Tensor of coherences parametrization of multiqubit density operators for entanglement characterization

Journal Article · Thu Jan 01 04:00:00 EST 2004 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.69.012311· OSTI ID:20640591

Altafini, Claudio ^[1]

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1. SISSA-ISAS, International School for Advanced Studies, via Beirut 2-4, 34014 Trieste (Italy)

For multiqubit densities, the tensor of coherences (or Stokes tensor) is a real parametrization obtained by the juxtaposition of the affine Bloch vectors of each qubit. While it maintains the tensorial structure of the underlying space, it highlights the pattern of correlations, both classical and quantum, between the subsystems and, due to the affine parametrization, it contains in its components all reduced densities of all orders. The main purpose of our use of this formalism is to deal with entanglement. For example, the detection of bipartite entanglement is straightforward, as it is the synthesis of densities having positive partial transposes between desired qubits. In addition, finding explicit mixtures for families of separable states becomes a feasible issue for few-qubit symmetric densities (we compute it for Werner states) and, more important, it provides some insight into the possible origin of entanglement for such densities.

• OSTI ID: 20640591
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 1 Vol. 69; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
CORRELATIONS
DENSITY
DETECTION
EIGENFUNCTIONS
EIGENVALUES
ENERGY LEVELS
INFORMATION THEORY
MIXTURES
QUANTUM MECHANICS
SYNTHESIS
VECTORS