标题： 双部分场景下测量的粗粒化与量子-经典过渡 显示英文标题

标题： Coarse-graining of measurement and quantum-to-classical transition in the bipartite scenario

摘要： 测量粗粒化与经典性涌现之间的联系已被研究了一段时间，尽管尚未被很好地理解。最近在（PRL$\textbf{112}$, 010402, (2014)）中指出，测量粗粒化可以使一个在锐利测量下会违反贝尔型不等式的态不违反这些不等式。我们在此研究了粗粒化测量对双部分猫态的影响。我们证明，虽然确实粗粒化会导致贝尔型不等式的非违反，但这在态的层面上并未反映出来。在这种测量下，测量后态可以是非经典的（在量子光学意义上），并且在某些情况下，粗粒化可能导致相对于粗粒化参数的非经典性的增加。虽然没有普遍的方法来量化非经典性，但我们使用量子光学中已知的概念，如维格纳函数的负性和Glauber-Sudarshan P分布的奇异性质来进行量化。 显示英文摘要

摘要： The connection between coarse-graining of measurement and emergence of classicality has been investigated for some time, if not well understood. Recently in (PRL $\textbf{112}$, 010402, (2014)) it was pointed out that coarse-graining measurements can lead to non-violation of Bell-type inequalities by a state which would violate it under sharp measurements. We study here the effects of coarse-grained measurements on bipartite cat states. We show that while it is true that coarse-graining does indeed lead to non-violation of a Bell-type inequality, this is not reflected at the state level. Under such measurements the post-measurement states can be non-classical (in the quantum optical sense) and in certain cases coarse-graning can lead to an increase in this non-classicality with respect to the coarse-graining parameter. While there is no universal way to quantify non-classicality, we do so using well understood notions in quantum optics such as the negativity of the Wigner function and the singular nature of the Gluaber-Sudharshan P distribution.