  We investigate the entanglement properties of the Kondo spin chain when it is
prepared in its ground state as well as its dynamics following a single bond
quench. We show that a true measure of entanglement such as negativity enables
to characterize the unique features of the gapless Kondo regime. We determine
the spatial extent of the Kondo screening cloud and propose an ansatz for the
ground state in the Kondo regime accessible to this spin chain; we also
demonstrate that the impurity spin is indeed maximally entangled with the Kondo
cloud. We exploit these features of the entanglement in the gapless Kondo
regime to show that a single local quench at one end of a Kondo spin chain may
always induce a fast and long lived oscillatory dynamics, which establishes a
high quality entanglement between the individual spins at the opposite ends of
the chain. This entanglement is a footprint of the presence of the Kondo cloud
and may be engineered so as to attain - even for very large chains- a constant
high value independent of the length; in addition, it is thermally robust. To
better evidence the remarkable peculiarities of the Kondo regime, we carry a
parallel analysis of the entanglement properties of the Kondo spin chain model
in the gapped dimerised regime where these remarkable features are absent.
