Driven Tunneling Dynamics BlochRedfield Theory versus Path Integral Approach.pdfVIP

Driven Tunneling Dynamics: Bloch-Redfield Theory versus Path Integral Approach 1 1 2,3 1 Ludwig Hartmann , Igor Goychuk , Milena Grifoni and Peter H¨anggi 1Institut f¨ur Physik, Universit¨at Augsburg, Universit¨atsstr. 1, D-86135 Augsburg, Germany 0 2Institut f¨ur Theoretische Festk¨orperphysik, Universit¨at Karlsruhe, D-76128 Karlsruhe, Germany 0 3Dipartimento di Fisica, INFM, Via Dodecaneso 33, I-16146, Genova, Italy 0 (Date: February 1, 2008) 2 In the regime of weak bath coupling and low temperature we demonstrate numerically for the r a 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 M agreement between these two methods is corroborated by a novel efficient analytical high-frequency 7 approach: it well approximates the decay of quantum coherence via a series of damped coherent 1 oscillations. Moreover, a suitably tuned control field can selectively enhance or suppress quantum coherence. ] h c e PACS number(s): 03.65.Db, 05.40.-a, 82.20.Mj m t- The dynamics of driven quantum systems which inter- regime is of relevance for many situations such as, e.g., a act with a large number of environmental degrees of free- for the challenge of ”battling decoherence” in quantum t