The $k$ -nonseparability is a kind of multipartite quantum correlation which can be used to characterize some aspects of multipartite entanglement. In this paper, we discuss the detection of $k$ -nonseparability of $n$ -partite quantum states from an information perspective and obtain some $k$ -nonseparability criteria in terms of quantum Fisher information. These criteria can identify many $k$ -nonseparable states, and their advantages over an important and well-known $k$ -nonseparability criterion [M. Huber et al., Phys. Rev. A 88, 042328 (2013)] are illustrated by several typical examples.The $k$-nonseparability is a kind of multipartite quantum correlation which can be used to characterize some aspects of multipartite entanglement. In this paper, we discuss the detection of $k$-nonseparability of $n$-partite quantum states from an information perspective and obtain some $k$-nonseparability criteria in terms of quantum Fisher information. These criteria can identify many $k$-nonseparable states, and their advantages over an important and well-known $k$-nonseparability criterion [M. Huber et al., Phys. Rev. A 88, 042328 (2013)] are illustrated by several typical examples.

Physical Review AApr 10, 201534 citations

Separability

Progress in theoretical chemistry and physicsJan 1, 20020 citations

Causal-diamond thermalization induces nonseparability in N-partite quantum systems

Hui-Chen Yang, Shu-Min Wu

We investigate the nonseparability of multipartite bosonic and fermionic $GHZ$ and $W$ states in a causal diamond spacetime using the Abe-Rajagopal (AR) $q$ -conditional entropy. The finite lifetime of the observer gives rise to a causal diamond horizon, which induces an Unruh-like thermal effect and leads to a nontrivial restructuring of nonseparability in $N$ -partite systems. Our main result is that the thermal effect can enhance a net nonseparability of fermionic $W$ states, in sharp contrast to the general expectation that relativistic thermalization leads to a monotonic degradation of bosonic nonseparability. In addition, we find that fermionic nonseparability is generally more robust than its bosonic counterpart under causal diamond restrictions. Among different entangled resources, $GHZ$ states exhibit stronger nonseparability and greater robustness than $W$ states under identical causal conditions. We further show that the nonseparability of $W$ states decreases with increasing particle number $N$ , whereas that of $GHZ$ states remains independent of $N$ in causal diamond spacetime. These results demonstrate that particle statistics, entanglement structure, and observer lifetime jointly determine the persistence of nonseparability in causally restricted spacetimes, providing insights for relativistic quantum information processing.We investigate the nonseparability of multipartite bosonic and fermionic $GHZ$ and $W$ states in a causal diamond spacetime using the Abe-Rajagopal (AR) $q$-conditional entropy. The finite lifetime of the observer gives rise to a causal diamond horizon, which induces an Unruh-like thermal effect and leads to a nontrivial restructuring of nonseparability in $N$-partite systems. Our main result is that the thermal effect can enhance a net nonseparability of fermionic $W$ states, in sharp contrast to the general expectation that relativistic thermalization leads to a monotonic degradation of bosonic nonseparability. In addition, we find that fermionic nonseparability is generally more robust than its bosonic counterpart under causal diamond restrictions. Among different entangled resources, $GHZ$ states exhibit stronger nonseparability and greater robustness than $W$ states under identical causal conditions. We further show that the nonseparability of $W$ states decreases with increasing particle number $N$, whereas that of $GHZ$ states remains independent of $N$ in causal diamond spacetime. These results demonstrate that particle statistics, entanglement structure, and observer lifetime jointly determine the persistence of nonseparability in causally restricted spacetimes, providing insights for relativistic quantum information processing.

gr-qcCross-listedarXiv:2608.07869Aug 11, 20260 citations

Nonseparability, Classical, and Quantum

Wayne C. Myrvold

This article examines the implications of the holonomy interpretation of classical electromagnetism. As has been argued by Richard Healey and Gordon Belot, classical electromagnetism on this interpretation evinces a form of nonseparability, something that otherwise might have been thought of as confined to nonclassical physics. Consideration of the differences between this classical nonseparability and quantum nonseparability shows that the nonseparability exhibited by the classical electromagnetism on the holonomy interpretation is closer to separability than might at first appear. 1 Introduction 2 Interpretations of Classical Electromagnetism 3 Quantum Nonseparability 4 The Holonomy Representation of the Classical Electromagnetic Field 5 Holonomy and Nonseparability: The Classical Electromagnetic Field 6 On Humean Supervenience 7 ConclusionThis article examines the implications of the holonomy interpretation of classical electromagnetism. As has been argued by Richard Healey and Gordon Belot, classical electromagnetism on this interpretation evinces a form of nonseparability, something that otherwise might have been thought of as confined to nonclassical physics. Consideration of the differences between this classical nonseparability and quantum nonseparability shows that the nonseparability exhibited by the classical electromagnetism on the holonomy interpretation is closer to separability than might at first appear. 1 Introduction 2 Interpretations of Classical Electromagnetism 3 Quantum Nonseparability 4 The Holonomy Representation of the Classical Electromagnetic Field 5 Holonomy and Nonseparability: The Classical Electromagnetic Field 6 On Humean Supervenience 7 Conclusion

The British Journal for the Philosophy of ScienceMar 4, 201122 citations

The

k

-nonseparability is a kind of multipartite quantum correlation which can be used to characterize some aspects of multipartite entanglement. In this paper, we discuss the detection of

k

-nonseparability of

n

-partite quantum states from an information perspective and obtain some

k

-nonseparability criteria in terms of quantum Fisher information. These criteria can identify many

k

-nonseparable states, and their advantages over an important and well-known

k

-nonseparability criterion [M. Huber et al., Phys. Rev. A 88, 042328 (2013)] are illustrated by several typical examples.

We investigate the nonseparability of multipartite bosonic and fermionic

GHZ

and

W

states in a causal diamond spacetime using the Abe-Rajagopal (AR)

q

-conditional entropy. The finite lifetime of the observer gives rise to a causal diamond horizon, which induces an Unruh-like thermal effect and leads to a nontrivial restructuring of nonseparability in

N

-partite systems. Our main result is that the thermal effect can enhance a net nonseparability of fermionic

W

states, in sharp contrast to the general expectation that relativistic thermalization leads to a monotonic degradation of bosonic nonseparability. In addition, we find that fermionic nonseparability is generally more robust than its bosonic counterpart under causal diamond restrictions. Among different entangled resources,

GHZ

states exhibit stronger nonseparability and greater robustness than

W

states under identical causal conditions. We further show that the nonseparability of

W

states decreases with increasing particle number

N

, whereas that of

GHZ

states remains independent of

N

in causal diamond spacetime. These results demonstrate that particle statistics, entanglement structure, and observer lifetime jointly determine the persistence of nonseparability in causally restricted spacetimes, providing insights for relativistic quantum information processing.