Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Entanglement in a molecular three-qubit system   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 $Cr_{7}Ni$-$Cu^{2+}$-$Cr_{7}Ni$
complex which serves as a three-qubit system at sufficiently low temperatures.

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The categories of this paper are: physics
26
The categories of this paper are: bayes-an
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
8
The categories of this paper are: hep-ex
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The categories of this paper are: math-ph
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
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The categories of this paper are: hep-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: eess