Effects of coupling strength of the electron–photon and the photon–environment interactions on the electron transport through multiple-resonances of a double quantum dot system in a photon cavity

Abstract

We study electron transport properties through a double quantum dot (DQD) system coupled to a single mode photon cavity, DQD-cavity. The DQD system has a complex multilevel energy spectrum, in which by tuning the photon energy several anti-crossings between the electron states of the DQD system and photon dressed states are produced, which have not been seen in a simple two level DQD system. Three different regions of the photon energy are studied based on anti-crossings, where the photon energy ranges are classified as “low”, “intermediate”, and “high”. The anti-crossings represent multiple Rabi-resonances, which lead to a current dip in the electron transport at the “intermediate” photon energy. Increasing the electron–photon coupling strength, gγ, the photon exchanges between the anti-crossing states are changed leading to a dislocation of the multiple Rabi resonance states. Consequently, the current dip at the intermediate photon energy is further reduced. Additionally, we tune the cavity–environment coupling, κ, to see how the transport properties in the strong coupling regime, gγ>κ, are changed for different directions of the photon polarization. Increasing κ with a constant value of gγ, a current enhancement in the intermediate photon energy is found, and a reduction in the current is seen for the “high” photon energy range. The current enhancement in the intermediate photon energy is caused by the weakening of the multiple Rabi-resonance in the system.