Transmission Coefficient of Ballistic Quantum Dot

We analyze the electron transmission through a ballistic quantum dot which is connected to two quantum point contacts. We demonstrate that the transmission and reflection of this structure is determined by the transfer time of the quantum-dot region which, in turn, is dependent on the applied electric field. The electric-field dependence of the transmission coefficient exhibits clearly pronounced peaks, and regions with negative differential transmission, and we discuss the conditions that should be satisfied in order to observe these effects in experiment.