论文标题
出现古典行为的阈值大小
Threshold size for the emergence of a classical-like behaviour
论文作者
论文摘要
在这项工作中，我们设计了一个过程，以估算系统的最小尺寸，超过该系统适合经典描述，即基于经典相位空间中代表点的描述。这是通过将量子状态与代表点通过广义相干状态（GCS）联系起来的，并设计了用于GCS歧视的POVM来获得的。定义了这种歧视的条件，以便POVM结果传达了足够的信息，以满足我们对我们任意选择的两个参数$ε$和实验设备设定的$δ$的信息，分别由两个参数$ε$计数。该过程暗示了系统的“大小”含义的定义，这是基于基本成分的数量$ n $，这些成分提供了全局代数，从而导致了出现的类似古典的古典描述的相位空间。因此，GCS歧视的上述条件可以变成$ n> n _ {\ rm t}（ε，δ）$，其中$ n _ {\ rm t}（\ rm t}（ε，δ）$是标题中提到的阈值。考虑了磁系统的特定情况，并详细介绍了Gedanken实验的详细信息。还给出了伪旋转和玻色子系统的结果。
In this work we design a procedure to estimate the minimum size beyond which a system is amenable to a classical-like description, i.e. a description based on representative points in classical phase-spaces. This is obtained by relating quantum states to representative points via Generalized Coherent States (GCS), and designing a POVM for GCS discrimination. Conditions upon this discrimination are defined, such that the POVM results convey enough information to meet our needs for reliability and precision, as gauged by two parameters $ε$, of our arbitrary choice, and $δ$, set by the experimental apparatus, respectively. The procedure implies a definition of what is meant by "size" of the system, in terms of the number $N$ of elementary constituents that provide the global algebra leading to the phase-space for the emergent classical-like description. The above conditions on GCS discrimination can be thus turned into $N>N_{\rm t}(ε,δ)$, where $N_{\rm t}(ε,δ)$ is the threshold size mentioned in the title. The specific case of a magnetic system is considered, with details of a gedanken experiment presented and thoroughly commented. Results for pseudo-spin and bosonic systems are also given.
