Before revision:  In contrast to parallel tempering , however, population annealing scales to a nearly arbitrary number of parallel processors and it is thus able to tap into the massively parallel computing power available in petaflop and future exaflop machines .
After revision:  In contrast to parallel tempering , however, population annealing scales to a nearly arbitrary number of parallel processors and it is thus able to tap into the massively parallel computing power available in supercomputers that is so much needed for a range of difficult computational problems .