Ultracompact Heat Funnels
In 1851, Hippolyte Fizeau performed a celebrated experiment in which light passed through moving water. He observed that the light could be dragged by the water such that its speed depended on the relative directions of the light and water. In 2021, scientists spotted an analogous effect—plasmonic Fizeau drag—where light is dragged by drifting electrons in graphene and other materials. Now Cheng-Wei Qiu at the National University of Singapore and his colleagues have shown theoretically how a similar phenomenon could be leveraged to create ultracompact funnels for thermal radiation [1]. These funnels could improve heat management in nanoscale devices.
The researchers considered a linear chain of pairs of silicon carbide nanoparticles that exhibit complex, many-body interactions. In their model, these particles are positioned above a single sheet of graphene and between two electrodes. A voltage applied to the electrodes causes electrons to drift across the graphene sheet, and thermal radiation emitted by the nanoparticles interacts with these electrons through so-called thermophotonic Fizeau drag.
Qiu and his colleagues’ calculations show that the emitted thermal radiation is focused toward one end of the nanoparticle chain. This effect increases the radiation’s total intensity by a factor of up to 278. The focusing is caused by a combination of the thermophotonic Fizeau drag and the nanoparticle interactions. Crucially for eventual nanoscale applications, the effect is achieved both efficiently and compactly. The researchers propose ways to realize their heat funnels experimentally and suggest that a stronger effect could be achieved using two-dimensional nanoparticle arrays or using larger graphene–nanoparticle structures.
–Ryan Wilkinson
Ryan Wilkinson is a Corresponding Editor for Physics Magazine based in Durham, UK.
References
- S. Yang et al., “Non-Hermitian thermophotonic funneling via nonreciprocal surface waves,” Phys. Rev. Lett. 134, 196901 (2025).