A major breakthrough in computer technology will use light to process information. Using ultra-cold sodium atoms light can be frozen and made immobile. This could be used to provide a place to store memory for a new generation of computers.
Professor Lene Hau, who became famous for her scientific breakthrough which slowed light from a speed of 186,000 miles per second to slower than a bicycle, calculates this frozen light can be used for "controlled coherent processing."
As traditional computers are reaching their limits, regarding size and speed, this new breakthrough may unleash a revolution in smaller, faster, optical computers. Thus the frozen light would work as a CPU in an optical computer. Source