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Proceedings Paper

Phonon decoherence in quantum dot qubits
Author(s): Eduardo R. Mucciolo; Serguei Vorojtsov; Harold U. Baranger
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Paper Abstract

The spin of an electron confined into a lateral semiconductor quantum dot has been proposed as a possible physical realization of a qubit. While the spin has the advantage of large decoherence times, operations with more than one qubit will necessarily involve orbital degrees of freedom, namely, charge, which is much more prone to decoherence. There are also alternative quantum dot qubit proposals that are entirely based on charge. We have used a realistic model to quantify the limitations imposed by acoustic phonons on the operation of quantum dot-based qubits. Our treatment includes essential aspects of the setup geometry, wave function profile and materials characteristics. The time dependence of the qubit density matrix is the presence of a phonon bath solved within the Born-Markov approximation. We find that the inclusion of geometric form factors makes the phonon-induced decoherence rates in double dot charge qubits nearly one order of magnitude lower than estimates previously in the literature. Moreover, our theoretical prediction for the quality factor of coherent charge oscillations based on phonon decoherence are higher than the values recently observed experimentally. This allows us to conclude that phonons are not the primary source of decoherence in double quantum dot qubits.

Paper Details

Date Published: 25 May 2005
PDF: 9 pages
Proc. SPIE 5815, Quantum Information and Computation III, (25 May 2005); doi: 10.1117/12.603649
Show Author Affiliations
Eduardo R. Mucciolo, Univ. of Central Florida (United States)
Serguei Vorojtsov, Duke Univ. (United States)
Harold U. Baranger, Duke Univ. (United States)

Published in SPIE Proceedings Vol. 5815:
Quantum Information and Computation III
Eric J. Donkor; Andrew R. Pirich; Howard E. Brandt, Editor(s)

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