Adiabatic approximation in open systems: An alternative approach

Abstract

The adiabatic approximation in open systems is formulated through the effective Hamiltonian approach. By introducing an ancilla, we embed the open system dynamics into a non-Hermitian quantum dynamics of a composite system composed of the open system and ancilla, the adiabatic evolution of the open system is then defined as the adiabatic dynamics of the composite system. Validity and invalidity conditions for this approximation as well as the relation to the other definition are established and discussed. A high-order adiabatic approximation for open systems is introduced. As an example, the adiabatic condition for an open spin- particle in time-dependent magnetic fields is analysed. © 2007 IOP Publishing Ltd.