Exploiting Kondo spin chains for generating long range distance independent entanglement |
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Authors: | Abolfazl Bayat Pasquale Sodano Sougato Bose |
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Affiliation: | (2) Jožef Stefan Institute, Ljubljana, Slovenia;(3) Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia; |
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Abstract: | 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. Moreover, we show that high entanglement between
very distant boundary spins is generated by suddenly connecting two long Kondo spin chains. We show that this procedure provides
an efficient way to route entanglement between multiple distant sites. 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. |
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