Spin-spin coupling-based quantum and classical phase transitions in two-impurity spin-boson models

TL;DR

This paper investigates phase transitions in two-impurity spin-boson models, revealing exact mappings, decoherence-free subspaces, and both classical and quantum phase transitions, enhancing understanding of complex quantum systems.

Contribution

It introduces an exact mapping of the two-impurity model to single-impurity models and analyzes phase transitions and decoherence-free subspaces in this context.

Findings

Existence of decoherence-free subspace.

Identification of classical and quantum phase transitions.

Exact mapping to single-impurity models.

Abstract

The class of two-interacting-impurity spin-boson models with vanishing transverse fields on the spin-pair is studied. The model can be exactly mapped into two independent standard single-impurity spin-boson models where the role of the tunnelling parameter is played by the spin-spin coupling. The dynamics of the magnetization is analysed for different levels of (an)isotropy. Further, the existence of a decoherence-free subspace as well as of both classical and quantum (first-order and Kosterlitz-Thouless type) phase transitions, in the Omhic regime, is brought to light.