Qubit Device With Aligned C-Axis Josephson Junctions
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Solution Overview
Problem
Conventional superconducting qubits based on low-temperature superconductors face limitations such as reduced coherence times and crosstalk due to magnetic field sensitivity and defects introduced by fabrication techniques, which are not suitable for high-temperature superconductors.
Innovation Solution
A qubit device is designed using anisotropic, layered superconductor materials for the Josephson junction, where the capacitor is fabricated independently of the superconductor layers, allowing for tailored design and reduced defect density, and the interconnects and electrodes are composed of low-critical-temperature materials for high-accuracy fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lithographic structuring or deposition techniques are applied to high-temperature superconductor materials, then fabrication can be performed, but significant densities of defects and decomposition of the material occur
Solution Approach 1:
The patent changes the fabrication approach from lithographic structuring to mechanical cleaving of crystalline high-temperature superconductor materials. This parameter change in the manufacturing method avoids the defects and decomposition caused by lithographic techniques while maintaining fabrication capability.
Solution Approach 2:
The patent replaces the chemical/electrical lithographic structuring process with a mechanical cleaving process. By using mechanical means to separate and shape the superconductor material, the patent avoids the harmful effects of lithographic techniques on the material structure.
2Ease of manufacture
If conventional low-temperature superconductor materials are used in Josephson junctions, then fabrication is straightforward, but magnetic field sensitivity reduces coherence times and increases crosstalk
Solution Approach 1:
The patent uses composite material structures with layered arrangements of superconducting and dielectric materials. This composite approach enables the use of high-temperature superconductors in Josephson junctions while maintaining fabrication feasibility and improving coherence times by reducing magnetic field sensitivity.
3Device complexity
If the capacitor is integrated with the superconductor layers in conventional fabrication, then device structure is compact, but defects from fabrication techniques affect both components
Solution Approach 1:
The patent segments the fabrication process into separate steps: first fabricating the Josephson junction with mechanically cleaved superconductor layers, then adding the capacitor structure separately. This segmentation allows each component to be optimized independently and avoids propagating fabrication defects between components.
4Reliability
If high-temperature superconductor materials are used in Josephson junctions, then coherence times can be improved, but fabrication techniques are not available
Solution Approach 1:
The patent utilizes the natural cleavage properties of crystalline high-temperature superconductor materials. The material's inherent crystalline structure allows it to be mechanically separated into thin layers without requiring external fabrication infrastructure, enabling self-service fabrication of Josephson junctions.
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 design significantly improves coherence times by reducing dielectric losses and crosstalk, achieving coherence times up to 1 second, a tenfold improvement over conventional qubits.
Implementation Method 1
The second superconductor layer is arranged over the first superconductor layer to form a Josephson junction between the first superconductor material and the second superconductor material
Implementation Method 2
The first c-axis and the second c-axis are aligned with each other at the Josephson junction. The aligned first and second c-axes at the Josephson junction intersect both the first superconductor layer and the second superconductor layer
Implementation Method 3
The capacitor comprises a first electrode and a second electrode. The first interconnect electrically connects the first electrode and the first superconductor layer. The second interconnect electrically connects the second electrode and the second superconductor layer
Data Source
AI summary
A qubit device comprises first and second superconductor layers a capacitor, first and second interconnects. The first superconductor layer comprises a first c-axis perpendicular to covalently bound atomic layers. The second superconductor layer comprises a second c-axis perpendicular to covalently bound atomic layers. The first and second superconductor layers form a Josephson junction, wherein the first c-axis and the second c-axis are aligned with each other at the Josephson junction. The aligned first and second c-axes intersect both the first superconductor layer and the second superconductor layer. The capacitor comprises a first electrode and a second electrode. The first interconnect electrically connects the first electrode and the first superconductor layer. The second interconnect electrically connects the second electrode and the second superconductor layer. The capacitor is arranged at a vertical position exceeding the vertical positions of both the first superconductor layer and the second superconductor layer.