Science_afficionado writes: There is a general consensus that ultimately photons will replace electrons running through wires in most of our microelectronic devices. One of the current technical barriers to the spread of optoelectronics has been the difficulty in miniaturizing the ultrafast optical switches required. Now a team of physicists at Vanderbilt has made terahertz optical switches out of nanoparticles of vanadium dioxide, a material long known for its ability to rapidly change phase between metallic to semiconducting states. They report in the Mar. 12 issue of Nano Letters that they have created individually addressable switches that are 200 nm in diameter and can switch between transparent and opaque states at terahertz rates.