General Theory of Decoherence of Qubit Systems in the Born-Markov Approximation

Abstract

General Theory of Decoherence of Qubit Systems in the Born-Markov Approximation R. Joynt Department of Physics, University of Wisconsin, Madison, Wisconsin, U.S.A. Nguyen Van Hieu, Nguyen Bich Ha, Nguyen Hung Son, Ho Cong Son and Nguyen Dang Vu Institute of Materials Science and Institute of Physics, Vietnam Academy of Science and Technology, Hanoi, Vietnam (Received 21 August 2007) The general theory of the decoherence of a two-level system as a qubit and a four-level system as a two-qubit system based on the Born-Markov approximation is presented. The derived formulae in the case of the twolevel system are applied to two examples of the qubit: a system of electron states in a double quantum dot as a charge qubit and that of Zeeman split electron states in a quantum dot as a spin qubit. A generalization to the study of the decoherence of n-qubit systems is discussed. PACS numbers: 03.65.Yz, 73.21.La, 73.63.Kv