Plasmons for New Light Sources

Artistic image of light trapped on the surface of a nanoparticle topological insulator (Source: ICL)

Principle for a new light source: Artistic image of light trapped on the surface of a nanoparticle topological insulator (Source: ICL)

According to the scientists behind a new study from Imperial College London the coupled light and electron would have proper­ties that could lead to circuits that work with photons instead of electrons. It would also allow researchers to study quantum physical pheno­mena, which govern particles smaller than atoms, on a visible scale.

In normal materials, light interacts with a whole host of electrons present on the surface and within the material. But by using theoretical physics to model the behaviour of light and a recently-disco­vered class of materials known as topo­logical insulators, Imperial researchers have found that it could interact with just one electron on the surface. This would create a coupling that merges some of the pro­perties of the light and the electron. Normally, light travels in a straight line, but when bound to the electron it would instead follow its path, tracing the surface of the material.

In the study, Vincenzo Giannini and colleagues modelled this inter­action around a nano­particle made of a topo­logical insulator. Their models showed that as well as the light taking the property of the electron and circu­lating the particle, the electron would also take on some of the properties of the light. Normally, as electrons are travel­ling along materials, such as electrical circuits, they will stop when faced with a defect. However, Giannini’s team dis­covered that even if there were imper­fections in the surface of the nano­particle, the electron would still be able to travel onwards with the aid of the light. If this could be adapted into photonic circuits, they would be more robust and less vul­nerable to disruption and physical imper­fections.

Giannini said: “The results of this research will have a huge impact on the way we conceive light. Topo­logical insu­lators were only discovered in the last decade, but are already providing us with new pheno­mena to study and new ways to explore important concepts in physics.” He added that it should be possible to observe the pheno­mena he has modelled in experiments using current techno­logy, and the team is working with experi­mental physicists to make this a reality.

He believes that the process that leads to the creation of this new form of light could be scaled up so that the pheno­mena could observed much more easily. Currently, quantum pheno­mena can only be seen when looking at very small objects or objects that have been super-cooled, but this could allow scientists to study these kinds of behaviour at room tem­perature. (Source: ICL)

Reference: G. Siroki et al.: Single-electron induced surface plasmons on a topological nanoparticle, Nat. Comm. 7,  12375 (2016); DOI: 10.1038/ncomms12375

Link: Theory and Simulation of Materials, Dept. of Physics, Imperial College London, United Kingdom

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