Superconducting Qubit Vacuum Capacitor Design
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Solution Overview
Problem
Current superconducting qubit designs suffer from short energy relaxation lifetimes due to significant coupling of the electric field to impurities in the dielectric substrate, limiting their scalability and computational capabilities.
Innovation Solution
A superconducting qubit design featuring a capacitor with a vacuum gap between its opposing surfaces, coated with superconducting material, minimizes the interaction of the electric field with the dielectric substrate by directing it into vacuum, thereby reducing energy losses and increasing the energy relaxation lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the capacitor uses a dielectric substrate to support the electrodes, then the mechanical stability and ease of manufacture are improved, but the electric field couples strongly to impurities in the substrate, reducing the energy relaxation lifetime
Solution Approach 1:
The invention extracts the electric field from the dielectric substrate environment by creating a vacuum gap between the capacitor electrodes. The capacitor is designed with two opposing superconducting electrodes separated by a vacuum space, eliminating the dielectric material that causes energy loss through coupling with impurities. This extraction of the electric field from the lossy dielectric environment directly resolves the contradiction by removing the source of energy relaxation while maintaining structural integrity through alternative support mechanisms.
Solution Approach 2:
The invention replaces the dielectric substrate environment with a vacuum environment between the capacitor electrodes. By evacuating the space between the opposing superconducting electrodes, the electric field interacts with a vacuum (inert environment) rather than a dielectric material containing impurities. This inert environment eliminates parasitic coupling and energy loss channels, thereby extending the energy relaxation lifetime without compromising the capacitor's functional integrity.
2Loss of energy
If the electric field is stored in the dielectric substrate, then the capacitor structure is compact and easy to fabricate, but energy losses increase due to coupling with substrate impurities
Solution Approach 1:
The invention extracts the electric field storage location from the dielectric substrate and places it in a vacuum gap between opposing superconducting electrodes. By removing the dielectric material from the electric field region, the source of energy loss through impurity coupling is eliminated. The electric field is now confined to the vacuum space, which does not contain lossy impurities, thereby dramatically reducing energy losses despite the increased structural complexity.
Solution Approach 2:
The invention changes the fundamental parameter of the capacitor's dielectric constant from a finite value (dielectric material) to vacuum permittivity (ε₀). This parameter change from using a dielectric substrate to using vacuum as the electric field medium fundamentally alters the energy loss characteristics. The vacuum environment provides a lossless storage medium for the electric field, eliminating the parasitic coupling and energy dissipation that occur in dielectric materials containing impurities.
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 design achieves energy relaxation lifetimes exceeding 100µs, significantly improving the qubit's coherence and enabling practical quantum computations and sensitive quantum sensing.
Implementation Method 1
the capacitor is configured such that, when the superconducting qubit is placed in a vacuum, a region between the opposing surfaces is evacuated
Implementation Method 2
This capacitor configuration ensures that the electric field energy of the capacitor is stored in vacuum
Implementation Method 3
the opposing surfaces are coated with a superconducting material
Implementation Method 4
a Josephson junction, wherein: the Josephson junction is connected to the capacitor
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
Provided is a superconducting qubit comprising a capacitor and a Josephson junction connected to the capacitor. The capacitor comprises two opposing surfaces coated with a superconducting material. When the superconducting qubit is placed in a vacuum, a region between the opposing surfaces is evacuated. A configuration of the capacitor is such that an energy relaxation lifetime of the qubit is at least 100µs. The capacitor may comprise two electrode structures comprising a dielectric material coated with a superconducting material, each opposing surface provided by a corresponding electrode structure. Three mutually perpendicular lines can be drawn through the dielectric material, each line intersecting the superconducting material on two opposing sides of the electrode structure.