We study energetic exchanges and fluctuations in two-stroke quantum thermodynamic engines where the working fluid is represented by two multilevel quantum systems, i.e., qudits, the heat flow is allowed by relaxation with two thermal reservoirs at different temperatures, and the work exchange is operated by a partial-swap unitary interaction. We identify three regimes of operation (heat engine, refrigerator, and thermal accelerator), present the thermodynamic uncertainty relations between the entropy production and the signal-to-noise ratio of work and heat, and derive the full joint probability of the stochastic work and heat. Our results bridge the gap between two-qubit and two-mode bosonic swap engines, and show which properties are maintained (e.g., a nonfluctuating Otto efficiency) and which are lost for increasing dimension (e.g., small violations of the standard thermodynamic uncertainty relations or the possibility of beating the Curzon-Ahlborn efficiency).

中文翻译：

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多级量子热力学交换引擎

我们研究了二冲程量子热力学引擎中的能量交换和涨落，其中工作流体由两个多能级量子系统（即 qudits）表示，通过两个不同温度的热库的弛豫允许热流，并且进行功交换通过部分交换单一交互。我们确定了三种运行机制（热机、制冷机和热加速器），呈现熵产生与功和热的信噪比之间的热力学不确定性关系，并推导出随机功和热。我们的结果弥合了双量子位和双模式玻色子交换引擎之间的差距，并显示了哪些特性得以保持（例如，非波动的奥托效率），哪些特性会随着维度的增加而丢失（例如，