On the complexity of stoquastic Hamiltonians

Stoquastic Hamiltonians, those for which all off-diagonal matrix elements in the standard basis are real and non-positive, are common in the physical world. We survey recent work on the complexity of stoquastic Hamiltonians. We discuss results relating stoquastic Hamiltonians and Merlin-Arthur games, including the result that stoquastic k-local Hamiltonian is StoqMA-complete, focusing in particular on the first non-trivial example of an MA-complete problem, stoquastic k-SAT.