Issue
EPL
Volume 87, Number 4, August 2009
Article Number 40003
Number of page(s) 6
Section General
DOI http://dx.doi.org/10.1209/0295-5075/87/40003
Published online 07 September 2009
EPL, 87 (2009) 40003
DOI: 10.1209/0295-5075/87/40003

Optimal control approach to dynamical suppression of decoherence of a qubit

H. Jirari

LPMMC, C.N.R.S., Université Joseph Fourier - BP 166, 38042 Grenoble-cedex 9, France, EU

hjirari@hotmail.com

received 7 April 2009; accepted in final form 28 July 2009; published August 2009
published online 7 September 2009

Abstract
We investigate optimal control of a single qubit coupled to an ohmic heat bath. For the weak bath coupling regime, we derive a Bloch-Redfield master equation describing the evolution of the qubit state parameterized by vectors in the Bloch sphere. By use of the optimal control methodology, we determine a field that generates a single-qubit rotation. We use techniques of automatic differentiation to compute the gradient for the cost functional.

PACS
02.30.Yy - Control theory.
03.67.-a - Quantum information.
03.65.Yz - Decoherence; open systems; quantum statistical methods.

© EPLA 2009