TY - JOUR
T1 - Canyon of current suppression in an interacting two-level quantum dot
AU - Karlström, O
AU - Pedersen, Jonas Nyvold
AU - Samuelsson, P
AU - Wacker, A
PY - 2011
Y1 - 2011
N2 - 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.
AB - 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.
U2 - 10.1103/PhysRevB.83.205412
DO - 10.1103/PhysRevB.83.205412
M3 - Journal article
SN - 0163-1829
VL - 83
SP - 205412-1 -205412-16
JO - Physical Review B Condensed Matter
JF - Physical Review B Condensed Matter
IS - 20
ER -