Quantum information processing: Cryptography, computation, and teleportation

Present information technology is based on the laws of classical physics. However, advances in quantum physics have stimulated interest in its potential impact on such technology. This article is a reasonably introductory review of three aspects of quantum information processing, cryptography, computation, and teleportation. In order to give a level of self-containment, I serve up hors d'oeuvres on the relevant parts of quantum physics and the sorts of quantum systems which might form the building blocks for quantum processors. Quantum cryptography utilizes states of individual quantum systems for the transfer of conventional classical bits of information. The impossibility of measuring quantum systems without disturbing them guarantees the detection of eavesdropping and hence secure information transfer is possible. In a sense, teleportation is the inverse of cryptography, using more robust classical bits to faithfully transfer a quantum state through a noisy environment. Quantum computation utilizes the evolving quantum state of a complex system, which consists of many interacting individuals. If such a machine could be built, it would be capable of solving some problems which are intractable on any conventional computer; I illustrate this with Shor's quantum factoring algorithm. I give some details of the current experimental achievements, proposals, and prospects for the future and of the patents granted to date. © 1996 IEEE.