Bridged Coplanar Waveguide Layout for Lower Dielectric Loss
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Solution Overview
Problem
Conventional quantum circuits employing coplanar waveguides (CPWs) suffer from significant energy losses in the dielectric substrate, which leads to inefficient performance despite aggressive substrate etching techniques.
Innovation Solution
The implementation of bridge conductor portions raised above the substrate or with substrate portions removed to create defined gaps between the conductor line and the substrate, reducing energy losses by minimizing the interaction between the conductor and the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If coplanar waveguide (CPW) is used as transmission line, then quantum circuit can be fabricated, but significant energy losses occur in the dielectric substrate
Solution Approach 1:
The patent introduces a vertical dimension by raising portions of the central conductor above the substrate plane using air bridges or etch holes. This three-dimensional configuration separates the conductor from the lossy dielectric substrate, reducing electromagnetic field penetration into the substrate while maintaining the CPW's planar fabrication advantages.
Solution Approach 2:
The patent introduces air bridges as intermediary structures that connect different levels of the conductor while minimizing contact with the dielectric substrate. These air-based intermediaries reduce the coupling between the conductor and the lossy substrate, thereby reducing energy losses.
2Loss of energy
If aggressive substrate etching is performed, then energy loss in substrate is reduced, but manufacturing complexity and difficulty increase
Solution Approach 1:
The patent segments the central conductor into multiple sections at different vertical levels. Some portions remain in the planar configuration while others are raised using air bridges or etch holes. This segmentation allows selective reduction of substrate interaction without requiring complete etching of the substrate, thereby reducing fabrication complexity.
3Loss of energy
If bridge conductor portions are raised above substrate, then energy loss is reduced, but device complexity increases
Solution Approach 1:
The patent applies local quality by raising only specific portions of the central conductor above the substrate using air bridges, while other portions remain in the planar configuration. This localized three-dimensional structure reduces energy loss in critical regions while maintaining simpler planar structures in other regions, balancing performance and complexity.
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 significantly reduces energy losses and signal attenuation, enhancing the performance of quantum computing circuits by optimizing the impedance and reducing electromagnetic field energy in the substrate and vacuum regions.
Implementation Method 1
optimizing the impedance and reducing electromagnetic field energy in the substrate and vacuum regions
Data Source
AI summary
Techniques for designing and fabricating quantum circuitry, including a coplanar waveguide (CPW), for quantum applications are presented. With regard to a CPW, a central conductor and two return conductor lines can be formed on a dielectric substrate, with one return conductor line on each side of the central conductor and separated from it by a space. The central conductor can have bridge portions that can be raised a desired distance above the substrate and base conductor portions situated between the bridge portions and in contact with the surface of the substrate; and/or portions of the substrate underneath the bridge portions of the central conductor can be removed such that the bridge portions, whether raised or unraised, can be the desired distance above the surface of the remaining substrate, and the base conductor portions can be in contact with other portions of the surface of the substrate that were not removed.