Trench Capacitor Layout for Compact, Low-Noise Quantum Circuits
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Solution Overview
Problem
Current superconducting quantum computing devices face challenges with large capacitor sizes that limit the number of qubits that can be fabricated and operated efficiently, leading to increased noise and reduced coherence times due to unwanted electric field interactions with external surfaces.
Innovation Solution
The design incorporates a trench capacitor with trenched sections within a substrate layer, enclosed by superconducting pads, and a Josephson junction, which reduces electric field participation at the substrate surface, minimizing noise and enhancing coherence by confining the electric field within the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional capacitors are used in superconducting quantum devices, then the device can operate, but the capacitor size becomes large which limits qubit density and increases noise
Solution Approach 1:
The capacitor structure transitions from a planar configuration to a three-dimensional trench-based design. The capacitor plates are positioned at different depths within the substrate, utilizing the vertical dimension to achieve compact footprint while maintaining capacitance. This dimensional transition allows significantly higher qubit density without increasing the device area.
Solution Approach 2:
The capacitor structure is nested within trenches etched into the substrate. The capacitor plates are positioned within these trenches, effectively nesting the capacitive elements within the substrate volume rather than occupying surface area. This nesting approach minimizes the footprint while preserving the electrical function.
2Reliability
If traditional capacitors are used, then the device can function, but electric field interactions with external surfaces increase noise and reduce coherence
Solution Approach 1:
The harmful interaction between the electric field and external surfaces is eliminated by extracting the capacitor structure from the surface plane and positioning it within trenches. The electric field is confined to the region between the capacitor plates deep within the substrate, preventing coupling with surface noise sources and improving qubit coherence.
Solution Approach 2:
The electric field distribution is made highly localized between the capacitor plates within the trench structure. By confining the field to a specific region away from surfaces and using the substrate as a shield, the local quality of the electromagnetic environment is improved, reducing noise and enhancing 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 allows for a smaller, more efficient superconducting device with reduced noise and improved qubit coherence, enabling increased qubit density within a cryogenic chamber while facilitating easier fabrication and reduced maintenance.
Implementation Method 1
a Josephson junction located between a first capacitor portion and a second capacitor portion of a capacitor
Data Source
AI summary
One or more systems, devices, methods of use and/or methods of fabrication provided herein relate to a superconducting device that can be operated with minimal electric field energy coupling at surface layers of the superconducting device and/or that can have a small footprint. According to one embodiment, a device can comprise a Josephson junction located between a first capacitor portion and a second capacitor portion of a capacitor, wherein at least a trenched section of the first capacitor portion is located beneath a surface of a substrate, and wherein at least a trenched section of the second capacitor portion is located beneath the surface of the substrate. According to another embodiment, a device can comprise a capacitor disposed within a substrate layer and the capacitor comprising a pair of material-filled trenches in the substrate layer, and a Josephson junction coupled to the capacitor.