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Canyon of current suppression in an interacting two-level quantum dot

Karlström, Olov LU ; Pedersen, Jonas LU ; Samuelsson, Peter LU and Wacker, Andreas LU (2011) In Physical Review B (Condensed Matter and Materials Physics) 83(20).
Abstract
Motivated by the recent discovery of a canyon of conductance suppression in a two-level equal-spin quantum dot system [Phys. Rev. Lett. 104, 186804 (2010)], the transport through this system is studied in detail. At low bias and low temperature a strong current suppression is found around the electron-hole symmetry point independent of the couplings, in agreement with previous results. By means of a Schrieffer-Wolff transformation we are able to give an intuitive explanation to this suppression in the low-energy regime. In the general situation, numerical simulations are carried out using quantum rate equations. The simulations allow for the prediction of how the suppression is affected by the couplings, the charging energy, the position... (More)
Motivated by the recent discovery of a canyon of conductance suppression in a two-level equal-spin quantum dot system [Phys. Rev. Lett. 104, 186804 (2010)], the transport through this system is studied in detail. At low bias and low temperature a strong current suppression is found around the electron-hole symmetry point independent of the couplings, in agreement with previous results. By means of a Schrieffer-Wolff transformation we are able to give an intuitive explanation to this suppression in the low-energy regime. In the general situation, numerical simulations are carried out using quantum rate equations. The simulations allow for the prediction of how the suppression is affected by the couplings, the charging energy, the position of the energy levels, the applied bias, and the temperature. We find that, away from electron-hole symmetry, the parity of the couplings is essential for the current suppression. It is also shown how broadening, interference, and a finite interaction energy cause a shift of the current minimum away from degeneracy. Finally we see how an increased population of the upper level leads to current peaks on each side of the suppression line. At sufficiently high bias we discover a coherence-induced population inversion. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review B (Condensed Matter and Materials Physics)
volume
83
issue
20
publisher
American Physical Society
external identifiers
  • wos:000290715600014
  • scopus:79961113985
ISSN
1098-0121
DOI
10.1103/PhysRevB.83.205412
language
English
LU publication?
yes
id
3bac9dcc-1410-40b0-8c61-1bef27b944eb (old id 1986256)
date added to LUP
2011-06-29 12:30:23
date last changed
2017-09-10 04:13:25
@article{3bac9dcc-1410-40b0-8c61-1bef27b944eb,
  abstract     = {Motivated by the recent discovery of a canyon of conductance suppression in a two-level equal-spin quantum dot system [Phys. Rev. Lett. 104, 186804 (2010)], the transport through this system is studied in detail. At low bias and low temperature a strong current suppression is found around the electron-hole symmetry point independent of the couplings, in agreement with previous results. By means of a Schrieffer-Wolff transformation we are able to give an intuitive explanation to this suppression in the low-energy regime. In the general situation, numerical simulations are carried out using quantum rate equations. The simulations allow for the prediction of how the suppression is affected by the couplings, the charging energy, the position of the energy levels, the applied bias, and the temperature. We find that, away from electron-hole symmetry, the parity of the couplings is essential for the current suppression. It is also shown how broadening, interference, and a finite interaction energy cause a shift of the current minimum away from degeneracy. Finally we see how an increased population of the upper level leads to current peaks on each side of the suppression line. At sufficiently high bias we discover a coherence-induced population inversion.},
  articleno    = {205412},
  author       = {Karlström, Olov and Pedersen, Jonas and Samuelsson, Peter and Wacker, Andreas},
  issn         = {1098-0121},
  language     = {eng},
  number       = {20},
  publisher    = {American Physical Society},
  series       = {Physical Review B (Condensed Matter and Materials Physics)},
  title        = {Canyon of current suppression in an interacting two-level quantum dot},
  url          = {http://dx.doi.org/10.1103/PhysRevB.83.205412},
  volume       = {83},
  year         = {2011},
}