Effects of noise-induced coherence on the performance of a four-level laser heat engine

Abstract: In this work, we study the effect of noise-induced coherence on the performance analysis of a degenerate four-level quantum heat engine with particular focus on the universal nature of efficiency, which refers to the appearance of the first two universal terms $\eta_C/2$ and $\eta_C^2/8$ in series expansion of the efficiency at maximum power under a left-right symmetry in the system. Firstly, for a two-parameter optimization scheme, we derive an analytic expression for the efficiency at maximum power for the near-equilibrium condition and show that presence of noise-induced coherence breaks the left-right symmetry of the system. However, when the operation of the engine is restricted to either high-temperature or low-temperature regime, we discuss the conditions under which the left-right symmetry can be retained in each case, giving rise to the universal characteristic of efficiency. In case of one-parameter optimization, we show that while the universality of the first linear term $\eta_c/2$ is robust and holds consistently across all conditions, the universality of the quadratic term $\eta_C^2/8$ depends on the constraints imposed on the control parameters. Finally, we examine the behavior of power as a function of noise-induced coherence parameter highlighting the role of matter-field coupling in determining the suitable operation regime for the heat engine to reap the benefits of noise-induced coherence.