SQUID Array Current Control for Hysteresis-Free Superconducting Tuning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing superconducting circuit control systems face challenges in efficiently tuning the amplitude of control currents to superconducting circuits, particularly during calibration, due to limitations in flux control and hysteretic behavior in current control methods.
Innovation Solution
A superconducting current control system utilizing an inductive coupler with a load inductor and control inductor, coupled with a SQUID array of RF SQUIDs, allows for precise control of the control current amplitude through bias currents, avoiding hysteretic effects by individually biasing each SQUID with a small amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a superconducting DAC is used to tune current amplitude, then sufficient current amplitude can be provided to the superconducting circuit, but the system complexity increases and hysteretic behavior occurs during calibration
Solution Approach 1:
The patent replaces the conventional superconducting DAC with a magnetic field-based control system using a bias coil and SQUID array. Instead of using complex digital-to-analog conversion circuitry, the system uses a bias current through the coil to generate magnetic flux that controls the SQUID array, which in turn controls the load current. This substitution reduces system complexity while maintaining control reliability.
Solution Approach 2:
The patent introduces a SQUID array as an intermediary component between the bias coil and the load inductor. The SQUID array acts as a mediator that converts small bias current changes into precise load current amplitude control. This intermediary approach allows for simplified control while avoiding direct complex DAC-to-inductor coupling.
2Productivity
If flux control is used to deliver current to the superconducting circuit, then operational power can be provided dynamically, but hysteretic behavior reduces control precision
Solution Approach 1:
The patent divides the current control function into segmented components: a bias coil for generating magnetic flux, a SQUID array for precise flux control, and a load inductor for current delivery. Each component performs a specific function, allowing dynamic tuning while the segmented architecture prevents hysteresis from propagating through the entire system. The SQUID array segments the control path to enable precise, hysteresis-free operation.
3Device complexity
If a single current control method is used, then the system structure is simple, but the dynamic range of current control is limited
Solution Approach 1:
The patent creates a multi-functional control system where the SQUID array serves multiple purposes: it acts as a current-controlled inductor, a flux modulator, and a precision current regulator. The same SQUID array structure enables both wide dynamic range control and precise amplitude tuning. The bias coil and SQUID array combination provides universal control capability across different current ranges without requiring multiple separate control circuits.
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 system provides a high dynamic range for controlling the amplitude of control currents, ensuring accurate and stable operation without hysteretic behavior, enhancing the tuning capabilities of superconducting circuits.
Implementation Method 1
The load inductor can be coupled to the current loop via an inductive coupling that implements a mutual inductance
Implementation Method 2
The current control element can include a SQUID array comprising a plurality of SQUIDs
Data Source
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.