The reduced state of a small system strongly coupled to a charger in thermal equilibrium may be athermal and used as a small battery once disconnected. By harnessing the battery-charger correlations, the battery’s extractable energy can increase above the ergotropy. We introduce a protocol that uses a quantum system as a memory that measures the charger and leaves the battery intact in its charged state. Using the information gained from the measurement, the daemonic ergotropy of the battery is extracted. Then the battery is reconnected to the charger, thermalizing and charging it. However, the memory should return to its initial standard state to close the thermodynamic cycle. Thus, on the one hand, the work cost of the cycle is the sum of the disconnecting and reconnecting battery-charger work plus the measurement and erasure work. On the other hand, the extracted energy is the daemonic ergotropy of the battery plus the ergotropy of the memory. The ratio of these quantities defines the efficiency of the cycle. The protocol is exemplified by a modified transverse spin 1/2 Ising chain, one spin functioning as the battery and the others as the charger. The memory is another auxiliary spin 1/2. We found pairs of measurement schemes from which we extract the same daemonic ergotropy from the battery, they dissipate the same amount of energy, and one leaves the memory in an active state, the other in a passive state. We study the memory’s ergotropy and the daemonic ergotropy of the battery. We find that with measurements, the efficiency can surpass that of the unmeasured protocol, given conditions on temperature, coupling, and choice of the measurement operators.

中文翻译：

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通过热化充电的恶魔量子电池


与处于热平衡状态的充电器紧密耦合的小型系统的还原状态可能是无热的，一旦断开连接，就会用作小型电池。通过利用电池充电器的相关性，电池的可提取能量可以增加到高于 ergotropy。我们介绍了一种协议，该协议使用量子系统作为存储器来测量充电器并使电池在充电状态下保持完整。使用从测量中获得的信息，提取电池的恶魔 Ergotropy。然后将电池重新连接到充电器，对其进行热化和充电。但是，存储器应返回到其初始标准状态以关闭热力学循环。因此，一方面，该周期的工作量是断开和重新连接电池充电器的工作加上测量和擦除工作的总和。另一方面，提取的能量是电池的恶魔般的 ergotropy 加上内存的 ergotropy。这些量的比率决定了循环的效率。该协议以改进的横向自旋 1/2 Ising 链为例，一个自旋用作电池，其他自旋用作充电器。内存是另一个辅助自旋 1/2。我们发现了成对的测量方案，我们从中提取相同的恶魔般的 ergotropy，它们消耗相同数量的能量，一个使内存处于主动状态，另一个处于被动状态。我们研究记忆的 ergotropy 和电池的 daemonic ergotropy。我们发现，在给定温度、耦合和测量操作员选择条件的情况下，通过测量，效率可以超过未测量的协议。