiment provides a high-temperature superconducting quantum voltage standard device based on a coplanar waveguide. Similar to Embodiments 1 and 2, a coplanar waveguide is used instead of the three-dimensional Fabry-Perot resonator in related technologies, and the high-temperature superconducting Josephson array is directly fabricated on the target center signal band of the coplanar waveguide. The difference lies in that, to optimize performance, an exponentially gradient line or lumped parameter matching network with a length of 0.5mm-3mm is designed as an impedance matching structure between the microwave input end of the coplanar waveguide 20 and the high-temperature superconducting Josephson array 30. This smoothly transitions the characteristic impedance from 50Ω to the high impedance presented by the array, ensuring efficient transmission of the microwave signal from the input end to the array and reducing reflection.

[0088] In the above embodiments, the coplanar waveguide is directly and locally coupled to each Josephson junction in traveling wave mode. Combined with the impedance matching structure's suppression of signal reflection, this ensures that the junction array efficiently obtains stable and sufficient microwave excitation, effectively improving the stability of the device's quantum voltage step.

[0089] In summary, this application provides a high-temperature superconducting quantum voltage standard device based on a coplanar waveguide and its fabrication method. In this method, a coplanar waveguide is used to replace the three-dimensional Fabry-Perot resonator in related technologies. The high-temperature superconducting Josephson array is directly fabricated on the target center signal band of the coplanar waveguide using standard microelectronic processing techniques (such as focused ion beam and ultraviolet lithography). This greatly simplifies the device structure and avoids the difficulties of precision processing and alignment of complex three-dimensional cavities, thereby significantly reducing the overall processing difficulty and manufacturing cost of the device.

[0090] Furthermore, the transmission modes supported by the coplanar waveguide are not sensitive to frequency. Combined with the optimization of the impedance matching structure, this enables the device to generate quantized voltage stably and efficiently over a wider microwave frequency range. While ensuring the clarity and stability of the quantized voltage step, it overcomes the inherent limitation of the Fabry-Perot resonator, which can only achieve effective excitation at discrete resonant frequency points, thus laying the foundation for realizing broadband tunable quantum voltage output.

[0091] Please see Figure 7 , Figure 7 Figure a shows the test results of devices using Fabry-Perot resonators in related technologies. Figure 7 Figure b shows the test results of the device provided in this application. The prepared device was installed in a shielded test box and placed inside a liquid nitrogen Dewar (77K). A microwave source and a precision voltmeter were connected for testing. Figure 7 As shown, the device using the coplanar waveguide coupling of the present invention has a much longer settling time than the device using the Fabry-Perot resonator, verifying the significant advantage of the present invention in terms of stability.

[0092] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A high-temperature superconducting quantum voltage standard device based on a coplanar waveguide, characterized in that, include: The substrate, and a coplanar waveguide and a high-temperature superconducting Josephson array located on the top surface of the substrate; The coplanar waveguide includes a first ground band, a second ground band, and a target center signal band located between the first ground band and the second ground band; the target center signal band is used as a microwave transmission structure to receive microwave signals. The high-temperature superconducting Josephson junction array includes N Josephson junctions connected in series with the target center signal band, used to couple with the microwave signal to generate a quantum voltage; the operating temperature range of the high-temperature superconducting Josephson junction array is 30K-100K; the N Josephson junctions are formed by the initial center signal band of a graphically preset region, and the remaining initial center signal band outside the region is used to constitute the target center signal band; The target center signal band includes an impedance matching structure, one end of which is used to receive microwave signals, and the other end is connected to the high-temperature superconducting Josephson junction array. The target center signal band and the high-temperature superconducting Josephson array are prepared simultaneously in the same process steps.

2. The high-temperature superconducting quantum voltage standard device according to claim 1, characterized in that, The material of the target center signal band includes yttrium barium copper oxide, thallium barium calcium copper oxide, bismuth strontium calcium copper oxide, iron-based superconductor, nickel-based superconductor, or a combination thereof.

3. The high-temperature superconducting quantum voltage standard device according to claim 2, characterized in that, The substrate is a single-crystal substrate; The Josephson knots within the preset region are arranged at intervals along the extension direction of the target center signal band.

4. The high-temperature superconducting quantum voltage standard device according to claim 2, characterized in that, The substrate is a bicrystalline substrate; The preset area includes N S-shaped high-temperature superconducting thin films connected end to end in sequence. The two ends of the overall pattern are connected to the target center signal band. The spacing between the film and the first ground band and the second ground band remains unchanged and spans across the domain and is perpendicular to the grain boundary line of the bicrystalline substrate. The N Josephson junctions are located within each of the S-type high-temperature superconducting thin films and are spaced apart at the grain boundaries.

5. The high-temperature superconducting quantum voltage standard device according to claim 2 or 3, characterized in that, The characteristic impedance of the impedance matching structure gradually increases along the direction toward the high-temperature superconducting Josephson junction.

6. The high-temperature superconducting quantum voltage standard device according to claim 5, characterized in that, Includes at least one of the following features: The length of the impedance matching structure is 0.5mm-3mm; The width of the target center signal band is 5μm-100μm; The spacing between the target center signal band, the first ground band, and the second ground band ranges from 10μm to 200μm.

7. A method for fabricating a high-temperature superconducting quantum voltage standard device based on a coplanar waveguide, characterized in that, include: A substrate is provided, wherein a high-temperature superconducting thin film and a metal thin film are sequentially stacked on the top surface of the substrate in a direction away from the substrate; A portion of the high-temperature superconducting thin film and the metal thin film are removed to form a coplanar waveguide; the coplanar waveguide includes a first ground band, a second ground band, and an initial center signal band located between the first ground band and the second ground band; The initial center signal band is partially patterned to form a high-temperature superconducting Josephson junction array, and the remaining initial center signal band is used to form the target center signal band. The operating temperature range of the high-temperature superconducting Josephson junction array is 30K-100K. The target center signal band is used as a microwave transmission structure to receive microwave signals. The high-temperature superconducting Josephson junction array is connected in series with the target center band. The target center signal band includes an impedance matching structure, one end of which is used to receive microwave signals, and the other end is connected to the high-temperature superconducting Josephson array.

8. The preparation method according to claim 7, characterized in that, The substrate is a single-crystal substrate; forming the high-temperature superconducting Josephson junction array includes: In a preset region of the initial central signal band, the pattern of the high-temperature superconducting Josephson array is defined by focusing helium ion beam technology; the high-temperature superconducting Josephson array includes N Josephson junctions arranged at intervals along the extension direction of the target central signal band on the target central signal band.

9. The preparation method according to claim 7, characterized in that, The substrate is a bicrystalline substrate; Forming the high-temperature superconducting Josephson junction array includes: In the preset region of the initial center signal band, the pattern of the high-temperature superconducting Josephson array is defined by ultraviolet lithography and argon ion etching technology; the preset region includes N S-shaped high-temperature superconducting thin films connected end to end in sequence, the two ends of the overall pattern are connected to the target center signal band, the spacing between the superconducting array and the first ground band and the second ground band remains unchanged and spans across and is perpendicular to the grain boundary line of the bicrystalline substrate; N Josephson junctions are located within each of the aforementioned S-type high-temperature superconducting thin films and are spaced apart along the grain boundary lines.

10. The preparation method according to any one of claims 8 or 9, characterized in that, Includes at least one of the following features: The high-temperature superconducting Josephson junction array comprises 1-10000 intrinsic high-temperature superconducting Josephson junctions connected in series; The material of the target center signal band includes yttrium barium copper oxide, thallium barium calcium copper oxide, bismuth strontium calcium copper oxide, iron-based superconductor, nickel-based superconductor, or a combination thereof; The width of the target center signal band is 5μm-100μm; The spacing between the target center signal band, the first ground band, and the second ground band ranges from 10μm to 200μm.

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