​In the never-ending quest to improve computing technology, IBM has just taken a big step smaller: It's found a way to store data on a single atom. A hard drive today takes about 100,000 atoms to store a single bit of data -- a 1 or 0. The IBM Research results announced Wednesday show how much more densely it might someday be possible to cram information. How much more densely? Today, you can fit your personal music library into a storage device the size of a penny. With IBM's technique, you could fit Apple's entire music catalog of 26 million...