2007/07/31 by C. Rodó, Gerardo Adesso, A. Sanpera · 1 citation
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1103/physrevlett.100.110505
published as Phys. Rev. Lett. 100, 110505 (2008) · 4 pages, 3 figures, improved presentation, a subfigure and some explicit analytical expressions added
arxiv created 2007/11/20 · arxiv updated 2009/12/01
We quantify correlations (quantum and/or classical) between two continuous variable modes in terms of how many correlated bits can be extracted by measuring the sign of two local quadratures. On Gaussian states, such `bit quadrature correlations' majorize entanglement, reducing to an entanglement monotone for pure states. For non-Gaussian states, such as photonic Bell states, ideal and real de-Gaussified photon-subtracted states, and mixtures of pure Gaussian states, the bit correlations are shown to be a \em monotonic function of the negativity. This yields a feasible, operational way to quantitatively measure non-Gaussian entanglement in current experiments by means of direct homodyne detection, without a full tomographical reconstruction of the Wigner function.