Stability and decoherence of optical bipolaron in symmetric quantum dot
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Stability and decoherence of optical bipolaron in symmetric quantum dot A. J. Fotuea , J.-R. D. Djomou, S. C. Kenfack, M. F. C. Fobasso, L. C. Fai Unité de Recherche de Matière Condensée, d Electronique et de Traitement de Signal (UR-MACETS), Department of Physics, Faculty of Science, University of Dschang, P. O. Box: 67, Dschang, Cameroon Received: 28 July 2020 / Accepted: 5 October 2020 © Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Optical bipolaron’s stability and decoherence confined in the symmetric quantum dot are investigated utilizing the modified Lee, Low, and Pines variational method. The binding energy of optical bipolaron in symmetrical quantum dot systems is obtained by computing the energy of the fundamental state, the energy of the ground state of the single polaron, and the prime state excited energy. The formation of the bipolaron in quantum dot structures is thus obtained. Optical bipolaron stability appears to be quite sensitive to the dimensionality of the quantum dot and the material, where α and η material parameters are considered. By investigating information processing, it is possible to compute Shannon’s entropy to study a qubit’s decoherence when in the superimposed state of the fundamental and the prime state excited. We see that decoherence time grows and shrinks with the dielectric constant and the dispersion coefficient. Thus, there exists a threshold dielectric constant and dispersion coefficient which maximizes decoherence time. This threshold dielectric constant and dispersion coefficient increases with the reduction in electron–phonon coupling. This study gives a guideline for the appropriate materials used in the construction of nanodevice.
1 Introduction The study of sub-micrometric-sized objects is currently a subject of major research in solidstate physics. This interest comes from the fact that the miniaturization of microelectronic components whose nanometric dimensions are factors that justify the taking into account of the quantum nature of the electron [1]. Advances in crystal growth technology have permitted the fabrication of semiconductor nanostructures having characteristic dimensions in the De Broglie wavelength range. In particular, the quantum dot system attracts significant interest in electronic and optical properties [2, 3]. The importance of interaction between the electron and phonon in the quantum dot (QD) structure on the relaxation of the carriers was explored considering the dimensional effect [4, 5]. Therefore, it becomes more important to examine the pairing of two polarons due to attractive interaction mediated via coupling between electron and phonon, as the strongest impacts caused by interactions between electron and phonon belong to this system. This pairing being characterized because at some material parameter values, the attractive electron–phonon interaction outweighs the Coulomb repulsive interac-
a e-mail: [email protected] (corresponding author)
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