Thermal Transition Filter Bias Line for Flux Trapping Mitigation
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Solution Overview
Problem
Superconducting circuits experience flux trapping due to noise currents that propagate during the cooling process to cryogenic temperatures, leading to operational issues.
Innovation Solution
A thermal transition filter system is integrated within the superconducting circuit, utilizing a conductive metal segment and superconducting filter bias lines with lower critical temperatures to divert noise currents away from the superconducting devices, providing a current path for dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If bias inputs are provided to superconducting devices during temperature transition, then the superconducting circuit can be biased for operation, but noise currents propagate causing flux trapping that deleteriously affects circuit operation
Solution Approach 1:
A filter circuit is introduced as an intermediary component between the bias input and the superconducting device. This filter circuit selectively allows bias currents to pass through to the superconducting device while blocking noise currents during temperature transition, thus mediating between the bias input and the superconducting device to prevent flux trapping while maintaining operational capability
Solution Approach 2:
The filter circuit exploits changes in electrical parameters (resistance, impedance) that occur during temperature transition from above to below the superconducting critical temperature. By designing the filter with temperature-dependent components, it automatically adapts its filtering characteristics based on the temperature parameter, blocking noise currents during transition while allowing bias currents during normal operation
2Reliability
If noise currents are blocked during temperature transition, then flux trapping is prevented, but the circuit complexity increases due to additional filter components
Solution Approach 1:
The filter circuit is merged with and integrated into the existing bias input线路, sharing physical space and electrical pathways with the superconducting device bias lines. This combining approach implements noise filtering functionality without adding separate, independent filter components, thus preventing flux trapping while minimizing increases in overall device complexity
3Object-affected harmful factors
If a thermal transition filter system is added to divert noise currents, then flux trapping is mitigated, but the device complexity increases
Solution Approach 1:
The filter circuit is implemented with locally optimized components positioned specifically at critical points in the bias input线路 where noise currents would most affect the superconducting device. Rather than implementing a comprehensive filter across the entire system, local filtering elements are strategically placed to provide noise current diversion with minimal additional complexity
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
Effectively mitigates flux trapping by diverting noise currents during temperature transitions, ensuring efficient operation without interference with normal superconducting device function.
Implementation Method 1
at very low cryogenic temperatures (e.g., less than 1K), superconducting metals can exhibit superconductivity in which electrons can propagate with approximately zero resistance
Implementation Method 2
As a superconducting circuit is cooled from a typical ambient temperature environment to a cryogenic temperature, and thus a temperature less than a superconducting critical temperature for superconducting devices
Implementation Method 3
The thermal transition filter system provides a current path to divert noise current provided from the bias input away from the superconducting device during a temperature transition
Data Source
AI summary
One example includes a superconducting circuit system. The system includes at least one bias input configured to provide a bias current to a superconducting device via at least one superconducting device bias line coupled to the superconducting device during operation of the superconducting device. The system further includes a thermal transition filter system interconnecting the superconducting device bias line and the bias input. The thermal transition filter system provides a current path to divert noise current provided from the bias input away from the superconducting device during a temperature transition from a first temperature to a second temperature. The first temperature is greater than a highest superconducting critical temperature associated with the superconducting circuit system and the second temperature is less than a lowest superconducting critical temperature for the superconducting circuit system.