Characterizing the relations among the three bipartite reduced density operators$ \rho _{AB} $,$ \rho _{AC} $and$ \rho _{BC} $of a tripartite mixed state$ \rho _{ABC} $has been an open problem in quantum information. One of such relations has been reduced by [Cadney et al, LAA. 452, 153, 2014] to a conjectured inequality in terms of matrix rank, namely$ r(\rho _{AB}) \cdot r( \rho _{AC})\ge r( \rho _{BC}) $for any$ \rho _{ABC}$. It is denoted as open problem 41 in the website “Open quantum problems-IQOQI Vienna”. We prove the inequality, and thus establish a complete picture of the four-party linear inequalities in terms of the 0-entropy. Our proof is based on the construction of a novel canonical form of bipartite matrices under local equivalence. We extend our result to inequalities in multipartite systems, as well as the condition when the inequality is saturated.Characterizing the relations among the three bipartite reduced density operators$ \rho _{AB}$,$ \rho _{AC}$and$ \rho _{BC}$of a tripartite mixed state$ \rho _{ABC}$has been an open problem in quantum information. One of such relations has been reduced by [Cadney et al, LAA. 452, 153, 2014] to a conjectured inequality in terms of matrix rank, namely$r(\rho _{AB}) \cdot r( \rho _{AC})\ge r( \rho _{BC})$for any$ \rho _{ABC}$. It is denoted as open problem 41 in the website “Open quantum problems-IQOQI Vienna”. We prove the inequality, and thus establish a complete picture of the four-party linear inequalities in terms of the 0-entropy. Our proof is based on the construction of a novel canonical form of bipartite matrices under local equivalence. We extend our result to inequalities in multipartite systems, as well as the condition when the inequality is saturated.

arXiv:2105.07679IEEE Transactions on Information TheoryDec 9, 20227 citations

Topological classification of multipartite entangled states by the hyperdeterminant

Akimasa Miyake

We find that the hyperdeterminant $Det A$ , related to an entanglement measure (the concurrence, 3-tangle for the 2,3-qubit respectively), is derived from a duality between the entangled states and separable states. In terms of $Det A$ and its singularities, the single copy of multipartite pure entangled states is classified into an onion structure of every closed subset, similarly to the local rank in the bipartite case. This reveals that many inequivalent multipartite entangled states are partially ordered such that entanglement measures like $Det A$ as well as local ranks are needed to distinguish them. In particular, the nonzero $Det A$ distinguishes generic entangled states of the maximal dimension (the outermost class of the onion structure). It suggests that the majority of multipartite entangled states never locally converts to the maximally entangled states in Bell's inequalities even probabilistically in general (e.g., in the $n \\geq 4$ -qubit), contrary to the widely known bipartite or 3-qubit cases. The classification is also useful for that of mixed states.We find that the hyperdeterminant $Det A$, related to an entanglement measure (the concurrence, 3-tangle for the 2,3-qubit respectively), is derived from a duality between the entangled states and separable states. In terms of $Det A$ and its singularities, the single copy of multipartite pure entangled states is classified into an onion structure of every closed subset, similarly to the local rank in the bipartite case. This reveals that many inequivalent multipartite entangled states are partially ordered such that entanglement measures like $Det A$ as well as local ranks are needed to distinguish them. In particular, the nonzero $Det A$ distinguishes generic entangled states of the maximal dimension (the outermost class of the onion structure). It suggests that the majority of multipartite entangled states never locally converts to the maximally entangled states in Bell's inequalities even probabilistically in general (e.g., in the $n \\geq 4$-qubit), contrary to the widely known bipartite or 3-qubit cases. The classification is also useful for that of mixed states.

Jun 18, 20021 citation

Stabilizer entropy cones as self-dual slices of linear rank cones: a five-party gap and dependence on the local dimension

Xidan Song, Ruifeng Cao

Entanglement entropies of multipartite pure states satisfy linear inequalities; for stabilizer states, the backbone of quantum error correction, the achievable entropy vectors generate a convex cone. We show that, after a linear lift, the closure of this cone is exactly the self-dual slice of a classical object on one more element than there are parties: the closed cone generated by the rank functions of arrangements of subspaces over $\mathrm{GF}(d)$ for a prime local dimension $d$ , and of subgroups of abelian groups of exponent dividing $d$ in general. This correspondence brings two features of rank inequalities into play. First, the purifier acts as an extra variable: already for five parties the stabilizer cone is strictly smaller than the quantum linear rank cone, with which earlier evidence suggested it might coincide; an explicit six-variable inequality witnesses the gap. Second, the characteristic of the field enters, so the cone depends on the local dimension. It does not for up to four parties. With enough parties, the cone of $\mathbb{Z}_d$ qudits is contained in that of $\mathbb{Z}_{d'}$ qudits if and only if $d$ divides $d'$ , and already for six parties the logical zero state of Steane's code lies outside the stabilizer cone of every odd local dimension. For this last result we show that the seven-variable characteristic-dependent inequalities we checked all follow from Shannon inequalities on the self-dual slice, and instead transfer one of them through a family of subgroups derived from the Fano plane.Entanglement entropies of multipartite pure states satisfy linear inequalities; for stabilizer states, the backbone of quantum error correction, the achievable entropy vectors generate a convex cone. We show that, after a linear lift, the closure of this cone is exactly the self-dual slice of a classical object on one more element than there are parties: the closed cone generated by the rank functions of arrangements of subspaces over $\mathrm{GF}(d)$ for a prime local dimension $d$, and of subgroups of abelian groups of exponent dividing $d$ in general. This correspondence brings two features of rank inequalities into play. First, the purifier acts as an extra variable: already for five parties the stabilizer cone is strictly smaller than the quantum linear rank cone, with which earlier evidence suggested it might coincide; an explicit six-variable inequality witnesses the gap. Second, the characteristic of the field enters, so the cone depends on the local dimension. It does not for up to four parties. With enough parties, the cone of $\mathbb{Z}_d$ qudits is contained in that of $\mathbb{Z}_{d'}$ qudits if and only if $d$ divides $d'$, and already for six parties the logical zero state of Steane's code lies outside the stabilizer cone of every odd local dimension. For this last result we show that the seven-variable characteristic-dependent inequalities we checked all follow from Shannon inequalities on the self-dual slice, and instead transfer one of them through a family of subgroups derived from the Fano plane.

cs.ITCross-listedarXiv:2610.18905Oct 13, 20260 citations

Inequalities for the Schmidt number of bipartite states

Daniel Cariello

arXiv:1902.11069Letters in Mathematical PhysicsNov 25, 201911 citations

Generalized Hardy-type tests for hierarchy of multipartite non-locality*

Fei Yang, Yuan Yu, Wen-Lu Lin +3 more

We propose a family of Hardy-type tests for an arbitrary n-partite system, which can detect different degrees of non-locality ranging from standard to genuine multipartite non-locality. For any non-signaling m-local hidden variable model, the corresponding tests fail, whereas a pass of this type of test indicates that this state is m non-local. We show that any entangled generalized GHZ state exhibits Hardy’s non-locality for each rank of multipartite non-locality. Furthermore, for the detection of m non-localities, a family of Bell-type inequalities based on our test is constructed. Numerical results show that it is more efficient than the inequalities proposed in [Phys. Rev. A 94 022110 (2016)].We propose a family of Hardy-type tests for an arbitrary n-partite system, which can detect different degrees of non-locality ranging from standard to genuine multipartite non-locality. For any non-signaling m-local hidden variable model, the corresponding tests fail, whereas a pass of this type of test indicates that this state is m non-local. We show that any entangled generalized GHZ state exhibits Hardy’s non-locality for each rank of multipartite non-locality. Furthermore, for the detection of m non-localities, a family of Bell-type inequalities based on our test is constructed. Numerical results show that it is more efficient than the inequalities proposed in [Phys. Rev. A 94 022110 (2016)].

Chinese Physics BNov 6, 20190 citations

Characterizing the relations among the three bipartite reduced density operators$ \rho _{AB}

,

\rho _{AC}

and

\rho _{BC}

of a tripartite mixed state

\rho _{ABC}

has been an open problem in quantum information. One of such relations has been reduced by [Cadney et al, LAA. 452, 153, 2014] to a conjectured inequality in terms of matrix rank, namely

r(\rho _{AB}) \cdot r( \rho _{AC})\ge r( \rho _{BC})

for any

\rho _{ABC}$. It is denoted as open problem 41 in the website “Open quantum problems-IQOQI Vienna”. We prove the inequality, and thus establish a complete picture of the four-party linear inequalities in terms of the 0-entropy. Our proof is based on the construction of a novel canonical form of bipartite matrices under local equivalence. We extend our result to inequalities in multipartite systems, as well as the condition when the inequality is saturated.

We find that the hyperdeterminant

Det A

, related to an entanglement measure (the concurrence, 3-tangle for the 2,3-qubit respectively), is derived from a duality between the entangled states and separable states. In terms of

Det A

and its singularities, the single copy of multipartite pure entangled states is classified into an onion structure of every closed subset, similarly to the local rank in the bipartite case. This reveals that many inequivalent multipartite entangled states are partially ordered such that entanglement measures like

Det A

as well as local ranks are needed to distinguish them. In particular, the nonzero

Det A

distinguishes generic entangled states of the maximal dimension (the outermost class of the onion structure). It suggests that the majority of multipartite entangled states never locally converts to the maximally entangled states in Bell's inequalities even probabilistically in general (e.g., in the

n \\geq 4

-qubit), contrary to the widely known bipartite or 3-qubit cases. The classification is also useful for that of mixed states.

\mathrm{GF}(d)

for a prime local dimension

d

, and of subgroups of abelian groups of exponent dividing

d

in general. This correspondence brings two features of rank inequalities into play. First, the purifier acts as an extra variable: already for five parties the stabilizer cone is strictly smaller than the quantum linear rank cone, with which earlier evidence suggested it might coincide; an explicit six-variable inequality witnesses the gap. Second, the characteristic of the field enters, so the cone depends on the local dimension. It does not for up to four parties. With enough parties, the cone of

\mathbb{Z}_d

qudits is contained in that of

\mathbb{Z}_{d'}

qudits if and only if

d

divides

d'

, and already for six parties the logical zero state of Steane's code lies outside the stabilizer cone of every odd local dimension. For this last result we show that the seven-variable characteristic-dependent inequalities we checked all follow from Shannon inequalities on the self-dual slice, and instead transfer one of them through a family of subgroups derived from the Fano plane.