Transport spectroscopy in degenerate quantum dot

Using the microscopic model proposed by us earlier, the tunnel current and differential conductivity through a degenerate quantum dot weakly coupled to the external electrodes, depending on the bias and gate voltages, were calculated. The behavior of this system is analyzed at two types of electron-electron interaction in the quantum dot: repulsive and attractive. It is shown that in the case of the attractive interaction, the dependence of electron levels occupation on voltage becomes nonlinear, and the transport properties of the system change dramatically. The method of transport spectroscopy made it possible to determine through which of the levels (both ground and excited) tunneling takes place depending on the applied voltages and to estimate the current through these levels, as well as the orientation of electron spins on them. The results can be used to understand and predict the properties of a quantum dot as a potential element for new generations of nanodevices and quantum computers. (author)