  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 reduce the effectiveness of the
recently proposed quantum computing schemes. The paper also presents general
observations on the nonlocal nature of quantum errors and the expected
performance of the proposed quantum error-correction codes that are based on
the assumption that the errors are either bit-flip or phase-flip or both. It is
argued that these codes cannot directly solve the initialization problem of
quantum computing.
