On Initializing Quantum Registers and Quantum Gates

The problem of initializing phase in a quantum computing system is considered. The initialization of phases is a problem when the system is initially present in an entangled state and also in the application of the quantum gate transformations since each gate will introduce phase uncertainty. The accumulation of these random phases will render the recently proposed quantum computing schemes ineffective for all but toy problems. I think I can safely say that nobody understands quantum mechanics. –Richard Feynman