Entanglement and nonlocality in diagonal symmetric states of N qubits

Ruben Quesada, Swapan Rana, Anna Sanpera

Research output: Contribution to journalArticleResearchpeer-review

8 Citations (Scopus)


© 2017 American Physical Society. We analyze entanglement and nonlocal properties of the convex set of symmetric N-qubit states which are diagonal in the Dicke basis. First, we demonstrate that within this set, semidefinite positivity of partial transposition (PPT) is necessary and sufficient for separability - which has also been reported recently by Yu [Phys. Rev. A 94, 060101(R) (2016)2469-992610.1103/PhysRevA.94.060101]. Furthermore, we show which states among the entangled diagonal symmetric are nonlocal under two-body Bell inequalities. The diagonal symmetric convex set contains a simple and extended family of states that violate the weak Peres conjecture, being PPT with respect to one partition but violating a Bell inequality in such partition. Our method opens directions to address entanglement and nonlocality on higher dimensional symmetric states, where presently very few results are available.
Original languageEnglish
Article number042128
JournalPhysical Review A
Issue number4
Publication statusPublished - 24 Apr 2017


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