Apparatus and methods for tunable superconducting resonators for quantum computing devices

Abstract

A superconducting coupling device includes a resonator structure. The resonator structure has a first end configured to couple to a first device and a second end configured to couple to a second device. A gate is positioned adjacent to a portion of the resonator structure. The gate is configured to receive a gate voltage and change a dynamic inductance of the portion of the resonator based on the gate voltage. The change in dynamic inductance causes the resonator structure to change a coupling strength between the first superconducting device and the second superconducting device.

Description

Technical Field

[0001] The present invention generally relates to superconductor devices, methods of manufacture, and systems for tuning qubit coupling in superconducting quantum devices. More specifically, the present invention relates to devices, methods, and systems for tunable superconducting resonators for quantum computing devices. Background Art

[0002] In the following, the "Q" prefix in a word or phrase indicates reference to the word or phrase in the context of quantum computing, unless explicitly distinguished otherwise when used.

[0003] Molecules and subatomic particles obey the laws of quantum mechanics, the branch of physics that explores how the physical world works at the most fundamental level. At this level, particles behave in strange ways, assume more than one state at the same time, and interact with other particles that are very far away. Quantum computing exploits these quantum phenomena to process information.

[0004] The computers we use today are called classical computers (also referred to herein as "conventional" computers or conventional nodes, or "CNs"). Conventional computers use conventional processors, semiconductor memories, and magnetic or solid-state storage devices manufactured using semiconductor materials and techniques, in the so-called von Neumann architecture. In particular, the processors in conventional computers are binary processors, i.e., they operate on binary data represented by 1s and 0s.

[0005] Quantum processors (q-processors) use the strange properties of entangled quantum bit devices (referred to here as "qubits") to perform computing tasks. In the specific field where quantum mechanics operates, particles of matter can exist in multiple states, such as an "on" state, an "off" state, and a simultaneous "on" and "off" state. Where binary computing using semiconductor processors is limited to using only on and off states (equivalent to 1 and 0 in binary code), quantum processors use these quantum states of matter to output signals that are useful in data computing.

[0006] Conventional computers encode information in bits. Each bit can take on a value of either 1 or 0. These 1s and 0s act as on / off switches that ultimately drive the computer's functions. Quantum computers, on the other hand, are based on qubits, which operate according to two key principles of quantum physics: superposition and entanglement. Superposition means that each qubit can represent both 1 and 0 at the same time. Entanglement means that qubits in superposition can be related to each other in a nonclassical way; that is, the state of one qubit (whether it is 1, 0, or both) can depend on the state of another qubit, and more information can be determined about the two qubits when they are entangled than when they are processed separately.

[0007] Using these two principles, qubits operate as more complex information processors, enabling quantum computers to function in a way that allows them to solve difficult problems that are intractable using conventional computers. IBM has successfully built and demonstrated the operability of a quantum processor using superconducting qubits (IBM is a registered trademark of International Business Machines Corporation in the United States and other countries.)

[0008] Superconducting devices such as qubits are fabricated using superconducting and semiconductor materials in known semiconductor fabrication techniques. Superconducting devices typically use one or more layers of different materials to achieve device characteristics and functions. The material layers may be superconducting, conductive, semiconductive, insulating, resistive, inductive, capacitive, or have any number of other properties. Different methods may have to be used to form different material layers, given the nature of the material, the shape, size, or placement of the material, other materials adjacent to the material, and many other considerations.

[0009] Superconducting devices are typically planar, ie, where superconductor structures are fabricated on one plane. Non-planar devices are three-dimensional (3D) devices where some structures are formed above or below a given fabrication plane.

[0010] The q-processor is implemented as a group of more than one qubit. These qubits are fabricated as a lattice of coplanar devices on a single fabrication plane. Such an implementation of the q-processor is generally accepted as a fault-tolerant quantum architecture, which is called the surface code scheme (SCS) or surface code architecture (SCA). Summary of the invention

[0011] The illustrative embodiments provide a superconducting device and a method and system for manufacturing the same. An embodiment of a superconducting coupling device includes a resonator structure. In an embodiment, the resonator structure has a first end configured to couple to a first device and a second end configured to couple to a second device. The embodiment further includes a gate positioned adjacent to a portion of the resonator structure. In the embodiment, the gate is configured to receive a gate voltage and change a dynamic inductance of the portion of the resonator based on the gate voltage, the change in the dynamic inductance causing the resonator structure to change the coupling strength between the first device and the second device.

[0012] In another embodiment, the change in kinetic inductance is a result of the gate changing the superfluid density of the portion of the resonator structure. In another embodiment, the change in kinetic inductance causes a change in the characteristic frequency of the resonator structure. In another embodiment, the change in the characteristic frequency of the resonator structure enables a change in the coupling strength between the first device and the second device.

[0013] In another embodiment, at least a portion of the resonator structure is formed of a superconducting material including magic angle twisted bilayer graphene, WTe2, Sn1-δ-xIn x Te or another suitable material. In another embodiment, the gate is formed of a metallic material or a superconducting material.

[0014] In another embodiment, a first device is capacitively coupled to a first end of the resonator structure and a second device is capacitively coupled to a second end of the resonator structure.

[0015] Another embodiment further comprises a ground plane connected to the resonator structure. In another embodiment, the ground plane is connected to the resonator structure through a shunt portion of the resonator structure.

[0016] Another embodiment further includes a substrate structure, wherein the resonator structure is disposed on a surface of the substrate structure.Another embodiment further includes an insulator disposed on the resonator structure, wherein the gate is disposed on the insulating structure.

[0017] Another embodiment also includes a ground plane disposed on a surface of the substrate proximate the resonator structure.

[0018] In another embodiment, the first device is a first qubit and the second device is a second qubit.

[0019] In another embodiment, the first device is a qubit and the second device comprises a readout measurement circuit of a quantum computing device.

[0020] In another embodiment, wherein the first device is a first transmon and the second device is a second transmon, and the resonator structure and the gate provide a tunable coupling between the first transmon and the second transmon.

[0021] One embodiment includes a manufacturing method for manufacturing the superconducting device.

[0022] One embodiment includes a manufacturing system for manufacturing the superconducting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The novel features which are believed to be characteristic of the invention are set forth in the appended claims. However, the invention itself, as well as the preferred mode of use, further objects and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings in which:

[0024] Figure 1 An example surface code architecture (SCA) illustrating problems that may be solved using the illustrative embodiments is depicted;

[0025] Figure 2 depicts an example gate tunable resonator according to an illustrative embodiment;

[0026] Figure 3 depicts an example split-gate tunable resonator in accordance with an illustrative embodiment;

[0027] Figure 4 depicts an example implementation of tuning a superconducting resonator in an SCA arrangement according to an illustrative embodiment;

[0028] Figure 5 depicts a cross-sectional view of a gate tunable resonator structure according to an illustrative embodiment;

[0029] Figure 6 depicts a cross-sectional view of a gate tunable resonator structure according to another illustrative embodiment;

[0030] Figure 7 depicts a cross-sectional view of a gate tunable resonator structure according to another illustrative embodiment; and

[0031] Figure 8 Depicted is an example implementation of tuning a superconducting resonator in an SCA arrangement in accordance with an illustrative embodiment. DETAILED DESCRIPTION

[0032] The illustrative embodiments used to describe the present invention generally address the above-mentioned and other related problems by providing a tunable superconducting resonator for a quantum computing device. The illustrative embodiments also provide a method and system for manufacturing a tunable superconducting resonator for a quantum computing device.

[0033] Figure 1 An illustrative surface code architecture (SCA) illustrating a problem that can be solved using an illustrative embodiment is depicted. A superconducting qubit architecture, such as SCA 100, arranges a plurality of qubits 102, 102A, and 102B into a lattice configuration on a planar two-dimensional (2D) grid. The qubits are coupled to each other and communicate using resonant lines 104 (also referred to as "buses"). The quantum state of a qubit 102 is read using a read line 106 that is capacitively coupled to a particular qubit.

[0034] Typically, read line 106 is a resonant line where dispersive readout is used to measure the qubit state of a particular qubit. Dispersive readout uses a dispersive interaction with the resonator, where the interaction results in a dispersive shift that causes the frequency of the resonator to change depending on the state of the qubit. The resonator frequency is interrogated with a microwave pulse, which is typically at a frequency close to the midpoint of the resonant frequency corresponding to the ground state and the excited state. The phase and amplitude of the reflected signal are used to distinguish the state of the qubit.

[0035] However, existing architectures using decentralized readout suffer from microwave crosstalk and / or frequency conflicts between qubits, resulting in reduced performance of quantum state measurements and correspondingly reduced performance of the quantum computer.

[0036] To address the above problems with existing architectures, attempts have been made to develop architectures that allow for tuning of coupling between qubits. Experimentally, tuning qubit coupling has previously relied on controlling circuit elements with magnetic flux. However, these flux-tunable qubits suffer from several disadvantages, including reduced coherence time due to flux noise, the need to finely tune the magnetic flux, their sensitivity to on-chip crosstalk (e.g., up to 30%), heating due to the current required to generate the flux, and degradation of qubit performance due to the shortened coherence time. Some recent activity has focused on developing voltage-controlled tuning of qubit coupling. One recent approach to developing voltage-controlled tuning has included proposals to controllably short two grounded transmons by gate-tuning semiconductor switches. Another recent approach uses a semiconductor nanowire-based voltage-controlled switch to controllably ground one end of a superconducting cavity to vary the coupling of a grounded gatemon.

[0037] A scheme is needed to provide a quantum computing device with a tunable superconducting resonator to solve the above-mentioned problems related to qubit coupling so as to provide multiple advantages, such as reduced microwave crosstalk and / or frequency conflict between qubits. For example, such a scheme would enable control of the coupling between qubit 102A and qubit 102B so as to reduce or eliminate microwave crosstalk and / or frequency conflict between qubit 102A and qubit 102B during readout or during application of control pulses to the qubits.

[0038] One embodiment provides a tunable coupling architecture for a quantum computing device. One embodiment includes a gate-tunable superconducting resonator in which a voltage applied to an adjacent gate tunes the superfluid density and kinetic inductance in a portion or all of the resonator structure coupled to a qubit. Tuning the kinetic inductance results in tuning of the characteristic frequency of the resonator, thereby enabling adjustment of the coupling strength between qubits to allow, for example, adjustment from weak coupling between qubits to strong coupling between qubits.

[0039] Kinetic inductance is the manifestation of the inertial mass of mobile charge carriers as an equivalent inductance and is observed in high carrier mobility conductors such as superconductors. Kinetic inductance is inversely proportional to carrier density (or superfluid density), such that when kinetic inductance increases, carrier density decreases.

[0040] In an embodiment, a changing gate voltage of the metal gate results in a change in charge density. The change in charge density results in a change in kinetic inductance and a corresponding change in the characteristic frequency of a resonator coupling the qubits. The change in the characteristic frequency of the resonator results in a change in the coupling strength between the qubits.

[0041] One or more embodiments provide gradually tunable coupling between nearest neighbor qubits through adjustment of gate voltage. Another embodiment provides multiplexed readout from qubits through a tunable readout resonator. Yet another embodiment provides the ability to turn off qubits with undesirable transition frequencies by turning off or reducing the coupling of the qubit with the undesirable transition frequency to one or more other qubits. One or more embodiments provide a novel quantum gate hardware approach using tunable superconducting resonators with faster gates and tunable coupling strength between qubits.

[0042] Another embodiment provides a method for manufacturing a tunable coupled resonator such that the method can be implemented as a software application. The application implementing the manufacturing method embodiment can be configured to operate in conjunction with an existing superconducting manufacturing system, such as a lithography system.

[0043] For clarity of description, and without implying any limitation thereto, the illustrative embodiments are described using an example number of qubits arranged in a lattice. Within the scope of the illustrative embodiments, an embodiment may be implemented with a different number of qubits, a different arrangement in a lattice, superconducting devices other than qubits, types of qubits not based on superconductors, or some combination thereof. An embodiment may be implemented to similarly improve other superconducting fabrication where tunable coupling to a superconducting element is desired.

[0044] In addition, simplified diagrams of example tunable coupled resonators are used in the drawings and illustrative embodiments. In the actual fabrication of tunable coupled resonators, there may be additional structures not shown or described herein or structures different from those shown and described herein without departing from the scope of the illustrative embodiments. Similarly, within the scope of the illustrative embodiments, the structures shown or described in the example tunable coupled resonators may be fabricated differently to produce similar operations or results as described herein.

[0045] The different shaded portions in the two-dimensional diagrams of example structures, layers and configurations are intended to represent different structures, layers, materials and configurations in example fabrication, as described herein. The different structures, layers, materials and configurations can be fabricated using suitable materials known to those of ordinary skill in the art.

[0046] The specific shapes, orientations, positions, or dimensions of the shapes depicted herein are not intended to limit the illustrative embodiments unless such characteristics are expressly described as being characteristic of the embodiments. The shapes, orientations, positions, dimensions, or some combination thereof are selected solely for purposes of clarity of the drawings and descriptions, and may have been exaggerated, minimized, or otherwise changed from actual shapes, orientations, positions, or dimensions that might be used in actual lithography to achieve purposes according to exemplary embodiments.

[0047] Furthermore, the illustrative embodiments are described with respect to specific actual or hypothetical superconducting devices (e.g., qubits) only as examples. The steps described by the different illustrative embodiments may be adapted to fabricate a variety of tunable coupled resonators in a similar manner, and such adaptations are contemplated within the scope of the illustrative embodiments.

[0048] When implemented in an application, the embodiments cause a manufacturing process to perform certain steps as described herein. The steps of the manufacturing process are shown in several figures. In a specific manufacturing process, not all steps are required. Without departing from the scope of the illustrative embodiments, some manufacturing processes may implement steps in different orders, combine certain steps, remove or replace certain steps, or perform some combination of these and other manipulations of steps.

[0049] The illustrative embodiments are described with respect to certain types of materials, electrical properties, structures, configurations, layer orientations, directions, steps, operations, planes, dimensions, quantities, data processing systems, environments, components, and applications, by way of example only. Any particular representation of these and other similar products is not intended to limit the invention. Any suitable representation of these and other similar products may be selected within the scope of the illustrative embodiments.

[0050] The illustrative embodiments are described using specific designs, architectures, layouts, patterns, and tools only as examples, and are not limited to the illustrative embodiments. The illustrative embodiments can be used in conjunction with other comparable or similarly used designs, architectures, layouts, patterns, and tools.

[0051] The examples in this disclosure are only for clarity of description and are not limited to the illustrative embodiments. Any advantages listed here are only examples and are not intended to limit the illustrative embodiments. Additional or different advantages can be achieved by specific illustrative embodiments. In addition, specific illustrative embodiments may have some, all, or none of the advantages listed above.

[0052] See also Figure 2 , which depicts an example gate tunable resonator in accordance with an illustrative embodiment. A top view 200 depicts a tunable superconducting resonator structure having a resonator center conductor 202 composed of a superconducting material and a metal gate 206 adjacent to the resonator 202, the resonator center conductor 202 being connected at one end to a coupling pad 204 and at the other end to a ground plane 210.

[0053] exist Figure 2 In the particular embodiment shown, the resonator center conductor 202 is shown in a zigzag configuration. In other particular embodiments, the resonator center conductor 202 may be in a straight configuration or any other suitable resonator configuration. In the embodiment shown, the metal gate 206 is a planar rectangular shape and is located substantially below and adjacent to the entire length of the resonator center conductor 202. In other particular embodiments, the metal gate 206 may have any suitable shape, size, or configuration. In other embodiments, other gate and qubit structures may be used, and the gate structure may not gate modulate the entire resonator center conductor 202, but may gate modulate only a portion of the resonator center conductor 202. In other embodiments, more than one qubit may be capacitively coupled to the resonator center conductor 202 at different locations along the length of the resonator center conductor 202. In one or more embodiments, the resonator center conductor 202 and the metal gate 206 are separated by an insulator material or a vacuum. In one embodiment, the metal gate 206 may overlap only a portion of the resonator, rather than overlapping substantially the entire length of the resonator.

[0054] In some embodiments, the ground plane 210 can be constructed in such a way that the resonator comprises a coplanar waveguide. In this geometry, the ground plane is separated from the resonator center conductor 202 on either side by a distance that does not vary along the length of the resonator. These dimensions are typically guided by design specifications for transmission lines with 50 ohm impedance in the frequency range of 1 MHz-20 GHz. Figure 2In the illustrated embodiment, the ground plane geometry is not shown for the sake of clarity.

[0055] In certain embodiments, possible superconducting materials that may form the resonator center conductor 202, coupling pad 204, gate 206, or ground layer 210 include one or more of aluminum, indium, niobium, niobium nitride, titanium niobium nitride, niobium diselenide, tantalum, titanium, or molybdenum rhenium. In certain embodiments, possible metal or conductive gate materials that may form the metal gate 206 include gold, platinum, palladium, gold alloys (e.g., palladium gold), copper, or graphite. It should be understood that the above is a non-exhaustive list of possible superconducting materials and metal materials, and other suitable superconducting materials or metal materials may be used in other embodiments. In some embodiments, the resonator may be composed only partially of a gate-tunable superconductor material, and other portions of the resonator may be composed of a material that is not gate-tunable. The coupling pad 204 is configured to capacitively couple the qubit 208 to the resonator center conductor 202.

[0056] In one embodiment, the gate voltage Vgate is applied to the metal gate 206 to cause a controllable change in the carrier density within the resonator center conductor 202, and thereby further cause a change in the dynamic inductance of the resonator center conductor 202, because the dynamic inductance Lk of the resonator center conductor 202 is proportional to the carrier density n S The change in dynamic inductance Lk also causes a change in the characteristic frequency of the resonator including the center conductor 202, which further changes the coupling strength between the qubit 208 and another device. Therefore, the gate voltage V gate Can be configured to tune the dynamic inductance L k , and thus can detune the resonator including the center conductor 202 to change the coupling strength between the qubit 208 and another device.

[0057] See also Figure 3, which depicts an example shunted gate tunable resonator in accordance with an illustrative embodiment. Top view 300 depicts a shunted tunable superconducting resonator structure having a resonator center conductor 302 constructed of a superconducting material connected at one end to a first coupling pad 304A and at another end to a second coupling pad 304B. The resonator center conductor 302 is connected to a shunt portion 312 that couples the resonator center conductor 302 to a ground plane 308. In one embodiment, the resonator center conductor 302 and the shunt portion 312 may be constructed of a conjoined body of the same superconducting material. A metal gate 306 is proximate to the shunt portion 312. In a particular embodiment, the ground plane 308 is a superconducting ground plane formed of a superconducting material. In other embodiments, other gate and qubit structures may be used, and the gate structure may gate modulate all or a portion of the resonator center conductor 302 and / or all or a portion of the shunt 312.

[0058] In some embodiments, the ground plane 308 can be constructed in such a way that the resonator comprises a coplanar waveguide. In this geometry, the ground plane is separated from the resonator center conductor 302 and the shunt 312 on either side by a distance that does not vary along the length of the resonator. These dimensions are typically guided by design specifications for transmission lines with 50 ohm impedance in the frequency range of 1 MHz-20 GHz. Figure 3 In the illustrated embodiment, the ground plane geometry is not shown for the sake of clarity.

[0059] exist Figure 3 In the particular embodiment shown, the resonator center conductor 302 is shown in a meandering configuration. In other particular embodiments, the resonator center conductor 302 can be in a straight configuration or any other suitable resonator configuration. In the embodiment shown, the metal gate 306 is a planar rectangular shape and is positioned approximately the entire length of the shunt portion 312. In other particular embodiments, the metal gate 306 can be any suitable shape, size, or configuration. In one or more embodiments, the resonator center conductor 302 and the metal gate 306 are separated by an insulator material or a vacuum.

[0060] First coupling pad 304A is configured to capacitively couple first qubit 310A to resonator center conductor 302, and second coupling pad 304B is configured to capacitively couple second qubit 310B to resonator center conductor 302. In some embodiments, first coupling pad 304A is configured to capacitively couple qubit 310A to resonator center conductor 302, and second coupling pad 304B is configured to capacitively couple to another device, such as a readout measurement circuit. In some embodiments, first coupling pad 304A is configured to capacitively couple qubit 310A to resonator center conductor 302, and second coupling pad 304B is directly coupled to a readout measurement circuit, such as using wire bonding or bump bonding.

[0061] In one embodiment, a gate voltage Vgate is applied to the metal gate 306 to cause a controllable change in the carrier density within the resonator center conductor 302, and thereby further cause a change in the dynamic inductance of the resonator center conductor 302, because the dynamic inductance Lk of the resonator center conductor 302 is proportional to the carrier density n S Inversely proportional to the dynamic inductance L k The change of further causes the change of the characteristic frequency of the resonator including the central conductor 302, which further changes the coupling strength between the first qubit 310A and the second qubit 310B. gate Can be configured to tune the dynamic inductance L k And thus the resonator including the center conductor 302 can be detuned to change the coupling strength between the first qubit 310A and the second qubit 310B.

[0062] See also Figure 4 , which depicts an example implementation of tuning a superconducting resonator in an SCA arrangement according to an illustrative embodiment. Top view 400 depicts a plurality of qubits 402 in a lattice configuration on a planar two-dimensional (2D) grid. The qubits are coupled to each other and communicate using resonant lines 404 (also referred to as "buses"). The quantum states of the qubits 102 are read using read lines 406, 406A that are capacitively coupled to a particular qubit. Each of the read lines 406A also includes a metal gate 408 disposed adjacent thereto to form a gate-tunable resonator such as described herein with respect to various embodiments.

[0063] In the illustrated embodiment, each readout line 406A and corresponding metal gate 408 forming a gate tunable resonator is configured to receive an individually controllable gate voltage to allow controlled coupling and decoupling of a particular qubit 402 to the readout line 406. In one or more embodiments, individually gate modulated portions of the gate tunable resonator provide the capability for multiplexed readout of qubits 406 via a tunable readout resonator.

[0064] See also Figure 5 , which depicts a cross-sectional view of a gate tunable resonator structure 500 according to an illustrative embodiment. The structure 500 includes a substrate structure 502 having a superconducting ground plane portion 504 formed on a surface (e.g., a top surface) of the substrate structure 502. In certain embodiments, the substrate structure 502 can be formed of any suitable substrate material, such as silicon (Si) or sapphire. The structure 500 also includes a resonator center conductor 506 disposed on a surface of the substrate structure 502 adjacent to the superconducting ground plane portion 504. The resonator center conductor 506 and the superconducting ground plane portion 504 together constitute a coplanar waveguide resonator. In some embodiments, the size and location of the components in the structure 500 can be designed to account for the capacitance caused by the gate 510.

[0065] exist Figure 5 In the illustrated embodiment, the resonator center conductor 506 is formed of magic angle twisted bilayer graphene (MATBG) material as a superconducting material. In a specific embodiment, the MATBG material is tuned to a superconducting critical temperature T between 0 Kelvin (K) and 1.7 K. c .

[0066] The structure 500 also includes an insulator layer or vacuum region 508 separating the resonator center conductor 506 and the metal gate 510. In one or more embodiments, the structure 500 is an example of a gate tunable resonator, such as with respect to Figure 2-4 In one or more embodiments, the resonator center conductor 506 is capacitively coupled between two superconducting devices (e.g. Figure 3 In some embodiments, structure 500 represents a cross-sectional view through structure 202, structure 302, and / or structure 306.

[0067] In one embodiment, the gate voltage V gate is applied to the metal gate 510 to cause a controllable change in the carrier density within the resonator center conductor 506, and thereby further cause a change in the dynamic inductance of the resonator center conductor 506, because the dynamic inductance L of the resonator center conductor 506 is k and carrier density n S Inversely proportional to the dynamic inductance L k The change of further causes the change of the characteristic frequency of the resonator in structure 500, which further changes the coupling strength between first qubit 310A and second qubit 310B. gate Can be configured to tune the dynamic inductance L kAnd thus the resonator in structure 500 can be tuned to change the coupling strength between first qubit 310A and second qubit 310B.

[0068] See also Figure 6 , which depicts a cross-sectional view of a gate tunable resonator structure 600 according to another illustrative embodiment. The structure 600 includes a substrate structure 602 having a superconducting ground plane portion 604 formed on a surface (e.g., a top surface) of the substrate structure 602. In certain embodiments, the substrate structure 602 can be formed of any suitable substrate material, such as silicon (Si) or sapphire. The structure 600 also includes a resonator center conductor 606 formed of a superconducting material disposed on a surface of the substrate structure 602 proximate to the superconducting ground plane portion 604. The resonator center conductor 606 and the superconducting ground plane portion 604 together constitute a coplanar waveguide resonator. In some embodiments, the size and location of the components in the structure 600 can be designed to account for the capacitance caused by the gate 610.

[0069] exist Figure 6 In the illustrated embodiment, the resonator center conductor 606 is formed of tungsten ditelluride (WTe2) material as a superconducting material. In a specific embodiment, the WTe2 material is tuned to a superconducting critical temperature T between 0K and 0.61K. c .

[0070] The structure 600 also includes an insulator layer or vacuum region 608 separating the resonator center conductor 606 from the metal gate 610. In one or more embodiments, the structure 600 is an example of a gate tunable resonator, such as with respect to Figure 2-4 In one or more embodiments, the resonator center conductor 606 is capacitively coupled between two superconducting devices (e.g. Figure 3 In some embodiments, structure 600 represents a cross-sectional view through structure 202, structure 302, and / or structure 306.

[0071] In one embodiment, a gate voltage Vgate is applied to the metal gate 610 to cause a controllable change in the carrier density within the resonator center conductor 606, and thereby further cause a change in the dynamic inductance of the resonator center conductor 606, because the dynamic inductance Lk of the resonator center conductor 606 is proportional to the carrier density n SThe change in dynamic inductance Lk further causes a change in the characteristic frequency of the resonator in structure 600, which further changes the coupling strength between first qubit 310A and second qubit 310B. Thus, the gate voltage Vgate can be configured to tune the dynamic inductance Lk and thus can tune the resonator in structure 600 to change the coupling strength between first qubit 310A and second qubit 310B.

[0072] See also Figure 7 , which depicts a cross-sectional view of a gate tunable resonator structure 700 according to another illustrative embodiment. The structure 700 includes a substrate structure 702 having a superconducting ground plane portion 704 formed on a surface (e.g., a top surface) of the substrate structure 702. In certain embodiments, the substrate structure 702 can be formed of any suitable substrate material, such as silicon (Si) or sapphire. The structure 700 also includes a resonator center conductor 706 formed of a superconducting material disposed on a surface of the substrate structure 702 proximate to the superconducting ground plane portion 704. The resonator center conductor 706 and the superconducting ground plane portion 704 together constitute a coplanar waveguide resonator. In some embodiments, the size and location of the components in the structure 700 can be designed to account for the capacitance caused by the gate 710.

[0073] exist Figure 7 In the embodiment shown, the resonator center conductor 706 is made of Sn as a superconducting material. 1-δ-x In x A thin layer of Te material is formed.

[0074] The structure 700 also includes an insulator layer or vacuum region 708 separating the resonator center conductor 706 and the metal gate 710. In one or more embodiments, the structure 700 is an example of a gate tunable resonator, such as with respect to Figure 2-4 In one or more embodiments, the resonator center conductor 706 is capacitively coupled between two superconducting devices (e.g. Figure 3 In some embodiments, structure 700 represents a cross-sectional view through structure 202, structure 302, and / or structure 306.

[0075] In one embodiment, the gate voltage V gate is applied to the metal gate 710 to cause a controllable change in the carrier density within the resonator center conductor 706, and thereby further cause a change in the dynamic inductance of the resonator center conductor 706, because the dynamic inductance L of the resonator center conductor 706 is k and carrier density n SThe change in dynamic inductance Lk further causes a change in the characteristic frequency of the resonator in structure 700, which further changes the coupling strength between first qubit 310A and second qubit 310B. Thus, gate voltage Vgate can be configured to tune dynamic inductance Lk and thus can tune the resonator in structure 700 to change the coupling strength between first qubit 310A and second qubit 310B.

[0076] See also Figure 8 , which depicts an example implementation of tuning a superconducting resonator in an SCA arrangement according to an illustrative embodiment. Top view 800 depicts a plurality of qubits 802 in a lattice configuration on a planar two-dimensional (2D) grid. The quantum state of qubit 802 is read using a read line 806 that is capacitively coupled to a particular qubit. The qubits are coupled to each other and communicate using resonant lines 804 (also referred to as a "bus"). Each of the resonant lines 804 also includes a gate 808 disposed adjacent thereto to form a gate-tunable resonator such as described herein with respect to various embodiments.

[0077] In the illustrated embodiment, each resonant line 804 and corresponding gate 808 forming a gate tunable resonator is configured to receive an individually controllable gate voltage to allow controlled coupling and decoupling of pairs of qubits 802. In one or more embodiments, these individually gate modulated portions of the gate tunable resonator provide the ability to gradually tune the coupling between nearest neighboring qubits. In one or more embodiments, the individually gate modulated portions of the gate tunable resonator provide the ability to turn off qubits with undesirable transition frequencies. In one or more embodiments, the individually gate modulated portions of the gate tunable resonator provide a novel quantum gate hardware approach with faster gates and tunable coupling strength between qubits.

[0078] Different embodiments of the present invention are described herein with reference to the relevant drawings. Without departing from the scope of the present invention, alternative embodiments may be designed. Although different connections and positional relationships (e.g., above, below, adjacent, etc.) are described between elements in the following description and the drawings, it will be appreciated by those skilled in the art that many positional relationships described herein are orientation-independent when the function is maintained even if the orientation changes. Unless otherwise indicated, these connections and / or positional relationships may be direct or indirect, and the present invention is not limited in this respect by schematic diagrams. Thus, the coupling of entities may refer to direct or indirect coupling, and the positional relationship between entities may be direct or indirect positional relationship. As an example of an indirect positional relationship, the reference to forming layer "A" on layer "B" in this specification includes the case where one or more intermediate layers (e.g., layer "C") are between layer "A" and layer "B", as long as the relevant features and functions of layer "A" and layer "B" are not substantially changed by this or these intermediate layers.

[0079] The following definitions and abbreviations are used to interpret the claims and specification. As used herein, the terms "comprises," "including," "having," or "containing" or any other variation thereof are intended to cover a non-exclusive inclusion. For example, a composition, mixture, process, method, article, or apparatus that includes a list of elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or apparatus.

[0080] Additionally, the term "illustrative" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or design described herein as "illustrative" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms "at least one" and "one or more" should be understood to include any integer greater than or equal to one, i.e., one, two, three, four, etc. The term "plurality" should be understood to include any integer greater than or equal to 2, i.e., two, three, four, five, etc. The term "connected" may include both indirect "connected" and direct "connected."

[0081] References in the specification to "one embodiment," "an embodiment," "an example embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but each embodiment may or may not include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is considered to be within the knowledge of those skilled in the art to affect such feature, structure, or characteristic in conjunction with other embodiments, whether or not explicitly described.

[0082] The terms "about", "substantially", "approximately" and variations thereof are intended to include the degree of error associated with the measurement of a particular quantity based on the equipment available at the time of filing this application. For example, "about" may include a range of ±8% or 5%, or 2% of a given value.

[0083] The description of different embodiments of the present invention has been presented for the purpose of illustration, but is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to best explain the principles of the embodiments, practical applications, or technical improvements over technologies found in the marketplace, or to enable other persons of ordinary skill in the art to understand the embodiments described herein.

Claims

1. A superconducting coupling device, comprising: a resonator structure having a resonator center conductor comprised of a superconducting material, the resonator structure having a first end configured to be coupled to a first device and a second end configured to be coupled to a second device; and a gate positioned proximate to the resonator center conductor of the resonator structure, the gate configured to receive a gate voltage and to change a dynamic inductance of the resonator center conductor based on the gate voltage, the change in the dynamic inductance causing the resonator structure to change a coupling strength between the first device and the second device, wherein the first device is a first transmission element and the second device is a second transmission element, and wherein the resonator structure and the gate provide a tunable coupling between the first transmission element and the second transmission element, The superconducting coupling device further includes an insulator disposed on the resonator structure, wherein the gate is disposed on the insulator.

2. A superconducting coupling device according to claim 1, wherein the change in the dynamic inductance is a result of the gate changing the superfluid density of the resonator center conductor of the resonator structure.

3. The superconducting coupling device of claim 1, wherein the change in the dynamic inductance causes a change in a characteristic frequency of the resonator structure.

4. A superconducting coupling device according to claim 3, wherein the variation of the characteristic frequency of the resonator structure enables the coupling strength between the first device and the second device to be varied.

5. The superconducting coupling device according to claim 1, wherein the resonator center conductor of the resonator structure is formed of a superconducting material, and the superconducting material comprises magic angle twisted bilayer graphene, WTe2 or Sn 1-δ-x In x Te. 6 . The superconducting coupling device according to claim 1 , wherein the gate electrode is formed of a metal material or a superconducting material.

7. The superconducting coupling device of claim 1, wherein the first device is capacitively coupled to a first end of the resonator structure and the second device is capacitively coupled to a second end of the resonator structure.

8. The superconducting coupling device of claim 1, further comprising a ground plane connected to the resonator structure.

9. A superconducting coupling device according to claim 8, wherein the ground plane is connected to the resonator structure through a shunt portion of the resonator structure.

10. The superconducting coupling device of claim 1, further comprising a substrate structure, wherein the resonator structure is arranged on a surface of the substrate structure.

11. The superconducting coupling device of claim 10, further comprising a ground plane disposed on the surface of the substrate structure close to the resonator structure.

12. The superconducting coupled device of claim 1, wherein the first device is a first qubit and the second device is a second qubit.

13. The superconducting coupled device of claim 1, wherein the first device is a qubit and the second device comprises a readout measurement circuit of a quantum computing device.

14. A method for manufacturing a superconducting coupling device, comprising: coupling a first end of the resonator structure to a first device; coupling a second end of the resonator structure, the second end being configured to be coupled to a second device; positioning a gate electrode adjacent to a resonator center conductor of the resonator structure, the resonator center conductor being comprised of a superconducting material, wherein the gate electrode is disposed on an insulator on the resonator structure; receiving a gate voltage from the gate; as well as changing a dynamic inductance of a center conductor of the resonator based on the gate voltage, the change in the dynamic inductance causing the resonator structure to change a coupling strength between the first device and the second device, The first device is a first transmission element and the second device is a second transmission element, and wherein the resonator structure and the gate provide tunable coupling between the first transmission element and the second transmission element.

15. The method of claim 14, wherein the change in the dynamic inductance is a result of the gate changing a superfluid density of the resonator center conductor of the resonator structure.

16. The method of claim 14, wherein the change in the dynamic inductance causes a change in a characteristic frequency of the resonator structure.

17. The method of claim 16, wherein the variation of the characteristic frequency of the resonator structure enables the coupling strength between the first device and the second device to be varied.

18. The method according to any one of claims 14 to 17, wherein the resonator center conductor of the resonator structure is formed of a superconducting material, the superconducting material comprising magic angle twisted bilayer graphene, WTe2 or Sn 1-δ-x In x Te.

19. A superconductor manufacturing apparatus comprising a lithography component, the superconductor manufacturing apparatus when operating on a die to manufacture a superconducting coupling device, performs operations comprising: coupling a first end of the resonator structure to a first device; coupling a second end of the resonator structure, the second end being configured to be coupled to a second device; positioning a gate electrode adjacent to a resonator center conductor of the resonator structure, the resonator center conductor being comprised of a superconducting material, wherein the gate electrode is disposed on an insulator on the resonator structure; receiving a gate voltage from the gate; as well as changing a dynamic inductance of a center conductor of the resonator based on the gate voltage, the change in the dynamic inductance causing the resonator structure to change a coupling strength between the first device and the second device, The first device is a first transmission element and the second device is a second transmission element, and wherein the resonator structure and the gate provide tunable coupling between the first transmission element and the second transmission element.

20. The superconductor manufacturing apparatus of claim 19, wherein the change in the dynamic inductance is a result of the gate changing the superfluid density of the resonator center conductor of the resonator structure.

21. The superconductor manufacturing apparatus of claim 19, wherein the change in the dynamic inductance causes a change in a characteristic frequency of the resonator structure.

22. The superconductor manufacturing apparatus according to claim 21, wherein the change in the characteristic frequency of the resonator structure enables the coupling strength between the first device and the second device to be changed.

23. The superconductor manufacturing apparatus according to any one of claims 19 to 22, wherein the resonator center conductor of the resonator structure is formed of a superconducting material, the superconducting material comprising magic angle twisted bilayer graphene, WTe2 or Sn 1-δ-x In x Te.

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