New advances in excitonics promise faster computers

Much of today's research in electronics is geared towards obtaining faster computing and higher communication speeds. Researchers at UC San Diego are no exception, and have recently announced they have made another important step towards achieving exciton-based computation at room temperatures. Excitonics exploits the unique properties of excitons instead of the usual electrons, and promises much faster performance by interfacing more naturally with optical communications such as fiber optics.

The findings were published in the advance issue of the journal Nature Photonics, and are a follow-up on the team's previous work on the subject, in which they demonstrated an exciton-based integrated circuit working at 1.5 K (around -272 °C), a temperature that can only be achieved in specialized research laboratories.

This time, the team managed to build an integrated circuit operating at temperatures of 125 K (about -148 °C). While this is still far from the general idea of warm, it is nonetheless a big step towards the ultimate goal of making exciton-based devices work at room temperatures. Temperatures around 100 K are, in fact, within the reach of a much broader community of researchers, because they can be easily reached with commercially-available liquid nitrogen.

"Our goal is to create efficient devices based on excitons that are operational at room temperature and can replace electronic devices where a high interconnection speed is important," Prof. Leonid Butov, who led the research efforts, explained.

In standard electronics, interfacing with optical communication is somewhat tricky, because it requires a finely-tuned transmitter like an LED or a laser diode to translate the electrical signal into photons that can travel in a fiber optics cable, and then back from optical to electrical.

Excitonics offer, however, an intrinsic advantage: when an exciton — a bound state of an electron and an electronic hole — decays, it releases energy directly as a flash of light that can be mapped into an optical signal, making excitonics a much faster and more efficient way of interfacing with fiber optics.

Researchers are just now making their first steps into this new field and much work is still to be done to get complex circuitry to run on a standard PC at room temperatures, but the prospect of achieving efficient computation using excitonics is certainly attractive and something that the team plans to keep working on in the future.

Ongoing research, particularly at MIT, is also considering the strong link between excitons and photons to improve the efficiency of solar cell technology, specifically by developing thin-film solar concentrators with efficiencies exceeding 30 percent.