Cascaded Josephson Isolators for Frequency-Multiplexed Microwave Signals
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Solution Overview
Problem
Existing microwave isolators in quantum computing struggle to effectively isolate frequency-multiplexed microwave signals across nonoverlapping bandwidths, as they are limited to a narrow frequency range and cannot handle signals outside their operational bandwidth without significant attenuation or loss.
Innovation Solution
A cascading multi-path interferometric Josephson isolator system is developed, utilizing nondegenerate three-wave-mixing Josephson devices with series coupling between Josephson devices, each operating in nonoverlapping bandwidths, allowing for efficient isolation and propagation of signals across a broader frequency range by isolating signals within their respective bandwidths and passing out-of-band signals without attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single microwave isolator is used, then isolation within its operational bandwidth is achieved, but signals outside its bandwidth suffer significant attenuation or loss
Solution Approach 1:
The patent divides the frequency isolation task into multiple segments by using several isolators, each tuned to a specific nonoverlapping frequency bandwidth. Each isolator segment handles a specific frequency range, and together they cover a broader spectrum without interference, resolving the contradiction between narrowband isolation effectiveness and broad frequency coverage.
Solution Approach 2:
Each isolator in the series is designed with local quality optimized for its specific frequency bandwidth, with resonant frequencies and coupling parameters tuned to its designated range. This localized optimization allows each component to achieve high isolation effectiveness within its bandwidth while the collective system achieves broad frequency coverage.
2Adaptability or versatility
If multiple isolators with overlapping bandwidths are used, then broader frequency coverage is achieved, but signals in overlapping regions experience interference and degradation
Solution Approach 1:
Each isolator is designed with distinct local quality parameters including nonoverlapping frequency bandwidths and specifically tuned resonant frequencies. This ensures that each isolator operates independently in its designated frequency range without interfering with others, maintaining signal integrity while achieving broad coverage.
Solution Approach 2:
The isolators are designed with asymmetric frequency response characteristics where each has a unique bandwidth and center frequency. This asymmetric design with nonoverlapping bandwidths prevents the symmetry-induced interference that would occur with identical or overlapping isolators, allowing broad frequency coverage without signal degradation.
3Adaptability or versatility
If a broadband isolator is designed, then frequency range coverage is improved, but isolation effectiveness within specific bandwidths is reduced
Solution Approach 1:
Instead of designing a single broadband isolator with compromised performance, the patent segments the frequency range into multiple narrowband isolators, each optimized for high isolation effectiveness in its specific bandwidth. The series configuration of these segmented isolators achieves overall broadband coverage while maintaining high isolation effectiveness in each segment.
Solution Approach 2:
The patent combines multiple narrowband isolators in series to create an effective broadband isolation system. By merging the isolation capabilities of individual narrowband isolators with nonoverlapping bandwidths, the system achieves both broad frequency coverage and high isolation effectiveness across the entire frequency range.
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 system achieves broader bandwidth isolation and propagation capabilities compared to single isolators, ensuring minimal signal loss while effectively filtering signals within specific frequency ranges, enhancing the reliability of quantum computing operations.
Implementation Method 1
A cascading microwave isolator includes a set of Josephson devices, each Josephson device in the set having a corresponding operating bandwidth of microwave frequencies
Implementation Method 2
nondegenerate three-wave-mixing Josephson devices
Implementation Method 3
A Josephson junction is formed by separating two thin-film superconducting metal layers by a non-superconducting material
Data Source
AI summary
A cascading microwave isolator (cascade) includes a set of Josephson devices, each Josephson device in the set having a corresponding operating bandwidth of microwave frequencies. 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 to isolate a signal at a first frequency from a frequency multiplexed microwave signal (multiplexed signal) in a first signal flow direction through the series coupling and the nth Josephson device to isolate a signal at an nth frequency from the multiplexed signal in the first signal flow direction through the series.