Tunable Parallel-Plate Capacitor for Cryogenic Superconducting Circuits

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Solution Overview

Problem

Existing superconducting integrated circuits face challenges in efficiently tuning the capacitance of parallel-plate capacitors, particularly due to the limitations of conventional methods like varicaps, MEMS, and piezoelectric effects, which are unsuitable for cryogenic temperatures and dissipative.

Innovation Solution

A tunable parallel-plate capacitor design using superconducting materials with a magnetic field generator or electric field generator to adjust capacitance, employing a superconducting loop or bias electrodes to introduce magnetic or electric fields, respectively, allowing discrete or monotonic tuning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional tuning methods (varicaps, MEMS, piezoelectric effects) are used, then capacitance can be adjusted, but they are unsuitable for cryogenic temperatures and dissipate energy

Engineering Contradiction:

Improvesuitability for cryogenic temperaturesVSAvoidenergy dissipation

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces mechanical tuning methods (MEMS, piezoelectric effects) with a magnetic field-based tuning mechanism using a SQUID. This substitution eliminates the need for mechanical moving parts and piezoelectric materials that fail at cryogenic temperatures, while the superconducting nature of the SQUID ensures zero energy dissipation during capacitance tuning.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameter from voltage-controlled (varicaps) or mechanically-controlled to magnetically-controlled via the SQUID. By applying magnetic flux through the SQUID, the effective capacitance is tuned by changing the magnetic parameter (flux) rather than using voltage or mechanical displacement, enabling cryogenic operation without energy loss.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a magnetic field generator is added to enable tuning, then capacitance can be adjusted, but device complexity increases

Engineering Contradiction:

Improvecapacitance tuning capabilityVSAvoidstructure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the magnetic field generator (SQUID) directly with the capacitor structure, integrating the tuning mechanism into the capacitor itself rather than adding it as a separate external component. This integration reduces overall device complexity while maintaining full capacitance tuning capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The SQUID structure serves multiple functions: it acts as both the magnetic field generator for tuning and as part of the capacitive structure itself. This multi-functionality reduces the need for separate components, thereby reducing device complexity while providing adaptability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables efficient capacitance tuning in superconducting integrated circuits, enhancing performance in high-bandwidth transmission lines, resonators, and capacitive coupling, suitable for non-stoquastic Hamiltonian implementations in quantum processors.

Implementation Method 1

a magnetic field generator operable to apply a magnetic field to the tunable parallel-plate capacitor to tune a capacitance of the tunable parallel-plate capacitor

Methodology Applied

Scientific EffectMagnetic field generation: Electromagnetic Induction

Implementation Method 2

the loop of superconducting material is driven by a current to generate a magnetic field, the magnetic field which tunes a capacitance of the tunable parallel-plate capacitor

Methodology Applied

Scientific EffectMagnetic flux: Magnetic Field

Implementation Method 3

Superconductivity is a set of physical properties observed in a material where electrical resistance of the material vanishes and magnetic flux fields are expelled from the material

Methodology Applied

Scientific EffectMeissner effect: Meissner Effect

Implementation Method 4

a dielectric interposed between the first capacitor plate and the second capacitor plate

Methodology Applied

Scientific EffectDielectric polarization: Dielectric

Data Source

PatentUS12501840B2Systems, articles, and methods for a tunable capacitor

Publication Date: 2025.12.16 D WAVE SYSTEMS INC

AI summary

In some implementations, a superconducting integrated circuit has a tunable parallel-plate capacitor, and a magnetic field generator operable to apply a magnetic field to the tunable parallel-plate capacitor to tune a capacitance of the tunable parallel-plate capacitor. The tunable parallel-plate capacitor includes a first capacitor plate having a plane, a second capacitor plate having a plane, and a dielectric interposed between the first capacitor plate and the second capacitor plate. The plane of the second capacitor plate is geometrically parallel to the plane of the first capacitor plate. In some implementations, a superconducting integrated circuit has a tunable parallel-plate capacitor, and an electric field generator operable to apply an electric field to the tunable parallel-plate capacitor to tune a capacitance of the tunable parallel-plate capacitor. The tunable parallel-plate capacitor includes a pair of capacitor plates, and a dielectric interposed between the pair of plates.