Vertical Epitaxial Josephson Junction for Qubit Coherence
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The coherence times of Josephson junction qubits are low due to defects introduced during formation or exposure to air, which existing technologies have not effectively addressed.
Innovation Solution
A vertical Josephson junction device is formed with an epitaxial stack on a substrate, featuring a first and second superconducting electrode separated by a dielectric layer, where the epitaxial stack laterally encases the junction to prevent defects and improve coherence times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Josephson junction layers are formed using conventional methods, then the device structure is created, but defects are introduced that reduce coherence times
Solution Approach 1:
The patent transitions from conventional planar Josephson junction fabrication to a vertical three-dimensional architecture. The epitaxial stack grows vertically with alternating superconducting and dielectric layers, allowing the junction to be formed in the vertical dimension rather than laterally. This dimensional change enables better isolation and reduces defects introduced during planar processing.
Solution Approach 2:
The invention employs composite epitaxial stacks comprising multiple materials with specific properties: superconducting materials (such as aluminum) alternating with dielectric materials (such as aluminum oxide). This composite structure is grown epitaxially to ensure crystalline quality and minimize defects at interfaces, directly addressing the coherence time issue through material composition and structural integrity.
2Ease of operation
If Josephson junction layers are exposed to air after formation, then the device can be accessed and connected, but oxidation and environmental damage occur that reduce coherence times
Solution Approach 1:
The vertical epitaxial structure inherently protects the Josephson junction interfaces from environmental exposure. The layered epitaxial growth creates a sealed vertical structure where the critical superconductor-dielectric interfaces are not exposed to air or moisture, effectively creating an inert environment that prevents oxidation and environmental degradation while maintaining device functionality.
Solution Approach 2:
The epitaxial dielectric layers formed between superconducting layers act as protective thin films that seal and isolate the sensitive Josephson junction interfaces. These epitaxially grown dielectric films provide a protective barrier against environmental factors while maintaining the electrical and structural integrity of the vertical junction structure.
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 epitaxial stack effectively isolates the Josephson junction from environmental defects, enhancing coherence times by preventing oxidation and other forms of damage.
Implementation Method 1
the epitaxial stack laterally encases the junction to prevent defects and improve coherence times
Implementation Method 2
a first superconducting electrode embedded in the epitaxial stack, and a second superconducting electrode embedded in the epitaxial stack
Implementation Method 3
the first superconducting electrode, the dielectric layer, and the second superconducting electrode form a vertical Josephson junction
Data Source
AI summary
A vertical Josephson junction device includes a substrate, and an epitaxial stack formed on the substrate. The vertical Josephson junction device includes a first superconducting electrode embedded in the epitaxial stack, and a second superconducting electrode embedded in the epitaxial stack, the second superconducting electrode being separated from the first superconducting electrode by a dielectric layer. In operation, the first superconducting electrode, the dielectric layer, and the second superconducting electrode form a vertical Josephson junction.