A single driven spin is investigated as the working substance of a six-stroke irreversible quantum Carnot cycle. The role of inner friction associated with the finite-time adiabatic transformations on the cycle efficiency and the harvested work are investigated in detail. The inner friction is found to significantly reduce the work output and the cycle efficiency which can make the engine incapable to produce positive work for the too fast adiabatic transformations. The ideal Carnot efficiency is found to be reached only for the quasistatic transformations. A deviation of the cycle efficiency from the classical Carnot efficiency has been given by an efficiency lag which is directly related to the total entropy production due to the inner friction. The released heat in the relaxation processes of the cycle is associated with the entropy production and the inner friction. The extension of the results for a scale-invariant quantum working substance and the possible experimental implementation of the irreversible quantum Carnot cycle in a liquid-state nuclear magnetic resonance setup are also discussed.

中文翻译：

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具有内摩擦的量子卡诺循环

研究了单驱动自旋作为六冲程不可逆量子卡诺循环的工作物质。详细研究了与有限时间绝热变换有关的内摩擦对循环效率和收获功的作用。发现内摩擦会显着降低功输出和循环效率，这会使发动机无法为过快的绝热转换产生正功。发现仅对于准静态转换才能达到理想的卡诺效率。效率滞后给出了循环效率与经典卡诺效率的偏差，效率滞后与内部摩擦导致的总熵产生直接相关。在循环的松弛过程中释放的热量与熵产生和内摩擦有关。还讨论了尺度不变量子工作物质的结果的扩展以及不可逆量子卡诺循环在液态核磁共振装置中的可能实验实现。