Local Kondo entanglement and its breakdown in an effective two-impurity Kondo model

TL;DR

This paper investigates the quantum entanglement properties in the two-impurity Kondo model, revealing a discontinuous breakdown of local Kondo entanglement at a quantum phase transition, with implications for quantum information and Kondo systems.

Contribution

It introduces a quantum entanglement perspective to analyze the two-impurity Kondo problem, highlighting the role of entanglement monogamy and local entanglement breakdown.

Findings

Discontinuous breakdown of local Kondo entanglement at the phase transition

Entanglement monogamy constrains the phase diagram

Frustrated cross-coupling influences the quantum phase transition

Abstract

Competition between the Kondo effect and Ruderman-Kittel-Kasuya-Yosida interaction in the two-impurity Kondo problem can be phenomenologically described by the Rasul-Schlottmann spin model. We revisit this model from the quantum entanglement perspective by calculating both the inter-impurity entanglement and the local Kondo entanglement, the latter being the entanglement between a local magnetic impurity and its spatially nearby conduction electron. A groundstate phase diagram is derived and a discontinuous breakdown of the local Kondo entanglement is found at the singular point, associated concomitantly with a jump in the inter-impurity entanglement. An entanglement monogamy holds in the whole phase diagram. Our results identify the important role of the frustrated cross-coupling and demonstrate the local characteristic of the quantum phase transition in the two-impurity Kondo problem. The implications of these results for Kondo lattices and quantum information processing are also briefly discussed.