Optimal control of dissipation for the example of the spin-boson model

Institut für Physik, Theory Division Karl-Franzens-Universität Graz - Universitätplatz 5, 8010 Graz, Austria

Corresponding authors: hamza.jirari@uni-graz.at walter.poetz@uni-graz.at

Received: 22 December 2006
Accepted: 10 January 2007

Abstract

The interaction of a quantum system with a bath, usually referred to as dissipation, can be controlled if one can establish quantum interference between the system-bath interaction and a coupling of the system to an external control field. This is demonstrated for the example of the spin-boson model in the strong-coupling limit for the system-bath interaction. It is shown that driving and trapping of the spin system leads to an optimum control problem which is nonlinear in the external control field. Using an indirect optimization strategy introducing a Lagrange-type adjoint state, we show that the spin system can be trapped in otherwise unstable quantum states and that it can be driven from a given initial state to a specified target state with high fidelity.