This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Adelaide University quantum engineers have found a new way to improve some of the world's most sensitive sensors of electromagnetic fields, a breakthrough that could help advance brain imaging, medical diagnostics, communications technology and next-generation quantum devices. The research, published today in Physical Review Applied, is led by the university's Quantum and Nano Technology Group (QuaNTeG) and solves a long-standing problem that has limited the performance of superconducting quantum interference devices, known as SQUIDs.
SQUIDs are among the most sensitive magnetic field detectors ever created. They are used in specialized applications including brain imaging systems, scientific instruments and advanced radio-frequency sensors. However, while they can detect incredibly small changes in magnetic fields, they have struggled to accurately identify when a magnetic field is exactly zero.
Until now, engineers have addressed this problem by building complex circuits containing hundreds or even thousands of differently sized superconducting loops. While effective, that approach reduces the overall sensitivity of the device. The Adelaide team, which includes doctoral students Ross Monaghan and Jonathan Marenkovic, discovered a simpler solution.
Instead of making loops different sizes, the researchers kept them the same size but strategically replaced some with "bare loops" that contain no Josephson junctions, a key component of traditional SQUID devices. These bare loops change how magnetic signals move through the circuit, creating what the researchers call a "synthetic area spread." The result is that the sensor behaves as though it contains many differently sized loops without needing them. Lead researcher Giuseppe Tettamanzi, an associate professor in Adelaide University's School of Chemical Engineering, said the discovery could help unlock the full potential of quantum sensing technologies.
"For decades, scientists have known how to make these devices identify an absolute magnetic field, but doing so required design compromises that reduced their performance," Tettamanzi said. "Our work shows there is another way. By introducing carefully positioned bare loops, we can achieve the same result while preserving the conditions needed for maximum sensitivity." The researchers developed the theory behind the approach and then confirmed the effect experimentally using fabricated superconducting circuits operating at very low temperatures.
The results showed the new design behaved exactly as predicted. Tettamanzi said the advance could eventually benefit a wide range of applications. "Highly sensitive superconducting quantum sensors have enormous potential in medicine, communications, industry and defense," he said.
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