论文标题
受热力学第三定律约束的量子测量
Quantum measurements constrained by the third law of thermodynamics
论文作者
论文摘要
在量子制度中，热力学的第三定律意味着纯状态的不符合性。如最近所示，这种不可识别性意味着测量系统与测量设备之间的统一相互作用永远无法实施理想的投影测量。在本文中，我们介绍了第三定律的操作表述，以实现最一般的物理转变类别，违反纯粹的侵犯是必要的，足以准备纯状态。随后，我们研究了这样的法律如何限制一般可观察物的测量，或者是肯定的操作员有价值的措施。我们确定了理想的投影测量值同时享受的几种理想的测量属性 - 因此，在这种情况下，所有测量值都被第三定律所排除 - 并确定第三定律是否允许这些属性获得对一般可观察物的一般测量以及在什么条件下获得的一般测量。结果表明，尽管第三定律排除了所有可观察到的这些属性中的一些属性，但其他法律可能会被足够“ unsharp”的观察物所享受。
In the quantum regime, the third law of thermodynamics implies the unattainability of pure states. As shown recently, such unattainability implies that a unitary interaction between the measured system and a measuring apparatus can never implement an ideal projective measurement. In this paper, we introduce an operational formulation of the third law for the most general class of physical transformations, the violation of which is both necessary and sufficient for the preparation of pure states. Subsequently, we investigate how such a law constrains measurements of general observables, or positive operator valued measures. We identify several desirable properties of measurements which are simultaneously enjoyed by ideal projective measurements -- and are hence all ruled out by the third law in such a case -- and determine if the third law allows for these properties to obtain for general measurements of general observables and, if so, under what conditions. It is shown that while the third law rules out some of these properties for all observables, others may be enjoyed by observables that are sufficiently "unsharp".
