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Conductance Simulations of Transport through a Quantum Dot in the Presence of a Sharp Drop in the Hybridization Function
Marc Ritter
08.08.2017 at 14:00
A single-impurity Anderson model is used as a minimal model for a Quantum Point Contact (QPC), which is then solved with the Numerical Renormalization Group (NRG) method. As the coupling between the QPC and the surrounding conduction electron bath is strongly energy-dependent, sharp features occur in the hybridization function. Since we are interested in the regime at the band edge, where the hybridization is suppressed to zero, this necessitates the application of the recently developed Open Wilson Chain approach to the NRG. Overall this results in a minimal model that can be efficiently simulated at any temperature using NRG. The qualitative correspondence to experimental results is discussed for a range of possible parameter choices. The model reproduces the quantised step in conductance as a function of QPC gate voltage. At zero temperature, a sub-structure very similar to the 0.7 anomaly in transport through a QPC is found. At this stage, some qualitative differences to experimental observations occur at finite temperatures.
A 318, Theresienstr. 37