Journal of Statistical Physics

, Volume 90, Issue 3–4, pp 889–898 | Cite as

Diagonalization of System plus Environment Hamiltonians

  • Stefan K. Kehrein
  • Andreas Mielke


A new approach to dissipative quantum systems modeled by a system plus environment Hamiltonian is presented. Using a continuous sequence of infinitesimal unitary transformations, the small quantum system is decoupled from its thermodynamically large environment. Dissipation enters through the observation that system observables generically “decay” completely into a different structure when the Hamiltonian is transformed into diagonal form. The method is particularly suited for studying low-temperature properties. This is demonstrated explicitly for the super-Ohmic spin-boson model.

Dissipative quantum systems flow equations spin-boson model 


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Copyright information

© Plenum Publishing Corporation 1998

Authors and Affiliations

  • Stefan K. Kehrein
    • 1
  • Andreas Mielke
    • 2
  1. 1.Theoretische Physik III—Elektronische Korreiationen und Magnetismus, Institut für PhysikUniversität AugsburgAugsburgGermany
  2. 2.Institut für Theoretische PhysikRuprecht-Karls-UniversitätHeidelbergGermany

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