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.