2015/01/21 by Yao Yao, Nengji Zhou, Yao, Yao +5
Physics and Astronomy · #FOS: Physical sciences #Physics of Superconductivity and Magnetism #Quantum Chromodynamics and Particle Interactions #Quantum Physics (quant-ph) #Quantum many-body systems
paper · pdf · doi:10.48550/arxiv.1501.05061
openalex publication_date 2015/01/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The spin-boson model is a paradigm for studying decoherence, relaxation, entanglement and other effects that arise in a quantum system coupled to environmental degrees of freedom. At zero temperature, a localization-delocalization phase transition is known to exist in the sub-Ohmic regime, where the standard density matrix renormalization group algorithm is inadequate due to the divergence in the number of low-frequency modes. This limitation is circumvented in this work by symmetrically optimizing the phonon basis and introducing an order parameter accounting for the U(1) symmetry for a two-bath spin-boson model, by which we are able to determine the classification and criticality of the phase transition explicitly. Compared with variational results, the critical phase is characterized by spontaneous vanishing of boson displacements in both the baths, resulting in an accurate phase diagram with three model parameters.