论文标题
极端量子状态
Extremal quantum states
论文作者
论文摘要
量子系统和经典系统之间的明显差异谓词破坏性量子技术。我们从各种观点仔细阅读量子性，集中于相位公式，因为它们可以超出特定的对称组。 Husimi $ Q $函数的对称性转移属性使其成为我们的基本工具。在后者方面，我们检查了诸如WEHRL熵，反向参与率，累积多极分布和计量能等数量，它们与任何量子状态的内在特性有关。我们使用这些数量来制定极端原则，并以这种方式确定哪种状态是“量子”最多和最少的；详细探讨了每个极端原理的相应特性和潜在实用性。尽管极端可变化的系统的极端极端是重合的，但我们对旋转系统的分析表明，在将极端原理应用于新环境时必须注意。
The striking differences between quantum and classical systems predicate disruptive quantum technologies. We peruse quantumness from a variety of viewpoints, concentrating on phase-space formulations because they can be applied beyond particular symmetry groups. The symmetry-transcending properties of the Husimi $Q$ function make it our basic tool. In terms of the latter, we examine quantities such as the Wehrl entropy, inverse participation ratio, cumulative multipolar distribution, and metrological power, which are linked to intrinsic properties of any quantum state. We use these quantities to formulate extremal principles and determine in this way which states are the most and least "quantum;" the corresponding properties and potential usefulness of each extremal principle are explored in detail. While the extrema largely coincide for continuous-variable systems, our analysis of spin systems shows that care must be taken when applying an extremal principle to new contexts.
