Although entanglement is considered as an essential resource for quantum information processing, whether entanglement helps for energy conversion or output in the quantum regime is still lack of experimental witness. Here, we report on an energy-conversion device operating as a quantum engine with the working medium acted by two entangled ions confined in a harmonic potential. The two ions are entangled by virtually coupling to one of the vibrational modes shared by the two ions, and the quantum engine couples to a quantum load, which is another shared vibrational mode. We explore the energy conversion efficiency of the quantum engine and investigate the useful energy (i.e., the maximum extractable work) stored in the quantum load by tuning the two ions in different degrees of entanglement as well as detecting the change of the phonons in the load. Our observation provides, for the first time, quantitative evidence that entanglement fuels the useful energy produced by the quantum engine, but not helpful for the energy conversion efficiency. We consider that our results may be useful to the study of quantum batteries for which one of the most indexes is the maximum extractable energy.

中文翻译：

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以二原子纠缠为工作介质的量子引擎能量转换装置

尽管纠缠被认为是量子信息处理的重要资源，但纠缠是否有助于量子领域的能量转换或输出仍然缺乏实验证据。在这里，我们报告了一种作为量子引擎运行的能量转换装置，其工作介质由限制在谐波势中的两个纠缠离子作用。两个离子通过虚拟耦合到两个离子共享的振动模式之一而纠缠，并且量子引擎耦合到量子负载，这是另一种共享的振动模式。我们通过调节不同纠缠度的两个离子以及检测负载中声子的变化来探索量子引擎的能量转换效率，并研究存储在量子负载中的有用能量（即最大可提取功） 。我们的观察首次提供了定量证据，表明纠缠为量子引擎产生的有用能量提供了燃料，但对能量转换效率没有帮助。我们认为我们的结果可能对量子电池的研究有用，量子电池的最重要指标之一是最大可提取能量。