Lossless Superconducting Microwave Switch via Phase Control

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Solution Overview

Problem

Existing microwave switches suffer from less than unity transmission, scalability issues, parasitic coupling, limited bandwidth, and require critical matching, which restrict their application in quantum computing and communication systems.

Innovation Solution

A lossless superconducting microwave switch is designed with two nondegenerate Josephson three-wave mixers and hybrid couplers, where the phase difference of pump drives induces a nonreciprocal phase shift, enabling unity transmission and scalability, and supporting five operational modes including reflection, transmission, and variable transmission-reflection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional microwave switches are used, then signal routing is achieved, but transmission is less than unity and losses occur

Engineering Contradiction:

Improvetransmission lossVSAvoidsignal integrity

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent replaces conventional mechanical or solid-state microwave switch mechanisms with a superconducting microwave switch based on Josephson junctions. This substitution eliminates resistive losses inherent in conventional switches, achieving unity transmission (|S21| = 1) when the switch is in the transmitted state, thereby resolving the contradiction between minimizing energy loss and maintaining signal integrity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes phase-dependent parameters of the Josephson junctions to control switch operation. By adjusting the phase difference between pump drives applied to the Josephson parametric converters, the switch can be tuned between different operational modes (reflected, transmitted, or variable transmission-reflection), enabling lossless signal routing while maintaining flexibility.

Inventive Principle:

Principle #35Parameter changes

2Speed

If conventional microwave switches are used, then signal routing is achieved, but bandwidth is limited

Engineering Contradiction:

ImprovebandwidthVSAvoidoperational flexibility

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The patent implements a dynamic control mechanism where the operational state of the microwave switch is determined by the phase difference of pump drives applied to the Josephson parametric converters. This dynamic phase control enables the switch to adapt its transmission and reflection characteristics in real-time, supporting multiple operational modes across a broad bandwidth without sacrificing operational flexibility.

Inventive Principle:

Principle #15Dynamics

3Object-generated harmful factors

If conventional microwave switches are used, then signal routing is achieved, but parasitic coupling occurs

Engineering Contradiction:

Improveparasitic couplingVSAvoidsignal purity

Core Design Contradiction:

Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent replaces conventional switch mechanisms with a superconducting Josephson-based switch that operates through quantum mechanical effects rather than mechanical or resistive processes. This substitution eliminates parasitic coupling effects inherent in conventional switches, producing cleaner signal routing with higher signal purity and greater reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Ease of operation

If conventional microwave switches are used, then signal routing is achieved, but critical matching is required

Engineering Contradiction:

Improvematching requirementVSAvoidsystem complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The superconducting microwave switch inherently provides impedance matching through its Josephson junction-based architecture. The quantum mechanical nature of the Josephson effect and the parametric conversion process automatically adapt to impedance conditions, eliminating the need for critical external matching components and simplifying system integration while maintaining ease of operation.

Inventive Principle:

Principle #25Self-service

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 solution achieves unity transmission, scalability, and flexible operation modes, enhancing the performance of microwave switches in quantum computing and communication systems by controlling signal routing based on phase differences.

Implementation Method 1

A lossless superconducting microwave switch is designed with two nondegenerate Josephson three-wave mixers

Methodology Applied

Scientific EffectJosephson effect: Josephson Effect

Data Source

PatentUS10396782B2Lossless variable transmission reflection switch controlled by the phase of a microwave drive

Publication Date: 2019.08.27 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A technique relates to a microwave switch. A first nondegenerate device includes a first port and a second port. A second nondegenerate device includes another first port and another second port, the second port being coupled to the another second port, where the first nondegenerate device and the second nondegenerate device are configured to receive a phase difference in microwave drives. A first input/output port is coupled to the first port and the another first port. A second input/output port is coupled to the first port and the another first port, where communication between the first input/output port and the second input/output port is based on the phase difference.