Quantum heat engines with Carnot efficiency at maximum power

Heat engines constitute the major building blocks of modern technologies. However, conventional heat with higher power yield lesser efficiency and vice versa respect various power-efficiency trade-off relations. This is also assumed to be true for operating in quantum regime. Here we show that these relations are not fundamental. We introduce deliver maximum Carnot one-shot finite-size These composed working systems a finite number particles restricted measurements. The operate one-step cycle by letting system simultaneously interact hot cold baths via semi-local thermal operations. By allowing entanglement between its constituents and, thereby, coherent transfer from baths, engine implements fastest possible reversible state transformation each cycle, resulting efficiency. Finally, propose physically realizable using optical systems.