NQPC = co-C=P

Adleman, DeMarrais, and Huang introduced the nondeterministic quantum polynomial-time complexity class NQP as an analogue of NP. Fortnow and Rogers 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. key words: computational complexity, theory of computation