Selective Dielectric Capping for SQUID Dephasing Reduction
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Solution Overview
Problem
Dephasing in quantum bits (qubits) due to random phase changes caused by surface spins and molecules, leading to noise and coherence loss in superconducting quantum interference devices (SQUIDs).
Innovation Solution
A dielectric capping layer is selectively applied to cover the superconductor material of SQUIDs, leaving Josephson junctions exposed, to reduce dephasing by moving adsorbates away from the high magnetic field areas while minimizing microwave energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a dielectric capping layer is applied to cover the superconductor material, then dephasing noise is reduced by moving adsorbates away from high magnetic field areas, but microwave energy loss increases due to the dielectric material
Solution Approach 1:
The patent applies selective capping where the dielectric capping layer is applied only to specific regions of the SQUID device - specifically covering the superconductor material in regions with high magnetic field density while leaving Josephson junction regions exposed. This local application strategy reduces dephasing noise in high-field areas without introducing excessive microwave energy loss, as the dielectric is absent from regions where it would cause significant energy dissipation.
2Object-affected harmful factors
If the dielectric capping layer covers the entire SQUID structure, then dephasing is reduced, but manufacturing complexity increases due to selective patterning requirements
Solution Approach 1:
The capping layer is segmented into distinct regions rather than being applied uniformly across the entire SQUID structure. The dielectric capping layer is deposited only in specific areas using selective masking techniques, creating spatially varying capping regions that correspond to high magnetic field areas. This segmentation approach reduces dephasing effectively while maintaining manageable manufacturing complexity through standard semiconductor fabrication patterning processes.
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 dielectric capping layer reduces dephasing noise by up to a factor of 5 and maintains low energy loss, enhancing coherence times and reducing noise contributions effectively.
Implementation Method 1
adsorbed molecular O2 is the dominant contributor to magnetism in superconducting thin films
Implementation Method 2
superconducting quantum interference devices (SQUIDs)
Implementation Method 3
flux qubit with three Josephson junctions inside a DC-SQUID
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
A device includes: a substrate; a superconducting quantum interference device (SQUID) including a superconductor trace arranged on an upper surface of the substrate and having at least one Josephson junction interrupting a path of the superconductor trace, in which the superconductor trace includes a first superconductor material that exhibits superconducting properties at or below a corresponding superconducting critical temperature; and a dielectric capping layer on an upper surface of the SQUID, in which the dielectric capping layer covers a majority of the superconductor trace of the SQUID, and the capping layer includes an opening through which a first region of the SQUID is exposed, the first region of the SQUID including a first Josephson junction.