Gate-Tunable Josephson Junctions Using Azimuthally Misaligned 2D Material Bilayers

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Solution Overview

Problem

Current Josephson junctions, crucial for quantum computers, lack gate-tunability, particularly those using thin aluminum as a weak-link, limiting their carrier density tunability and performance in devices like microwave detectors.

Innovation Solution

The development of Josephson junctions with a superconducting bilayer comprising two azimuthally misaligned two-dimensional materials, where the weak-link region is an integral part of the bilayer, allowing for tunability through electrostatic gating or lattice defects, enabling scalable integration into microwave detectors and other devices without separate superconducting leads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If thin aluminum layers are used as a weak-link in Josephson junctions, then the junction structure is simple and manufacturable, but the carrier density is not gate-tunable

Engineering Contradiction:

Improvemanufacturability of Josephson junctionVSAvoidgate-tunability of carrier density

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent changes the material parameter from conventional thin aluminum to two-dimensional materials (such as graphene, transition metal dichalcogenides) for the weak-link region. This material parameter change enables gate-tunability of carrier density while maintaining the Josephson junction structure, directly resolving the contradiction between ease of manufacture and adaptability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures where two-dimensional materials are integrated with superconducting leads to form the Josephson junction. The weak-link region consists of composite structures including bilayer graphene, twisted bilayer graphene, or other 2D materials combined with superconductors, enabling both manufacturability and gate-tunability simultaneously.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If single-layer graphene is used as a barrier between superconducting leads, then gate voltage-tunability is achieved, but the tunability range is limited

Engineering Contradiction:

Improvegate voltage-tunability of Josephson junctionVSAvoidtunability range and performance

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent transitions from single-layer graphene to composite two-dimensional material structures, specifically bilayer graphene, twisted bilayer graphene, or other multi-layer 2D materials. These composite structures provide enhanced tunability ranges and improved performance while maintaining gate voltage control, directly addressing the limitation of single-layer graphene.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent introduces spatial variation in the weak-link region by creating localized structures such as nanoribbons, nanostrips, or regions with specific twist angles in bilayer graphene. This local quality variation enables enhanced tunability in specific regions, improving overall device performance while maintaining gate control.

Inventive Principle:

Principle #3Local quality

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 allows for gate-tunable Josephson junctions with enhanced tunability and performance, enabling efficient detection of microwave radiation by transitioning from a zero-bias to a higher-voltage state, facilitating the development of advanced quantum computing components and devices.

Implementation Method 1

a superconducting bilayer comprising two azimuthally misaligned layers of a two-dimensional material

Methodology Applied

Scientific EffectSuperconductivity: Superconductivity

Implementation Method 2

Josephson junctions are composed of two superconductors separated by a thin or narrow non-superconducting barrier or 'weak link'

Methodology Applied

Scientific EffectJosephson effect: Josephson Effect

Data Source

PatentUS11711984B2Superconducting bilayers of two-dimensional materials with integrated Josephson junctions

Publication Date: 2023.07.25 WISCONSIN ALUMNI RES FOUND

AI summary

Josephson junctions (JJ) based on bilayers of azimuthally misaligned two-dimensional materials having superconducting states are provided. Also provided are electronic devices and circuits incorporating the JJs as active components and methods of using the electronic devices and circuits. The JJs are formed from bilayers composed of azimuthally misaligned two-dimensional materials having a first superconducting segment and a second superconducting segment separated by a weak-link region that is integrated into the bilayer.