Josephson Four-Port Circulator for On-Chip Cryogenic Isolation
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Solution Overview
Problem
Commercial cryogenic circulators are large, heavy, difficult to thermalize, and require ferrites and magnets, which are challenging to integrate on chip and can negatively affect superconducting circuits.
Innovation Solution
A superconducting four-port circulator is developed using nondegenerate three-wave mixing Josephson devices coupled in parallel, eliminating the need for ferrites and magnets, and allowing for integration on chip or PCB, with enhanced thermalization and reduced size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If commercial cryogenic circulators are used, then circulator function is achieved, but size and weight become large
Solution Approach 1:
The patent replaces the mechanical/ferrite-based commercial circulator system with a superconducting quantum circuit implementation using Josephson junctions. The circulator function is achieved through quantum interference and parametric coupling mechanisms rather than traditional ferrite materials and mechanical structures, eliminating the need for heavy magnets and ferrite components.
Solution Approach 2:
The invention operates at cryogenic temperatures (millikelvin range) and uses quantum parameter regimes (Josephson energy, charging energy, coupling rates) to achieve circulator functionality. By changing the operating temperature and energy scale parameters, the system achieves non-reciprocal signal transmission without requiring the physical dimensions and materials of commercial circulators.
2Reliability
If commercial cryogenic circulators are used, then circulator function is achieved, but integration on chip becomes difficult
Solution Approach 1:
The patent merges the circulator function with superconducting qubit circuits by using the same Josephson junction technology platform. The circulator is implemented as an integrated quantum circuit component that can be fabricated using standard superconducting circuit techniques (Josephson junctions, transmission lines, capacitors) on the same chip, eliminating the need for separate commercial circulator components.
Solution Approach 2:
The invention replaces the external mechanical circulator system with an on-chip superconducting circuit implementation. The non-reciprocal signal routing is achieved through quantum interference in superconducting loops and parametric coupling, allowing direct integration with qubit circuits without external components.
3Reliability
If ferrites and magnets are used in circulators, then circulator function is achieved, but negative effects on superconducting circuits occur
Solution Approach 1:
The patent extracts and removes the ferrite and magnet components from the circulator system entirely. The non-reciprocal signal transmission is achieved through purely superconducting mechanisms (Josephson junctions and quantum interference), eliminating the harmful magnetic fields and material incompatibilities that ferrites and permanent magnets introduce to superconducting quantum circuits.
4Reliability
If commercial cryogenic circulators are used, then circulator function is achieved, but thermalization becomes difficult
Solution Approach 1:
The patent merges the circulator with the superconducting quantum circuit platform, allowing both components to be thermalized together at the same cryogenic stage. The integrated design ensures that all components operate at the base temperature without the thermalization challenges of external commercial circulators, as the entire system is fabricated and cooled together as a single quantum device.
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, and efficiently thermalizable four-port circulator with reversible isolation direction, suitable for high-density integration on chip, operating in frequency conversion mode without photon gain.
Implementation Method 1
nondegenerate three-wave mixing Josephson devices
Implementation Method 2
Josephson devices
Data Source
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AI summary
A technique relates to a superconducting device. A first mixing device has a first mixing port and a second mixing port. A second mixing device has another first mixing port and another second mixing port. The first and second mixing devices are superconducting nondegenerate three-wave mixing devices. The first mixing port and the another first mixing port are configured to couple to a first coupler. The second mixing port and the another second mixing port are configured to couple to a second coupler.