Indifferent electromagnetic modes: Bound states and topology
Horsley, SAR
Date: 11 November 2019
Journal
Physical Review A
Publisher
American Physical Society
Publisher DOI
Abstract
At zero energy the difference in the number of spin-up and spin-down modes of the Dirac equation is determined by the topology of both space and the gauge field in which the system sits. Writing Maxwell's equations in a Dirac-like form, we identify cases where a combination of material parameters plays the role of "energy." At zero ...
At zero energy the difference in the number of spin-up and spin-down modes of the Dirac equation is determined by the topology of both space and the gauge field in which the system sits. Writing Maxwell's equations in a Dirac-like form, we identify cases where a combination of material parameters plays the role of "energy." At zero energy we thus find electromagnetic modes that are indifferent to local changes in the material parameters, with a dispersion relation depending only on the asymptotic values of the material parameters at infinity. We give several examples and show that this theory has implications for non-Hermitian media, where it can be used to construct permittivity profiles that are either reflectionless or act as coherent perfect absorbers or lasers.
Physics and Astronomy
Faculty of Environment, Science and Economy
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