NQP_C = co-C_=P
<|reference_start|>NQP_C = co-C_=P: 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.<|reference_end|>
@article{yamakami1998nqp_{c},
    title={NQP_{C} = co-C_{=}P},
    author={Tomoyuki Yamakami and Andrew C. Yao},
    journal={Inform.Proc.Lett. 71 (1999) 63-69},
    year={1998},
    archivePrefix={arXiv},
    eprint={quant-ph/9812032},
    primaryClass={quant-ph cs.CC}
}