Spatiotemporal buildup of the Kondo screening cloud

Abstract

We investigate how the Kondo screening cloud builds up as a function of space and time. Starting from an impurity spin decoupled from the conduction band, the Kondo coupling is switched on at time t=0. We work at the Toulouse point where one can obtain exact analytical results for the ensuing spin dynamics at both zero and nonzero temperature T. For t>0 the Kondo screening cloud starts building up in the wake of the impurity spin being transported to infinity. In this buildup process the impurity spin--conduction band spin susceptibility shows a sharp light cone due to causality, while the corresponding correlation function has a tail outside the light cone. At T=0 this tail has a power law decay as a function of distance from the impurity, which we interpret as due to initial entanglement in the Fermi sea.Comment: 10 pages, 9 figure

Real-space structure of the impurity screening cloud in the resonant level model

“…Because of solvability, the Toulouse point is widely used in many studies of Kondo physics. For example, it has been used for non-equilibrium calculations for Kondo impurities [26,27,28,29]. Spatial structures in the bath have been studied for the Toulouse point in Ref.…”

Inertia effects in the real-time dynamics of a quantum spin coupled to a Fermi sea

“…The Kondo effect is a true quantum effect which originates from the two-fold spin degeneracy and is protected by time-reversal symmetry. Longitudinal spin dynamics, such as the time-dependent Kondo screening, has been studied recently [3,4] by starting from an initial state with a fully polarized spin, which can be prepared with the help of local magnetic field. The longitudinal dynamics is initiated by suddenly switching off the field.…”

Linear response of a one-dimensional conductor coupled to a dynamical impurity with a Fermi edge singularity

“…I study the correlations that the two-level system induces between the otherwise noninteracting degrees of freedom of the bath. This is in the same spirit as recent studies on the screening cloud around an impurity that displays a Kondo effect [5][6][7][8][9][10]. In a previous work, I considered static density correlations among electrons in the system's ground state [25].…”

“…In turn, the impurity induces correlations between the otherwise noninteracting electrons in the Fermi sea [5][6][7][8][9][10]. At present, we have a more complete understanding of the dissipative dynamics of the impurity than we have of impurityinduced spatial and temporal correlations induced in the Fermi sea [9].…”