From medical diagnostics and quantum technologies to fusion energy and particle physics, many of tomorrow's key technologies rely on precisely controlled magnetic fields. Now, researchers at the Universitat Autònoma de Barcelona and Chalmers University of Technology have developed a method that can transform the magnetic field from a single source into virtually any other magnetic field, with mathematical precision.
Magnetic fields are invisible yet essential components in technologies ranging from MRI scanners and particle accelerators to atomic clocks and future quantum computers. Each of these applications requires magnetic fields with specific shapes and properties. Today, creating such tailored magnetic fields requires researchers and engineers to design specialized, carefully optimized magnets or large systems of coils for each individual application, a complex and resource-intensive process.
Now, a team of physicists from the Universitat Autònoma de Barcelona (UAB) and Chalmers University of Technology has developed a method that makes it possible to transform the magnetic field from a single source, such as a coil or a permanent magnet, into a broad class of predetermined magnetic fields with exact mathematical precision.
The breakthrough, known as magnetic omniconversion, has been published in Science Advances and enables simple magnetic sources to be used for a wide range of important applications.
“This is a universal method that removes previous limitations on how accurately an existing magnetic field can be transformed into another one,” says Witlef Wieczorek, Professor of Quantum Technology at Chalmers University of Technology and one of the study's co-authors.
A magnetic sculptor delivers mathematical precision
Creating magnetic fields with a specific shape, such as uniform or quadrupolar fields, typically requires custom-built magnets or advanced coil systems carefully optimized for a particular purpose.
“Using combinations of coils, it is possible to approximate a desired magnetic field to high precision, but with magnetic omniconversion the field generated is mathematically exact,” explains Fabian Resare, PhD student in Quantum Technology at Chalmers and co-author of the study.
The researchers' magnetic omniconversion acts as a kind of magnetic sculptor. By combining materials that either attract or repel magnetic fields, such as ferromagnetic and superconducting materials, they can steer and reshape a magnetic field into exactly the desired form. When these materials are arranged in a carefully calculated geometry, they determine how the magnetic field distributes over space. In this way, the researchers can effectively transform" the field from a simple source into almost any other magnetic field with high precision.
Paving the way for novel technological capabilities
To demonstrate the method experimentally, the researchers built a prototype capable of transforming the non-uniform magnetic field from a simple coil into an almost perfectly uniform magnetic field. The device consisted of a superconducting aluminium tube and cast-iron components, which were manufactured by Lars Jönsson from the mechanical workshop at the Department of Microtechnology and Nanoscience. When the device was cooled to temperatures below one kelvin, close to absolute zero, the measurements showed that the magnetic field inside the device closely matched the researchers' calculations, providing an important experimental proof of concept.
The team has filed a patent application for the technology and hopes the method will find practical applications in society and research.
“We hope that our magnetic omniconversion approach will contribute to the development of advanced instrumentation for quantum technologies and other areas, where a precise spatial control of magnetic fields is essential,” says Witlef Wieczorek.
More Information About the Study
The study was carried out by Jaume Cunill-Subiranas, Natanael Bort-Soldevila, Nuria Del-Valle, and Carles Navau from the Department of Physics at the Universitat Autònoma de Barcelona (UAB), Spain, together with Witlef Wieczorek and Fabian Resare from the Division of Quantum Technology, Department of Microtechnology and Nanoscience, Chalmers University of Technology.
Funding
The project was funded by Horizon Europe (the EU project SuperMeQ), the Spanish Ministry of Science, Innovation and Universities (PID2023-149054NB-I00), an AGAUR-FI Joan Oró fellowship (Generalitat de Catalunya), the European Research Council (ERC) through the SuperQLev project, and the Knut and Alice Wallenberg Foundation.
- Head of Division, Quantum Technology, Microtechnology and Nanoscience
- Doctoral Student, Quantum Technology, Microtechnology and Nanoscience