Quench of non-Markovian coherence in the deep sub-Ohmic spin-boson model: A unitary equilibration scheme

TL;DR

This paper demonstrates a method to rapidly quench non-Markovian coherence in the deep sub-Ohmic spin-boson model by unitarily heating the bosonic bath, providing insights into unitary equilibration and thermalization processes.

Contribution

It introduces a novel unitary heating scheme to quench coherence in the spin-boson model, linking to the eigenstate-thermalization hypothesis.

Findings

Coherence is quickly quenched by unitarily heating the bath.

The method effectively simulates thermal effects without dissipation.

Provides a new approach to study unitary equilibration in quantum systems.

Abstract

The deep sub-Ohmic spin-boson model shows a longstanding non-Markovian coherence at low temperature. Motivating to quench this robust coherence, the thermal effect is unitarily incorporated into the time evolution of the model, which is calculated by the adaptive time-dependent density matrix renormalization group algorithm combined with the orthogonal polynomials theory. Via introducing a unitary heating operator to the bosonic bath, the bath is heated up so that a majority portion of the bosonic excited states is occupied. It is found in this situation the coherence of the spin is quickly quenched even in the coherent regime, in which the non-Markovian feature dominates. With this finding we come up with a novel way to implement the unitary equilibration, the essential term of the eigenstate-thermalization hypothesis, through a short-time evolution of the model.