For the first time, scientists have been able to definitively determine whether a material possesses the intrinsic properties required for certain types of quantum computing chips. The findings, published in Science, mark a step forward in the global effort to realise robust quantum systems.
The research focused on uranium ditelluride (UTe₂), a superconductor previously considered a promising candidate for topological quantum computing. While UTe₂ did not fully match theoretical expectations, the ability to conduct such a conclusive analysis represents a landmark achievement in quantum materials science.
This international collaboration included theoretical input from Professor Dung-Hai Lee of the University of California, Berkeley, and material synthesis from Professors Sheng Ran at Washington University in St. Louis and Johnpierre Paglione at the University of Maryland.
At the core of the discovery was a series of experiments conducted by the Davis Group at UCC, using highly specialised scanning tunnelling microscopy (STM) technology. Operating in a unique mode developed by Professor Séamus Davis, Professor of Quantum Physics at UCC, the group employed an advanced STM technique – known as ‘Andreev STM’ – available in only three laboratories worldwide: UCC, Oxford University, and Cornell University.
Led by PhD researcher Joe Carroll and Marie Curie postdoctoral fellow Kuanysh Zhussupbekov, the team applied this STM mode to probe the quantum properties of UTe₂. Rather than using traditional metallic tips, the researchers employed a superconducting probe, allowing them to isolate and observe only the exotic particles known as Majorana fermions on the material’s surface.
“Traditionally researchers have searched for topological superconductors by taking measurements using metallic probes,” said Carroll.
“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.”
While UTe₂ turned out to be an intrinsic topological superconductor of a slightly different type than previously anticipated, the significance of the result lies in the validation of the probing method itself. Scientists can now apply this tool to a broader range of materials to determine their suitability for topological quantum computing, potentially accelerating the discovery of viable candidates.
The search for such materials has intensified as countries and corporations invest heavily in quantum technologies. Quantum processors, which use quantum bits or qubits to perform operations, have the potential to solve certain problems in seconds that would take classical computers years to compute. However, current devices remain fragile and prone to error due to environmental noise and instability.
Earlier this year, Microsoft introduced what it called the world’s first Quantum Processing Unit (QPU) powered by a ‘Topological Core’, using synthetic topological superconductors assembled from layered conventional materials.
The method developed in Cork opens the door to identifying single materials that could replace such complex architectures. This, in turn, may improve energy efficiency, simplify chip design, and enable higher qubit density – critical steps towards scaling up quantum processors.
The research from UCC brings scientists closer to resolving one of quantum computing’s fundamental material challenges and offers a practical path toward unlocking stable, large-scale quantum technologies.
