Diamond may be forever, but until now, scientists barely understood why it could become forever superconducting—a puzzle that researchers at Penn State University, the University of Chicago, and Argonne National Laboratory have finally begun to solve.
Two decades ago, physicists made a surprising discovery: under the right conditions, diamond could shed its legendary sparkle and instead allow electricity to flow through it with zero resistance. Diamond's other exceptional properties—its extreme hardness, high thermal conductivity, and transparency across much of the light spectrum—had already made it invaluable to science and technology. Superconductivity promised to add another dimension entirely. Yet despite two decades of knowing it was possible, scientists lacked a fundamental understanding of how the phenomenon actually worked, which severely limited its practical applications.
Jyotirmay Dwivedi, a graduate student working in Nitin Samarth's laboratory at Penn State, led the effort to uncover this hidden physics. The team, published recently in the Proceedings of the National Academy of Sciences, discovered that diamond becomes superconducting through what they call "granular superconductivity"—a surprising structure hidden within what appears to be a perfectly uniform material.
The process begins with doping: adding boron atoms to diamond to change its electrical properties. Using facilities at Penn State's Applied Research Lab, the researchers synthesized extremely high-quality diamond thin films with a random distribution of boron atoms. What they found was unexpected. Within this disordered landscape, the boron atoms formed a mosaic of superconducting "puddles"—microscopically isolated regions where electricity could flow without resistance—that somehow linked up to allow conductivity across the entire material. Even more intriguingly, in films that were structurally homogeneous and crystalline, the superconductivity remained granular, suggesting the puddles arise from something more fundamental than simple boron clustering.
"This serendipitous discovery caught us totally by surprise because these are structurally homogeneous, crystalline films," Samarth said of the finding. "So, the question was: where is this granularity coming from?"
The implications ripple far beyond pure physics. The superconducting mosaic is tunable—it can be stretched and skewed by adjusting magnetic fields, electrical current, and temperature. By understanding how electrons move through and between these puddles, scientists can now begin to engineer them more effectively, potentially linking them together with greater precision. That capability opens a door to a radically different kind of quantum technology.
David Awschalom, director of the Chicago Quantum Exchange and co-author of the study, envisions quantum devices that integrate multiple functions into a single material. "Imagine a future technology that combines light, spin, superconductivity, and magnetism, all in a single material that one could also integrate with today's microelectronics," he said. The potential lies at the intersection of previously separate domains—superconducting qubits and semiconductor qubits working together on one chip.
Current quantum systems demand extreme cooling to operate, consuming enormous amounts of energy. By raising the operating temperature of these superconducting systems, quantum technology could become more accessible and efficient. The roadmap revealed by this research suggests that diamond—already prized for its hardness and transparency—might become the material that finally brings together the disparate branches of quantum science into functional, practical devices.