Decoherence of Polaron in Asymmetric Quantum Dot Qubit Under an Electromagnetic Field
American Journal of Modern Physics
Volume 4, Issue 3, May 2015, Pages: 138-148
Received: Apr. 29, 2015; Accepted: May 13, 2015; Published: Jun. 3, 2015
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Authors
Alain Jerve Fotue, Mesoscopic and Multilayers Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang, Cameroon
Sadem Christian Kenfack, Mesoscopic and Multilayers Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang, Cameroon
Nsangou Issofa, Mesoscopic and Multilayers Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang, Cameroon
Maurice Tiotsop, Mesoscopic and Multilayers Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang, Cameroon
Michel Pascal Tabue Djemmo, Mesoscopic and Multilayers Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang, Cameroon; Laboratory of Mechanics and Modeling of Physical Systems, Faculty of Science, University of Dschang, Dschang, Cameroon
Amos Veyongni Wirngo, Mesoscopic and Multilayers Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang, Cameroon
Hilaire Fotsin, Laboratory of Electronics and Signal Processing, Department of Physics, Faculty of Science, University of Dschang, Dschang, Cameroon
Lukong Cornelius Fai, Mesoscopic and Multilayers Structures Laboratory, Department of Physics, Faculty of Science, University of Dschang, Dschang, Cameroon
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Abstract
In this paper, we investigate the time evolution of the quantum mechanical state of a polaron using the Pekar type variational method on the electric-LO-phonon and the magnetic-LO-phonon strong coupling in a quantum dot. We obtain the Eigen energies and the Eigen functions of the ground state and the first excited state, respectively. In a quantum dot, this system can be viewed as a two level quantum system qubit. The superposition state polaron density oscillates in the quantum dot with a period τ_0when the polaron is in the superposition of the ground and the first-excited states. The spontaneous emission of phonons causes the decoherence of the qubit. We show that the density matrix of the qubit decays with the time while the coherence term of the density matrix element 〖 p〗_01 (〖 or p〗_10) decays with the time as well for different coupling strengths, confinement lengths, and dispersion coefficients. The Shannon entropy is evaluated in order to investigate the decoherence of the system.
Keywords
Polaron, Quantum Dot, Qubit, Electric Field, Magnetic Field, Cyclotron Frequency, Shannon Entropy, Decoherence
To cite this article
Alain Jerve Fotue, Sadem Christian Kenfack, Nsangou Issofa, Maurice Tiotsop, Michel Pascal Tabue Djemmo, Amos Veyongni Wirngo, Hilaire Fotsin, Lukong Cornelius Fai, Decoherence of Polaron in Asymmetric Quantum Dot Qubit Under an Electromagnetic Field, American Journal of Modern Physics. Vol. 4, No. 3, 2015, pp. 138-148. doi: 10.11648/j.ajmp.20150403.16
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