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Quantifying entanglement of a two-qubit system via measurable and invariant moments of its partially transposed density matrix.
- Source :
-
Physical Review A: Atomic, Molecular & Optical Physics . Feb2015, Vol. 91 Issue 2-A, p1-10. 10p. - Publication Year :
- 2015
-
Abstract
- We describe a direct method to determine the negativity of an arbitrary two-qubit state in experiments. The method is derived by analyzing the relation between the purity, negativity, and a universal entanglement witness for two-qubit entanglement. We show how the negativity of a two-qubit state can be calculated from just three experimentally accessible moments of the partially transposed density matrix of a two-photon state. Moreover, we show that the negativity can be given as a function of only six invariants, which are linear combinations of nine invariants from the complete set of 21 fundamental and independent two-qubit invariants. We analyze the relation between these moments and the concurrence for some classes of two-qubit states (including the X states, as well as pure states affected by the amplitude-damping and phase-damping channels). We also discuss the possibility of using the universal entanglement witness as an entanglement measure for various classes of two-qubit states. Moreover, we analyze how noise affects the estimation of entanglement via this witness. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 10502947
- Volume :
- 91
- Issue :
- 2-A
- Database :
- Academic Search Index
- Journal :
- Physical Review A: Atomic, Molecular & Optical Physics
- Publication Type :
- Periodical
- Accession number :
- 101696135
- Full Text :
- https://doi.org/10.1103/PhysRevA.91.022323