A Note on Bulk Quantum Turing Machine
  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. 
Tetsushi Matsui