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Entangled Rings

Kevin M. O'Connor·William K. Wootters
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Abstract

Consider a ring of N qubits in a translationally invariant quantum state. We ask to what extent each pair of nearest neighbors can be entangled. Under certain assumptions about the form of the state, we find a formula for the maximum possible nearest-neighbor entanglement. We then compare this maximum with the entanglement achieved by the ground state of an antiferromagnetic ring consisting of an even number of spin-1/2 particles. We find that, though the antiferromagnetic ground state does not maximize the nearest-neighbor entanglement relative to all other states, it does so relative to other states having zero z-component of spin.

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Kevin M. O'Connor, William K. Wootters. 2000-09-14. Entangled Rings. https://doi.org/10.1103/physreva.63.052302

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