Kondo Cloud Mediated Long Range Entanglement After Local Quench in a Spin Chain

TL;DR

This paper demonstrates that a local quench in a gapless Kondo spin chain induces long-range, robust entanglement mediated by the Kondo Cloud, offering a new way to detect the Kondo Cloud and connect condensed matter phenomena with quantum information.

Contribution

It reveals how local quenches can generate and distinguish Kondo Cloud mediated entanglement, providing a novel method to detect the Kondo Cloud through entanglement dynamics.

Findings

Long-lived entanglement between chain ends in the gapless Kondo regime.

Entanglement is mediated by the Kondo Cloud and is independent of chain length for large chains.

Decoupling an end distinguishes between local end effects and global Kondo Cloud effects.

Abstract

We show that, in the gapless Kondo Regime, a single local quench at one end of a Kondo spin chain induces a fast and long lived oscillatory dynamics. This quickly establishes a high quality entanglement between the spins at the opposite ends of the chain. This entanglement is mediated by the Kondo Cloud, attains a constant high value independent of the length for large chains, and shows thermal robustness. In contrast, when the Kondo cloud is absent, e.g. in the gapped dimer regime, only finite size end to end effects can create some entanglement on a much longer time-scale for rather short chains. By decoupling one end of the chain during the dynamics one can distinguish between this end-end effect which vanishes, and the global Kondo cloud mediated entanglement, which persists. This quench approach paves the way to detect the elusive Kondo cloud through the entanglement between two individual spins. Our results show that non-perturbative cooperative phenomena from condensed matter may be exploited for quantum information.