Abstract
If the bits of computers are someday scaled down to the size of individual atoms, quantum mechanical effects may profoundly change the nature of computation itself. The wave function of such a quantum computer could consist of a superposition of many com-putations carried out simultaneously; this kind of parallelism could be exploited to make some important computational problems, like the prime factoring of large integers, tractable. However, building such a quantum computer would place undreamed of demands on the experimental realization of highly quantum-coherent systems; present-day experimental capabilities in atomic physics and other fields permit only the most rudimentary implementation of quantum computation.