BUFFALO, N.Y. — In a groundbreaking development for quantum computing, an international team of researchers has demonstrated the feasibility of creating a Josephson junction using only one superconductor. This discovery could pave the way for more streamlined and adaptable quantum computing designs.
The team, whose findings were published in Nature Communications, reported experimental evidence showing that superconducting behavior can be induced in a non-superconducting material, mimicking the behavior of a traditional Josephson junction. The experiment involved vanadium, a superconducting metal, which was able to transfer its superconducting properties across a barrier to iron, a non-superconducting metal, creating synchronized electron pairing.
Understanding the Josephson Junction
Traditionally, a Josephson junction consists of two superconductors separated by a thin insulating layer. It allows for the flow of electrical current with zero resistance, a phenomenon driven by paired electrons. This principle is a cornerstone of quantum computing, earning the 2025 Nobel Prize in Physics for advancements in the field. The new research suggests that similar effects can be achieved with a single superconductor, potentially simplifying quantum computer architecture.
Igor Žutić, SUNY Distinguished Professor at the University at Buffalo, likened the phenomenon to an army battalion marching in step along a riverbank, causing citizens on the opposite side to form their own militia and march to a different beat. “In our experiment, there was only one battalion,” Žutić explained, “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.”
Experimental Breakthrough
The experiments were conducted in the lab of Farkhad Aliev, PhD, at the Autonomous University of Madrid, with collaboration from institutions in Spain, France, Romania, and China. The study was supported by the U.S. Department of Energy’s Office of Science Basic Energy Sciences.
By analyzing the electrical noise — the small fluctuations in electron flow — the researchers observed that electrons in the iron moved in large, coordinated groups, a behavior typical of Josephson junctions with two superconductors. This was unexpected, given that iron is a ferromagnet and typically incompatible with superconductivity.
Iron’s Unique Role
In most ferromagnets, electrons have spins aligned in the same direction, while superconductors have paired electrons with opposite spins. Yet, in this experiment, the iron managed to form superconducting pairs from electrons with the same spin direction, a significant deviation from conventional understanding.
“The iron essentially created a different type of superconductivity from vanadium,” Žutić noted. “In other words, the citizens organized in their own way but kept time well enough to march as an army and send their own rhythm back across the river.”
Implications for Quantum Computing
This discovery opens new avenues for the development of topological superconductors, which are more resistant to environmental disturbances. These materials could protect quantum information, often tied to electron spin, in a manner that prevents disruptions from unraveling the core processes.
Žutić highlighted the potential for using common materials like iron and magnesium oxide, which are already prevalent in magnetic computer hard drives and memory devices. “We have added a superconducting twist to commercially viable devices,” he said, suggesting a future where quantum computing components could be more accessible and cost-effective.
Future Prospects
While the exact mechanism by which iron achieves same-spin electron pairing remains a mystery, the researchers are optimistic about its potential applications. The ability to lock an electron’s spin into place could address one of the significant challenges facing conventional quantum computers, where even minor environmental changes can disrupt electron spin.
As the scientific community continues to explore these findings, the implications for quantum computing and related technologies are profound. The ability to create Josephson junctions with a single superconductor could revolutionize the design and functionality of quantum computers, making them more efficient and adaptable to a broader range of applications.
The research marks a significant step forward in understanding superconductivity and its potential uses, with the promise of further breakthroughs on the horizon.
