Introduction to Quantum Information Theory

Ruskai, Mary Beth

doi:10.1117/3.537698.ch9

Book: The Handbook of Nanotechnology. Nanometer Structures: Theory, Modeling, and Simulation

Editor(s): Akhlesh Lakhtakia

Author(s): Mary Beth Ruskai

Published: 2004

https://doi.org/10.1117/3.537698.ch9

Abstract

In nanotechnology, one is dealing with physical systems at a scale so small that quantum effects are important. As the size of computer chips decreases, one eventually reaches the point where quantum effects, wanted or not, occur. If these quantum effects can be controlled, they can be exploited to build computers that can do some tasks more effectively than classical ones. Moreover, quantum particles can be be used advantageously for other purposes in information technology, most notably for communication and cryptography. In fact, experiments demonstrating the feasibility of the process known as quantum key distribution (QKD) are quite impressive. QKD, which is described in Sec. 9.5.1, is likely to be practical long before a full-fledged quantum computer (QC) is built. The area of quantum information theory (QIT) encompasses quantum computation, quantum communication, and quantum cryptography. A device for implementing any of these is called a quantum information processor. We begin by considering methods of encoding information in such devices.