SQUID Array Current Control for Wide-Range Superconducting Biasing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current superconducting current control systems face challenges in precisely tuning the amplitude of control currents to superconducting circuits, often resulting in suboptimal performance due to limitations in dynamic range and the need for large bias currents, which increase complexity and cost.
Innovation Solution
A superconducting current control system utilizing an inductive coupler with a load inductor and a control inductor, coupled with a SQUID array of RF SQUIDs, where each SQUID is inductively coupled to a bias line, allowing for precise control of the load current amplitude through the adjustment of a bias current, thereby controlling the control current amplitude to the superconducting circuit device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a superconducting current control system uses a conventional current control element to tune the amplitude of control current, then the system can provide operational power to superconducting circuits, but the dynamic range is limited and large bias currents are required which increase complexity and cost
Solution Approach 1:
The current control element is segmented into multiple SQUID arrays (first SQUID array and second SQUID array) connected in parallel. Each array can be independently controlled by separate bias lines, allowing for finer granularity in current amplitude control. This segmentation enables precise tuning of control current amplitude while reducing the bias current required per array, thereby reducing overall system complexity and cost.
Solution Approach 2:
The system employs dynamic flux control through multiple bias lines that can be adjusted in real-time to tune the amplitude of control current. The SQUID arrays respond dynamically to bias current changes, enabling adaptive control of the operational power delivered to superconducting circuits. This dynamic control mechanism achieves high precision amplitude tuning without requiring large fixed bias currents.
2Adaptability or versatility
If large bias currents are used to control the amplitude of load current through a conventional current control element, then sufficient control range is achieved, but the system complexity and cost increase
Solution Approach 1:
By dividing the current control function across multiple SQUID arrays connected in parallel, each array handles a portion of the total control current. This allows the system to achieve a wide control amplitude range using smaller individual bias currents for each array, rather than requiring one large bias current, thereby reducing system complexity.
Solution Approach 2:
Multiple SQUID arrays are merged in parallel configuration to collectively provide the full control current amplitude range. The combined effect of multiple arrays with smaller bias currents achieves the same versatility as a single array with large bias current, but with reduced complexity and cost.
3Measurement precision
If a SQUID array is used to control current amplitude with inductive coupling to bias lines, then precise tuning is achieved without hysteretic behavior, but the device structure becomes more complex
Solution Approach 1:
Inductive couplers serve as intermediary elements that magnetically couple the bias lines to the SQUID arrays without direct electrical connection. This indirect coupling mechanism enables precise control of SQUID flux and thus control current amplitude while avoiding hysteretic behavior associated with direct switching. The inductive coupling structure, while adding some complexity, provides the necessary precision and smooth control.
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
This solution provides a higher dynamic range for control current amplitude adjustment without hysteretic behavior, reducing complexity and cost by enabling precise tuning within the superconducting cold space, thus enhancing the performance and efficiency of superconducting circuit operations.
Implementation Method 1
an inductive coupler comprising a load inductor and a control inductor, the inductive coupler being configured to inductively provide a control current from the control inductor to a superconducting circuit device based on a load current being provided through the load inductor
Implementation Method 2
a current control element comprising a superconducting quantum interference device (SQUID) array comprising a plurality of SQUIDs, each of the SQUIDs being inductively coupled to a bias line, the bias line being configured to conduct a bias current to control an amplitude of the load current
Implementation Method 3
each of the plurality of SQUIDs comprises a Josephson junction and an inductor opposite the Josephson junction that is inductively coupled to the bias line
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
One example includes a superconducting current control system. The system includes an inductive coupler comprising a load inductor and a control inductor. The inductive coupler can be configured to inductively provide a control current from the control inductor to a superconducting circuit device based on a load current being provided through the load inductor. The system also includes a current control element comprising a superconducting quantum interference device (SQUID) array comprising a plurality of SQUIDs. The current control element can be coupled to the inductive coupler to control an amplitude of the load current through the load inductor, and thus to control an amplitude of the control current to the superconducting circuit device.