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arXiv · 0705.0957

Entanglement and Criticality in Quantum Impurity Systems

Karyn Le Hur·Philippe Doucet-Beaupre·Walter Hofstetter
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Abstract

We investigate the entanglement between a spin and its environment in impurity systems which exhibit a second-order quantum phase transition. As an application, we employ the spin-boson model, describing a two-level system (spin) coupled to a subohmic bosonic bath with power-law spectral density, ${\cal J}(ω)\propto ω^s$ and $0<s<1$. Combining Wilson's Numerical Renormalization Group method and hyperscaling relations, we demonstrate that the entanglement between the spin and its environment is always enhanced at the quantum phase transition resulting in a visible cusp (maximum) in the entropy of entanglement. We formulate a correspondence between criticality and impurity entanglement entropy, and the relevance of these ideas to Nano-systems is outlined.

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Karyn Le Hur, Philippe Doucet-Beaupre, Walter Hofstetter. 2007-08-30. Entanglement and Criticality in Quantum Impurity Systems. https://doi.org/10.1103/physrevlett.99.126801

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