Charge fluctuations in quantum point contact

We present studies of the role of charge fluctuations in transport through a quantum point contact (QPC). Our model of QPC is based on assumption of a specific electronic energy structure with a resonant level below the electronic sub-band. We show that charge fluctuations lead to a dynamical Coulomb blockade effect, which is responsible for reduction of the conductance to the value 2/3×(2e2/h). The evolution of conductance with a magnetic field and as a function of source-drain voltage is presented as well. The conductance plateau at 2/3×(2e2/h) evolves continuously with an increase of the voltage to a 0.8 or 0.4 plateau, depending on the relative position of the resonant state with respect to the Fermi energy at zero bias. Our simple model shows many similarities with experimental characteristics.