Josephson Junction Layout Using Angled Evaporation to Avoid Parasitics
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Solution Overview
Problem
Existing methods for preparing Josephson junctions introduce parasitic junctions, which affect the coherence of quantum bit assemblies, thereby impairing the performance of quantum computing devices.
Innovation Solution
A method involving the preparation of a photoresist film layer with an undercut structure on a substrate, where two non-parallel strip-shaped openings are formed, and superconducting layers are obliquely evaporated at different angles to create a Josephson junction, ensuring that only one junction is formed at the intersection and no parasitic junctions are introduced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a double-dip evaporation method with oblique plating is used to prepare a Josephson junction, then the junction can be formed with proper structure, but extra parasitic junctions are introduced into the quantum bit assembly
Solution Approach 1:
The photoresist structure is divided into multiple separate opening regions (first opening, second opening, third opening) with different orientations. Each opening is designed to receive evaporated material from specific directions, segmenting the formation process to prevent unwanted intersections that would create parasitic junctions.
Solution Approach 2:
The photoresist openings are designed with asymmetric orientations - the first opening has a first orientation, the second opening has a second orientation different from the first, and the third opening has a third orientation different from both. This asymmetric design ensures that evaporated materials deposited at different angles only form the intended junction at their intersection point without creating additional parasitic junctions.
2Ease of manufacture
If parasitic junctions are present in the quantum bit assembly, then the device can be manufactured, but the coherence of the quantum bit assembly is affected
Solution Approach 1:
The photoresist structure is pre-designed with multiple openings of specific orientations before evaporation begins. This preliminary configuration ensures that subsequent evaporation steps will only create the intended Josephson junction at the intersection point, preventing parasitic junctions from forming and preserving quantum bit coherence.
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 improves the coherence of quantum bit assemblies by eliminating parasitic junctions, enhancing the performance of quantum computing devices.
Implementation Method 1
performing, at a first angle, evaporation on the photoresist film layer obliquely to the substrate, to prepare a first strip-shaped superconducting layer
Implementation Method 2
performing, at a second angle, evaporation on the photoresist film layer obliquely to the substrate, to prepare a second strip-shaped superconducting layer
Implementation Method 3
an intersection of the first strip-shaped superconducting layer and the second strip-shaped superconducting layer being isolated by an oxidation layer
Data Source
AI summary
A method and device for preparing a Josephson junction are provided. The method includes: preparing a photoresist film layer comprising an undercut structure on a substrate, the undercut structure comprising a first strip-shaped opening and a second strip-shaped opening; performing, at a first angle, evaporation on the photoresist film layer obliquely to the substrate, to prepare a first strip-shaped superconducting layer through the first strip-shaped opening; and performing, at a second angle, evaporation on the photoresist film layer obliquely to the substrate, to prepare a second strip-shaped superconducting layer through the second strip-shaped opening, the first strip-shaped superconducting layer and the second strip-shaped superconducting layer crossing each other, and an intersection of the first strip-shaped superconducting layer and the second strip-shaped superconducting layer being isolated by an oxidation layer to form a Josephson junction.