QMA, or Quantum Merlin-Arthur, is a complexity class in quantum computing that is analogous to the classical complexity class NP (nondeterministic polynomial time). In QMA, a "quantum verifier" (Arthur) interacts with a "quantum proof" (Merlin) in order to determine the correctness of a solution to a decision problem.
Articles by others on the same topic
QMA is the class of promise problems with a polynomial-size quantum witness checked by a uniform polynomial-size quantum circuit. YES instances have an accepting witness with probability at least ; NO instances have acceptance at most for every witness, including mixed states. The verifier's acceptance is linear in the witness density operator. Inverse-polynomial or exponentially small error can be obtained through QMA error reduction.