A Simpler SQUID Array Finds Magnetic Zero Without Sacrificing Its Design

Researchers at Adelaide University have demonstrated a different way for an array of superconducting quantum interference devices, or SQUIDs, to determine an absolute magnetic field. Their peer-reviewed paper, published in Physical Review Applied on October 26, 2026, reports that carefully placed superconducting loops without Josephson junctions can reproduce an effect that previously required loops of different sizes.

Key finding: An engineered distribution of junction-free loops made uniform-area arrays behave like arrays with deliberately mismatched areas.

Why magnetic zero is difficult

A SQUID uses superconducting loops interrupted by Josephson junctions to turn changes in magnetic flux into an electrical response. Arrays can amplify that response, but their output repeats periodically. Without an added design cue, the same voltage can correspond to more than one field value, making the absolute field ambiguous.

One established solution is to build an array from loops with incommensurate, or deliberately different, areas. The Adelaide paper argues that this helps identify a unique field value but prevents every individual loop from sharing the geometry that best supports the array’s maximum response.

A synthetic spread instead of different sizes

The researchers derived a mathematical correspondence between the placement of bare superconducting loops and an equivalent distribution of physical loop areas. They then fabricated several two-dimensional superconducting quantum interference filter arrays and found that the measured voltage-to-flux patterns followed the theory.

The bare loops do not contain the Josephson junctions that define an active SQUID cell. Their position instead changes how magnetic flux contributes across the network. The full array therefore behaves as if its active loops had different effective areas even though their physical areas remain uniform.

This is an electronics and sensing result, not a new form of quantum computer. It also differs from a recent NewTqnia report on a superconducting neural-network chip processing fusion data: both use cryogenic circuits, but one concerns magnetometry while the other concerns computation.

Where SQUIDs already matter

The US National Institute of Standards and Technology describes SQUIDs as exceptionally sensitive quantum magnetometers. Existing uses include reading weak signals in brain-imaging systems, scientific instruments and superconducting detector arrays. That context explains the appeal of an absolute sensor that does not trade away an optimized loop design.

Adelaide University says potential applications include brain monitoring, radio-frequency receivers and other electromagnetic sensing platforms. Those are prospective uses. The published experiment establishes the circuit principle, not improvements in patient imaging, manufacturing cost or system-level sensitivity in those environments.

What evidence should come next

The next useful comparisons are direct measurements against conventional unequal-area arrays under the same noise, bandwidth and fabrication conditions. System tests must also show whether the synthetic-area approach retains its advantage after cryogenic packaging, readout electronics and environmental shielding are included.

Image: Superconducting circuit used in the Adelaide University research. Credit: Adelaide University.