In 1994 Peter Shor 65] published a factoring algorithm for a quantum computer that finds the prime factors of a composite integer N more efficiently than is possible with the known algorithms for a classical com- puter. Since the difficulty of the factoring problem is crucial for the se- curity of a public key encryption system, interest (and funding) in quan- tum computing and quantum computation suddenly blossomed. Quan- tum computing had arrived...