We propose a quantum heat engine based on the ultrafast dynamical control of the magnetic properties of a nanoscale working body. The working principle relies on nonlinear phononics, an example for dynamical materials design. We describe the general recipe for identifying candidate materials, and also propose ${\mathrm{Cr}}_2{\mathrm{O}}_3$ as a promising working body for a quantum Otto cycle. Using a spin Hamiltonian as a model for ${\mathrm{Cr}}_2{\mathrm{O}}_3$, we investigate the performance in terms of efficiency, output power, and quantum friction. To assess the assumptions underlying our effective spin Hamiltonian, we also consider a working substance composed of several unit cells. We show that even without an implementation of transitionless driving, the quantum friction is very low compared to the total produced work and the energy cost of counterdiabatic driving is negligible. This is an advantage of the working substance, as experimentally hard-to-implement shortcuts to adiabaticity are not needed. Moreover, we discuss some remarkable thermodynamic features due to the quantumness of the proposed system such as a nonmonotonic dependence of the efficiency on the temperature of the hot bath. Finally, we explore the dependence of the performance on the system parameters for a generic model of this type of quantum heat engine and identify properties of the energy spectrum required for a well-performing quantum heat engine.

中文翻译：

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基于动态材料设计的量子热机

我们提出了一种基于超快动力学控制纳米级工作体磁性的量子热机。工作原理依赖于非线性声子，这是动态材料设计的一个例子。我们描述了识别候选材料的一般方法，并提出了${铬}_2{\mathrm{Ø}}_3$作为量子奥托循环的有希望的工作机构。使用自旋哈密顿量作为模型${铬}_2{\mathrm{Ø}}_3$，我们从效率，输出功率和量子摩擦方面研究了性能。为了评估有效自旋哈密顿量基础的假设，我们还考虑了由几种晶胞组成的工作物质。我们表明，即使不实施无级变速驱动，与总生产功相比，量子摩擦也非常低，并且反绝热驱动的能源成本可忽略不计。这是工作物质的优点，因为不需要实验上难以实现的绝热捷径。此外，由于所提出系统的量子性，我们讨论了一些非凡的热力学特征，例如效率对热水浴温度的非单调依赖性。最后，