Scaling of running time of quantum adiabatic algorithm for propositional   satisfiability
  We numerically study quantum adiabatic algorithm for the propositional satisfiability. A new class of previously unknown hard instances is identified among random problems. We numerically find that the running time for such instances grows exponentially with their size. Worst case complexity of quantum adiabatic algorithm therefore seems to be exponential. 
Marko Znidaric