Second-order gradient independent input feedback positive feedback superconducting quantum interference device

Abstract

The present disclosure relates to a second-order gradient independent input feedback type positive feedback superconducting quantum interference device, comprising: eight superconducting gaskets, the eight superconducting gaskets include four input superconducting gaskets and four feedback superconducting gaskets, one input superconducting gasket and one feedback superconducting gasket form a superconducting loop, the four superconducting loops are arranged in a central symmetric manner, and the four feedback superconducting gaskets include two positive feedback superconducting gaskets and two negative feedback superconducting gaskets; an input coil, the input coil is coupled with the four superconducting input superconducting gaskets; a negative feedback coil, the negative feedback coil is coupled with the two negative feedback superconducting gaskets; a positive feedback coil, the positive feedback coil is coupled with the two positive feedback superconducting gaskets, and the two positive feedback superconducting gaskets and the two negative feedback superconducting gaskets are symmetrical along the horizontal symmetry lines of the eight superconducting gaskets. At least it can effectively reduce the crosstalk phenomenon between multiple coils and improve the coupling coefficient and energy transfer efficiency between coils.

Description

Technical Field

[0001] The present disclosure relates to the technical field of superconducting electronics, and in particular to a second-order gradient independent input feedback type positive feedback superconducting quantum interference device. Background Art

[0002] The superconducting quantum interference device (SQUID) is the most sensitive magnetic field sensor currently. Its equivalent energy resolution is close to the quantum limit level and is widely used in biomagnetic measurement and geomagnetic detection. The current sensor based on SQUID can accurately measure tiny currents and other signals that can be equivalently converted into magnetic flux. It is the only readout device for instruments such as superconducting transition edge sensor (TES), metallic magnetic calorimeter (MMC), and cryogenic current comparator (CCC). Therefore, as a key core device of modern large-scale scientific devices in cosmology and biomedicine, the research on its preparation process, configuration design, principle theoretical simulation, and amplification readout technology is crucial, and it is an important part of solving the "bottleneck" of superconducting chip technology in my country.

[0003] The noise level of the SQUID current sensor determines its measurement sensitivity and is one of the important indicators of the SQUID current sensor. A large part of the overall noise level of the SQUID current sensor comes from the circuit noise of the room temperature end readout circuit, and the size of this part of the noise is inversely proportional to the square of the flux-to-voltage conversion coefficient of the SQUID current sensor. Therefore, improving the flux-to-voltage conversion coefficient of the SQUID current sensor can effectively reduce its noise, thereby improving the resolution of the SQUID current sensor.

[0004] The APF method is one of the effective methods to improve the flux-to-voltage conversion coefficient of the SQUID current sensor. By connecting a forward-coupled inductor in parallel to the SQUID loop, the SQUID loop is provided with flux positive feedback, thereby realizing an offset asymmetric flux-voltage characteristic curve, which significantly improves the flux-to-voltage conversion coefficient.

[0005] However, in order to implement the APF method, the input coil, positive feedback coil and negative feedback coil need to be coupled to the SQUID loop at the same time. The traditional APF-SQUID couples the three coils to the same superconducting pad at the same time, which greatly increases the crosstalk between the three coils and reduces the coupling coefficient and energy transfer efficiency between the coils. Summary of the invention

[0006] Based on this, it is necessary to provide a second-order gradient independent input feedback type positive feedback superconducting quantum interference device to address the above technical problems, which can at least effectively reduce the crosstalk phenomenon between multiple coils and improve the coupling coefficient and energy transfer efficiency between coils.

[0007] In order to achieve the above-mentioned purpose and other purposes, in the first aspect, the present disclosure provides a second-order gradient independent input feedback type positive feedback superconducting quantum interference device, including: eight superconducting gaskets, the eight superconducting gaskets include four input superconducting gaskets and four feedback superconducting gaskets, one input superconducting gasket and one feedback superconducting gasket form a superconducting loop, the four superconducting loops are arranged in a central symmetrical manner, and the four feedback superconducting gaskets include two positive feedback superconducting gaskets and two negative feedback superconducting gaskets; an input coil, the input coil is coupled with the four superconducting input superconducting gaskets; a negative feedback coil, the negative feedback coil is coupled with the two negative feedback superconducting gaskets; a positive feedback coil, the positive feedback coil is coupled with the two positive feedback superconducting gaskets, and the two positive feedback superconducting gaskets and the two negative feedback superconducting gaskets are symmetrical along the horizontal symmetry lines of the eight superconducting gaskets.

[0008] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, four input superconducting gaskets and four feedback superconducting gaskets are formed to form four superconducting loops arranged in a central symmetrical manner, and the input coil is coupled with the four superconducting input superconducting gaskets, the negative feedback coil is coupled with the two negative feedback superconducting gaskets, and the positive feedback coil is coupled with the two positive feedback superconducting gaskets. This avoids the problem of coupling the input coil, the positive feedback coil and the feedback coil to the same superconducting gasket in the prior art, which increases the crosstalk between the three coils and reduces the coupling coefficient and energy transfer efficiency between the coils. It can at least effectively reduce the crosstalk phenomenon between multiple coils and improve the coupling coefficient and energy transfer efficiency between the coils.

[0009] In addition, the problem of increased complexity of the device, which reduces its symmetry and causes increased interference of the ambient magnetic field on the device, is also avoided.

[0010] In one embodiment, the input coil is wrapped around four input superconducting pads and forms an input port on a horizontal symmetry line of the eight superconducting pads.

[0011] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, the input coil is only wrapped around four input superconducting loops, avoiding interference of other coils on the input superconducting loops, and can effectively reduce the crosstalk between the input coil and other coils, and improve the coupling coefficient and energy transfer efficiency of the input coil. At the same time, it also avoids the increase in the complexity of the device, which reduces its symmetry and leads to the problem of increased interference of the ambient magnetic field on the device.

[0012] In one embodiment, the negative feedback coil is wrapped around two negative feedback superconducting gaskets to form a negative feedback port; the positive feedback coil is wrapped around two positive feedback superconducting gaskets to form a positive feedback port on the horizontal symmetry line of the eight superconducting gaskets in a direction away from the input port.

[0013] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, the bias current is input through the bias port, the positive feedback voltage is input through the positive feedback coil port, and the negative feedback voltage is input through the negative feedback port to realize the flux locking working mode and the offset flux voltage characteristic curve, so that the superconducting quantum interference device can accurately detect the output voltage corresponding to the current to be detected.

[0014] In one embodiment, the positive feedback coil includes a target resistance.

[0015] In one of the embodiments, a bias coil is also included, which includes a first resistor, a second resistor, a first Josephson junction and a second Josephson junction, wherein the first Josephson junction and the second Josephson junction are respectively connected to two positive feedback superconducting gaskets and two negative feedback superconducting gaskets, the first resistor and the second resistor are connected in parallel, and the first Josephson junction and the second Josephson junction are both superconductingly connected to the positive feedback port.

[0016] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, the two Josephson junctions, two resistors and the attenuation resistor modulate the magnetic flux so that the bias coil can accurately output the detection voltage through the positive feedback port.

[0017] In one embodiment, each input superconducting pad includes: a substrate; a first superconducting layer located on the substrate; a first insulating layer located on the first superconducting layer; and a superconducting coil layer located on the first insulating layer.

[0018] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, an input superconducting gasket is formed through the structure of the substrate, the superconducting layer and the insulating layer, which can accurately capture the magnetic flux of the input loop.

[0019] In one embodiment, each feedback superconducting gasket includes: a substrate; a first superconducting layer located on the substrate; a first insulating layer located on the first superconducting layer; and a superconducting coil layer located on the first insulating layer.

[0020] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, a feedback superconducting gasket is formed through the structure of the substrate, superconducting layer and insulating layer, which can accurately regulate the magnetic flux of the second-order gradient independent input feedback type positive feedback superconducting quantum interference device.

[0021] In one embodiment, the positive feedback coil includes: a first superconducting layer located on a substrate; a first insulating layer located on the first superconducting layer; a superconducting coil layer located on a second insulating layer; and a resistance layer located on the superconducting coil layer.

[0022] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, a positive feedback coil is formed by the first superconducting layer, the superconducting coil layer and the resistance layer, which can accurately regulate the magnetic flux of the second-order gradient independent input feedback type positive feedback superconducting quantum interference device.

[0023] In one embodiment, the negative feedback coil includes: a first superconducting layer, located on a substrate; a first insulating layer, located on the first superconducting layer; and a superconducting coil layer, located on a second insulating layer; wherein the winding directions of the positive feedback coil and the negative feedback coil are opposite, and the winding directions of the input coil and the positive feedback coil are the same.

[0024] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, the magnetic flux of the superconducting quantum interference device is adjusted by a positive feedback coil with the same winding direction as the input coil and a negative feedback coil with the opposite winding direction as the input coil, thereby ensuring that the superconducting quantum interference device can realize the magnetic flux locking working mode and the offset magnetic flux voltage characteristic curve.

[0025] In the second aspect, the embodiment of the present disclosure also provides a method for preparing a second-order gradient independent input feedback type positive feedback superconducting quantum interference device, including: providing a substrate; forming a first superconducting layer on the substrate, and etching the first superconducting layer to obtain a first superconducting layer of a first target pattern; forming a first insulating layer on the first superconducting layer; forming a second superconducting layer on the first insulating layer; forming a second insulating layer on the second superconducting layer; forming a superconducting coil layer on the second insulating layer, etching the superconducting coil layer to obtain a superconducting coil layer for forming an input coil, a negative feedback coil and a positive feedback coil, and forming a plurality of grooves penetrating the first insulating layer in the superconducting coil layer, wherein superconducting material is deposited in the grooves for connecting the superconducting coil layer and the first superconducting layer; forming a resistance layer on the superconducting coil layer, the resistance layer being used to form a first resistance, a second resistance and a target resistance.

[0026] In the preparation method of the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, four superconducting loops arranged in a central symmetrical manner are formed with four input superconducting gaskets and four feedback superconducting gaskets, and the input coil is coupled with the four superconducting input superconducting gaskets, the negative feedback coil is coupled with the two negative feedback superconducting gaskets, and the positive feedback coil is coupled with the two positive feedback superconducting gaskets. This avoids the problem of coupling the input coil, the positive feedback coil and the feedback coil to the same superconducting gasket in the prior art, which increases the crosstalk between the three coils and reduces the coupling coefficient and energy transfer efficiency between the coils. It can at least effectively reduce the crosstalk phenomenon between multiple coils and improve the coupling coefficient and energy transfer efficiency between the coils.

[0027] In addition, it also avoids the problem of increasing the complexity of the device, which reduces its symmetry and causes increased interference of the ambient magnetic field on the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 It is a schematic structural diagram of a second-order gradient independent input feedback type positive feedback superconducting quantum interference device provided in one embodiment;

[0030] Figure 2 It is a schematic structural diagram of another second-order gradient independent input feedback type positive feedback superconducting quantum interference device provided in one embodiment;

[0031] Figure 3 An equivalent circuit diagram of a second-order gradient independent input feedback type positive feedback superconducting quantum interference device provided in one embodiment;

[0032] Figure 4 The present invention is a flow chart of a method for preparing a second-order gradient independent input feedback type positive feedback superconducting quantum interference device provided in one embodiment.

[0033] Description of reference numerals:

[0034] 1. Input superconducting gasket; 2. Input superconducting gasket; 3. Input superconducting gasket; 4. Input superconducting gasket; 5. Negative feedback superconducting gasket; 6. Negative feedback superconducting gasket; 7. Positive feedback superconducting gasket; 8. Positive feedback superconducting gasket; 9. First Josephson junction; 10. Second Josephson junction; 11. First resistor; 15. Second resistor; 12. Target resistor; 13. First superconducting layer; 14. Superconducting coil layer; 201. Substrate; 202. Second superconducting layer; 203. First insulating layer; 204. Second insulating layer; 205. Resistor layer; 301. Input coil; 302. Negative feedback coil; 303. Positive feedback coil; A. Input port; B. Negative feedback port; C. Positive feedback port; D. Horizontal symmetry line. DETAILED DESCRIPTION

[0035] In order to facilitate understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are shown in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thorough and comprehensive.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present disclosure belongs. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure.

[0037] It should be understood that when an element or layer is referred to as being "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. On the contrary, when an element is referred to as being "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, components, regions, layers, doping types and / or parts, these elements, components, regions, layers, doping types and / or parts should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, doping type or part from another element, component, region, layer, doping type or part. Therefore, without departing from the teachings of the present disclosure, 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.

[0038] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that, in addition to the orientations shown in the figures, spatially relative terms also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, an element or feature described as "under other elements" or "under it" or "under it" will be oriented as being "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0039] When used herein, the singular forms "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 "consisting of" and / or "comprising" are used in this specification, the presence of features, integers, steps, operations, elements and / or components can be determined, but the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups is not excluded. At the same time, when used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0040] Embodiments of the invention are described herein with reference to cross-sectional views which are schematic representations of ideal embodiments (and intermediate structures) of the present disclosure, such that variations in the shapes shown due to, for example, manufacturing techniques and / or tolerances are anticipated. Thus, embodiments of the present disclosure should not be limited to the particular shapes of the regions shown herein, but rather include deviations in shapes due to, for example, manufacturing techniques. For example, an implanted region shown as a rectangle typically has rounded or curved features and / or an implant concentration gradient at its edges rather than a binary change from an implanted region to a non-implanted region. Similarly, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation is performed. Thus, the regions shown in the figures are schematic in nature, their shapes do not represent the actual shape of the region of the device, and do not limit the scope of the present disclosure.

[0041] See also Figure 1-Figure 3 It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the present application in a schematic manner. The illustrations only show the components related to the present application rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0042] See also Figure 3 , Figure 3 The equivalent circuit diagram of the second-order gradient independent input feedback type positive feedback superconducting quantum interference device provided in one embodiment. It should be noted that APF-SQUID (superconducting quantum interference device) is an extremely sensitive magnetic field sensor based on a superconducting loop and a Josephson junction. It uses the quantum interference effect to detect extremely weak magnetic field changes and is widely used in physics research, medical imaging, geological exploration and other fields. SQUID consists of two Josephson junctions connected in parallel on a superconducting loop. The superconducting loop is used to capture and measure magnetic flux. Two parallel Josephson junctions respond to changes in magnetic flux through the Josephson effect and the flux quantization effect.

[0043] like Figure 3 As shown in the figure, the superconducting loop can capture the tiny current input by the input coil 301, and the bias current is input through the bias port D. The negative feedback port B and the positive feedback port C can apply flux modulation to the superconducting loop, so that the superconducting loop is in a flux locking working mode, and the extremely weak magnetic field generated by the input current can be detected and measured with high precision.

[0044] Please continue reading Figure 1As an example, one aspect of the present application provides a structural schematic diagram of a second-order gradient independent input feedback type positive feedback superconducting quantum interference device, including: eight superconducting gaskets, the eight superconducting gaskets include four input superconducting gaskets and four feedback superconducting gaskets, one input superconducting gasket and one feedback superconducting gasket form a superconducting loop, the four superconducting loops are arranged in a central symmetrical manner, the four feedback superconducting gaskets include two positive feedback superconducting gaskets and two negative feedback superconducting gaskets, an input coil, the input coil is coupled with the four superconducting input superconducting gaskets; a negative feedback coil, the negative feedback coil is coupled with two negative feedback superconducting gaskets; a positive feedback coil, the positive feedback coil is coupled with two positive feedback superconducting gaskets, and the two positive feedback superconducting gaskets and the two negative feedback superconducting gaskets are symmetrical along the horizontal symmetry lines of the eight superconducting gaskets.

[0045] Please continue reading Figure 1 , Figure 1 The input superconducting gasket 1, the input superconducting gasket 2, the input superconducting gasket 3, and the input superconducting gasket 4 are four input superconducting gaskets. Figure 1 The negative feedback superconducting gasket 5 and the negative feedback superconducting gasket 6 are two negative feedback superconducting gaskets. Figure 1 The positive feedback superconducting gasket 7 and the positive feedback superconducting gasket 8 are two positive feedback superconducting gaskets.

[0046] As an example, see Figure 1 The input superconducting gasket 1 and the negative feedback superconducting gasket 5 form a superconducting loop, the input superconducting gasket 2 and the negative feedback superconducting gasket 6 form a superconducting loop, the input superconducting gasket 3 and the negative feedback superconducting gasket 7 form a superconducting loop, and the input superconducting gasket 4 and the negative feedback superconducting gasket 8 form a superconducting loop.

[0047] Here, if Figure 1 As shown in , the two superconducting pads in each superconducting loop are superconductingly connected.

[0048] Among them, Figure 1 As shown in , the four superconducting loops are arranged in a central symmetrical manner, and the four input superconducting gaskets are also arranged in a central symmetrical manner, and the four feedback superconducting gaskets are also arranged in a central symmetrical manner. The two positive feedback superconducting gaskets and the two negative feedback superconducting gaskets are symmetrical along the horizontal symmetry line of the eight superconducting gaskets.

[0049] Among them, Figure 1 As shown in , the input coil is coupled to the four superconducting input superconducting gaskets; the negative feedback coil is coupled to two negative feedback superconducting gaskets; and the positive feedback coil is coupled to two positive feedback superconducting gaskets.

[0050] Here, it should be noted that Figure 1The positions of the input coil 301, the negative feedback coil and the positive feedback coil are only examples. The present application does not limit the positions of the input coil 301, the negative feedback coil and the positive feedback coil. Those skilled in the art can adjust the positions of the input coil 301, the negative feedback coil and the positive feedback coil as required, for example, they can change the diameter and number of turns of the coil.

[0051] Among them, Figure 1 As shown in FIG. 1 , the superconducting coil layer 14 wrapped around the two negative feedback superconducting gaskets is the negative feedback coil 302 , and the negative feedback coil 302 is coupled to the two negative feedback superconducting gaskets.

[0052] Among them, Figure 1 As shown in FIG. 1 , the superconducting coil layer 14 wrapped around the two positive feedback superconducting gaskets is the positive feedback coil 302 , and the positive feedback coil 302 is coupled to the two positive feedback superconducting gaskets.

[0053] Here, it should be noted that Figure 1 The positions of the negative feedback coil 302 and the positive feedback coil are only examples. The present application does not limit the positions of the negative feedback coil 302 and the positive feedback coil. Those skilled in the art can adjust the positions of the negative feedback coil 302 and the positive feedback coil as required. For example, the negative feedback coil 302 and the positive feedback coil can be formed either on the superconducting loop or under the superconducting loop.

[0054] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, four superconducting loops composed of four input superconducting gaskets and four feedback superconducting gaskets are formed, which are arranged in a centrally symmetrical manner, and the negative feedback coil is coupled with the two negative feedback superconducting gaskets, and the positive feedback coil is coupled with the two positive feedback superconducting gaskets. This avoids the problem of coupling the input coil, the positive feedback coil and the feedback coil to the same superconducting gasket in the prior art, which increases the crosstalk between the three coils and reduces the coupling coefficient and energy transfer efficiency between the coils. At least it can effectively reduce the crosstalk phenomenon between multiple coils and improve the coupling coefficient and energy transfer efficiency between the coils.

[0055] In addition, the problem of increased complexity of the device, which reduces its symmetry and causes increased interference of the ambient magnetic field on the device, is also avoided.

[0056] For details, please continue to refer to Figure 1 The input coil 301 is wrapped around four input superconducting gaskets and forms an input port A on the horizontal symmetry line D of the eight superconducting gaskets; the negative feedback coil is wrapped around two negative feedback superconducting gaskets and forms a negative feedback port; the positive feedback coil is wrapped around two positive feedback superconducting gaskets and forms a positive feedback port on the horizontal symmetry line of the eight superconducting gaskets in a direction away from the input port.

[0057] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, the bias current is input through the bias port, the positive feedback voltage is input through the positive feedback coil port, and the negative feedback voltage is input through the negative feedback port, so as to realize the flux feedback working mode and the bias type voltage flux characteristic curve, and can accurately detect the voltage of the current to be detected.

[0058] Wherein, the positive feedback coil also includes a target resistor 12.

[0059] Please continue reading Figure 1 The second-order gradient independent input feedback type positive feedback superconducting quantum interference device also includes: a bias coil, which is connected to four superconducting loop groups to form a bias port.

[0060] Here, it should be noted that the bias port and the positive feedback port are common ports in the embodiment of the present application, and the bias port is also the positive feedback port.

[0061] Please continue reading Figure 1 , further comprising a bias coil, wherein the bias coil comprises a first resistor, a second resistor, a first Josephson junction and a second Josephson junction,

[0062] The first Josephson junction and the second Josephson junction are respectively connected to the two positive feedback superconducting gaskets and the two negative feedback superconducting gaskets, the first resistor and the second resistor are connected in parallel, and the first Josephson junction and the second Josephson junction are both superconductingly connected to the positive feedback port.

[0063] As an example, see Figure 1 and Figure 2 , wherein the first superconducting layer and the second superconducting layer together constitute a Josephson junction structure.

[0064] Here, it should be noted that, through the steps of deposition and etching, the second superconducting layer only exists in the Josephson junction structure, and it is not necessary to form the second superconducting layer on the input superconducting pad and the feedback superconducting pad.

[0065] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, the modulation effect of the magnetic flux by two Josephson junctions, two resistors and attenuation resistor enables the bias coil to accurately output the detection voltage through the positive feedback port.

[0066] See also Figure 1 and Figure 2 Each input superconducting loop includes: each input superconducting pad includes: a substrate; a first superconducting layer located on the substrate; a first insulating layer located on the first superconducting layer; and a superconducting coil layer located on the first insulating layer.

[0067] As an example, see Figure 1 The superconducting coil layer 14 first wraps around the input superconducting gasket 1 for a large circle, then wraps around the input superconducting gasket 2 for a circle, then wraps around the input superconducting gasket 1 for a small circle, then wraps around the input superconducting gasket 3 for a large circle, then wraps around the input superconducting gasket 4 for a circle, then wraps around the input superconducting gasket 3 for a small circle, and finally forms two input ports of the input port A through the first superconducting layer 202 and the superconducting coil layer 14.

[0068] For details, please continue to refer to Figure 1 When the input coil 301 crosses, it is necessary to use the first superconducting layer 202 to form a span of the input coil 301. For example, after wrapping around the input superconducting gasket 3 for half a circle and then wrapping around the input superconducting gasket 4 for one circle, it is necessary to cross the superconducting coil layer 14 once. At this time, two grooves penetrating the first insulating layer 203 need to be formed ( Figure 1 The input superconducting material is filled in the grooves, so that the input superconducting gasket 3 goes around half a circle and then passes through the two grooves, and crosses the superconducting coil layer 14 by using the first superconducting layer 202.

[0069] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, an input superconducting loop is formed by the structure of the substrate 201, the superconducting layer and the insulating layer, and the magnetic flux of the input loop can be accurately captured.

[0070] In one embodiment, each feedback superconducting gasket includes: a substrate; a first superconducting layer located on the substrate; a first insulating layer located on the first superconducting layer; and a superconducting coil layer located on the first insulating layer.

[0071] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, a negative feedback superconducting gasket is formed through the structure of the substrate 201, the superconducting layer and the insulating layer, which can accurately regulate the magnetic flux of the second-order gradient independent input feedback type positive feedback superconducting quantum interference device.

[0072] In one embodiment, the positive feedback coil includes: a first superconducting layer located on the substrate; a first insulating layer located on the first superconducting layer; a superconducting coil layer located on a second insulating layer; and a resistance layer located on the superconducting coil layer.

[0073] For details, please continue to refer to Figure 1When the positive feedback coil crosses, it is necessary to use the first superconducting layer to form a crossover of the positive feedback coil. For example, after half a circle around the positive feedback superconducting gasket 6, a larger circle around the positive feedback gasket 5, and then another half circle around the positive feedback superconducting gasket 6, it is necessary to cross the superconducting coil layer 14 once. At this time, two grooves penetrating the first insulating layer need to be formed ( Figure 1 The black dots in the superconducting coil layer 14 are formed in the groove, and the superconducting material is filled in the groove, so that the positive feedback superconducting gasket 5 is wrapped around once and then passes through the two grooves, and the first superconducting layer is used to cross the superconducting coil layer.

[0074] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, a positive feedback coil is formed by the first superconducting layer, the superconducting coil layer and the resistance layer, which can accurately adjust the magnetic flux of the second-order gradient independent input feedback type positive feedback superconducting quantum interference device and enable the superconducting quantum interference device to accurately output the detection value of the current to be detected, thereby ensuring the detection accuracy and sensitivity of the second-order gradient independent input feedback type positive feedback superconducting quantum interference device.

[0075] In one embodiment, the negative feedback coil includes: a first superconducting layer located on the substrate; a first insulating layer located on the first superconducting layer; and a superconducting coil layer located on a second insulating layer.

[0076] The positive feedback coil and the negative feedback coil are wound in opposite directions, and the input coil and the positive feedback coil are wound in the same direction.

[0077] For details, please continue to refer to Figure 1 When the negative feedback coil crosses, it is necessary to use the first superconducting layer to form a crossover of the negative feedback coil. For example, after winding half a circle on the negative feedback superconducting gasket 8 and then winding one circle on the negative feedback superconducting gasket 7, it is necessary to wind half a circle on the negative feedback superconducting gasket 8, and it is necessary to cross the superconducting coil layer 14 once. At this time, it is necessary to form two grooves penetrating the first insulating layer 203 ( Figure 1 The black dots in the superconducting coil layer 14 are formed in the grooves, and the superconducting material is filled in the grooves so that the negative feedback superconducting gasket 7 is surrounded by one circle and then passes through the two grooves, and the first superconducting layer is used to cross the superconducting coil layer 14.

[0078] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, the magnetic flux of the superconducting quantum interference device is adjusted by a positive feedback coil with the same winding direction as the input coil and a negative feedback coil with the opposite winding direction as the input coil, thereby ensuring the detection accuracy and sensitivity of the second-order gradient independent input feedback type positive feedback superconducting quantum interference device.

[0079] The first superconducting layer 202 , the first insulating layer 203 and the second superconducting layer 13 form a first Josephson junction 9 and / or a second Josephson junction 10 .

[0080] In the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, a highly sensitive second-order gradient independent input feedback type positive feedback superconducting quantum interference device can be formed by forming a superconducting loop structure of a double Josephson junction.

[0081] Please refer to Figure 4 As an example, the present disclosure provides a method for preparing a second-order gradient independent input feedback type positive feedback superconducting quantum interference device, comprising the following steps:

[0082] Step S1000: providing a substrate 201 .

[0083] The substrate 201 may be made of semiconductor material or insulating material. The substrate 201 may be a single-layer structure or a multi-layer structure. For example, the substrate 201 may be a silicon substrate 201 or a silicon dioxide substrate 201. Alternatively, for example, the substrate 201 may be a layered substrate 201 including silicon / silicon carbide, silicon on insulator, or silicon germanium on insulator. Therefore, the type of the substrate 201 should not limit the protection scope of the present disclosure.

[0084] Step S2000: forming a first superconducting layer 202 on the substrate 201, and etching the first superconducting layer 202 to obtain the first superconducting layer 202 with a first target pattern.

[0085] The first superconducting layer 202 is also called (Bottom Electrode, BE layer), that is, a superconducting thin film layer.

[0086] Specifically, the material of the first superconducting layer 202 may be polycrystalline niobium (Nb).

[0087] As an example, a magnetron sputtering method may be used to deposit and etch the corresponding pattern (for example, a positive plate + positive resist method may be used).

[0088] The thickness of the first superconducting layer 202 may be 100 nm to 200 nm.

[0089] Step S3000 : forming a first insulating layer 203 on the first superconducting layer 202 .

[0090] The first insulating layer 203 is also an isolation layer.

[0091] Specifically, the material of the first insulating layer 203 may be aluminum oxide ( ).

[0092] As an example, the corresponding pattern may be etched out by ion beam etching after anodization (for example, a positive plate + positive resist method may be used).

[0093] The thickness of the first superconducting layer 202 may be 9 nm-11 nm.

[0094] Step S4000 : forming a second superconducting layer 13 on the first insulating layer 203 .

[0095] Specifically, the material of the second superconducting layer 13 may be polycrystalline niobium (Nb).

[0096] As an example, a magnetron sputtering method may be used to deposit and etch the corresponding pattern (for example, a positive plate + positive resist method may be used).

[0097] The thickness of the second superconducting layer 13 may be 100 nm to 200 nm.

[0098] Step S5000 : forming a second insulating layer 204 on the second superconducting layer 13 .

[0099] Specifically, the material of the second insulating layer 203 may be silicon oxide ( )wait.

[0100] As an example, chemical vapor deposition may be used to deposit and etch corresponding patterns (eg, a negative plate + positive resist method may be used).

[0101] The thickness of the first superconducting layer 202 may be 350 nm-370 nm.

[0102] Step S6000: forming a superconducting coil layer on the second insulating layer, etching the superconducting coil layer to obtain a superconducting coil layer for forming an input coil, a negative feedback coil and a positive feedback coil, and forming a plurality of grooves penetrating the first insulating layer in the superconducting coil layer, wherein the grooves are filled with superconducting material for connecting the superconducting coil layer and the first superconducting layer.

[0103] Specifically, the material of the superconducting coil layer 14 may be polycrystalline niobium (Nb).

[0104] As an example, the corresponding pattern may be etched out by ion beam etching after anodization (for example, a positive plate + positive resist method may be used).

[0105] The thickness of the first superconducting layer 202 may be 390 nm-410 nm.

[0106] Step S7000 : forming a resistance layer 205 on the superconducting coil layer 14 .

[0107] Specifically, the material of the resistance layer 205 may be a PdAu thin film or the like.

[0108] As an example, electron beam evaporation may be used to deposit and etch corresponding patterns (for example, a positive plate + positive resist method may be used).

[0109] The thickness of the resistance layer 205 may be 50 nm-500 nm.

[0110] The resistor layer 205 is used to form the first resistor 11 , the second resistor 15 and the attenuation resistor 12 .

[0111] In the preparation method of the second-order gradient independent input feedback type positive feedback superconducting quantum interference device in the above embodiment, four superconducting loops arranged in a central symmetrical manner are formed with four input superconducting gaskets and four feedback superconducting gaskets, and the input coil is coupled with the four superconducting input superconducting gaskets, the negative feedback coil is coupled with the two negative feedback superconducting gaskets, and the positive feedback coil is coupled with the two positive feedback superconducting gaskets. This avoids the problem of coupling the input coil, the positive feedback coil and the feedback coil to the same superconducting gasket in the prior art, which increases the crosstalk between the three coils and reduces the coupling coefficient and energy transfer efficiency between the coils. It can at least effectively reduce the crosstalk phenomenon between multiple coils and improve the coupling coefficient and energy transfer efficiency between the coils.

[0112] In addition, the problem of increased complexity of the device, which reduces its symmetry and causes increased interference of the ambient magnetic field on the device, is also avoided.

[0113] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, 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.

[0114] The above embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the patent of the present disclosure shall be subject to the attached claims.

Claims

1. A second-order gradient independent input feedback type positive feedback superconducting quantum interference device, characterized in that: include: Eight superconducting gaskets, the eight superconducting gaskets include four input superconducting gaskets and four feedback superconducting gaskets, one input superconducting gasket and one feedback superconducting gasket form a superconducting loop, the four superconducting loops are arranged in a central symmetric manner, the four feedback superconducting gaskets include two positive feedback superconducting gaskets and two negative feedback superconducting gaskets, an input coil coupled to the four input superconducting pads; A negative feedback coil, wherein the negative feedback coil is coupled to two negative feedback superconducting gaskets; A positive feedback coil, wherein the positive feedback coil is coupled to two positive feedback superconducting gaskets, and the two positive feedback superconducting gaskets are symmetrical with the two negative feedback superconducting gaskets along a horizontal symmetry line of the eight superconducting gaskets; Also included is a bias coil, wherein the bias coil includes a first resistor, a second resistor, a first Josephson junction, and a second Josephson junction. The first Josephson junction and the second Josephson junction are respectively connected to the two positive feedback superconducting gaskets and the two negative feedback superconducting gaskets, the first resistor and the second resistor are connected in parallel, and the first Josephson junction and the second Josephson junction are both superconductingly connected to the positive feedback port.

2. The second-order gradient independent input feedback type positive feedback superconducting quantum interference device according to claim 1, characterized in that: The input coil is wrapped around the four input superconducting pads and forms an input port on a horizontal symmetry line of the eight superconducting pads.

3. The second-order gradient independent input feedback type positive feedback superconducting quantum interference device according to claim 2, characterized in that: The negative feedback coil is wrapped around two negative feedback superconducting gaskets to form a negative feedback port; The positive feedback coil is wound around two positive feedback superconducting pads and forms a positive feedback port on the horizontal symmetry line of the eight superconducting pads in a direction away from the input port.

4. The second-order gradient independent input feedback type positive feedback superconducting quantum interference device according to claim 3, characterized in that: The positive feedback coil includes a target resistance.

5. The second-order gradient independent input feedback type positive feedback superconducting quantum interference device according to claim 1, characterized in that: Each input superconducting shim includes: substrate; A first superconducting layer, located on the substrate; a first insulating layer, located on the first superconducting layer; The superconducting coil layer is located on the first insulating layer.

6. The second-order gradient independent input feedback type positive feedback superconducting quantum interference device according to claim 1, characterized in that: Each feedback superconducting spacer includes: substrate; A first superconducting layer, located on the substrate; A first insulating layer, located on the first superconducting layer; The superconducting coil layer is located on the first insulating layer.

7. The second-order gradient independent input feedback type positive feedback superconducting quantum interference device according to claim 6, characterized in that: The positive feedback coil comprises: A first superconducting layer, located on the substrate; A first insulating layer, located on the first superconducting layer; a superconducting coil layer, located on the second insulating layer; The resistance layer is located on the superconducting coil layer.

8. The second-order gradient independent input feedback type positive feedback superconducting quantum interference device according to claim 6, characterized in that: The negative feedback coil comprises: A first superconducting layer, located on the substrate; A first insulating layer, located on the first superconducting layer; a superconducting coil layer, located on the second insulating layer; The positive feedback coil and the negative feedback coil are wound in opposite directions, and the input coil and the positive feedback coil are wound in the same direction.

9. A method for preparing a second-order gradient independent input feedback type positive feedback superconducting quantum interference device, characterized in that: include: providing a substrate; forming a first superconducting layer on the substrate, and etching the first superconducting layer to obtain a first superconducting layer of a first target pattern; forming a first insulating layer on the first superconducting layer; forming a second superconducting layer on the first insulating layer; forming a second insulating layer on the second superconducting layer; A superconducting coil layer is formed on the second insulating layer, and the superconducting coil layer is etched to obtain a superconducting coil layer for forming an input coil, a negative feedback coil, and a positive feedback coil, and a plurality of grooves penetrating the first insulating layer are formed in the superconducting coil layer, wherein superconducting materials are deposited in the grooves for connecting the superconducting coil layer and the first superconducting layer; forming a resistance layer on the superconducting coil layer, wherein the resistance layer is used to form a first resistance, a second resistance and a target resistance; Among them, the second-order gradient independent input feedback type positive feedback superconducting quantum interference device includes: Eight superconducting gaskets, the eight superconducting gaskets include four input superconducting gaskets and four feedback superconducting gaskets, one input superconducting gasket and one feedback superconducting gasket form a superconducting loop, the four superconducting loops are arranged in a central symmetric manner, the four feedback superconducting gaskets include two positive feedback superconducting gaskets and two negative feedback superconducting gaskets, an input coil coupled to the four input superconducting pads; A negative feedback coil, the negative feedback coil being coupled to the two negative feedback superconducting gaskets; A positive feedback coil, wherein the positive feedback coil is coupled to two positive feedback superconducting gaskets, and the two positive feedback superconducting gaskets are symmetrical with the two negative feedback superconducting gaskets along a horizontal symmetry line of the eight superconducting gaskets; Also included is a bias coil, wherein the bias coil includes a first resistor, a second resistor, a first Josephson junction, and a second Josephson junction. Wherein, the first Josephson junction and the second Josephson junction are respectively connected to the two positive feedback superconducting gaskets and the two negative feedback superconducting gaskets, the first resistor and the second resistor are connected in parallel, and the first Josephson junction and the second Josephson junction are both superconductingly connected to the positive feedback port; Wherein, the positive feedback coil includes a target resistance.

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