Kinetic Inductance Qubit Circuits With Compound Josephson Junctions

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Solution Overview

Problem

Existing superconducting quantum processors face challenges in efficiently storing and controlling quantum states due to limitations in energy storage and coupling mechanisms, which affect the performance and scalability of quantum computations.

Innovation Solution

The integration of high kinetic inductance materials and compound Josephson junctions in superconducting integrated circuits, including a first layer with parallel paths interrupted by Josephson junctions, allows for efficient energy storage and coupling, enabling the formation of kinetic inductance devices such as qubits and couplers, with a second layer in a separate plane for additional devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If high kinetic inductance materials are integrated into superconducting quantum processors, then energy storage efficiency is improved, but device complexity increases

Engineering Contradiction:

Improveenergy storage efficiencyVSAvoiddevice complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent combines kinetic inductance devices with quantum processor components into an integrated structure where the kinetic inductance device forms part of the quantum processor substrate. This merging approach allows energy storage functionality to be incorporated without adding separate discrete components, thereby improving energy storage efficiency while minimizing the increase in device complexity through spatial integration.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of operation

If compound Josephson junctions with parallel paths are used, then control of quantum states is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvecontrol of quantum statesVSAvoidmanufacturing precision

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The compound Josephson junction is segmented into multiple parallel paths, each containing a Josephson junction. This segmentation provides independent control pathways for quantum states, allowing precise control through individual path manipulation. The parallel structure enables separate tuning of each path's properties to achieve desired quantum state control while distributing the manufacturing precision requirements across multiple simpler sub-structures rather than one complex single path.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If multiple layers are used for additional devices, then adaptability is improved, but fabrication complexity increases

Engineering Contradiction:

ImproveadaptabilityVSAvoidfabrication

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent utilizes multiple layers stacked in the vertical dimension to provide additional devices and functionality. By transitioning from a single-plane to a multi-layer three-dimensional architecture, the system achieves enhanced adaptability and versatility without significantly complicating the fabrication process. Each layer can be fabricated using standard sequential deposition and patterning techniques, allowing additional functionality to be added by simply building upward rather than expanding laterally.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances the energy storage efficiency and control of quantum states, improving the performance and scalability of quantum processors by maximizing kinetic inductance and simplifying fabrication, thereby supporting advanced quantum computations.

Implementation Method 1

each Josephson junction comprising a restriction in the first layer of high kinetic inductance material and an inductance electrically in parallel with the compound Josephson junction

Methodology Applied

Scientific EffectJosephson effect: Josephson Effect

Implementation Method 2

a first layer of high kinetic inductance material directly or indirectly overlying at least a portion of the substrate, the first layer of high kinetic inductance material comprising a superconducting device

Methodology Applied

Scientific EffectKinetic inductance: Superconductivity

Data Source

PatentUS20250386743A1Kinetic inductance devices, methods for fabricating kinetic inductance devices, and articles employing the same

Publication Date: 2025.12.18 1372934 B C LTD

AI summary

Superconducting integrated circuits and methods of forming these circuits are discussed. One superconducting integrated circuit has a substrate and a control device formed by a layer of high kinetic inductance material overlying the substrate. The control device has a loop of material, electrical connections between the loop of material and a power line, a coupling element connected to the loop of material, a pair of Josephson junctions that interrupt the loop of material, and an energy storage element connected to the loop of material. An alternative superconducting integrated circuit has a kinetic inductance device formed in a high kinetic inductance layer. The device has a compound Josephson junction structure with two parallel current paths with respective Josephson junctions, a loop of material connected to the compound Josephson junction structure, and a coupling structure. The circuit also has an additional device that couples to the coupling structure.