CN217881568U - Circuit assembly and superconducting quantum interferometer - Google Patents

Abstract

The application discloses circuit assembly, superconductive quantum interferometer belongs to quantum chip and makes the field. The circuit assembly includes a first conductor element, a second conductor element, and a multi-junction element having a plurality of josephson junctions. Wherein the first electrode of the multi-junction element is connected to the first conductor element and wherein a selected one or more of the plurality of second electrodes is used for the second conductor element connection. Since the circuit module has a plurality of josephson junctions, it is possible to connect the second electrodes corresponding to the qualified junctions to the second conductor element by screening the junctions so as to obtain satisfactory junctions. If the circuit component is applied to the quantum device, the success rate of manufacturing the quantum device can be improved, and meanwhile, the manufacturing cost is reduced, and the manufacturing period is shortened.

Description

Circuit assembly and superconducting quantum interferometer

Technical Field

The application belongs to the field of quantum chip preparation, and particularly relates to a circuit assembly and a superconducting quantum interferometer.

Background

The qubits and the tunable couplers on the superconducting quantum chips each have a corresponding josephson junction. Therefore, whether the performance of the josephson junction is qualified or not will have an important influence on the performance of the superconducting quantum chip.

When the performance of a plurality of qubits and the adjustable coupler on one chip is poor, the quantum chip manufactured based on the qubits cannot achieve the required target performance. Meanwhile, the time and resource cost for fabricating one chip are high, and thus it is necessary to consider the design scheme of the josephson junction in order to shorten the fabrication period and reduce the fabrication cost for fabricating a quantum device satisfying the performance requirements by applying a qualified josephson junction.

SUMMERY OF THE UTILITY MODEL

In view of the above, the present application discloses a circuit component and a superconducting quantum interferometer, which can be applied to a superconducting quantum computing system, thereby reducing the manufacturing cost of the superconducting quantum system and shortening the manufacturing period.

The scheme exemplified in the present application is implemented as follows.

In a first aspect of the present application, the present application example provides a circuit assembly comprising a first conductor element, a second conductor element, and a multi-junction element.

Wherein the multi-junction element comprises:

a first electrode configured to be connected to the first conductor element, extending in a first predetermined direction, the first electrode defining a plurality of junction regions sequentially spaced along an extension trace of the first electrode;

a plurality of barrier elements coupled to the first electrode and respectively located at the plurality of junction regions in a one-to-one correspondence; and

a plurality of second electrodes configured to be connected to the second conductor element through at least a selected one of the plurality of second electrodes, each of the plurality of second electrodes extending in a second predetermined direction crossing the first predetermined direction, the plurality of second electrodes corresponding to the plurality of barrier elements one to one and being coupled to the barrier elements;

at any junction region, the first electrode, the barrier element, and the second electrode are sequentially stacked to form a Josephson junction.

Since the performance of the josephson junction plays an important role in the performance of superconducting quantum devices (such as superconducting quantum bits, etc.), a josephson junction whose performance meets design requirements is required when manufacturing superconducting quantum devices. The circuit components in the examples of the present application can be used to fabricate satisfactory superconducting quantum devices containing josephson junctions at lower cost (e.g., in terms of time and resource utilization).

In the above circuit module, the first conductor element, the multijunction element, and the second conductor unit are arranged. Wherein the first conductor element and the second conductor element can be used for the access of the circuit assembly into various circuit systems. The multi-junction element includes a first electrode, a plurality of barrier elements, and a plurality of second electrodes, and a plurality of josephson junctions are formed by the three. Wherein the first electrode of the multijunction element is connected to the first conductor element and the second element is selected so that at least one of the elements is connected to the second element.

Thus, one or more josephson junctions may be introduced into various desired circuitry using the circuit assembly. These josephson junctions may be selectively connected with the second element by one or more of the second electrodes, and thus one or more josephson junctions meeting performance requirements may be introduced into the circuitry based on the circuit assembly in the examples of the present application, so that higher performance superconducting quantum devices may be obtained.

Compared with the method that Josephson junctions in required quantity are directly manufactured, the method is introduced into a circuit system to manufacture superconducting quantum devices, and then testing and screening qualified devices are carried out; or a scheme of manufacturing a single Josephson junction, screening qualified Josephson junctions and introducing the junctions into a circuit system to manufacture a superconducting quantum device, the circuit assembly of the example of the application is provided with a plurality of Josephson junctions at one time, the Josephson junctions can be conveniently and optionally tested, and then the qualified Josephson junctions can be introduced into the circuit system, thereby improving the yield of the superconducting quantum device, shortening the manufacturing period of obtaining the qualified superconducting quantum device, reducing the manufacturing cost,

according to some examples of the application, the first electrode is connected to the first pad, and the first electrode is connected to the first conductor element through the first pad;

and/or the plurality of second electrodes are connected with the plurality of independent second bonding pads in a one-to-one correspondence manner, and at least one selected second electrode is connected with the second conductor element through the corresponding second bonding pad;

and/or the second electrodes have lengths defined along a second preset direction, and the lengths of the second electrodes in the plurality of second electrodes are the same.

According to some examples of the present application, the circuit assembly further includes a bar-shaped member extending from the second conductor in a second predetermined direction, the bar-shaped member being configured to be connected to the second electrode of the selected at least one;

or the circuit assembly further comprises a strip-shaped component formed by extending the second conductor along a second preset direction, the second electrode is connected with the second bonding pad, and the strip-shaped component is configured to be connected with the second electrode of at least one selected second electrode through the second bonding pad.

According to some examples of the application, the strip-like member is of unitary construction with the second conductor element.

According to some examples of the present application, the bar member includes a first bar and a second bar, the first bar is correspondingly connected to the second electrode of the selected at least one, and the second bar is not connected to the second electrode.

According to some examples of the present application, the number of the first bars is the same as the number of the second electrodes of the selected at least one;

and/or the number of the second bars is the same as the number of the second electrodes except for the selected at least one of the plurality of second electrodes.

According to some examples of the present application, the second conductor element includes a first part and a second part configured independently, the number of the second electrodes of the selected at least one being at least two;

and part of at least two second electrodes is connected with the first component, and the rest part of at least one selected second electrode is connected with the second component.

According to some examples of the present application, the number of second electrodes connected to component one is equal to the number of second electrodes connected to component two.

According to some examples of the present application, the second conductor has a plurality of bar-shaped members extending in the second preset direction, and is connected to the second electrode of the selected at least one through at least some of the bar-shaped members.

According to some examples of the present application, the extension length of each of the plurality of bar-shaped members in the second preset direction is the same.

According to some examples of the present application, an extension length of each of the bar-shaped members connected to the first member in the second predetermined direction is different, and an extension length of each of the second electrodes connected to the first member in the second predetermined direction is different;

and/or the extension lengths of the strip-shaped components connected with the second component along the second preset direction are different, and the extension lengths of the second electrodes connected with the second component along the second preset direction are different.

According to some examples of the application, the length of each strip-shaped part corresponding to the first part along the second preset direction gradually increases from the middle line to the side of the first part;

and/or the length of each strip-shaped component corresponding to the second component along the second preset direction gradually increases from the middle line to the side of the second component.

According to some examples of the application, the first electrode defines a centerline perpendicular to the first predetermined direction, and the first feature and the feature are symmetrically located on opposite sides of the centerline.

According to some examples of the present application, the second electrodes have lengths along a second preset direction, and the lengths of the second electrodes corresponding to the first connecting parts are gradually reduced in sequence from the middle line to the side of the first connecting part;

and/or the second electrodes have lengths along a second preset direction, and the lengths of the second electrodes corresponding to the second connecting parts are gradually reduced from the middle line to the side of the second connecting part.

In a second aspect, examples of the application present a superconducting quantum interferometer comprising a superconducting circuit forming a superconducting loop with the josephson structure and a josephson junction introduced by the aforementioned circuit assembly.

Has the advantages that:

compared with the prior art, the circuit assembly and the superconducting quantum interferometer can be used for manufacturing qualified Josephson junctions with lower cost and higher efficiency and various superconducting quantum devices manufactured based on the Josephson junctions.

In the existing scheme, fabricated josephson junctions are directly applied to quantum devices and used at a later stage. This may cause the quantum device to be unable to be used normally or to meet expected requirements due to problems such as the performance of the josephson junction, and further, the josephson junction needs to be re-fabricated and the quantum device needs to be re-fabricated based on the re-fabricated josephson junction. Such fabrication and feedback mechanisms result in long fabrication cycles and high trial and error costs for quantum devices. In the circuit assembly manufactured in the example of the application, a plurality of josephson junctions (more than the number of josephson junctions required by the target in the quantum device) are configured, so that the circuit assembly can be applied to the quantum device, and one or more josephson junctions meeting the requirements are screened from the circuit assembly in the manufacturing process and are connected into the circuit, so that the josephson junctions in the formed quantum device meet the requirements of the corresponding device, and the peripheral circuits and devices of the pre-manufactured josephson junctions are not wasted.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments or the prior art of the present application, the drawings used in the description of the embodiments or the prior art will be briefly described below.

Fig. 1 is a schematic structural diagram of a circuit assembly according to an embodiment of the present disclosure;

FIG. 2 shows a schematic diagram of the structure of a multi-junction element in the circuit assembly of FIG. 1;

figure 3 discloses a schematic diagram of the cooperating structure of the first electrode, barrier element and second electrode in the multi-junction cell of figure 2;

FIG. 4 is a schematic diagram of another circuit assembly according to an embodiment of the present disclosure;

fig. 5 is a schematic diagram illustrating a connection manner of a first conductor element and a first electrode in the circuit assembly based on the structure of fig. 4;

fig. 6 shows a schematic structural diagram of a pad in a circuit assembly in an example of the present application, in which a first electrode and two second electrodes are respectively configured to provide a measurement node;

fig. 7 is a schematic diagram showing a structure in which a first electrode and eight second electrodes are provided respectively with pads in a circuit component in an example of the present application;

fig. 8 shows a schematic structural view of another circuit assembly in an example of the present application and in which selected two second electrodes are connected to a second conductor element;

fig. 9 shows a schematic view of another circuit assembly in an example of the present application and a selected two second electrodes connected to a two-part second conductor element;

fig. 10 is a schematic view showing another circuit assembly in the example of the present application and a structure in which two selected second electrodes are connected to the second conductor element provided with the bar member;

FIG. 11 discloses a schematic diagram of a circuit assembly exemplarily disclosed by the present application in which the lengths of respective second electrodes (of which selected two have been connected to a second conductor element) are gradually changed, and the lengths of the corresponding second conductor elements are also gradually changed;

fig. 12 discloses a schematic diagram of a comparative structure of a magnetic flux plane (among a diagrams) of a circuit assembly (selected two second electrodes have been connected to second conductor elements; wherein B and C represent the definition of two magnetic flux planes) and a conventional circuit structure in which only two josephson junctions are arranged, in an example of the present application.

Icon: 20-circuit components; 10-a multi-junction element; 201-a first conductor element; 202-a second conductor element; 101-a first electrode; 102-a second electrode; 103-barrier elements; 301-component one; 302-part two; 401 — a first pad; 4011-first transfer band; 402-a second pad; 4021-a second transfer tape; 403-bar elements.

Detailed Description

Because the time and resource costs for producing quantum chips are high, it is desirable that various components and process conditions used in the manufacturing process meet the design requirements to minimize problems at the later stage of the process. For superconducting quantum chips, an important constituent structure is the josephson junction. At present, in the practice of the present inventors, josephson junctions need to be tested when applied to superconducting quantum chips. If the performance of the tested Josephson junction can not meet the requirement, the performance of the quantum chip manufactured based on the Josephson junction can not reach the expectation.

Currently, the present inventors apply josephson junctions in superconducting quantum chips, for example, by fabricating peripheral structures (including various lines and components) except for the josephson junctions, and then fabricating a required number (e.g., two) of josephson junctions at appropriate positions in the quantum chips. And then performing performance test on the two manufactured Josephson junctions, and combining the two manufactured Josephson junctions with a line or connecting other components if the performance of the two manufactured Josephson junctions meets the requirement. However, if the performance of the fabricated josephson junction does not meet the corresponding requirements, the quantum chip is "abandoned" because the performance of the fabricated josephson junction cannot meet the expected performance, so that the peripheral structure needs to be fabricated again, then the josephson junction is fabricated and tested, and the junction is combined with various lines or structures in the quantum chip after the test is qualified.

It is known that the above-mentioned manufacturing method will result in high production cost and long production period for obtaining quantum chips satisfying design or performance requirements. The foregoing is particularly true in view of possible uncertainty and instability of the josephson junction fabrication process. In other words, based on the current production process, when the performance of the manufactured josephson junction does not meet the expectations, a large amount of waste, i.e., the cost of manufacturing the josephson junction and the cost of manufacturing the peripheral structure at the early stage, may occur. In particular, if the performance of the peripheral structure fabricated in the previous stage is acceptable, it is considered that the resource waste caused by "discarding" the acceptable peripheral structure due to the performance failure of the josephson junction is unacceptable.

In view of this, the inventors of the present application propose an optimized solution that can be used to design and fabricate josephson junctions used in quantum chips. In general, in the examples of the present application, the inventors chose to prepare multiple josephson junctions. I.e. the number of josephson junctions actually fabricated is greater, e.g. at least one, than the number of qualified josephson junctions required by the design. For example, assuming that the number of qualified josephson junctions required for design is two, the scheme exemplified in the present application may design at least three josephson junctions.

The scheme of the example of the present application configures a plurality of josephson junctions, and since the number thereof is greater than the number of josephson junctions actually required, when one or more josephson junctions do not satisfy requirements during the test, other remaining josephson junctions may be employed as potential available replacements. That is, in the scheme exemplified in the present application, there may be used, in terms of number, a qualified josephson junction, and, as an alternative, a josephson junction.

Thus, when the scheme exemplified in the application is used, after the Josephson junction test meets the requirements, the corresponding Josephson junctions can be connected into the circuit, so that various needed devices based on the Josephson junctions can be formed. Therefore, the scheme can avoid the problems of overhigh input time cost and the like caused by the unsuccessful manufacture of single Josephson junction.

Based on such recognition, the inventors propose a circuit assembly 20 in the present example. Referring to fig. 1, the circuit assembly 20 includes a first conductor element 201 (e.g., a bit capacitor, such as a qubit capacitor, or a coupler, or a line, such as a transmission line, etc., of a qubit in a superconducting quantum chip), a second conductor element 202 (e.g., a ground conductor, such as a ground plane, or a line, such as a transmission line, etc., of a superconducting quantum chip), and a multijunction element (not labeled); thus, the circuit assembly 20 may be switched into the circuitry of the quantum chip or connected with some structure through the first conductor element 201 and the second conductor element 202. In fig. 1, the first conductor elements are connected to the first electrodes, while the second conductor elements are not connected to the respective second electrodes (it is necessary to connect a selected one or more of the second electrodes to the second conductor elements after the test has been performed).

In particular, the multi-junction elements in circuit assembly 20 represent elements having multiple josephson junctions; i.e., a multi-junction refers to a plurality (e.g., at least two) of josephson junctions. As described above, the number (N1) of josephson junctions of the middle-junction element is selected according to the number (N2) of acceptable josephson junctions to be designed in the actual quantum chip. Wherein N1 and N2 are positive integers, and N1-N2>1; i.e. the difference between N1 and N2 is at least 1. And it is understood that when the circuit assembly 20 is applied to an actual quantum chip, a portion of the josephson junctions in the multi-junction element may be selectively accessed into the circuit structure. In addition, it is noted that the number of josephson junctions used in quantum chips, such as superconducting quantum chips, may be significant, but not all of them, or generally not all, are introduced by the circuit assembly 20 in the examples. In other words, a local or selected one of the regions in the superconducting quantum chip, to which the circuit assembly 20 in the example can be bonded when several josephson junctions need to be used in that region, thereby introducing the required number of eligible josephson junctions.

Referring again to fig. 1, generally, the multijunction element of the circuit assembly is disposed between a first conductor element 201 and a second conductor element 202. That is, the first conductor element 201 and the second conductor element 202 are substantially spaced apart along the extending direction of the first electrode 101, the first predetermined direction X.

Referring to fig. 2, an exemplary multi-junction device includes a first electrode 101, a second electrode 102, and a barrier device (not shown in fig. 2, refer to fig. 2 and fig. 3). The multi-junction element of figure 2 comprises a first electrode 101 distributed laterally and nine second electrodes 102 distributed longitudinally. It is noted that the multi-junction elements shown in fig. 2 do not correspond exactly in structure (e.g., the number and pitch of the second electrodes 102, etc.) to the multi-junction elements in the circuit component 20 of fig. 1; both of which constitute alternatives to the multi-junction element in circuit assembly 20 of the present example. It is known that, in terms of circuit structure, the first electrode and each second electrode together form nine parallel josephson junctions. These structures have one electrode, the first electrode, in common and the other electrode, the second electrode, each independently. Therefore, when any one josephson junction is to be measured, only one measuring point is selected on the first electrode, and then one measuring point is selected on the second electrode corresponding to the josephson junction to be measured, so that the measurement can be carried out.

Here, the first electrode 101 (which may be substantially linear or curved) extends in a first predetermined direction X, which is a horizontal direction in fig. 2. And for convenience of the following description, the first electrode 101 is defined with a plurality of junction regions along the extending track of the first electrode 101, and the junction regions are sequentially arranged at intervals. These junction regions may be over the entire area of the extended track of the first electrode 101, or be part of the track area arranged to the first electrode 101.

The first conductor element 201 is connected to the first electrode 101, for example, the first electrode 101 is connected to a pad, such as a first pad, and then connected to the first conductor element 201 directly or indirectly (for example, through the first transfer tape 4011) via the pad. The pad thereof and the first conductor element 201 may be indirectly connected by additionally configuring a connection line. The connection scheme of the second conductor element 202 to the second electrode 102 will be described in detail later.

The plurality of barrier elements in multi-junction element 10 are equal in number and one-to-one in location to the plurality of junction regions. Based on this, the barrier elements are respectively arranged to the junction regions of the first electrode 101. It is to be understood that the respective barrier elements bonded to the first electrode 101 may be sequentially spaced apart from each other, or the respective barrier elements may be bonded to each other (for example, in some examples, a plurality of barrier elements are obtained by means of oxidation of the surface of the first electrode 101 in the form of an aluminum film, thereby obtaining a barrier layer of a unitary film layer structure). In an example, the barrier element is bonded to the first electrode 101 by a lift-off process, or optionally in combination with a plating, photolithography, etching, or the like, or by selective oxidation, or by other means. Specifically, the process may be appropriately selected according to the materials of the first electrode 101, the barrier element 103, and the second electrode 102, which is not particularly limited in the present application.

Further, the second electrode 102 in the multi-junction element 10 is selected to extend along a second predetermined direction Y, vertical in fig. 2, which is staggered with respect to the first predetermined direction, so that the first electrode 101 and the second electrode 102 substantially assume a cross-like distribution. The first preset direction and the second preset direction may be perpendicular to each other, or may intersect with each other according to a desired angle or posture. Meanwhile, the second electrode 102 may also be a surface bonded to the barrier element 103. Thus, the first electrode 101, the barrier element, and the second element have a substantially stacked structure in this order, see fig. 3. The different three selected according to the materials of the first electrode 101, the barrier element 103 and the second electrode 102 may constitute various alternative specific forms of josephson junctions. For example, a typical josephson junction is in the form of a first electrode 101 of aluminum, a second electrode 102 of aluminum, and a piece of barrier element 103 of aluminum oxide, thereby forming a superconducting-insulating-superconducting josephson junction. In this regard, in the multi-junction element, at each crossing position (or junction position) of the first electrode 101 and the second electrode 102, a josephson junction is formed by the first electrode 101, the barrier element 103 and the second electrode 102. Thus, in a multi-junction element, the number of all junction regions in the first electrode 101 and the number of all barrier elements are equal, and also equal to the number of all second electrodes 102, and also equal to the number of all josephson junctions in the multi-junction element. Of course, in some cases, more barrier elements 103 (in the case where the barrier elements are separated) and more second electrodes 102 may be optionally configured; that is, in the case where the aforementioned one junction region and one second electrode 102 are paired one by one, a plurality of barrier elements are additionally provided, or a plurality of second electrodes 102 are additionally provided. However, since these additionally arranged barrier elements 103 or additionally arranged second electrodes 102 do not constitute (due to the fact that the second electrodes are in direct contact with the first electrodes or the surfaces of the barrier elements do not cover the second electrodes, etc.) the josephson junctions in the multi-junction element, these additionally arranged second electrodes 102 or barrier elements 103 are not used specifically, and the additional arrangements are usually unnecessary operations-unless needed for this purpose, for example, for making other structures, or connecting certain components, in view of the manufacturing cost.

Referring to fig. 1 and fig. 2 again, each of the second electrodes 102 has an equal length or a substantially equal length along the second predetermined direction Y. However, in other examples, the second electrodes 102 of the multi-junction element may be constructed in a manner of non-equal lengths (extension lengths calculated along the second predetermined direction Y). It is advantageous to have each second electrode 102 in a multi-junction element be arranged at equal lengths, in view of simplicity and ease of fabrication.

The first conductor element 201 is electrically connected to the first electrode 101 for transmitting signals. Meanwhile, the second conductor element 202 and each of the second electrodes 102 are disconnected from each other, that is, the second conductor element 202 and each of the second electrodes 102 are not in an electrical connection state. As described previously, all of the second electrodes 102 are configured to be connected with the second conductor element 202 through a selected at least one thereof. The at least one selected second electrode 102 is the second electrode 102 corresponding to the josephson junction that is determined to be satisfactory in a suitable manner.

For example, as shown in fig. 1, a schematic diagram of a circuit assembly 20 having a first electrode 101 and six second electrodes 102 is shown. Wherein the first conductor element 201 is connected to the first electrode 101 by means of a suitable conductor track. The second conductor element 202 is suitably near or near the end of the second electrode 102, but is not substantially in contact with or substantially connected, and may subsequently be selectively connected as desired.

In addition, the first conductor element 201 and the second conductor element 202 are illustrated as suitable rectangular blocks in fig. 1, but it should be noted that this does not constitute a limitation to the structure and size of the first conductor element 201 and the second conductor element 202 in the circuit assembly 20 of the present application, and may be configured with various suitable structural forms and sizes as needed in different scenarios. Structurally, both may have different relative size dimensions (e.g., rectangular areas) based on the approach shown in fig. 1. For example, the first conductor element 201 may be smaller relative to the second conductor element 202, while the second conductor element 202 needs to be arranged in correspondence with each second electrode 102, in order to connect the corresponding second electrode 102 with the second conductor element 202 when it is really needed, while reducing the complex wiring arrangement when connecting the second electrode with the second conductor element later. Such a design for example allows for the first conductor element 201 to cooperate with one first electrode 101, whereas the second conductor element 202 may cooperate with a selected number of second electrodes 102 of the plurality of second electrodes 102. Therefore, the arrangement of the first conductor element 201 with too large area can be avoided by adopting the foregoing scheme, and the problem that the second electrode 102 needs to be connected through a complicated circuit due to too small area of the second conductor element 202 can also be avoided.

Further, the manner in which the two conductor elements cooperate with the multi-junction element has been briefly described above and will be described in more detail below.

As mentioned above, since the selected number of second electrodes 102 in the multi-junction element are connected to the second conductor element 202, when the second electrodes 102 are equal in length, the connection members (which are selectively manufactured and may be the second electrodes 102 corresponding to qualified josephson junctions disposed so that the connection members are connected to the second conductor element 202 after the measurement of the josephson junctions) for connecting the second electrodes 102 to the second conductor element 202 may also be selected to be equal in length; please refer to fig. 8, 9 and 10 later. In other cases, when the lengths of the selected number of second electrodes 102 are different (see fig. 11), the length of the connecting member for connecting the second electrodes 102 and the second conductor element 202 may be appropriately adjusted. The connecting member can be described as a second adaptor strip 4021, for example.

In connection with the above, the second electrode and the second conductor element may be connected directly or indirectly. With respect to the manner of indirect connection, in some examples, the second electrode 102 and the second conductor element 202 may be indirectly connected by means of a pad, such as a second pad, as shown in fig. 9 and 10. Further, in addition to the second electrode 102 provided with the second pad 402, the second pad 402 and the second conductor element 202 may also be connected directly or indirectly. In fig. 9, the second pad is directly connected to the second conductor element; in fig. 10 and 11, the second pad and the bar-like member 403 extending from the second conductor element are indirectly connected by the aforementioned connection member (second via tape 4021).

In fig. 10 and 11, the second conductor element is arranged with a strip-like member 403, and is connected to the second electrode 102 through the strip-like member 403 by means of a second tap 4021 to connect to the second pad 402 of the second electrode 102.

When the second conductor element 202 is indirectly connected to the second electrode 102 (or the second pad 402 configured therewith) through the bar-shaped members 403 (for example, through the second via-tape 4021, which may be used as the aforementioned connecting member), the bar-shaped members 403 may correspond to the second electrode 102 in number and position. Also based on this solution, the bar-shaped member 403 and the second conductor element 202 may be of an integral structure or may be integrally formed in the process.

As can be seen from the above discussion, the second tap 4021 is selectively configured. That is, when the measured josephson junction fails, the second electrode corresponding to the junction is not connected to the second conductor element, and accordingly the second junction band is not arranged corresponding to the junction. Conversely, when the josephson junction being measured passes, the second electrode corresponding to that junction is connected to the second conductor element and correspondingly connected via the second transition zone. I.e. the second strap is connected at both ends to the second conductor element (or its extended strip-like member) and the second electrode (or its second pad), respectively.

Further, in some examples, when the number of josephson junctions selected to be connected to a circuit in a certain region of the quantum chip is plural, such as two, then the bar-shaped members 403 arranged in the second electrode 102 may also be correspondingly arranged in plural. And are described as a first bar and a second bar for convenience of description and distinction. Therefore, of all the second electrodes 102, the second electrode 102 selected to be connected to the second conductor element 202 is connected to the first bar, while the second bar is not connected to the second electrode 102. Wherein, the number of the second electrodes 102 selected to be connected with the second conductor elements 202 and the number of the first bars may be equal, so that they may correspond to each other one by one; or the number of the first electrodes and the number of the second electrodes may be different, the number of the second electrodes 102 and the number of the first bars may be selected according to different situations. These descriptive relationships apply equally to the second strips, in cooperation with the number of second electrodes 102 not selected for connection with the second conductor element 202-the number of second strips is the same (may also be different) as the number of second electrodes 102 of all the second electrodes 102 except for the one selected for connection with the second conductor element 202.

Further, in some optional examples, the one-piece second conductor element 202 in fig. 1 may also be optionally constructed in a split structure, see fig. 4 and 5, and fig. 9 and 11. Fig. 4 discloses a schematic structural diagram of another circuit assembly 20 in the present application example, and the main differences of the circuit assembly 20 in fig. 1 are: in fig. 4, the second conductor element 202 is made up of two parts, part one 301 and part two 302 respectively; and the first component 301 and the second component 302 are independent of each other, with a gap along the second predetermined direction X.

Briefly, in conjunction with FIG. 4, the second conductor element 202 is constructed as a first member 301 and a second member 302 (which are substantially identical and symmetrically distributed; other embodiments are also possible without being limited to the illustrated embodiments). In this case, a portion of the respective second electrodes 102 for introducing a qualified josephson junction into the quantum chip circuit may be connected with the component one 301, while the remaining second electrodes 102 may be connected with the component two 302. Alternatively, the number of the second electrodes 102 of a portion of the front and the number of the remaining second electrodes 102 may be equal or different.

Further, for the aforementioned example that the second conductor element 202 is provided with the extended bar-shaped component 403, and the bar-shaped component 403 is connected to the second electrode 102 through the second tap 4021, referring to fig. 11, the bar-shaped component 403 extended from the first component 301 and the bar-shaped component 403 extended from the second component 302 may be configured with different length dimensions in the extending direction.

Further, when the second conductor element 202 is formed of a plurality of parts, for example, in the case of the first part 301 and the second part 302, the first part 301 and the second part 302 may be symmetrically distributed (for example, symmetrical about a midpoint of the first electrode 101 along the first predetermined direction X, that is, a perpendicular bisector of the first electrode 101 along the first predetermined direction X is a symmetry axis). Each of the bar-shaped members 403 corresponding to the first member 301 may have a length along the second predetermined direction that gradually increases from the middle line to the side of the first member 301 (it is understood that the lengths of the corresponding second electrodes 102 may gradually decrease in sequence).

Meanwhile, on the other side, the lengths of the strip-shaped components 403 corresponding to the second component 302 may gradually increase from the middle line to the side of the second component 302 along the second predetermined direction (it is understood that the lengths of the corresponding second electrodes 102 may gradually decrease in sequence). In such a scheme, the line resistance does not have a large influence on the junction resistance; wherein the line resistance is the resistance of a portion of the connecting line (on the JJ layer) from the test pad to the junction; and is composed of a left part and a right part of a knot.

Alternatively, when the second conductor element 202 is provided with the strip-like members 403, and the strip-like members 403 are connected with the second electrode 102 or the second pad 402 thereof, then the lengths of the strip-like members 403 may be the same, as shown in fig. 10.

Based on the circuit component 20, as an example of an application that can be understood, a Superconducting Quantum Interference Device (SQUID) is proposed in the present application. The superconducting quantum interferometer includes a superconducting circuit and a circuit assembly 20 as previously described. The circuit assembly 20 may be connected to the superconducting circuit via the first conductor element 201 and the second conductor element 202 as its two ends, respectively, and at the same time, the josephson junctions in the circuit assembly 20 are also selected such that the second electrodes 102 corresponding to these selected josephson junctions are connected to the second conductor element 202, and the second electrodes 102 not corresponding to these selected josephson junctions are not connected to the second conductor element 202. Thus, by connecting a selected second electrode 102 in the circuit assembly 20 with the second conductor element 202, the circuit assembly 20 which is switched into the superconducting circuit introduces a selected josephson junction (which may be one or more) into the superconducting circuit. For example, for a radio frequency superconducting quantum interferometer (RFSQUID), a josephson junction may be introduced in the superconducting circuit; whereas for a direct current superconducting quantum interferometer (DC SQUID), two josephson junctions are introduced (in parallel) in the superconducting circuit.

As previously described, circuit assembly 20 is applied when, such as selectively introducing a number of josephson junctions into a superconducting circuit to make a superconducting quantum interferometer, it is necessary to screen the josephson junctions in circuit assembly 20. Accordingly, to more clearly illustrate the application of the circuit assembly 20, it will be described below either separately or integrated into a superconducting quantum interferometer.

An alternative exemplary approach to fabricating the circuit assembly 20 by photolithography, plating, etching, and the like, alone or in combination with optional other semiconductor processes, is as follows:

a first electrode 101 is fabricated on a substrate (if applied in a superconducting quantum chip, and the surface of the substrate may be configured with a superconducting material such as an aluminum layer), then a barrier element is formed by oxidizing the surface of the first electrode 101, then a plurality of second electrodes 102 are fabricated, and each second electrode 102 is overlaid on the barrier element. Alternatively, in other examples, a plurality of second electrodes 102 are fabricated, barrier elements are formed on the surfaces of the second electrodes 102 by, for example, oxidizing or other operations, and then the first electrodes 101 are fabricated to cross over the respective second electrodes 102, and the first electrodes 101 also cover the respective barrier elements.

To confirm that the mutual inductance generated between the josephson junction in the examples of the present application and the z-line of the qubit in the superconducting quantum chip can satisfy the design requirements, the mutual inductance between the josephson junction in the examples of the present application and the z-line of the qubit in the superconducting quantum chip is simply analyzed. The mutual inductance of the magnetic flux plane part is distributed in space and the ratio of mutual inductance in the distribution area.

The Josephson junction and the structures such as the z line, the bit or the coupler and the like are subjected to mutual inductance simulation in electromagnetic simulation software. Referring to fig. 12, a SQUID comprising two symmetrically distributed josephson junctions is exemplified by two second electrodes 102 symmetrically distributed on the perpendicular bisector of the first electrode 101.

The measured values of the josephson junction room temperature resistances corresponding to the two symmetrically distributed second electrodes 102 satisfy the design index value. As can be seen from simulation analysis, the mutual inductance of the structure of the present application (C in fig. 12, the scheme of the present application) is consistent with the mutual inductance of the SQUID (a in fig. 12, the existing scheme) in which only 2 josephson junctions are fabricated.

Further, by dividing the complete magnetic flux plane M0 in one of the SQUIDs into four regions M1, M2, M3, and M4 (B in fig. 12). Simulation results show that: in the SQUID constructed based on the circuit assembly 20 of the present example, the mutual inductance of the partial flux region m1 to the entire flux plane m is 90%; the mutual inductance of the sum of the partial flux areas m1 and m2 to the complete flux plane m is 96%. The results show that the majority of the mutual inductance from the z-line and the SQUID structure is concentrated in magnetic flux plane m 1. The same results as above can be obtained by analyzing the SQUID formed by the two second electrodes 102 (which may be symmetrically or asymmetrically distributed) and the first electrode 101 at other positions.

Further, an exemplary scheme incorporating a fabrication method of screening josephson junctions in the circuit assembly 20 is as follows:

first, an aluminum layer on the surface of the substrate is etched, and selective areas are reserved during etching to serve as a pad structure connected with other components and a conductor element. Based on the area determined and constrained by the pad, the magnetic flux in this area can be calculated. This magnetic flux can be used for subsequent measurement and evaluation of the performance of the circuit arrangement 20 in the present example. Next, josephson junctions, in which the first electrode 101 and the second electrode 102 are connected to the pad structures described above, are fabricated by, for example, oblique evaporation. These josephson junctions are then screened and, after obtaining josephson junctions of sufficient performance and quantity, the aforementioned pads are mated with the respective conductor elements in the circuit assembly 20 by means of the transfer ribbons.

The screening protocol may typically be to measure the resistance of the josephson junction and determine whether it meets expected or design requirements. It should be noted that it is not intended to indicate that the josephson junction satisfying the resistance requirement after the above resistance test is required to satisfy the josephson junction in a specific scenario, and therefore, such screening may be a preliminary screening, and screening or measurement of other items may be performed under other test conditions or requirements.

For example, with a first pad 401 connected to the first electrode 101 and a second pad 402 connected to the second electrode 102 in fig. 6 as measurement points, the room temperature resistance of the josephson junction is measured; the test equipment may be a probe card (probe card) commonly used in integrated circuits, an example of which may be selected as a femto probe.

The selection of the room temperature resistance as the condition for screening and measurement in some examples of the present application may be considered as follows:

in the design process of the quantum chip, the frequency of the qubit is determined, and then the Josephson energy is determined according to the frequency of the qubit and the non-harmonic parameter. And determining the critical current of the Josephson junction by the Josephson energy, and finally determining the normal temperature resistance of the Josephson junction by the critical current of the Josephson junction.

The parameters designed in the above process are as follows:

off-resonance

Charging energy

Qubit frequency

Josephson energy

Wherein the Planck constant h =6.620755 x 10 ^-34 J · s, C is the bit capacitance, and the electron charge amount e =1.602176634 × 10 ^-19 C。

Since a commonly used josephson junction is in the form of an Al-AlOx-Al josephson junction. Therefore, when the temperature is far below the superconducting transition temperature of aluminum, 1.18K, the critical current of the Josephson junction can be estimated empirically, and the resistance value of the room temperature resistor of the Josephson junction can be further obtained according to the estimated value.

In fig. 6, a partial structure of the circuit assembly 20 is shown, in which one first electrode 101 and two second electrodes 102 are depicted. Wherein each second electrode 102 is provided with a second pad 402. Therefore, when measuring the room temperature resistance of each josephson junction, different josephson junctions can be selected to be one measuring point from the second bonding pad 402 correspondingly connected to the second electrode 102, and the other measuring points can be provided from the first bonding pad 401 connected to the first electrode 101. Or in other examples, the corresponding second pad 402 and the proximity of the first electrode 101 to the junction may be selected as two measurement points for different josephson junctions.

Briefly, in some examples, the first pad 401 is selected as a constant measurement point, while a corresponding different second pad 402 is selected as another measurement point for different josephson junctions. Considering that the first electrode 101 and the second electrode 102 are generally constructed in a relatively small size, it is a beneficial attempt to take the first pad 401 and the second pad 402, respectively, as measuring points. For example, in fig. 7, the first measurement point for performing the room temperature resistance measurement is a first pad 401 connected to the first electrode 101, and the second measurement point may be different second pads 402 connected to the respective second electrodes 102 (including eight second electrodes 102 and corresponding eight second pads 402, and thus having eight second measurement points).

In addition, in order to facilitate those skilled in the art to implement the exemplary embodiments of the present application, a method of fabricating a superconducting quantum interferometer is described below.

The manufacturing method comprises the following steps:

step 1, providing the circuit component 20.

In this circuit assembly 20, the first electrode 101 and the first conductor element 201 may be connected in advance by a conductor structure (e.g., a transfer tape, which may be described as a bond in some cases), or may be connected in a subsequent step 3.

And 2, screening at least one Josephson junction from the circuit assembly 20.

The screening is to obtain josephson junctions that meet design performance requirements. The mode of screening is selected according to the performance criteria required to be achieved by the josephson junction. In the examples of the present application, it is mainly concerned with screening operations for electrical properties of josephson junctions. Thus, the method of screening may for example comprise electrically measuring the circuit component 20 to obtain measurement results from which josephson junctions are selected according to a predetermined pattern.

As mentioned before, the electrical measurement may be to confirm whether the room temperature resistance of the measured josephson junction meets the design requirements. And based on this, one way of measurement is: a first node is provided by the first electrode 101 and a second node is provided by the second electrode 102. Wherein the first node and the second node may be provided by pads connected to the electrodes. The existence of a josephson junction or a plurality of josephson junctions between the two nodes can be confirmed according to the configuration position of the selected first node and the second node corresponding to the selected second electrode 102.

Thus, the resistance between the two nodes may be measured using a suitable measuring instrument or apparatus, such that the resistance of the josephson junction of interest between the two nodes may be directly or indirectly obtained. After the measurement described above, the resistance value between the two nodes can be obtained, so that the room temperature resistance of the josephson junction desired to be measured can be determined. Therefore, when the designed performance index is the preset normal temperature resistance of the Josephson junction, the Josephson junction can be determined to be qualified when the measured value of the normal temperature resistance is the same as the preset value of the normal temperature resistance or the deviation of the measured value of the normal temperature resistance and the preset value of the normal temperature resistance is within the receiving range. It can then be switched into the circuit to form the SQUID.

And 3, after the first electrode and the first conductor element are connected, and the second electrode corresponding to the screened at least one Josephson junction is connected with the second conductor element, connecting the at least one Josephson junction into a superconducting circuit through the first conductor element 201 and the second conductor element 202 to form a superconducting ring.

Wherein the first electrode and the first conductor element may be connected during the manufacturing of the circuit assembly or may be connected after the testing and screening of the circuit assembly. In addition, with respect to the manufacturing flow of the whole quantum chip, in some examples, the first conductor element and the second conductor element may be connected with various suitable circuits and devices in the quantum chip already in the process of manufacturing the circuit assembly. Thus, in such an example, the introduction of a josephson junction into the circuit by the circuit components may then be a test and screening and connecting the selected second electrode with the second conductor element without connecting the first and second conductor elements with further lines.

After one or more josephson junctions meeting the requirements are obtained by measurement, as described in step 3, the second electrode 102 corresponding to the qualified josephson junctions can be connected to the second conductor element 202, so as to facilitate access to the superconducting circuit through the first conductor element 201 and the second conductor element 202, so as to superconduct the loop.

The construction, features and functions of the present application have been described in detail and illustrated in the drawings, the present application is not limited to the embodiments, but rather the invention is intended to cover all modifications, equivalents and equivalents falling within the spirit and scope of the present application.

Claims (15)

1. A circuit assembly comprising a first conductor element, a second conductor element, and a multi-junction element, wherein the multi-junction element comprises:

a first electrode configured to be connected to the first conductor element, extending in a first predetermined direction, the first electrode defining a plurality of junction regions sequentially spaced along an extension track of the first electrode;

a plurality of barrier elements coupled to the first electrode and respectively located at the plurality of junction regions in a one-to-one correspondence; and

a plurality of second electrodes configured to be connected to the second conductor element through a selected at least one of the plurality of second electrodes, each of the plurality of second electrodes extending in a second predetermined direction crossing the first predetermined direction, the plurality of second electrodes corresponding to the plurality of barrier elements one-to-one and being coupled to the barrier elements;

at any one of the junction regions, the first electrode, the barrier element, and the second electrode are sequentially stacked to form a josephson junction.

2. The circuit assembly of claim 1, wherein the first electrode is connected to a first pad, and the first electrode is connected to the first conductor element through the first pad;

and/or the plurality of second electrodes are connected with the plurality of independent second bonding pads in a one-to-one correspondence manner, and the selected at least one second electrode is connected with the second conductor element through the corresponding second bonding pad;

and/or each second electrode has a length defined along the second preset direction, and the lengths of the second electrodes in the plurality of second electrodes are the same.

3. The circuit assembly of claim 1, further comprising a strip member extending from the second conductor along the second predetermined direction, the strip member being configured to connect to the second electrode of the selected at least one;

or, the circuit assembly further includes a strip member formed by extending the second conductor along the second preset direction, the second electrode is connected to the second pad, and the strip member is configured to be connected to the second electrode of the selected at least one through the second pad.

4. A circuit assembly according to claim 3, wherein the strip-like member is of unitary construction with the second conductor element.

5. The circuit assembly according to claim 3 or 4, wherein the bar member comprises a first bar and a second bar, the first bar is correspondingly connected to the second electrode of the selected at least one, and the second bar is not connected to the second electrode.

6. The circuit assembly of claim 5, wherein the number of the first bars is the same as the number of the second electrodes of the selected at least one;

and/or the number of the second strip-shaped parts is the same as that of the second electrodes except for the selected at least one second electrode.

7. The circuit assembly of claim 1, wherein the second conductor element includes independently configured component one and component two, the number of second electrodes of the selected at least one being at least two;

and part of the at least two second electrodes is connected with the first component, and the rest of the selected at least one second electrode is connected with the second component.

8. The circuit assembly of claim 7, wherein the number of second electrodes connected to the first component is equal to the number of second electrodes connected to the second component;

and/or the first electrode defines a midline perpendicular to the first preset direction, and the first part and the second part are positioned at two sides of the midline.

9. The circuit assembly according to claim 7 or 8, wherein the second conductor has a plurality of bar-shaped members extending in the second predetermined direction, and is connected to the second electrode of the selected at least one through at least some of the bar-shaped members.

10. The circuit assembly according to claim 9, wherein the extension length of each strip-like member of the plurality of strip-like members in the second predetermined direction is the same.

11. The circuit assembly according to claim 9, wherein the extension length of each strip-shaped component connected with the first component in the second predetermined direction is different, and the extension length of each second electrode connected with the first component in the second predetermined direction is different;

and/or the extension lengths of the strip-shaped components connected with the second component along the second preset direction are different, and the extension lengths of the second electrodes connected with the second component along the second preset direction are different.

12. The circuit assembly of claim 11, wherein the first electrode defines a centerline perpendicular to the first predetermined direction, and a length of each of the strip-shaped members corresponding to the first component gradually increases from the centerline to a side of the first component along the second predetermined direction;

and/or the first electrode defines a center line perpendicular to the first preset direction, and the length of each strip-shaped component corresponding to the second component gradually increases from the center line to the side of the second component along the second preset direction.

13. The circuit assembly of claim 12, wherein the first component and the component are symmetrically located on opposite sides of the centerline.

14. The circuit assembly of claim 13, wherein the second electrodes have lengths along the second predetermined direction, and the lengths of the second electrodes corresponding to the first components are gradually decreased in sequence from the middle line to the side of the first components;

and/or the second electrodes have lengths along the second preset direction, the lengths of the second electrodes correspondingly connected with the second component are gradually reduced from the middle line to the side where the second component is located.

15. A superconducting quantum interferometer, comprising: a superconducting circuit and a josephson junction introduced by the circuit assembly of any of claims 1 to 14, the superconducting circuit forming a superconducting loop with the josephson structure.

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