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Theory of time-dependent transport in quantum dot systems
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. (Condensed Matter Theory Group)
2003 (English)In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 92, no 6, 471-477 p.Article in journal (Refereed) Published
Abstract [en]

The formulation of the time-dependent tunnel current in quantum dot (QD) systems in the (generalized) transfer Hamiltonian formalism is reconsidered, taking into account the nonorthogonality between the subsystems. Exploiting the fact that only the total charge in the system is conserved, in general, gives rise to a new formulation of the transport theory. As a result, it is shown necessary to depart from the orthodox picture, in which the current is treated as a local property of the system. A general formula for the current is derived. By expressing properties of the quantum dot in the Hubbard I approximation with the loop correction, thereby including strong correlations of the QD states, numerical results are given for various time-dependent source-drain voltages

Place, publisher, year, edition, pages
2003. Vol. 92, no 6, 471-477 p.
Keyword [en]
transport theory, time-dependence, non-equilibrium, tunneling, mesoscopic system, quantum dot, non-orthogonality, strong correlations
National Category
Physical Sciences
URN: urn:nbn:se:uu:diva-90022DOI: 10.1002/qua.10527OAI: oai:DiVA.org:uu-90022DiVA: diva2:162042
Available from: 2002-10-11 Created: 2002-10-11 Last updated: 2013-06-14Bibliographically approved
In thesis
1. Non-Orthogonality and Electron Correlations in Nanotransport: Spin- and Time-Dependent Currents
Open this publication in new window or tab >>Non-Orthogonality and Electron Correlations in Nanotransport: Spin- and Time-Dependent Currents
2002 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The concept of the transfer Hamiltonian formalism has been reconsidered and generalized to include the non-orthogonality between the electron states in an interacting region, e.g. quantum dot (QD), and the states in the conduction bands in the attached contacts. The electron correlations in the QD are described by means of a diagram technique for Hubbard operator Green functions for non-equilibrium states.

It is shown that the non-orthogonality between the electrons states in the contacts and the QD is reflected in the anti-commutation relations for the field operators of the subsystems. The derived forumla for the current contains corrections from the overlap of the same order as the widely used conventional tunneling coefficients.

It is also shown that kinematic interactions between the QD states and the electrons in the contacts, renormalizes the QD energies in a spin-dependent fashion. The structure of the renormalization provides an opportunity to include a spin splitting of the QD levels by polarizing the conduction bands in the contacts and/or imposing different hybridizations between the states in the contacts and the QD for the two spin channels. This leads to a substantial amplification of the spin polarization in the current, suggesting applications in magnetic sensors and spin-filters.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2002. 101 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 756
Physics, non-orthogonality, non-equilibrium, transport, nanosystem, quantum dot, spin-dependent, renormalization, Green function, diagram technique, many-body states, Hubbard operator, electron correlations, time-dependent, Fysik, icke-ortogonal, icke-jämvikt, transport, nanosystem, kvantprick, spinberoende, renormering, Green-funktion, diagramteknik, mångkropparstillstånd, Hubbadoperator, elektronkorrelationer, tidsberoende
National Category
Physical Sciences
Research subject
urn:nbn:se:uu:diva-2687 (URN)91-554-5418-6 (ISBN)
Public defence
2002-11-01, Polhemssalen, Uppsala, 10:15
Available from: 2002-10-11 Created: 2002-10-11 Last updated: 2012-03-18Bibliographically approved

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