Multi-path Josephson Isolator for Cryogenic Quantum Circuits
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Solution Overview
Problem
Existing cryogenic isolators in quantum computing are large, heavy, difficult to thermalize, and incorporate ferrites and magnets that are challenging to integrate on chip, causing issues with size, weight, and magnetic flux interference in superconducting circuits.
Innovation Solution
A multi-path interferometric Josephson isolator based on nondegenerate three-wave mixing Josephson devices, which uses two nondegenerate microwave mixers configured to allow microwave signal transmission in one direction while blocking it in the opposite direction, eliminating the need for ferrites and strong magnets, and allowing for compact and lightweight integration on chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cryogenic isolators are used, then effective microwave signal isolation is achieved, but the device size and weight increase significantly
Solution Approach 1:
The patent replaces the mechanical/ferrite-based isolator system with a superconducting quantum circuit-based isolator. The new design uses Josephson junctions and microwave resonators to achieve isolation through quantum interference effects rather than traditional ferrite materials and mechanical components, thereby dramatically reducing weight while maintaining isolation effectiveness
Solution Approach 2:
The patent changes the operating parameters and physical state by using superconducting materials at cryogenic temperatures. This parameter change enables the system to achieve isolation through superconducting quantum effects rather than conventional electromagnetic effects, resulting in a lighter and more compact device
2Reliability
If conventional cryogenic isolators are used, then effective microwave signal isolation is achieved, but the device volume increases
Solution Approach 1:
The patent replaces the bulky mechanical/ferrite-based isolator structure with a planar superconducting quantum circuit layout. The isolation function is achieved through microwave resonance and quantum interference in a two-dimensional circuit configuration, dramatically reducing the device footprint while maintaining isolation performance
Solution Approach 2:
The patent transitions from a three-dimensional ferrite-based isolator structure to a two-dimensional planar superconducting circuit layout. This dimensional reduction enables compact integration on chip while preserving the isolation function through microwave resonance and quantum interference effects
3Reliability
If conventional cryogenic isolators with ferrites and magnets are used, then isolation function is achieved, but integration on chip becomes difficult
Solution Approach 1:
The patent replaces ferrite materials and magnet components with superconducting quantum circuits that can be fabricated using standard thin-film deposition and lithography techniques. This substitution enables monolithic integration on chip while maintaining the isolation function through quantum interference effects
Solution Approach 2:
The patent creates a universal platform where superconducting quantum circuits serve multiple functions: they act as both the quantum processing elements and the isolation components. This multi-functionality eliminates the need for separate ferrite isolator components, enabling seamless integration on chip
4Reliability
If conventional cryogenic isolators are used, then isolation is achieved, but the device becomes heavy and difficult to thermalize
Solution Approach 1:
The patent replaces heavy ferrite and magnet components with lightweight superconducting quantum circuits. The new design uses thin-film superconducting materials deposited on substrates, dramatically reducing mass while improving thermalization characteristics due to the small thermal capacity of the superconducting structures
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 provides a compact, lightweight microwave isolator that can be integrated on chip, reducing size and weight constraints while maintaining effective isolation, and allows for reversible direction of isolation by adjusting pump phase differences, enhancing compatibility with superconducting quantum circuits.
Implementation Method 1
A first nondegenerate microwave mixer device (first mixer) having a first port and a second port, the first mixer configured to receive a microwave input of a first frequency via the first port, and to generate an idler signal of a second frequency at the second port
Implementation Method 2
Multi-path interferometric Josephson isolator based on nondegenerate three-wave mixing Josephson devices
Implementation Method 3
Multi-path interferometric Josephson isolator
Data Source
AI summary
A microwave isolator device includes two nondegenerate microwave mixer devices, each mixer configured to receive a microwave input of an input frequency via a first port and to generate an idler signal of an idler frequency at a second port. The second ports of both mixers are coupled together. A first input/output (I/O) port is coupled to the first ports of the two mixers, and a second I/O port is also coupled to the first ports of the two mixers. A microwave signal (signal) communicated between the first I/O port and the second I/O port is transmitted while propagating in a first direction between the first I/O port to the second I/O port through the first mixer and the second mixer and to be blocked while propagating in a second direction between the second I/O port to the first I/O through the first mixer and the second mixer.