Cascaded Josephson Switches for Frequency-Multiplexed Microwave Routing

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Solution Overview

Problem

Existing microwave switches in quantum computing are limited in their ability to selectively switch frequency-multiplexed microwave signals, as they often operate within narrow, overlapping bandwidths, making it difficult to manage signals outside their operational frequency range effectively.

Innovation Solution

A cascading multi-path interferometric Josephson switch (MPIJSW) system is developed, utilizing nondegenerate three-wave-mixing Josephson devices with series coupling between Josephson devices, each with distinct operating bandwidths, allowing for selective switching of frequency-multiplexed microwave signals by reflecting or transmitting signals based on their frequency through the use of nonoverlapping bandwidths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If existing microwave switches operate within narrow, overlapping bandwidths, then device complexity is reduced, but the ability to selectively switch frequency-multiplexed microwave signals is limited

Engineering Contradiction:
Improveability to selectively switch frequency-multiplexed microwave signalsVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the frequency spectrum into multiple non-overlapping bandwidths, with each Josephson device in the cascade responsible for a specific frequency range. This segmentation allows the system to handle broad frequency multiplexed signals while each individual device maintains manageable complexity and operates within its designated bandwidth without interference from others.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-dimension approach (one switch handling one frequency) to a multi-dimensional cascade architecture where multiple switches operate in series, each handling a different frequency dimension. This dimensional expansion enables comprehensive frequency multiplexed signal control while distributing the operational burden across multiple specialized components.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If a single MPIJSW device is used, then device complexity is minimized, but the operational bandwidth is insufficient for frequency-multiplexed signals

Engineering Contradiction:
Improveoperational bandwidthVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple MPIJSW devices in a cascade configuration, each tuned to non-overlapping frequency bandwidths. This merging of multiple specialized devices creates a unified system with extended operational bandwidth capable of handling frequency-multiplexed signals, while the modular nature of the cascade keeps individual device complexity low.

Inventive Principle:
Principle #5Merging (Combining)

3Adaptability or versatility

If Josephson devices have nonoverlapping bandwidths, then selective signal switching is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improveselective signal switching capabilityVSAvoidbandwidth alignment precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent assigns each Josephson device in the cascade a specific local quality characteristic - a designated non-overlapping frequency bandwidth. This local specialization allows each device to be optimized for its specific frequency range, improving selective switching capability while the modular cascade structure makes the precision requirements manageable through standardized design and assembly procedures.

Inventive Principle:
Principle #3Local quality

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 cascading MPIJSW system enables broader bandwidth operation, allowing for efficient switching of all or specific frequency-multiplexed microwave signals by ensuring each device in the cascade only acts on signals within its own bandwidth, thereby enhancing the overall switching capability beyond that of single MPIJSW devices.

Implementation Method 1

A Josephson junction is formed by separating two thin-film superconducting metal layers by a non-superconducting material. When the metal in the superconducting layers is caused to become superconducting - e.g. by reducing the temperature of the metal to a specified cryogenic temperature - pairs of electrons can tunnel from one superconducting layer through the non-superconducting layer to the other superconducting layer.

Methodology Applied
Scientific EffectJosephson effect: Josephson Effect

Implementation Method 2

The present invention relates to a device, method, and system for selective switching of frequency-multiplexed microwave signals using cascading multi-path interferometric Josephson switches in nonoverlapping bandwidths, where the switches are based on nondegenerate three-wave-mixing Josephson devices.

Methodology Applied
Scientific EffectNondegenerate three-wave mixing:

Data Source

PatentEP3718212B1Selective switching of frequency multiplexed microwave signals using cascading multi-path interferometric josephson switches with nonoverlapping bandwidths
Publication Date: 2023.11.08 INTERNATIONAL BUSINESS MACHINE CORPORATION
  • EP3718212B1 patent drawingFigure 1
  • EP3718212B1 patent drawingFigure 2
  • EP3718212B1 patent drawingFigure 3

AI summary

A cascading selective microwave switch (cascade) includes a set of Josephson devices, each Josephson device in the set having a corresponding operating bandwidth of microwave frequencies, wherein different operating bandwidths have different corresponding center frequencies. A series coupling is formed between first Josephson device from the set and an nth Josephson device from the set. the series coupling causes the first Josephson device in an open state to reflect back to an input port of the first Josephson device a signal of a first frequency from a frequency multiplexed microwave signal (multiplexed signal) and the nth Josephson device in a closed state to transmit a signal of an nth frequency in the multiplexed signal from an input port of the nth Josephson device to an output port of the nth Josephson device.