标题： 工作方面 显示英文标题

标题： Aspects of work

摘要： 各种定义和确定量子系统上所做的功的方法进行了比较。 然而，任何操作性定义的功都必须考虑两个事实，首先，功描述的是一个过程而不是系统的瞬时状态，其次，量子系统对与测量装置的相互作用是敏感的。 我们根据产生的后测量状态以及找到特定功值的概率来比较不同的测量场景。 特别是，我们分析了一种最近提出的功计在高斯指针态情况下的应用，并将其与通过两种投影测量和替代地两种高斯测量获得的结果进行比较。 在有效测量强度较强的情况下，可以恢复投影两次能量测量的功分布。 在相反的极限情况下，平均功值不再依赖于任何测量。 然而，该值的波动却发散。 通过突然变化的磁场中的自旋示例来说明功计的性能。 显示英文摘要

摘要： Various approaches of defining and determining work performed on a quantum system are compared. Any operational definition of work, however, must allow for two facts, first, that work characterizes a process rather than an instantaneous state of a system, and, second, that quantum systems are sensitive to the interactions with a measurement apparatus. We compare different measurement scenarios on the basis of the resulting post-measurement states and the according probabilities for finding a particular work value. In particular, we analyze a recently proposed work-meter for the case of a Gaussian pointer state and compare it with the results obtained by two projective and, alternatively, two Gaussian measurements. In the limit of a strong effective measurement strength the work distribution of projective two energy measurements can be recovered. In the opposite limit the average of work becomes independent of any measurement. Yet the fluctuations about this value diverge. The performance of the work-meter is illustrated by the example of a spin in a suddenly changing magnetic field.