Researchers at University College Cork (UCC) in Ireland have created a potent new tool for identifying the next generation of materials required for large-scale, fault-tolerant quantum computing, according to a study published in Science.
Joe Carroll, a PhD researcher at the Davis Group in UCC. Image Credit: Claire Keogh
As a result of the noteworthy discovery, scientists can now definitively ascertain whether a material could be successfully employed in specific quantum computing microchips for the first time.
The study’s main conclusions are the outcome of a significant international collaboration that included material synthesis by professors Sheng Ran and Johnpierre Paglione of the University of Maryland and Washington University in St. Louis, respectively, and leading theoretical work by Professor Dung-Hai Lee of the University of California, Berkeley.
Researchers from UCC's Davis Group were able to conclusively ascertain whether the known superconductor Uranium ditelluride (UTe2) possessed the properties necessary to be an inherent topological superconductor using equipment that could only be found in three labs worldwide.
A topological superconductor is a unique material that contains new quantum particles called Majorana fermions at its surface. Theoretically, they could be used to store quantum data steadily, free from the chaos and noise that characterize current quantum computers. For decades, physicists have been searching for an intrinsic topological superconductor, but no material has ever been found that meets all of the requirements.
UTe2 has been regarded as a strong candidate material for intrinsic topological superconductivity since its discovery in 2019, but no research has properly assessed its suitability - until now.
A team led by Joe Carroll, a PhD researcher at the Davis Group, and Kuanysh Zhussupbekov, a Marie Curie postdoctoral fellow, used a scanning tunneling microscope (STM) operating in a new mode created by Séamus Davis, Professor of Quantum Physics at UCC, to definitively determine whether UTe2 is the proper type of topological superconductor.
The investigations conducted utilizing the “Andreev” STM, which is only available in Prof. Davis' labs in Cork, Oxford University in the United Kingdom, and Cornell University in New York, discovered that UTe2 is an intrinsic topological superconductor, but not the type that physicists had been looking for.
However, the first-of-its-kind experiment is a breakthrough in and of itself. When asked about the experiment, Mr. Carroll characterized it as follows:
Traditionally researchers have searched for topological superconductors by taking measurements using metallic probes. They do this because metals are simple materials, so they play essentially no role in the experiment. What’s new about our technique is that we use another superconductor to probe the surface of UTe2. By doing so we exclude the normal surface electrons from our measurement leaving behind only the Majorana fermions.
Joe Carroll, PhD Researcher, University College Cork
Carroll also stated that this technology would enable scientists to immediately determine whether other materials are suited for topological quantum computing.
Quantum computers can solve complex mathematical problems in seconds that existing computers would take years to solve. Governments and businesses around the world are currently racing to develop quantum processors with ever-increasing quantum bits, but the unpredictable nature of quantum operations is stifling development.
Earlier this year, Microsoft revealed Majorana 1, which it describes as “the world’s first Quantum Processing Unit (QPU) powered by a Topological Core.”
Microsoft claimed that to make this breakthrough, synthetic topological superconductors based on intricately developed stacks of conventional materials were necessary.
However, the Davis Group's new research means that scientists can now find single materials to replace these complex circuits, potentially leading to higher efficiencies in quantum processors and facilitating many more qubits on a single chip, bringing humanity closer to the next generation of quantum computing.
Journal Reference:
Gu, Q., et al. (2025) Pair wave function symmetry in UTe2 from zero-energy surface state visualization. Science. doi.org/10.1126/science.adk7219