2017/03/06 by Chun Yang, Adrian Feiguin, Adrian E. Feiguin · 33 citations
Computer Science · Physics and Astronomy · #Anderson impurity model #Condensed matter physics #Electron #Excited state #Kondo effect #Magnetic impurity #Physics #Physics of Superconductivity and Magnetism #Quantum #Quantum Information and Cryptography #Quantum and electron transport phenomena #Quantum entanglement #Quantum mechanics #Singlet state #Spins #Wave function #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.95.115106
published in Physical review. B./Physical review. B 95(11) (American Physical Society) · Final version published in PRB
openalex publication_date 2017/03/06 · arxiv created 2017/03/07 · arxiv updated 2017/03/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We disentangle all the individual degrees of freedom in the quantum impurity problem to deconstruct the Kondo singlet, both in real and energy space, by studying the contribution of each individual free electron eigenstate. This is a problem of two spins coupled to a bath, where the bath is formed by the remaining conduction electrons. Being a mixed state, we resort to the ``concurrence'' to quantify entanglement. We identify ``projected natural orbitals'' that allow us to individualize a single-particle electronic wave function that is responsible of more than 90% of the impurity screening. In the weak coupling regime, the impurity is entangled to an electron at the Fermi level, while in the strong coupling regime, the impurity counterintuitively entangles mostly with the high energy electrons and disentangles completely from the low-energy states carving a ``hole'' around the Fermi level. This enables one to use concurrence as a pseudo order parameter to compute the characteristic ``size'' of the Kondo cloud, beyond which electrons are weakly correlated to the impurity and are dominated by the physics of the boundary.