Transport properties of quantum dots with strong electron-phonon interaction

We theoretically examine the transport properties of quantum dots with strong electron-phonon interaction. When a separation between discrete electron-levels in a quantum dot matches the energy of the LO phonons, the electron-phonon interaction results in polarons, coherent states consisting of an electron and LO phonons. The Rabi splitting between two levels in the quantum dot is observable in a peak structure of the differential conductance G as a function of the bias voltage. The polaron formation suppresses the peak height of G, which is due to the competition between the resonant tunneling (resonance between a level in the dot and states in the leads) and the polaron formation (Rabi oscillation between two levels in the dot). G shows a sharp dip at the midpoint between the split peaks. This is attributable to the destructive interference between bonding and anti-bonding states in a composite system of an electron and phonons. (C) 2002 Elsevier Science B.V. All rights reserved.