Designing and implementing small quantum circuits and algorithms

It appears, in principle, that the laws of quantum mechanics allow a quantum computer to solve certain mathematical problems more rapidly than can be done using a classical computer. However, in order to build such a quantum computer a number of technological problems need to be overcome. A stepping stone to this goal is the implementation of relatively simple quantum algorithms using current experimental techniques. This paper explores small scale quantum algorithms from two different perspectives. Firstly, it shows how small scale quantum algorithms can be tailored to fit current schemes for implementing a quantum computer. Secondly, I review a simple model of computation, based on read-only-memory. This model allows the comparison of the space-efficiency of reversible error-free classical computation with reversible, error-free quantum computation. The quantum model has been shown to be more powerful than the classical model.