Bi-Layer Superconducting Ground Plane for Tunable Inductance

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Solution Overview

Problem

It is challenging to create a large magnetic inductance in a compact planar geometry, such as in integrated circuits, while also being able to tune the inductance over a wide range of values and carry appreciable supercurrents.

Innovation Solution

A bi-layer ground plane is constructed with a first superconducting layer having low carrier concentration and high penetration depth, and a second layer with high carrier concentration and low penetration depth, allowing for tunable inductance by adjusting a bias current, which increases magnetic energy storage and penetration depth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a large magnetic inductance is created in a compact planar geometry, then the inductance value increases, but the ability to tune the inductance over a wide range of values and carry appreciable supercurrents deteriorates

Engineering Contradiction:

Improvemagnetic energy storageVSAvoidtunable inductance range

Core Design Contradiction:

Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The ground plane is divided into two distinct superconducting layers with different critical current densities. The first layer (higher critical current density) provides stable supercurrent carrying capability, while the second layer (lower critical current density) enables large penetration depth modulation. This segmentation allows the system to simultaneously achieve large magnetic energy storage and wide tunable inductance range by independently optimizing each layer's function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent utilizes changes in the penetration depth parameter of the superconducting ground plane by adjusting the bias current. By varying the current through the second superconducting layer, the penetration depth can be modulated over a ten- to fifty-fold range, which directly controls the magnetic coupling and enables wide tunable inductance while maintaining compact planar geometry.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If a single-layer ground plane is used, then the device complexity is reduced, but the penetration depth modulation range and noise tolerance deteriorate

Engineering Contradiction:

Improveground plane structureVSAvoidnoise tolerance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The ground plane is constructed as a composite structure with two superconducting layers having different critical current densities. This composite design provides synergistic benefits: the first layer ensures stable supercurrent transport with high critical current density, while the second layer enables large penetration depth modulation and enhanced noise tolerance. The combination achieves performance unattainable with a single layer without excessive complexity.

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If the penetration depth is increased to enable tuning, then the inductance tunability improves, but the supercurrent carrying capacity deteriorates

Engineering Contradiction:

Improveinductance tunabilityVSAvoidsupercurrent carrying capacity

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The supercurrent carrying function is segregated from the penetration depth modulation function into different layers. The first superconducting layer with higher critical current density is optimized for carrying large supercurrents, while the second layer with lower critical current density is optimized for penetration depth modulation. This functional segmentation resolves the contradiction by allowing each layer to excel at its designated task without compromising the other.

Inventive Principle:

Principle #1Segmentation

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

The bi-layer ground plane enables a ten- to fifty-fold increase in penetration depth, achieving a tunable inductance range of about 20% with improved noise tolerance and magnetic energy storage, suitable for quantum processors and other devices.

Implementation Method 1

a ground plane which is electrically communicatively coupleable to an electrical ground, depositing a superconducting layer to at least partially overlie the insulating layer, and forming a superconducting feature in the superconducting layer

Methodology Applied

Scientific EffectSuperconductivity: Superconductivity

Data Source

PatentUS20260074102A1Superconducting tunable inductance

Publication Date: 2026.03.12 D WAVE SYSTEMS INC

AI summary

A superconducting integrated circuit is fabricated by depositing a ground plane to at least partially overlie a substrate, depositing an insulating layer to at least partially overlie the ground plane, depositing a superconducting layer to at least partially overlie the insulating layer, and forming a superconducting feature in the superconducting layer. An inductance of the superconducting feature is tunable by adjusting a bias current in the ground plane. The ground plane is electrically communicatively coupleable to an electrical ground. Depositing a ground plane includes depositing a first superconducting material to at least partially overlie the substrate and depositing a second superconducting material to at least partially overlie the first superconducting material. A second critical current density of the second superconducting material is higher than a first critical current density of the first superconducting material.