Quantum Computing
Quantum computation (QC) is a type of computation where unitary and measurement operations are executed on linear superpositions of basis states. This chapter provides a brief introduction to QC. We begin with a discussion of basic models for QC such as quantum TMs, quantum gates, and circuits and related complexity results. We then discuss a number of topics in quantum information theory including bounds for quantum communication and I/O complexity, methods for quantum data compression and quantum error correction (that is, techniques for decreasing decoherence errors in QC), Furthermore, we enumerate a number of methodologies and technologies for doing QC. Finally, we discuss resource bounds for QC including bonds for processing time, energy, and volume, particularly emphasizing challenges in determining volume bounds for observationapparatus. © 2009 John Wiley & Sons, Inc.