QUANTUM INFORMATION-PROCESSING - CRYPTOGRAPHY, COMPUTATION, AND TELEPORTATION

Present information technology is based on the laws of classical physi cs. However, advances in quantum physics have stimulated interest in i fs potential impact on such technology. This article is a reasonably i ntroductory review of three aspects of quantum information processing, cryptography, computation, and teleportation. In order to give a leve l of self-containment, I serve lip hers d'oeuvres on the relevant part s of quantum physics and the sorts of quantum systems which might form the building blocks for quantum processors. Quantum cryptography util izes states of individual quantum systems for the transfer of conventi onal classical bits of information. The impossibility of measuring qua ntum systems without disturbing them guarantees the detection of eaves dropping and hence secure information transfer is possible. In a sense , teleportation is the inverse of cryptography, using more robust clas sical bits to faithfully transfer a quantum state through a noisy envi ronment. Quantum computation utilizes the evolving quantum state of a complex system, which consists of many interacting individuals. If suc h a machine could be built, it would be capable of solving some proble ms which are intractable on any conventional computer; I illustrate th is with Shor's quantum factoring algorithm. I give some details of the current experimental achievements, proposals, and prospects for the f uture and of the patents granted to date.