Author(s)

Martin Tchoffo, Georges Collince Fouokeng, Siaka Massou, Ngwa Engelbert Afuoti, Issofa Nsangou, Lukong Cornelius Fai, Alex Ghislain Tchouadeu, Jean-Pierre Kenné

De- partment of Physics, Faculty of Sciences and Technics, University of Abomey-Calavi, Cotonou, Benin.
Department of Mechanical Engineering, Laboratory of Integrated Production Technologies, University of Québec, Québec, Canada.
Department of Physics, Laboratory of Mesoscopic and Multilayer Structures, University of Dschang, Dschang, Cameroon.
Department of Physics, Laboratory of Mesoscopic and Multilayer Structures, University of Dschang, Dschang, Cameroon; Department of Thermal Engineering and Energetics, Douala University Institute of Technology, Douala, Cameroun.

This present issue is an extension of the work of Y. Xiao-Zhong et al. who investigated the influence of constant external magnetic field on the decoherence of a central electron spin of atom coupled to an anti-ferromagnetic environment. We have shown in this work that the character variability of the field induces oscillations amongst the eigen modes of the environment. This observation is made via the derivation of the transition probability density of state, a manner by which critical parameters (parameters where transition occur) of the system could be obtained as it shows resonance peak. We equally observed that the two different magnons modes resulting from the frequency splitting via the application of the time-varying external B-Field, exhibit each a resonant peak of similar amplitude at different temperature ranges. This additional information shows that the probability for the central spin system to remain in its initially prepared diabatic state is enhanced for some temperature ranges for the corresponding two magnon modes. Hence, these temperature ranges where the probability density is maximum could save as decoherence free environment; an important requirement for the implementation of quantum computation and information processing in solid state circuitry. The theoretical and numerical results presented for the decoherence time and the probability density are that of a decohered central electron spin coupled to an anti-ferromagnetic spin bath. The theory is based on a spin wave approximation and on the density matrix using both transformations of Bloch, Primakov and Bogoliobuv in the adiabatic limit.

Decoherence; Spin Wave; Anti-Ferromagnetic Environment; Central Spin; Variable B-Field

M. Tchoffo, G. Fouokeng, S. Massou, N. Afuoti, I. Nsangou, L. Fai, A. Tchouadeu and J. Kenné, "Effect of the Variable B-Field on the Dynamic of a Central Electron Spin Coupled to an Anti-Ferromagnetic Qubit Bath," World Journal of Condensed Matter Physics, Vol. 2 No. 4, 2012, pp. 246-256. doi: 10.4236/wjcmp.2012.24042.