Engineering news

Theory could lead to 'radiationless revolution'

PE

Visualisation of dark matter as energy confined within non radiating anapoles. Photo credit Andrey Miroshnichenko
Visualisation of dark matter as energy confined within non radiating anapoles. Photo credit Andrey Miroshnichenko

Method to confine electromagnetic energy could combat energy loss in future technologies

Visualisation of dark matter as energy confined within non-radiating anapoles. Photo credit: Andrey Miroshnichenko

Physicists at the Australian National University (ANU) have found a new way to confine electromagnetic energy without it leaking away, which could help combat energy losses in future technologies.

The theory could have broad ranging applications from explaining dark matter to aiding the development of tiny lasers on the surface of materials, called spasers, and also in the creation of efficient X-ray lasers by high-order harmonic generation.

However, Dr Andrey Miroshnichenko, from the ANU research school of physics and engineering and lead researcher on the project, said it appears to contradict a fundamental tenet of electrodynamics; that accelerated charges create electromagnetic radiation.

Miroshnichenko said: "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.

Miroschnichenko said: "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 two different components, a conventional electric dipole and a toroidal dipole (associated with poloidal current configuration), which produce identical fields at a distance.

If these two configurations are out of phase then the radiation will be cancelled out, even though the electromagnetic fields are non-zero in the area close to the currents.

Miroshnichenko, in collaboration with colleagues from Germany and Singapore, successfully tested his new theory with a single silicon nanodiscs between 160 and 310 nanometres in diameter and 50 nanometres high, which he was able to make effectively invisible by cancelling the disc's scattering of visible light.

This type of excitation is known as an anapole (from the Greek, 'without poles').

Miroshnichenko's insight came while trying to reconcile differences between two mathematical descriptions of radiation; one based on Cartesian multipoles and the other on vector spherical harmonics used in a Mie basis set.

Miroshnichenko said: "The two gave different answers, and they shouldn't. Eventually we realised the Cartesian description was missing the toroidal components.

"We realised that these toroidal components were not just a correction, they could be a very significant factor."

 

 

Share:

Read more related articles

Professional Engineering magazine

Professional Engineering app

  • Industry features and content
  • Engineering and Institution news
  • News and features exclusive to app users

Download our Professional Engineering app

Professional Engineering newsletter

A weekly round-up of the most popular and topical stories featured on our website, so you won't miss anything

Subscribe to Professional Engineering newsletter

Opt into your industry sector newsletter

Related articles