Two-bath spin-boson model: Phase diagram and critical properties

Benedikt Bruognolo; Andreas Weichselbaum; Cheng Guo; Jan von Delft; Imke Schneider; Matthias Vojta

doi:10.1103/physrevb.90.245130

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arXiv · 1410.3821

Two-bath spin-boson model: Phase diagram and critical properties

Benedikt Bruognolo·Andreas Weichselbaum·Cheng Guo·Jan von Delft·Imke Schneider·Matthias Vojta

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Abstract

The spin-boson model, describing a two-level system coupled to a bath of harmonic oscillators, is a generic model for quantum dissipation, with manifold applications. It has also been studied as a simple example for an impurity quantum phase transition. Here we present a detailed study of a U(1)-symmetric two-bath spin-boson model, where two different components of an SU(2) spin 1/2 are coupled to separate dissipative baths. Non-trivial physics arises from the competition of the two dissipation channels, resulting in a variety of phases and quantum phase transitions. We employ a combination of analytical and numerical techniques to determine the properties of both the stable phases and the quantum critical points. In particular, we find a critical intermediate-coupling phase which is bounded by a continuous quantum phase transition which violates the quantum-to-classical correspondence.

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Benedikt Bruognolo, Andreas Weichselbaum, Cheng Guo, Jan von Delft, Imke Schneider, Matthias Vojta. 2014-10-14. Two-bath spin-boson model: Phase diagram and critical properties. https://doi.org/10.1103/physrevb.90.245130

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