arXiv:quant-ph/0608121 · Physical Review A

Entanglement in general two-mode continuous-variable states: Local approach and mapping to a two-qubit system

Ho-Chih Lin, Andrew J. Fisher

Published Oct 15, 2007• 2 citations

Abstract

We present an approach to the analysis of entanglement in smooth bipartite continuous-variable states. One or both parties perform projective filterings via preliminary measurements to determine whether the system is located in some region of space; we study the entanglement remaining after filtering. For small regions, a two-mode system can be approximated by a pair of qubits and its entanglement fully characterized, even for mixed states. Our approach may be extended to any smooth bipartite pure state or two-mode mixed state, leading to natural definitions of concurrence and negativity densities. For Gaussian states both these quantities are constant throughout configuration space.

DOI: 10.1103/physreva.76.042320

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