The class of problems for which the task is to output a quantum certificate for a QMA problem, when such a certificate exists. Thus, the desired output is a quantum state.
Defined in [JWB03], where it is also shown that state preparation for 3-local Hamiltonians is FQMA-complete. The authors also observe that, in contrast to the case of FNP versus NP, there is no obvious reduction of FQMA problems to QMA problems.
No class.