Japanese tech firm NTT is building a sophisticated optical computer NNT/LASOLV [Science and Core Technology Laboratory Group] A machine made from a 5-kilometre-long fibre optic cable coiled into a box a few metres across could give quantum computers a run for their money on certain tasks. The device, which performs calculations using pulses of light, will be one of the most sophisticated optical computers ever built.

The device, which is being built by Hiroyuki Tamura and colleagues at Japanese tech firm NTT, is specially designed to solve optimisation problems. These involve finding the best solution out of many possible …