A quantum two-level system immersed in a sub-Ohmic bath experiences enhanced low-frequency quantum statistical fluctuations which render the nonequilibrium quantum dynamics highly non-Markovian. Upon using the numerically exact time-evolving matrix product operator approach, we investigate the phase diagram of the polarization dynamics. In addition to the known phases of damped coherent oscillatory dynamics and overdamped decay, we identify a new third region in the phase diagram for strong coupling showing an aperiodic behaviour. We determine the corresponding phase boundaries. The dynamics of the quantum two-state system herein is not coherent by itself but slaved to the oscillatory bath dynamics.
@article{arxiv.2208.10313,
title = {The Hidden Phase of the Spin-Boson Model},
author = {Florian Otterpohl and Peter Nalbach and Michael Thorwart},
journal= {arXiv preprint arXiv:2208.10313},
year = {2022}
}