This field focuses on understanding how quantum systems interact with each other. Engineering and exploiting complex many-body quantum systems for quantum information purposes pose some of the most outstanding challenges in quantum physics. Such arrays can serve as versatile model systems for condensed matter physics, or as useful quantum information processors and effective setups for precision atomic and molecular physics measurements. In another perspective, shrinking technology is leading to an extension of thermodynamics to the quantum realm, where notions like temperature and work lose their usual meanings, and the classical laws do not necessarily apply. The focus of the field is, on the one hand, designing more efficient quantum machines and on the other, describing the spread of information through quantum systems.