  Whether the class QMA (Quantum Merlin Arthur) is equal to QMA1, or QMA with
one-sided error, has been an open problem for years. This note helps to explain
why the problem is difficult, by using ideas from real analysis to give a
"quantum oracle" relative to which they are different. As a byproduct, we find
that there are facts about quantum complexity classes that are classically
relativizing but not quantumly relativizing, among them such "trivial"
containments as BQP in ZQEXP.
