In the words of Niels Bohr, "Anyone who is not shocked by quantum theory has not understood it!" Shocking indeed to find that quantum bits, or qubits, can be both 1 and 0 at the same time! Or that it can be impossible to eavesdrop on a message sent as qubits! Our scientists are exploiting such quantum weirdness to build quantum logic gates as a step towards a super-powerful quantum computer. In other work they are inventing ultra-secure crytography systems in which data is coded in the quantum states of individual photons.

"Subatomic Logic," Scientific American

Information is physical, and computation obeys physical laws. Ones and zeros — elementary classical bits of information — must be represented in physical media to be stored and processed. Traditionally, these objects are well described by classical equations of motion. But increasingly, as we edge towards the limits of semiconductor technology, we reach a new regime where the laws of quantum physics become dominant. Strange new phenomena, like entanglement and quantum coherence, become available as new resources. How can such resources be utilized for computation? What physical systems allow construction and control of quantum phenomena? How is this relevant to future directions in information technology? These are the questions of quantum computation — questions at the focus of our research at IBM.

Right from its birth in 1900, quantum mechanics has had an unreal, too-strange-to-be-true quality to it. Dealing as it does in probabilities, waves, interference patterns and tunneling (the ability to go from one place to another without passing through the in-between space), quantum mechanics just doesn't have the intuitive certainty of conventional Newtonian mechanics — the system that uses such tangible qualities as force, acceleration and mass to predict the discernable behavior of matter and machines.

Despite its strangeness, however, an understanding of quantum mechanics has been absolutely central to today's high-tech, wired world. Without it, computers, television, satellites, telephones and most other modern gadgets would probably not be as sophisticated and plentiful as they are now. IBM scientists have played important roles in many quantum mechanical developments, but none is as far out and improbable — yet as potentially important — as the development of quantum information techniques.

An outgrowth of seminal IBM Research studies in the 1970s on the energy-efficiency limits of the very act of computation, quantum information theory currently predicts that small bits of matter that are both exquisitely intertwined yet absolutely isolated are capable of such incredible feats as: