Entanglement in a valence-bond solid state.

  title={Entanglement in a valence-bond solid state.},
  author={Heng Fan and Vladimir E. Korepin and Vwani P. Roychowdhury},
  journal={Physical review letters},
  volume={93 22},
We study entanglement in a valence-bond solid state, which describes the ground state of an Affleck-Kennedy-Lieb-Tasaki quantum spin chain, consisting of bulk spin-1's and two spin-1/2's at the ends. We characterize entanglement between various subsystems of the ground state by mostly calculating the entropy of one of the subsystems; when appropriate, we evaluate concurrences as well. We show that the reduced density matrix of a continuous block of bulk spins is independent of the size of the… 
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