Entanglement Negativity in the Kondo Model at Finite Temperature

Entanglement is useful to characterize many-body ground states. It will be also interesting to study entanglement in many-body thermal states. We compute the entanglement negativity between the impurity and the bath for the single-impurity Kondo model and for the single-impurity Anderson model at finite temperature, using the numerical renormalization group method. For the Kondo model, the negativity detects the features of the low-energy Fermi-Liquid quasiparticles, such as universal power-law thermal suppression [1] of the entanglement. For the Anderson model, the negativity shows the temperature dependence which reflects the renormalization group flow of the model.
[1] S.-S. B. Lee, J. Park, and H.-S. Sim, Macroscopic Quantum Entanglement of a Kondo Cloud at Finite Temperature, Phys. Rev. Lett. 114, 057203 (2015)