Entanglement in a molecular three-qubit system

Abstract

We study the entanglement properties of a molecular three-qubit system described by the Heisenberg spin Hamiltonian with anisotropic exchange interactions and including an external magnetic field. The system exhibits first order quantum phase transitions by tuning two parameters, $x$ and $y$, of the Hamiltonian to specific values. The three-qubit chain is open ended so that there are two types of pairwise entanglement : nearest-neighbour (n.n.) and next-nearest-neighbour (n.n.n.). We calculate the ground and thermal state concurrences, quantifying pairwise entanglement, as a function of the parameters $x$, $y$ and the temperature $T$. The entanglement threshold and gap temperatures are also determined as a function of the anisotropy parameter $x$. The results obtained are of relevance in understanding the entanglement features of the recently engineered molecular $C{r}_{7}Ni$-$C{u}^{2+}$-$C{r}_{7}Ni$ complex which serves as a three-qubit system at sufficiently low temperatures.

9 pages, 13 figures, revtex4

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• Entanglement in a first order quantum phase transition
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• Thermal entanglement properties of small spin clusters
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Cited by in corpus (5)

• Quantum Discord in the Ground and Thermal States of Spin Clusters
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• Genuine Tripartite Entanglement in a Spin-Star Network at Thermal Equilibrium
• Competition of Direct and Indirect Sources of Thermal Entanglement in a spin star network
• Two-spin and multi-spin quantum entanglement in V12 polyoxovanadate molecular nanomagnet