Optimal control approach to dynamical suppression of decoherence of a qubitH. Jirari
LPMMC, C.N.R.S., Université Joseph Fourier - BP 166, 38042 Grenoble-cedex 9, France, EU
received 7 April 2009; accepted in final form 28 July 2009; published August 2009
published online 7 September 2009
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.
02.30.Yy - Control theory.
03.67.-a - Quantum information.
03.65.Yz - Decoherence; open systems; quantum statistical methods.
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