Consistent Histories and Quantum Computation

点击翻译按钮获取中文摘要

This Small Grant for Exploratory Research (SGER), funded by the Theory of Computing (TOC) Program, CCR, by the Theoretical Physics Program, PHY and by the Informations Technologies Office, DARPA, explores the application of the consistent history formulation of quantum mechanics to some central problems in the new field of quantum computation. These applications include improving algorithms for quantum computation (1) by carrying out measurements at itermediate times, and (2) by error detection and correction. Quantum computation has recently attracted a lot of attention, because Peter Shor showed that certain tasks, including factoring large numbers, could be carried out in polynomial time on a quantum computer, whereas no polynomial-time algorithm for factoring on a ``classical'' computer is presently known. Clearly, if it could be built, such a computer would have many important applications in many areas of computational science, including in communications and information processing. Actually constructing such a quantum computer represents a daunting task, because of severe technical difficulties. One of the goals of this SGER project is to initiate a collaborative effort between computer scientists, theoretical physicists, and experimental physicists at Carnegie Mellon University, in order to explore the applications of the consistent histories framework to determining the feasibility of such a quantum computing device. The consistent histories approach make it possible to think about the computational process in more realistic terms (where atoms, photons, etc. are actually doing something over time) than is possible in the usual ``textbook'' approach, that views the quantum system as a ``great smokey dragon'' up until the point in time at which a final measurement is made, and the wave function of the system ``collapses'' into something which is physically understandable.***