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Yazar: Erol, Volkan × search.filters.applied.f.publicationcategory: Makale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanı ×

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  • Küçük Resim
    Yayın
    Analysis of entanglement measures and LOCC maximized quantum fisher information of general two qubit systems
    (Nature Publishing Group, 2014-06-24) Erol, Volkan; Özaydın, Fatih; Altıntaş, Azmi Ali
    Entanglement has been studied extensively for unveiling the mysteries of non-classical correlations between quantum systems. In the bipartite case, there are well known measures for quantifying entanglement such as concurrence, relative entropy of entanglement (REE) and negativity, which cannot be increased via local operations. It was found that for sets of non-maximally entangled states of two qubits, comparing these entanglement measures may lead to different entanglement orderings of the states. On the other hand, although it is not an entanglement measure and not monotonic under local operations, due to its ability of detecting multipartite entanglement, quantum Fisher information (QFI) has recently received an intense attraction generally with entanglement in the focus. In this work, we revisit the state ordering problem of general two qubit states. Generating a thousand random quantum states and performing an optimization based on local general rotations of each qubit, we calculate the maximal QFI for each state. We analyze the maximized QFI in comparison with concurrence, REE and negativity and obtain new state orderings. We show that there are pairs of states having equal maximized QFI but different values for concurrence, REE and negativity and vice versa.
  • Küçük Resim
    Yayın
    Quantum fisher information of bipartitions of W states
    (Polish Acad Sciences Inst Physics, 2015-04-24) Özaydın, Fatih; Altıntaş, Azmi Ali; Yeşilyurt, Can; Buğu, Sinan; Erol, Volkan
    We study the quantum Fisher information (QFI) of W states and W-like states under decoherence. In particular, we find that on the contrary to amplitude damping and depolarizing decoherence, a W-like state of 3 qubits obtained by discarding 1 qubit of a genuine W state of 4 qubits is more robust than a genuine W state of 3 qubits under amplitude amplifying and phase damping decoherence.