Conditional work statistics of quantum measurements
Conditional work statistics of quantum measurements
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DOI：
10.22331/q-2019-08-19-175
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发表时间：
2019-08-08
期刊：
影响因子：
6.4
通讯作者：
Romito, Alessandro
中科院分区：
文献类型：
--
作者：
Mohammady, M. Hamed;Romito, Alessandro
在本文中，我们引入了一个定义的条件能量变化由于一般的量子测量，作为条件能量的变化之前，和之后，测量过程中评估。通过对这些条件能量施加最小的物理要求，我们表明，测量后的条件能量的最一般的表达式是简单的哈密顿量的预期值给定的测量后的状态。相反，在测量过程之前的条件能量示出由弱值的哈密顿量的真实的分量给出。我们的定义概括了众所周知的内部能量变化分布的概念，如随机热力学。通过确定系统和测量设备的条件能量变化，我们得到了量子测量的完整条件功统计，并表明，如果测量过程保持总能量，则对于所有测量结果，条件功统计都为零。此外，通过将测量过程中的循环热机，我们量化的不可恢复的工作，由于测量。这被证明总是非负的，从而满足第二定律，并将是独立的两类投影测量的设备的细节。
In this paper we introduce a definition for conditional energy changes due to general quantum measurements, as the change in the conditional energy evaluated before, and after, the measurement process. By imposing minimal physical requirements on these conditional energies, we show that the most general expression for the conditional energy after the measurement is simply the expected value of the Hamiltonian given the post-measurement state. Conversely, the conditional energy before the measurement process is shown to be given by the real component of the weak value of the Hamiltonian. Our definition generalises well-known notions of distributions of internal energy change, such as that given by stochastic thermodynamics. By determining the conditional energy change of both system and measurement apparatus, we obtain the full conditional work statistics of quantum measurements, and show that this vanishes for all measurement outcomes if the measurement process conserves the total energy. Additionally, by incorporating the measurement process within a cyclic heat engine, we quantify the non-recoverable work due to measurements. This is shown to always be non-negative, thus satisfying the second law, and will be independent of the apparatus specifics for two classes of projective measurements.