Principles of quantum computing

It has recently been recognized that computers could be profoundly more powerful, if the possibilities offered by the basic principles of quantum mechanics were exploited more completely in machine design. It is physically possible for the binary state of a computer itself to obey quantum mechanics, i.e., to evolve along a superposition of different (logical) pathways that could interfere with one another. This is what is meant by a quantum computer. It has recently been shown that such a computer can perform a class of computational problems, including prime factorization, very rapidly. Quantum computers will require an art that is radically different from any that the computer industry practices today. The bits of such a computer will have to be represented by the states of individual atoms. The use of one such atomic degree of freedom, the "spin", is illustrated below.