Bi-SQUID Electrostatic Gating for Linear Quantum Magnetic Sensing

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Solution Overview

Problem

Existing quantum magnetic field receiving devices, such as those using DC-SQUIDs, operate in highly non-linear regimes due to their intrinsic periodic and sinusoidal magnetic flux-to-voltage response, making them less suitable for quantum sensing applications that require linearity.

Innovation Solution

A quantum magnetic field receiving device incorporating a Bi-SQUID configuration with an electrostatic gating circuit that applies electrostatic fields to tune the critical supercurrents of the Josephson Junctions, thereby improving the linearity of the magnetic flux-to-voltage response.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If DC-SQUID devices are used as quantum magnetic field receivers, then high sensitivity and signal-to-noise ratio are achieved, but the magnetic flux-to-voltage response becomes highly non-linear and periodic

Engineering Contradiction:

ImprovesensitivityVSAvoidlinearity of response

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent applies dynamics by making the critical currents of the Josephson junctions可调 (tunable) through electrostatic gating. The gate voltages applied to the first and second Josephson junctions allow dynamic adjustment of their critical currents to satisfy the relationship Ic1 = -Ic2, transforming the inherently periodic DC-SQUID response into a linear Bi-SQUID response while maintaining high sensitivity.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If electrostatic gating circuits are added to tune critical supercurrents, then linearity of magnetic flux-to-voltage response is improved, but device complexity increases

Engineering Contradiction:

Improvelinearity of responseVSAvoidcircuit complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies universality by using electrostatic gating circuits that can simultaneously tune multiple Josephson junctions (both the first and second junctions in the Bi-SQUID configuration). This multi-functional approach allows the same gating mechanism to control the critical currents of multiple junctions, achieving linear response while managing device complexity through a unified control strategy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of operation

If Bi-SQUID configuration with tuned critical currents is implemented, then linearity is improved, but fabrication difficulty increases due to precise current matching requirements

Engineering Contradiction:

Improvelinearity of responseVSAvoidfabrication precision

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by pre-configuring the Bi-SQUID structure with symmetric Josephson junctions during fabrication, where the junctions are designed to have equal critical currents. The electrostatic gating is then applied afterward to fine-tune the critical currents and achieve the precise Ic1 = -Ic2 relationship, separating the fabrication process from the tuning process to reduce manufacturing difficulty.

Inventive Principle:

Principle #10Preliminary action

4Adaptability or versatility

If multiple Josephson junctions with different critical currents are used, then device functionality is enhanced, but the magnetic flux-to-voltage response becomes non-linear

Engineering Contradiction:

Improvedevice functionalityVSAvoidlinearity of response

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent applies parameter changes by systematically adjusting the critical current parameters of the Josephson junctions through electrostatic gating. By changing the gate voltages applied to the first and second Josephson junctions, the critical currents are tuned to satisfy Ic1 = -Ic2, transforming the response characteristics from non-linear to linear while maintaining the enhanced functionality provided by multiple junctions.

Inventive Principle:

Principle #35Parameter changes

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 device achieves improved linearity of the magnetic flux-to-voltage response, closer to the theoretical ideal, which enhances its performance in quantum sensing applications, including increased bandwidth, reduced Size Weight and Power (SWaP), and improved Signal-to-Noise Ratio (SNR).

Implementation Method 1

an electrostatic gating circuit configured to apply a first electrostatic field to the first Josephson Junction and a second electrostatic field to the second Josephson Junction

Methodology Applied

Scientific EffectElectrostatic field effect: Electric Field

Implementation Method 2

a first critical supercurrent of the junction material of the first Josephson Junction is tuneable by applying the first electrostatic field to the junction material

Methodology Applied

Scientific EffectJosephson effect: Josephson Effect

Implementation Method 3

magnetic fields are repelled by the loop of superconducting material

Methodology Applied

Scientific EffectMeissner effect: Meissner Effect

Data Source

PatentUS20250044380A1A quantum magnetic field receiving device

Publication Date: 2025.02.06 UNIVERSITY OF ADELAIDE

AI summary

A quantum magnetic field receiving device includes a superconducting quantum interference device (SQUID) or a superconducting quantum interference filter (SQIF) and an electrostatic gating circuit configured to apply electrostatic fields to Josephson Junctions of the SQUID or SQIF.