Driven Tunneling Dynamics: Bloch-Redfield Theory versus Path Integral Approach

TL;DR

This paper compares the path integral and Bloch-Redfield methods for spin-boson dynamics in weak coupling and low temperature regimes, demonstrating their equivalence and introducing an analytical high-frequency approximation.

Contribution

It establishes the equivalence of two common approximation methods and introduces a new analytical high-frequency approach for quantum coherence decay.

Findings

Excellent agreement between the two methods.

The high-frequency approach accurately models coherence decay.

Control fields can modulate quantum coherence effectively.

Abstract

In the regime of weak bath coupling and low temperature we demonstrate numerically for the spin-boson dynamics the equivalence between two widely used but seemingly different roads of approximation, namely the path integral approach and the Bloch-Redfield theory. The excellent agreement between these two methods is corroborated by a novel efficient analytical high-frequency approach: it well approximates the decay of quantum coherence via a series of damped coherent oscillations. Moreover, a suitably tuned control field can selectively enhance or suppress quantum coherence.