Abstract: We study quantum correlations and complexity of simulation, characterized by quantum mutual information and entanglement entropy in operator space respectively, for thermal states in critical, non-critical and quantum chaotic spin chains. A simple general relation between the two quantities is proposed. We show that in all cases mutual information and entanglement entropy saturate with the system size, whereas as a function of the inverse temperature, we find logarithmic divergences for critical cases and uniform bounds in non-critical cases. A...
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Topics: 
Quantum mechanics
Statistical physics