Plasmon Polaritons Dragged By Electron Flow

When immersed in an electrical current flowing through a sheet of graphene, quasiparticles comprised of photon and electron waves — plasmon polaritons — have the potential to change speeds, according to a new study. However, while going against the flow of electrons, the polaritons appear to shift gears more easily in one direction — to a somewhat slower speed.

The discovery is significant for plasmonics, a science known for finding innovative and efficient ways to control light at the practically invisible size of individual atoms — for optical computers, nanolasers, and other applications such as imprinting patterns into semiconductors. There are two advantages to plasmon polaritons. They’re a suitable proxy for altering light because of their slower speed than photons. Polariton waves are likewise extremely small; dozens of them can fit into the wavelength of a single photon.

Electrons and photons combine to form polaritons, which have the best of both worlds. They’re small but nonetheless quantum, allowing for manipulation on ultra-fast time scales. You can send information in nanoscale circuits on ultrafast timescales as soon as you can control the speed and direction of polaritons. It’s one of the components that photon-based circuits are currently lacking.

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