Clump of gold nanoparticles acts as energy-efficient logic gates

New Scientist : A microchip is a highly organized arrangement of silicon-based transistors and other circuit elements. However, it requires significantly more energy than a human brain to do significantly less work. A goal of researchers is to design a computer that can perform calculations efficiently without having been programmed to perform those particular calculations. Wilfred van der Wiel of the University of Twente in the Netherlands and his colleagues have developed a proof-of-concept system that does just that. They spread 20-nm gold particles in a rough circle, each separated from the next by 1 nm, and surrounded the arrangement with electrodes. Then they used a genetic algorithm to determine what voltages should be applied across which electrodes to get the system to behave as a network of transistors. As the researchers ran the algorithm, they found voltages that allowed the system to behave as each of the six basic logic gates and another that let the system “add” two bits of information. The arrangement had to be cooled to 0.3 °C above absolute zero, but van der Wiel believes that it could be adjusted to work at room temperature.