Researchers at the National University of Singapore (NUS) have designed and manufactured circuits that can reach speeds of up to 245 THz, tens of thousands of times faster than contemporary microprocessors. The results open up possible new design routes for plasmonic-electronics, that combine nano-electronics with the fast operating speed of optics.
When light interacts with some metals, it can be captured in the form of collective, extremely fast oscillations of electrons called plasmons. If harnessed, the interaction of photons and electrons could be used to build ultra-fast computers (among other things). But these phenomena occur at a scale so small that we don't yet have the tools to investigate them, let alone harness them.
Assistant Professor Christian A. Nijhuis and his team have now found a way to harness quantum-plasmonic effects even with the current generation of electronics, using a process called "quantum plasmonic tunneling."
The team built a molecular-scale circuit consisting of two plasmonic resonators (structures that can convert photons into plasmons) separated by a single layer of molecules only 0.5 nanometers in size.
Using electron microscopy, Nijhuis and colleagues saw that the layer of molecules allowed the quantum plasmonic tunneling effects to take place, allowing the circuit to operate at frequencies of up to 24 THz. What's more, the frequency of the circuit could be adjusted by changing the material of the molecular layer.
This marks the first time that scientists have observed the quantum plasmonic tunneling effects directly, and is a convincing demonstration that molecular electronics can indeed handle speeds that are miles beyond that of contemporary electronics.
Future applications include plasmonic-electronics hybrids that combine nanoelectronics with the fast operating speed of optics, and single-molecule photon detectors. The researchers will now focus their efforts on trying to integrate these devices into actual electronic circuits.
The results were published in the latest issue of the journal Science.
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