Benedikt Lechtenberg

Spatial and temporal propagation of Kondo correlations

We address the fundamental question how the spatial Kondo correlations are building up in time assuming an initially decoupled impurity spin

Realistic quantum critical point in one-dimensional two-impurity models

\vec{S}_{\rm imp}

A chemically driven quantum phase transition in a two-molecule Kondo system

. We investigate the time-dependent spin-correlation function

Transfering spin into an extended π orbital of a large molecule

\chi(\vec{r},t) = \langle \vec{S}_\mathrm{imp} \vec{s}(\vec{r}) \rangle (t)

Spectral properties of a molecular wire in the Kondo regime

in the Kondo model with antiferromagnetic and ferromagnetic couplings where

Interplay between Charge, Magnetic and Superconducting Order in a Kondo Lattice with an Attractive Hubbard Interaction.

\vec{s}(\vec{r})

Effective low-energy description of the two-impurity Anderson model: RKKY interaction and quantum criticality

denotes the spin density of the conduction electrons after switching on the Kondo coupling at time

Equilibrium and real-time properties of the spin correlation function in the two-impurity Kondo model

t=0

Parity Symmetry Protected Spin Entanglement in the Two Impurity Model

. We present data obtained from a time-dependent numerical renormalisation group (TD-NRG) calculation. We gauge the accuracy of our two-band NRG by the spatial sum-rules of the equilibrium correlation functions and the reproduction of the analytically exactly known spin-correlation function of the decoupled Fermi sea. We find a remarkable building up of Kondo-correlation outside of the light cone defined by the Fermi velocity of the host metal. By employing a perturbative approach exact in second-order of the Kondo coupling, we connect these surprising correlations to the intrinsic spin-density entanglement of the Fermi sea. The thermal wave length supplies a cutoff scale at finite temperatures beyond which correlations are exponentially suppressed. We present data for the frequency dependent retarded spin-spin susceptibility and use the results to calculate the real-time response of a weak perturbation in linear response: within the spatial resolution no response outside of the light cone is found.

Topological protected quantum critical point in 1D Two Impurity Models

We show that the two-impurity Anderson model exhibits an additional quantum critical point at infinitely many specific distances between both impurities for an inversion symmetric one-dimensional dispersion. Unlike the quantum critical point previously established, it is robust against particle-hole or parity symmetry breaking. The quantum critical point separates a spin doublet from a spin singlet ground state and is, therefore, protected. A finite single-particle tunneling