Josephson junction device, Josephson junction circuit and superconducting quantum chip

Abstract

The utility model discloses a Josephson junction device, a Josephson junction circuit and a superconducting quantum chip. The Josephson junction device comprises a first superconducting plate which is formed on a substrate and is provided with a first edge inclined relative to a preset direction and a second edge perpendicular to the preset direction; the second superconducting plate is located on the first superconducting plate, and an insulating layer is arranged between the second superconducting plate and the first superconducting plate; the third superconducting plate is formed on the substrate, insulated from the first superconducting plate and provided with a first part located on the outer side of the first edge, a second part located on the outer side of the second edge and a third part connected with the first part and the second part; wherein the second superconducting plate is connected with the first part at the first edge and is separated from the second part at the second edge. According to the utility model, disconnection between the Josephson junction and the external circuit can be avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of quantum chips, in particular to a Josephson junction device, a Josephson junction circuit and a superconducting quantum chip. Background Art

[0002] The Josephson junction is a three-layer thin film structure consisting of two layers of superconducting metal films, such as niobium film or aluminum film, with a barrier layer (usually a very thin oxide film) sandwiched in between, forming a three-layer structure of S (superconductor) - I (semiconductor or insulator) - S (superconductor). By adjusting the overlapping area of ​​the two layers of superconducting metal films, the area of ​​the Josephson junction region can be adjusted, and then the resistance of the Josephson junction can be adjusted.

[0003] The Josephson junction is usually formed on a substrate, and the signal of the Josephson junction is transmitted to the external circuit through the upper superconducting metal film. When the two superconducting metal films are not completely overlapped, a part of the upper superconducting metal film will be formed on the substrate. Since there is a height difference between the lower superconducting metal film and the substrate, and the upper superconducting metal film is usually prepared by oblique evaporation, if the thickness of the upper superconducting metal film is less than that of the lower superconducting metal film, it is often the case that the part of the upper superconducting metal film located on the lower superconducting metal film and the part located on the substrate are disconnected on the side of the lower superconducting metal film that is opposite to the evaporation direction, which causes the Josephson junction to be disconnected from the external circuit and unable to transmit signals. Utility Model Content

[0004] The utility model aims to provide a Josephson junction device, a Josephson junction circuit and a superconducting quantum chip to solve the problem of disconnection between the Josephson junction and the external circuit in the prior art, and to avoid the occurrence of disconnection between the Josephson junction and the external circuit.

[0005] In order to solve the above technical problems, the utility model provides a Josephson junction device, comprising:

[0006] A first superconducting plate, formed on a substrate, having a first edge inclined relative to a preset direction and a second edge perpendicular to the preset direction;

[0007] a second superconducting plate, located on the first superconducting plate, with an insulating layer between the second superconducting plate and the first superconducting plate;

[0008] a third superconducting plate formed on the substrate, insulated from the first superconducting plate, having a first portion located outside the first edge, a second portion located outside the second edge, and a third portion connecting the first portion and the second portion;

[0009] The second superconducting plate is connected to the first portion at the first edge and is separated from the second portion at the second edge.

[0010] Preferably, the insulating layer completely covers the first superconducting plate.

[0011] Preferably, the second superconducting plate is connected to the first part via a superconducting connecting portion.

[0012] Preferably, the superconducting connection portion is in a slope shape, and the superconducting connection portion slopes from the first portion to the second superconducting plate in the preset direction.

[0013] Preferably, the superconducting connecting portion is respectively connected to the upper surface of the first portion and the side wall of the second superconducting plate.

[0014] Preferably, the first edge and the second edge are two adjacent edges.

[0015] Preferably, the inner angle formed by the first edge and the second edge is an acute angle.

[0016] Preferably, the first superconducting plate is in the shape of a right-angled trapezoid, and the first edge is the hypotenuse of the right-angled trapezoid.

[0017] In order to solve the above technical problems, the utility model also provides a Josephson junction circuit, comprising any of the aforementioned Josephson junction devices and a first superconducting strip and a second superconducting strip located on the substrate, wherein the first superconducting strip is connected to the first superconducting plate along a direction perpendicular to the preset direction, and the second superconducting strip is connected to the second part along the preset direction.

[0018] In order to solve the above technical problems, the utility model also provides a superconducting quantum chip, including any one of the aforementioned Josephson junction devices, or the aforementioned Josephson junction circuit.

[0019] Different from the prior art, the Josephson junction device provided by the utility model comprises a first superconducting plate, a second superconducting plate and a third superconducting plate, wherein the first superconducting plate comprises a first edge inclined relative to a preset direction and a second edge perpendicular to the preset direction, the second superconducting plate is only overlapped on the first superconducting plate, the third superconducting plate is insulated from the first superconducting plate and is only connected to the second superconducting plate at the first edge, and since the first edge is designed as a bevel, it is easier to realize the connection between the second superconducting plate and the third superconducting plate, and the signal of the Josephson junction can be transmitted to the external circuit via the third superconducting plate, thereby avoiding the occurrence of the disconnection between the Josephson junction and the external circuit.

[0020] The Josephson junction circuit and superconducting quantum chip provided by the present invention include the aforementioned Josephson junction device, which belong to the same inventive concept as the aforementioned Josephson junction device and have the same technical effects, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the top view structure of a Josephson junction device provided in an embodiment of the utility model.

[0022] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure in the BB direction. DETAILED DESCRIPTION

[0023] The specific implementation of the utility model will be described in more detail below in conjunction with the schematic diagram. The advantages and features of the utility model will become clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the utility model.

[0024] In the description of the present invention, it should be understood that the terms "center", "up", "down", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0026] Please refer to Figure 1 The embodiment of the utility model provides a Josephson junction device, which includes a first superconducting plate 1, a second superconducting plate 2 and a third superconducting plate 3.

[0027] The first superconducting plate 1 is formed on a substrate 10 , and has a first edge L1 inclined relative to a preset direction A and a second edge L2 perpendicular to the preset direction A.

[0028] The second superconducting plate 2 is located on the first superconducting plate 1 , with an insulating layer (not shown schematically in the figure) between the second superconducting plate 2 and the first superconducting plate 1 .

[0029] The third superconducting plate 3 is formed on the substrate 10 , insulated from the first superconducting plate 1 , and has a first portion 31 located outside the first edge L1 , a second portion 32 located outside the second edge L2 , and a third portion 33 connecting the first portion 31 and the second portion 32 .

[0030] The second superconducting plate 2 is connected to the first portion 31 at the first edge L1 and is separated from the second portion 32 at the second edge L2.

[0031] The first superconducting plate 1 is made of a superconducting material. For example, the first superconducting plate 1 is made of a material such as a tantalum nitride film or an aluminum film covering the substrate 10. The tantalum nitride film or the aluminum film exhibits superconducting properties at low temperatures. The first superconducting plate 1 is in the shape of a polygon, and the first edge L1 and the second edge L2 are two edges thereof. In this embodiment, the first edge L1 and the second edge L2 are two adjacent edges, and the inner angle formed by the first edge L1 and the second edge L2 is an acute angle. In some other embodiments, the first edge L1 and the second edge L2 may be non-adjacent edges, for example, there are other edges between the first edge L1 and the second edge L2.

[0032] To facilitate the process of preparing the first superconducting plate 1 , the edges of the first superconducting plate 1 except the first edge L1 may be arranged to be perpendicular or parallel to the preset direction A. For example, the shape of the first superconducting plate 1 is a right-angled trapezoid, and the first edge L1 is the hypotenuse of the right-angled trapezoid.

[0033] The insulating layer can be formed on the first superconducting plate 1 by a physical method or by a chemical method. In the present embodiment, the insulating layer is formed by a chemical method. The insulating layer is made of an oxide of the material used for the first superconducting plate 1, and the oxide layer formed by oxidizing the first superconducting plate 1 serves as the insulating layer. The insulating layer can be formed by natural oxidation, or by dry oxidation, wet oxidation, or a combination of dry oxidation and wet oxidation. In other embodiments, an insulating layer with insulating properties can be added directly to the first superconducting plate 1 by a physical method, such as depositing or pasting a layer of oxide. In the present embodiment, the insulating layer can completely cover the first superconducting plate 1, not only covering the upper surface of the first superconducting plate 1, but also covering the side of the first superconducting plate 1, so that the third superconducting plate 3 will not be in direct contact with the first superconducting plate 1, ensuring that the third superconducting plate 3 is insulated from the first superconducting plate 1.

[0034] The second superconducting plate 2 may be made of the superconducting material used in the first superconducting plate 1. The second superconducting plate 2 may cover the first superconducting plate 1 in whole or in part. In this embodiment, the area of ​​the second superconducting plate 2 is smaller than that of the first superconducting plate 1 and does not extend beyond the edge of the first superconducting plate 1. In order to facilitate the connection between the second superconducting plate 2 and the first portion 31 of the third superconducting plate 3, the second superconducting plate 2 is flush with the first edge L1 of the first superconducting plate 1.

[0035] The third superconducting plate 3 may also be made of the superconducting material used in the first superconducting plate 1. The first part 31 and the third part 33 of the third superconducting plate 3 may contact the insulating layer of the side wall of the first superconducting plate 1, and the second part 32 may form a gap with the insulating layer of the side wall of the first superconducting plate 1. It should be noted that in order to distinguish and show the first part 31, the second part 32 and the third part 33, a dividing line is used in the figure to show the difference, and the dividing line does not mean that the first part 31, the second part 32 and the third part 33 are spliced, and they can be integrally formed, for example, the first part 31, the second part 32 and the third part 33 are formed by one deposition process.

[0036] Please refer to Figure 1 and Figure 2 In this embodiment, the second superconducting plate 2 is connected to the first portion 31 through the superconducting connection portion 4. The superconducting connection portion 4 is connected to the first portion 31 located outside the first edge L1 and located on the substrate 10 on one hand, and is connected to the second superconducting plate 2 located on the first superconducting plate 1 on the other hand, thereby realizing the electrical connection between the second superconducting plate 2 and the first portion 31. Specifically, the superconducting connection portion 4 is connected to the upper surface of the first portion 31 and the side wall of the second superconducting plate 2 respectively.

[0037] In this embodiment, the superconducting connection portion 4 is in a slope shape, and the superconducting connection portion 4 slopes in a preset direction A from the first portion 31 toward the second superconducting plate 2 .

[0038] During the process preparation, the second superconducting plate 2, the third superconducting plate 3, and the superconducting connection portion 4 can be formed together. For example, the side of the first superconducting plate 1 away from the second edge L2 is partially blocked, and then the first superconducting plate 2 is inclinedly evaporated from the side away from the second edge L2 toward the second edge L2 in the preset direction A, and the part of the substrate 10 outside the first superconducting plate 1 is also within the evaporation range, so that the second superconducting plate 2 is formed on the first superconducting plate 1, the third superconducting plate 3 is formed on the substrate 10, and the first part 31 of the third superconducting plate 3 and the superconducting connection portion 4 of the second superconducting plate 2 are formed. Since the side wall where the first edge L1 is located faces the evaporation direction, the second superconducting plate 2 is not directly connected to the first part 31 at the first edge L1, but a superconducting connection portion 4 is formed here to connect the second superconducting plate 2 with the first part 31. Since the side wall where the second edge L2 is located is facing away from the evaporation direction, the second part 32 can only be formed at a certain distance from the first superconducting plate 1, so that the second superconducting plate 2 is separated from the second part 32.

[0039] Please refer again Figure 1Another embodiment of the utility model further provides a Josephson junction circuit. The Josephson junction circuit includes the Josephson junction device of the aforementioned embodiment and a first superconducting strip 5 and a second superconducting strip 6 located on a substrate 10, wherein the first superconducting strip 5 is connected to the first superconducting plate 1 along a direction perpendicular to a preset direction A, and the second superconducting strip 6 is connected to the second portion 32 of the third superconducting plate 3 along a preset direction A. The first superconducting strip 5 and the second superconducting strip 6 can be used as paths for signal transmission. If a signal flows into the first superconducting strip 5, the signal passes through the insulating layer from the first superconducting plate 1, then passes through the second superconducting plate 2 from the insulating layer, and then passes through the superconducting connecting portion 4 from the second superconducting plate 2, and passes through the first portion 31, the third portion 33, and the second portion 32 from the superconducting connecting portion 4 in sequence, and finally flows out from the second superconducting strip 6.

[0040] Another embodiment of the utility model further provides a superconducting quantum chip, which includes the Josephson junction device of the above embodiment or the Josephson junction circuit of the above embodiment.

[0041] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example" or "specific example" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

[0042] The above are only preferred embodiments of the present invention and do not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, may make any equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which shall be deemed as the content of the technical solution of the present invention and still fall within the protection scope of the present invention.

Claims

1. A Josephson junction device, characterized in that: include: A first superconducting plate, formed on a substrate, having a first edge inclined relative to a preset direction and a second edge perpendicular to the preset direction; a second superconducting plate, located on the first superconducting plate, with an insulating layer between the second superconducting plate and the first superconducting plate; a third superconducting plate formed on the substrate, insulated from the first superconducting plate, having a first portion located outside the first edge, a second portion located outside the second edge, and a third portion connecting the first portion and the second portion; The second superconducting plate is connected to the first portion at the first edge and is separated from the second portion at the second edge.

2. The Josephson junction device according to claim 1, characterized in that: The insulating layer completely covers the first superconducting plate.

3. The Josephson junction device according to claim 1, characterized in that: The second superconducting plate is connected to the first portion via a superconducting connecting portion.

4. The Josephson junction device according to claim 3, characterized in that: The superconducting connection portion is in a slope shape, and the superconducting connection portion slopes from the first portion toward the second superconducting plate in the preset direction.

5. The Josephson junction device according to claim 3, characterized in that: The superconducting connection parts respectively connect the upper surface of the first part and the side walls of the second superconducting plate.

6. The Josephson junction device according to claim 1, characterized in that: The first edge and the second edge are two adjacent edges.

7. The Josephson junction device according to claim 6, characterized in that: An inner angle formed by the first edge and the second edge is an acute angle.

8. The Josephson junction device according to claim 6, characterized in that: The first superconducting plate is in the shape of a right-angled trapezoid, and the first edge is a hypotenuse of the right-angled trapezoid.

9. A Josephson junction circuit, characterized in that: The device comprises a Josephson junction device according to any one of claims 1 to 8, and a first superconducting strip and a second superconducting strip located on the substrate, wherein the first superconducting strip is connected to the first superconducting plate along a direction perpendicular to the preset direction, and the second superconducting strip is connected to the second portion along the preset direction.

10. A superconducting quantum chip, characterized in that: It comprises the Josephson junction device according to any one of claims 1 to 8, or the Josephson junction circuit according to claim 9.

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