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This talk explores quantum information in condensed matter, focusing on Kondo physics and entanglement in the Kondo ground state. It discusses generating long-range entanglement in gapped and gapless systems, emphasizing the exponential decay in intrinsic length scales for the former and algebraic correlations decay in the latter. The Kondo Spin Chain's correlations decay exponentially despite being gapless. The discussion includes the Kondo phase, dimer phase, local quench, and optimal parameters. The modified strategy in Kondo reveals high-value, distance-independent entanglement mediated by the cloud, while in the dimer phase, entanglement is end-to-end and decays exponentially. The presentation also covers interacting clouds, impurity entanglement, and results emphasizing entanglement measures in capturing Kondo physics properties, generating oscillatory dynamics in the Kondo regime, and mediating long-range distance-independent entanglement through Kondo clouds.
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Entanglement in the Kondo Spin Chain Abolfazl Bayat1, Sougato Bose1, Pasquale Sodano2 1 University College London, London, UK. 2 University of Perugia, Perugia, Italy. Engineering of States and Devices: Theory and Experiments
Contents of the Talk Quantum Information Condensed Matter 1. Kondo physics 2. Entanglement in the Kondo ground state 3. Generating a long range entanglement
Gapped Systems Excited states Ground state The intrinsic length scale of the system impose an exponential decay
Gapless Systems Continuum of excited states Ground state There is no length scale in the system so correlations decay algebraically
Kondo Physics Despite the gapless nature of the Kondo system, correlations decay exponentially
Kondo Spin Chain E. S. Sorensen et al., J. Stat. Mech., P08003 (2007)
Entanglement as a Witness of the Cloud A B Impurity L
Scaling B A Impurity L N-L-1 Kondo Phase: Dimer Phase:
Scaling Properties of the Kondo regime Kondo Phase: Dimer Phase:
Local Quench Quench
Optimality and Distance independence Independent of length N, when cloud contains N-2 spins we generate a constant Entanglement
Entanglement in the Modified Strategy Kondo: High value distance independent entanglement mediated by the cloud. Dimer: Entanglement is just due to an end-end effect which decays exponentially.
Entanglement Rotor Dispatching centre With interacting the clouds impurities get entangled
Summary of Results • With using the entanglement measures, one can capture the properties of the Kondo physics. • A local quench generates an oscillatory dynamics in the Kondo regime. • Kondo cloud mediates long range distance independent • entanglement between individual ending. • References: • 1- Abolfazl Bayat, Pasquale Sodano, Sougato Bose, Physical Review B 81, 064429 (2010) • 2- Pasquale Sodano, Abolfazl Bayat,Sougato Bose, Physical Review B 81, 100412(R) (2010)