Beyond bits: the future of quantum information processing

Today's computers operate on the same fundamental principle as the mechanical devices dreamed up by Charles Babbage in the 19th century and later formalized by Alan Turing: one stable state of the machine represents one number. Even seemingly nonstandard computation models, such as the one based on DNA, share this basic principle. Recently, physicists and computer scientists have realized that not only do their ideas about computing rest on partly accurate principles, but they miss out on a whole class of computation. Quantum physics offers powerful methods of encoding and manipulating information that are not possible within a classical framework. The potential applications of these quantum information processing methods include provably secure key distribution for cryptography, rapid integer factoring, and quantum simulation. The authors discuss the directions that quantum information theory appears to be heading and the research and applications it has accrued.