Stochastic gradient ascent outperforms gamers in the Quantum Moves game

Abstract

In a recent work on quantum state preparation, S{\o}rensen and colleagues explore the possibility of using video games to help design quantum control protocols. The authors present a game called "Quantum Moves" in which gamers have to move an atom from A to B by means of optical tweezers. They report that, players succeed where purely numerical optimization fails [1]. Moreover, by harnessing the player strategies they can outperform the most prominent established numerical methods [1]. The aim of this manuscript is to analyze the problem in detail and show that those claims are untenable. In fact a simple stochastic local optimization method can easily find very good solutions to this problem in a few 1000 trials rather than the astronomical $7.4\times 10^{8}$ trials of the most successful optimization method reported in [1]. Next, counter-diabatic driving is used to generate protocols without resorting to numeric optimization; the protocols are shown to outperform virtually all players. The analysis moreover results in an accurate analytic estimate of the quantum speed limit which, apart from zero-point motion, is shown to be entirely classical in nature. The latter might explain why gamers are remarkably good at the game.