On the notion of composite system

On separable states for composite systems of distinguishable fermions

We study characterization of separable (classically correlated) states for composite systems of distinguishable fermions that are represented as CAR algebras.

On the notion of quantum copulas

Working with multivariate probability distributions Sklar introduced the notion of copula in 1959, which turned out to be a key concept to understand the structure of distributions of composite systems. Roughly speaking Sklar proved that a joint distribution can be represented with its marginals and a copula. The main goal of this paper is to present a quantum analogue of the notion of copula. Our main theorem states that for any state of a composite quantum system there exists a unique copula such that they are connected to each other by invertible matrices, moreover, they are both separable …

熵界作为酉算子的不确定性度量

Entropic Bounds as Uncertainty Measure of Unitary Operators

本文在猜测博弈框架下重新定义酉算子对的不确定性，推导其熵不确定性关系，并揭示算子可区分性、相容性及最大不相容性与相互无偏基之间的联系。

Ergodiscord：关联量子性的一种操作性且独特的概念

Ergodiscord: An Operational and Distinct Notion of Quantumness of Correlations

本文提出操作性非经典性量化器 ergodiscord，用于刻画多体量子态中的关联量子性，并揭示非局域能量锁定及其超可加性现象，为量子储能装置设计提供新思路。

Deformed entropy and information relations for composite and noncomposite systems

The notion of conditional entropy is extended to noncomposite systems. The q-deformed entropic inequalities, which usually are associated with correlations of the subsystem degrees of freedom in bipartite systems, are found for the noncomposite systems. New entropic inequalities for quantum tomograms of qudit states including the single qudit states are obtained. The Araki{Lieb inequality is found for systems without subsystems.

Entanglement in indistinguishable particle systems

For systems consisting of distinguishable particles, there exists an agreed upon notion of entanglement which is fundamentally based on the possibility of addressing individually each one of the constituent parties. Instead, the indistinguishability of identical particles hinders their individual addressability and has prompted diverse, sometimes discordant definitions of entanglement. In the present review, we provide a comparative analysis of the relevant existing approaches, which is based on the characterization of bipartite entanglement in terms of the behaviour of correlation functions. …