Volume 77, Number 5, March 2007
Article Number 50005
Number of page(s) 5
Section General
Published online 23 February 2007
EPL, 77 (2007) 50005
DOI: 10.1209/0295-5075/77/50005

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

H. Jirari and W. Pötz

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

received 22 December 2006; accepted in final form 10 January 2007; published March 2007
published online 23 February 2007

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.

02.30.Yy - Control theory.
03.65.Yz - Decoherence; open systems; quantum statistical methods.

© Europhysics Letters Association 2007