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Thermal and ground-state entanglement in Heisenberg XX qubit rings

Xiaoguang Wang
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Abstract

We study the entanglement of thermal and ground states in Heisernberg $XX$ qubit rings with a magnetic field. A general result is found that for even-number rings pairwise entanglement between nearest-neighbor qubits is independent on both the sign of exchange interaction constants and the sign of magnetic fields. As an example we study the entanglement in the four-qubit model and find that the ground state of this model without magnetic fields is shown to be a four-body maximally entangled state measured by the $N$-tangle.

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Xiaoguang Wang. 2002-05-26. Thermal and ground-state entanglement in Heisenberg XX qubit rings. https://doi.org/10.1103/physreva.66.034302

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