Strong-Coupling Effects in Quantum Novikov Heat Engine

In this paper, we study a quantum Novikov heat engine under strong system-bath coupling using the Reaction-Coordinate Polaron Transformation (RCPT) framework. Instead of classical heat transfer laws, we employ a qubit as an external mediator for heat transfer between the working fluid and the hot thermal bath. We analyze key performance metrics, including efficiency at maximum power output and the ecological function, demonstrating how strong coupling significantly influences energy transfer dynamics. Our results reveal the existence of an optimal coupling strength that maximizes power and Ecological performance, while excessive coupling leads to reduced efficiency due to non-equilibrium effects. Furthermore, we show that strong coupling enables high power output even at low qubit energy gaps, a finding with important implications for designing high-performance quantum thermal devices. These findings contribute to a deeper understanding of strong coupling thermodynamics and provide a framework for optimizing quantum heat engines beyond the weak coupling regime. The findings are particularly relevant for optimizing quantum thermal devices, such as photovoltaic systems, where strong system-bath interactions play a critical role in energy conversion efficiency.