Seeing the unseen: observation of an anapole with dielectric nanoparticles

Nonradiating current configurations attract attention of physicists for many years as possible models of stable atoms in the field theories. One intriguing example of such a nonradiating source is known as anapole (which means without poles in Greek), and it was originally proposed by Yakov Zeldovic...

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Bibliographic Details
Published in:arXiv.org 2014-11
Main Authors: Miroshnichenko, Andrey E, Evlyukhin, Andrey B, Ye Feng Yu, Bakker, Reuben M, Chipouline, Arkadiy, Kuznetsov, Arseniy I, Lukyanchuk, Boris, Chichkov, Boris N, Kivshar, Yuri S
Format: Article
Language:English
Subjects:
Dark matter
Dipole moments
Electric dipoles
Electromagnetic properties
Elementary particles
Far fields
Nanoparticles
Nuclear physics
Physicists
Reciprocity
Scattering
Universe
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Summary:Nonradiating current configurations attract attention of physicists for many years as possible models of stable atoms in the field theories. One intriguing example of such a nonradiating source is known as anapole (which means without poles in Greek), and it was originally proposed by Yakov Zeldovich in nuclear physics. Recently, an anapole was suggested as a model of elementary particles describing dark matter in the Universe. Classically, an anapole mode can be viewed as a composition of electric and toroidal dipole moments, resulting in destructive interference of the radiation fields due to similarity of their far-field scattering patterns. Here we demonstrate experimentally that dielectric nanoparticles can exhibit a radiationless anapole mode in visible. We achieve the spectral overlap of the toroidal and electric dipole modes through a geometry tuning, and observe a highly pronounced dip in the far-field scattering accompanied by the specific near-field distribution associated with the anapole mode. The anapole physics provides a unique playground for the study of electromagnetic properties of nontrivial excitations of complex fields, reciprocity violation, and Aharonov-Bohm like phenomena at optical frequencies.
ISSN:2331-8422