The formulation of models describing quantum versions of heat engines plays an important role in the quest toward establishing the laws of thermodynamics in the quantum regime. Of particular importance is the description of stroke-based engines which can operate at finite-time. In this paper we put forth a framework for describing stroboscopic, two-stroke engines, in generic quantum chains. The framework is a generalization of the so-called SWAP engine and is based on a collisional model, which alternates between pure heat and pure work strokes. { The transient evolution towards a limit-cycle is also fully accounted for. Moreover, we show that once the limit-cycle has been reached, the energy of the internal sites of the chain no longer changes, with the heat currents being associated exclusively to the boundary sites.} Using a combination of analytical and numerical methods, we show that this type of engine offers multiple ways of optimizing the output power, without affecting the efficiency. {Finally, we also show that there exists an entire class of models, characterized by a specific type of inter-chain interaction, which always operate at Otto efficiency, irrespective of the operating conditions of the reservoirs.

中文翻译：

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频闪式二冲程量子热机

描述热机量子形式的模型的模型在寻求建立量子态中热力学定律的过程中起着重要作用。特别重要的是对可以在有限时间运行的基于冲程的发动机的描述。在本文中，我们提出了一个框架来描述通用量子链中的频闪，二冲程发动机。该框架是所谓的SWAP引擎的概括，并且基于碰撞模型，该碰撞模型在纯热和纯工作冲程之间交替。{也已充分考虑了向极限周期过渡的过程。而且，我们表明，一旦达到极限循环，链的内部位置的能量就不再改变，而热流仅与边界位置相关。}结合分析和数值方法，我们证明了这种类型的引擎提供了多种优化输出功率的方式，而不会影响效率。{最后，我们还表明，存在一类完整的模型，其特征是链间相互作用的特定类型，无论储层的运行条件如何，这些模型始终以奥托效率运行。