Non-Markovian effects in the spin-boson model at zero temperature

TL;DR

This paper studies memory effects in the zero-temperature spin-boson model, revealing how non-Markovian dynamics depend on bath speed and system-bath coupling, with complex behaviors observed.

Contribution

It applies a recent non-Markovianity measure and numerically exact methods to analyze the spin-boson model across various parameters, uncovering new insights into memory effects.

Findings

Non-Markovian dynamics occur at weak coupling with a fast bath.

Memory effects are absent at strong coupling in incoherent regimes.

Non-monotonic dependence of non-Markovianity on coupling strength when system and bath time scales are similar.

Abstract

We investigate memory effects in the spin-boson model using a recently proposed measure for non-Markovian behavior based on the information exchange between an open system and its environment. Employing the numerical exact multilayer multiconfguration time-dependent Hartree approach, we simulate the dynamics of the spin-boson model at zero temperature for a broad range of parameters. For a fast bath, i.e. in the scaling limit, we find non-Markovian dynamics for a coherently decaying spin at weak system-bath coupling, whereas memory effects are absent for stronger coupling in the regimes of incoherent decay and localization. If the time scales of system and bath are comparable, a complex, non-monotonic dependence of non-Markovianity on the system-bath coupling strength is observed.