Josephson Junction Array Bias Layout for Homogeneous Current
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Solution Overview
Problem
High-temperature superconducting devices face challenges in achieving a homogeneous current distribution across large networks of Josephson junctions due to bias currents being concentrated on the edges, leading to reduced response and sensitivity, especially in three-dimensional structures.
Innovation Solution
A superconducting device with a network of parallel Josephson junctions and conductive strips arranged on separate substrates, supplied with currents of opposite signs to achieve a uniform current distribution, ensuring each strip is within a specific distance from the junctions to enhance homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the network width is increased to improve sensitivity, then the number of Josephson junctions increases, but the bias current becomes concentrated on the edges causing non-uniform distribution
Solution Approach 1:
A conductive strip is introduced as an intermediary element between the bias current source and the Josephson junctions. This strip acts as a current distributor that spreads the bias current uniformly across all junctions in the network, preventing edge concentration and ensuring homogeneous current distribution throughout the expanded network.
Solution Approach 2:
The conductive strip is positioned at a specific optimized distance from the Josephson junctions to achieve uniform current distribution. By carefully controlling the local geometric parameters (distance, width, position), the current density is made homogeneous across the entire junction array, enabling large networks to operate with uniform current distribution.
2Manufacturing precision
If resistors are added to achieve homogeneous current distribution, then current uniformity improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces the electrical component approach (using resistors to control current distribution) with a geometric/configuration-based approach. By optimizing the physical arrangement and dimensions of the conductive strip relative to the Josephson junctions, current uniformity is achieved through geometric design rather than additional electrical components, thereby reducing device complexity.
Solution Approach 2:
The solution extracts and eliminates the need for resistive elements from the device structure. Instead of adding resistors to control current distribution, the patent uses a simplified configuration with a conductive strip whose geometric parameters are optimized to achieve the desired current distribution, removing unnecessary components and simplifying the overall device.
3Manufacturing precision
If multi-layer superconducting structures are used to achieve homogeneous current distribution, then current uniformity improves, but manufacturing difficulty increases due to technology constraints
Solution Approach 1:
Instead of using multi-layer superconducting structures (vertical dimension), the patent achieves current homogenization by optimizing parameters in the horizontal plane. The conductive strip is positioned at a specific distance from the junctions, and its width and position are optimized to ensure uniform current distribution, thereby solving the problem in two dimensions rather than requiring three-dimensional multi-layer fabrication.
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 results in a more homogeneous current distribution, improving sensitivity and response, allowing for larger networks and broader bandwidth, without requiring multi-layer structures or resistors, and maintaining sensitivity even with high-temperature superconducting materials.
Implementation Method 1
this distribution is controlled by the Meissner effect
Implementation Method 2
Superconducting circuits based on Josephson junctions have a very low noise level, and are, particularly as electromagnetic field detectors, very sensitive
Data Source
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AI summary
The invention relates to a superconducting device (10) comprising: - an array (12) of Josephson junctions (28) in parallel, - at least one conductive strip (16) contained in a second plane facing the first plane of the array (12), each strip (16) being made of gold, of aluminium, of copper, of palladium, of an alloy of the aforementioned elements, of Ta2N or of cuprate, and - a power supply (22) that supplies the Josephson junctions (28) and each strip (16) with currents of opposite signs and having an amplitude chosen so that the total of the currents flowing through each strip (16) is equal to the current flowing through the array (12) to within 10%, each strip (16) being at a distance from a Josephson junction (28) smaller than or equal to 40% of the width defined for the array (12).