Quantum Fuel with Multilevel Atomic Coherence for Ultrahigh Specific Work in a Photonic Carnot Engine (original) (raw)

We investigate scaling of work output and efficiency of a photonic Carnot engine with the number of quantum coherent resources. Specifically, we consider a generalization of the "phaseonium fuel" for the photonic Carnot engine, which was first introduced as a three-level atom with two lower states in a quantum coherent superposition by [M. O. Scully, M. Suhail Zubairy, G. S. Agarwal, and H. Walther, Science {\bf 299}, 862 (2003)], to the case of N+1N+1N+1 level atoms with NNN coherent lower levels. Deriving a multilevel mesoscopic master equation for the system, we evaluate the harvested work by the engine, and its efficiency. We find that efficiency and extracted work scale quadratically with the number of quantum coherent levels. Quantum coherence boost to the specific energy (work output per unit mass of the resource) is a profound fundamental difference of quantum fuel from classical resources. Besides, we examine the dependence of cavity loss on the number of atomic levels and find that multilevel phaseonium fuel can be utilized to beat the decoherence due to cavity loss. Our results bring the photonic Carnot engines much closer to the capabilities of current resonator technologies.