Separate two superconductors with a thin layer of material and something strange happens.
Their superconductivity—a property driven by paired electrons that allows electricity to flow without energy loss—can leak into the barrier and link together, synchronizing their behavior despite the separation.
This device is known as a Josephson junction. It's the foundational building block of quantum computers and advances of it won the 2025 Nobel Prize in Physics.
But what if a Josephson junction could function with only one superconductor—potentially opening new possibilities for simpler and more flexible quantum computing designs? An international team has obtained the first-ever experimental evidence of exactly that, measuring electrical behavior that mimics a Josephson junction with two superconductors even though only one was present.
Their results, published in Nature Communications, suggest that the superconducting metal vanadium leaked superconducting behavior across a barrier and induced electron pairing—a hallmark of superconductivity—in the iron on the other side.
While superconductors are known to induce weak superconducting behavior in nearby materials, the iron's induced behavior was strong enough to produce Josephson junction-like synchronization between it and the vanadium.
"A typical Josephson junction with two superconductors is like two army battalions marching in step along opposite banks of a river. In our experiment, there was only one battalion—yet it's as if its marching caused citizens on the other side to form a militia and begin marching to the beat of a different drum," says the study's co-corresponding author, Igor Žutić, SUNY Distinguished Professor in the Department of Physics in the University at Buffalo College of Arts and Sciences.
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