Scientists have been toying with the idea of quantum computers since the early 1980's but it is only in the last few years that they have begun to take them seriously.
Computer designers first started thinking about quantum theory when they realized how their circuit elements were shrinking. If you make the transistors on a microchip small enough a strange thing happens. Electrons disappear from your memory circuits and reappear some where else without ever having existed any where between the two position. Imagine beaming our new Yorkers instantly from the Bronx to Coney Island without going through turnstiles or using he subway at all!
It was a disturbing thought for engineers whose machines required exact control over the electrons that powered them. But theoreticians wondered whether there might be some way to harness such strange phenomena.
By the mid 1990's some physicists had worked out ways to get quantum devices to carryout basic logic operations in the lab. It now seems possible that someone someday will produce a machine based on quantum theory. A decade ago not even the theoreticians held out much hope.