Numerical variational simulations of quantum phase transitions in the sub-Ohmic spin-boson model with multiple polaron ansatz

Abstract

With extensive variational simulations, dissipative quantum phase transitions in the sub-Ohmic spin-boson model are numerically studied in a dense limit of environmental modes. By employing a generalized trial wave function composed of coherent-state expansions, transition points and critical exponents are accurately determined for various spectral exponents, demonstrating excellent agreement with those obtained by other sophisticated numerical techniques. Besides, the quantum-to-classical correspondence is fully confirmed over the entire sub-Ohmic range, compared with theoretical predictions of the long-range Ising model. Mean-field and non-mean-field critical behaviors are found in the deep and shallow sub-Ohmic regimes, respectively, and distinct physical mechanisms of them are uncovered.

10 pages, 9 figures, 2 tables

References in corpus (6)

• Numerical Renormalization Group for Bosonic Systems and Application to the Subohmic Spin-Boson Model
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Cited by in corpus (4)

• Nonadiabatic Field: A Conceptually Novel Approach for Nonadiabatic Quantum Molecular Dynamics
• Transient dynamical phase diagram of the spin-boson model
• Transient Dynamical Phase Diagram of the Spin-Boson Model at Finite Temperature
• Quantum criticality in sub-Ohmic systems with three competing terms: beyond conventional spin-boson physics