# Is any QMA-intermediate problem known?

Similar to the class of classical NP-intermediate problems (e.g. Graph Isomorphism), is there any "QMA-intermediate" problem known, that is in QMA but not known to be QMA-complete? Has this been studied systematically before?

• And I suppose you want that the problem is not known to be in NP (or BQP, of course). – Alessandro Cosentino Jul 25 '14 at 14:50
• Yes, of course. Thanks for pointing that out. – Martin Schwarz Jul 25 '14 at 15:18
• Everything in QMA${}_1$, UniqueQMA, QCMA, etc. Pretty much any problem in any subclass of QMA. Perhaps you could be more specific about which subclasses of QMA you wish to exclude? (Such as BQP and NP.) – Robin Kothari Jul 26 '14 at 3:52
• Indeed! I should have thought of these well known restrictions on QMA immediately! Somehow I was thinking more in terms of concrete problems, but of course you're right. You may want to put this as an answer. – Martin Schwarz Jul 26 '14 at 6:42