The Transition Between Quantum Coherence and Incoherence

TL;DR

This paper investigates a transformed Caldeira-Leggett Hamiltonian and reveals a transition between quantum coherence and incoherence, characterized by two distinct fixed point families with different spectral properties.

Contribution

It demonstrates that the Hamiltonian has two fixed point families with different coherence properties, challenging the previous assumption of a single fixed point.

Findings

Identification of two fixed point families with distinct coherence properties

The transition is linked to degeneracy in the spectral function of the spin-flip operator

Clarification of the model's behavior in terms of spectral degeneracy and non-degeneracy

Abstract

We show that a transformed Caldeira-Leggett Hamltonian has two distinct families of fixed points, rather than a single unique fixed point as often conjectured based on its connection to the anisotropic Kondo model. The two families are distinguished by a sharp qualitative difference in their quantum coherence properties and we argue that this distinction is best understood as the result of a transition in the model between degeneracy and non-degeneracy in the spectral function of the ``spin-flip'' operator.