Memory-keeping effects and forgetfulness in the dynamics of a qubit coupled to a spin chain

Apollaro, Tony J. G.; Di Franco, Carlo; Plastina, Francesco; Paternostro, Mauro

Memory-keeping effects and forgetfulness in the dynamics of a qubit coupled to a spin chain

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Published Version

Date

2011

Authors

Apollaro, Tony J. G.

Di Franco, Carlo

Plastina, Francesco

Paternostro, Mauro

Publisher

American Physical Society

Published Version

10.1103/PhysRevA.83.032103

Abstract

Using recently proposed measures for non-Markovianity [H.-P. Breuer, E. M. Laine, and J. Piilo, Phys. Rev. Lett. 103, 210401 (2009)], we study the dynamics of a qubit coupled to a spin environment via an energy-exchange mechanism. We show the existence of a point, in the parameter space of the system, where the qubit dynamics is effectively Markovian and that such a point separates two regions with completely different dynamical behaviors. Indeed, our study demonstrates that the qubit evolution can in principle be tuned from a perfectly forgetful one to a deep non-Markovian regime where the qubit is strongly affected by the dynamical backaction of the environmental spins. By means of a theoretical quantum process tomography analysis, we provide a complete and intuitive characterization of the qubit channel.

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Citation

Apollaro, T. J. G., Di Franco, C., Plastina, F. and Paternostro, M. (2011) 'Memory-keeping effects and forgetfulness in the dynamics of a qubit coupled to a spin chain', Physical Review A, 83(3), 032103 (10pp). doi: 10.1103/PhysRevA.83.032103