The paper Optical processing units vs. GPUs and TPUs: conditions for performance and energy advantage written by Egor O. Kimlichenko, Dmitrii S. Batanov, Dmitry A. Ivanov, Konstantin S. Domaratskiy, Nikita S. Shmyrin, Evgenia E. Solokhina, Liliana R. Bayslanova, Artem V. Chetvertukhin, Andrey A. Grunin, and Andrey A. Fedyanin has been published in Optics Express.