Josephson Junction Spacer for Decoherence Reduction

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Solution Overview

Problem

Josephson junctions in quantum computing devices face decoherence issues due to intrinsic and extrinsic elements, leading to energy loss and unpredictability in signal reproduction, which affects the performance of quantum bits (qubits).

Innovation Solution

A Josephson junction circuit is designed with a nonconductive spacer between superconductor electrodes, using integrated circuit manufacturing techniques for precise dimensional control, reducing decoherence by isolating the electrodes electrically and conforming the spacer to the perimeter of the first superconductor electrode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If superconductor electrodes are placed in direct contact within the Josephson junction structure, then electrical connection is achieved, but decoherence increases due to intrinsic and extrinsic elements

Engineering Contradiction:

Improvesignal reproduction predictabilityVSAvoiddecoherence rate

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

A nonconductive spacer is introduced as an intermediary element between the first and second superconductor electrodes. The spacer is deposited on the perimeter of the first superconductor electrode and extends into the junction stack, electrically isolating the electrodes from each other while maintaining the Josephson junction functionality through the interface layer, thereby reducing decoherence caused by direct electrode contact.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The Josephson junction structure is segmented into distinct electrical zones by the nonconductive spacer. The spacer divides the junction region into a first region containing the first superconductor electrode and a second region containing the second superconductor electrode, preventing direct electrical interaction and reducing decoherence between the electrodes.

Inventive Principle:

Principle #1Segmentation

2Reliability

If a nonconductive spacer is added to reduce decoherence, then signal predictability improves, but device complexity increases

Engineering Contradiction:

Improvedecoherence reductionVSAvoidjunction structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The nonconductive spacer serves multiple functions simultaneously: it provides electrical isolation between superconductor electrodes to reduce decoherence, defines the geometric boundaries of the junction regions, and maintains structural integrity during fabrication. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Manufacturing precision

If integrated circuit manufacturing techniques are used for precise dimensional control, then manufacturing precision improves, but manufacturing process complexity increases

Engineering Contradiction:

Improvedimensional controlVSAvoidfabrication process simplicity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The nonconductive spacer is deposited on the perimeter of the first superconductor electrode before the second superconductor electrode is formed. This preliminary action establishes precise dimensional boundaries and electrical isolation zones in advance, enabling accurate control of junction geometry and reducing the need for complex post-fabrication adjustments.

Inventive Principle:

Principle #10Preliminary action

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 solution effectively reduces decoherence rates and enhances the reproducibility and predictability of signal performance in Josephson junctions, improving the duration of resonance and energy efficiency in quantum computing circuits.

Implementation Method 1

Josephson junctions are one type of structure or hardware device capable of storing quantum bits for use in quantum computers

Methodology Applied

Scientific EffectJosephson effect: Josephson Effect

Implementation Method 2

A nonconductive spacer can be used to reduce decoherence in a Josephson junction

Methodology Applied

Scientific EffectElectrical insulation: Electrical Resistance

Data Source

PatentUS10170679B2Josephson junction with spacer

Publication Date: 2019.01.01 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

Various embodiments are directed toward a circuit configured to act as a Josephson junction. The circuit includes: a junction stack on a substrate, the junction stack including a portion of a first superconductor electrode, with an interface layer on a top side of the first superconductor electrode and configured to act as a tunneling barrier for the junction stack. The circuit may also comprise a first portion of a second superconductor electrode on top of the interface layer. A spacer may separate the portion of the first superconductor electrode in the junction stack from a second portion of the second superconductor electrode outside the junction stack where the second superconductor electrode overlays the first superconductor electrode, the second portion of the second superconductor electrode contacting the substrate on at least one side of the spacer.