  Adleman, DeMarrais, and Huang introduced the nondeterministic quantum
polynomial-time complexity class NQP as an analogue of NP. Fortnow and Rogers
implicitly showed that, when the amplitudes are rational numbers, NQP is
contained in the complement of C_{=}P. Fenner, Green, Homer, and Pruim improved
this result by showing that, when the amplitudes are arbitrary algebraic
numbers, NQP coincides with co-C_{=}P. In this paper we prove that, even when
the amplitudes are arbitrary complex numbers, NQP still remains identical to
co-C_{=}P. As an immediate corollary, BQP differs from NQP when the amplitudes
are unrestricted.
