Entanglement witnesses in spin models

  title={Entanglement witnesses in spin models},
  author={G{\'e}za T{\'o}th},
  journal={Physical Review A},
  • G. Tóth
  • Published 9 June 2004
  • Physics
  • Physical Review A
We construct entanglement witnesses using fundamental quantum operators of spin models which contain two-particle interactions and have a certain symmetry. By choosing the Hamiltonian as such an operator, our method can be used for detecting entanglement by energy measurement. We apply this method to the Heisenberg model in a cubic lattice with a magnetic field, the XY model, and other familiar spin systems. Our method provides a temperature bound for separable states for systems in thermal… 

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  • O. Gühne
  • Mathematics
    Physical review letters
  • 2004
A family of necessary separability criteria for finite-dimensional systems is derived based on inequalities for variances of observables based on covariance matrices and it is shown that every pure bipartite entangled state violates some of these inequalities.