Visualization of dark matter as energy confined within non-radiating anapoles. Credit: Andrey Miroshnichenko
Akin to throwing a pebble into a pond with no splash, this theory could have many apps from explaining dark matter to combating energy losses in future technologies. It appears to contradict a fundamental tenet of electrodynamics, that accelerated charges create electromagnetic radiation, said Dr Miroshnichenko, ANU. “This problem has puzzled many people. It took us a year to get this concept clear in our heads.”
The fundamental new theory could be used in quantum computers, lead to new laser technology and may even hold the key to understanding how matter itself hangs together. “Ever since the beginning of quantum mechanics people have been looking for a configuration which could explain the stability of atoms and why orbiting electrons do not radiate.”
>>The absence of radiation is the result of the current being divided between 2 different components, a conventional electric dipole and a toroidal dipole (associated with poloidal current configuration), which produce identical fields at a distance. If these 2 configurations are out of phase then the radiation will be cancelled out, even though the electromagnetic fields are non-0 in the area close to the currents.
Dr Miroshnichenko, with colleagues from Germany and Singapore, successfully tested his new theory with a single silicon nanodiscs 160-310 nm in diameter and 50 nm high, which he was able to make effectively invisible by cancelling the disc’s scattering of visible light. This type of excitation = anapole (from the Greek, ‘without poles’).
Dr Miroshnichenko’s insight came while trying to reconcile differences between two different mathematical descriptions of radiation; one based on Cartesian multipoles and the other on vector spherical harmonics used in a Mie basis set. “The two gave different answers, and they shouldn’t. Eventually we realised the Cartesian description was missing the toroidal components,” Dr Miroshnichenko said.
“We realised that these toroidal components were not just a correction, they could be a very significant factor.” The confined energy of anapoles could be important in the development of tiny lasers on the surface of materials, called spasers, and also in the creation of efficient Xray lasers by high-order harmonic generation. http://www.eurekalert.org/pub_releases/2015-08/anu-ntl082615.php
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