  Recently, among experiments for realization of quantum computers, NMR quantum
computers have achieved the most impressive succession. There is a model of the
NMR quantum computation,namely Atsumi and Nishino's bulk quantum Turing
Machine. It assumes, however, an unnatural assumption with quantum mechanics.
We, then, define a more natural and quantum mechanically realizable modified
bulk quantum Turing Machine, and show its computational ability by comparing
complexity classes with quantum Turing Machine's counter part.
