The nonlinear conductance observed in a quantum point contact is theoretically reproduced for the entire range of applied bias. The single-impurity Anderson model with two reservoirs at different chemical potentials is studied for a sequential change of the gate voltage. The imbalance in the left and right Kondo coupling strength is introduced by the displacement of the Kondo impurity by the electric field produced in the constriction of quantum point contact. We reveal the origin of the side peaks and study the behavior of the height and width of the zero-bias anomaly.
Resistively-detected NMR (RDNMR) is a unique characterization method enabling highly-sensitive NMR detection for a single quantum nanostructure, such as a quantum point contact (QPC). In many studies, we use dynamic nuclear polarization and RDNMR detection in a quantum Hall breakdown regime of a local QPC filling factor of 1 ($ν_{\rm{qpc}} = 1$). However, the lineshapes of RDNMR signal are proved to be complicated and still not fully understood yet. Here, we systematically polarize the nuclear spins by current-pumping from the close vicinity of $ν_{\rm{qpc}} = 1$ conductance plateau all the wa…
We report a dual resonance feature in ballistic conductance through a quantum Hall graphene nanoribbon with a magnetic quantum dot. Such a magnetic quantum dot localizes Dirac fermions exhibiting anisotropic eigenenergy spectra with broken time-reversal symmetry. Interplay between the localized states and quantum Hall edge states is found to be two-fold, showing Breit-Wigner and Fano resonances, which is reminiscent of a double quantum dot system. By fitting the numerical results with the Fano-Breit-Wigner lineshape from the double quantum dot model, we demonstrate that the two-fold resonance …
Entropic signatures of the single-impurity Kondo state
Stewart Blusson Quantum Matter Institute, University of British Columbia（不列颠哥伦比亚大学斯图尔特·布拉斯森量子物质研究所）；Department of Physics and Astronomy, University of British Columbia（不列颠哥伦比亚大学物理与天文学系）；Department of Physics and Astronomy, Purdue University（普渡大学物理与天文学系）；Microsoft Quantum（微软量子）
