Driven tunneling dynamics: Bloch-Redfield theory versus path-integral approach

In the regime of weak bath coupling and low temperature we demonstrate nume rically 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 the se two methods is corroborated by an efficient analytical high-frequency ap proach: 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.