Can we transfer magnetic fields across long distances?

Transferring electromagnetic waves would suppose a great improvement for many technologies. This can be seen with information being circulated worldwide via optic fibers. However, a device capable of doing this with static magnetic fields does not exist. A Catalan, German and Austrian group of physicists has now found a surprisingly simple solution for this problem.

In Innsbruck, theoretical physicist Oriol Romero-Isart and his team have developed a new technology to transfer magnetic fields to arbitrary long distances, which is comparable to transmitting and routing light in optical fibers. They have theoretically proposed and already tested this new device experimentally, which is comparable to transmitting and routing light in optical fibers.

"Our theoretical studies have shown that we need a material with extreme anisotropic properties to transfer and route static magnetic fields," explained Romero-Isart. Therefore the material has to have really good permeability in one direction but zero in the perpendicular direction.

It does not exists any material with this extreme anisotropy, so the group of physicists found another way to solve this obstacle. They used a ferromagnetic cylinder and wrapped it with a superconductor shell, to act as a magnetic insulator. "Superconductors are perfect magnetic insulators," explains Romero-Isart. The researcher's calculations showed that a structure of alternated superconducting and soft ferromagnetic concentric cylindrical layers could transfer more than 90% of the magnetic field to any distance. Remarkably, the researchers also calculated that up to 75 % of the magnetic field can be transferred by using only a bilayer scheme – a ferromagnetic core with a superconducting outer layer.

After theoretically proposing this scheme, the team experimentally demonstrated such a device. They wrapped a ferromagnet made of cobalt and iron with a high-temperature superconductor and conducted several tests. "Even though our technical set-up wasn't perfect, we could show that the staticmagnetic field is transferred well by the hose," says Prof. Sanchez, the Catalan group leader of Oriol Romero-Isart's collaborators.

This new method could be used, for example, for future quantum technology coupling distant quantum systems magnetically, applications in spintronics and other nano technologies.

The work of the physicists from the Universitat Autonoma de Barcelona, the Max-Planck-Institute of Quantum Optics, the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences and the Institute for Theoretical Physics of the University of Innsbruck has been published in the renowned journal Physical Review Letters.