Benchmarking quantum simulationFinding a solution to a problem often amounts to an optimization problem and thus can be recast in terms of the lowest-energy state of a system. To find such ground states, mathematical methods based on annealing were developed. To reach the ground state more quickly than with the earlier classical methods, a quantum-mechanical approach was proposed; however, the evidence for quantum speed-up is contradictory. Heimet al.show that the results depend on how the problem is described and how the optimization routine is implemented. This development should be valuable for benchmarking quantum machines.Science, this issue p.215