Quantum criticality of the Ohmic spin-boson model in a high dense spectrum: symmetries,quantum fluctuations and correlations

TL;DR

This paper investigates the quantum critical behavior of the Ohmic spin-boson model with a dense spectrum of environmental modes using large-scale variational simulations, revealing symmetry breaking, quantum fluctuations, and critical exponents.

Contribution

It provides a comprehensive numerical analysis of quantum criticality in the Ohmic spin-boson model, including symmetry breakdown and critical exponents in dense environments.

Findings

Accurate determination of critical coupling and exponents.

Uncovering quantum criticality in both delocalized phase and at transition.

Validation of variational methods for dense spectral environments.

Abstract

Study of dissipative quantum phase transitions in the Ohmic spin-boson model is numerically challenging in a dense limit of environmental modes. In this work, large-scale numerical simulations are carried out based on the variational principle. The validity of variational calculations, spontaneous breakdown of symmetries, and quantum fluctuations and correlations in the Ohmic bath are carefully analyzed, and the critical coupling as well as exponents are accurately determined in the weak tunneling and continuum limits. In addition, quantum criticality of the Ohmic bath is uncovered both in the delocalized phase and at the transition point.