Rabi flop-assisted electron tunneling through the quantum dots

Abstract

When the external electromagnetic field (EF) with the frequency $\omega $ acts on the discrete levels in the quantum dot (QD), it induces the mixed quantum state characterized by Rabi flops (RF). The RF process involves the oscillations in the level population $\delta n_{\alpha \beta }\left( t\right) $ accompanied by the cyclical absorption and re-emission of photons. The RF time dynamics depend on the Rabi frequency $\omega _{\mathrm{R}}$ and detuning $\Delta =\omega - \omega_Q $, where $\omega_Q =\left( \varepsilon _{\beta }- \varepsilon _{\beta }\right) /\hbar$, $\varepsilon _{\alpha} $ and $\varepsilon _{\beta} $ are the level energies. By using the Floquet formalism to solve the time-dependent wave equations for the voltage-biased QD exposed to EF, we examine how RF is expressed in the electric current. We find that the Rabi flop-assisted tunneling (RFAT) is pronounced in the I-V curves as steps and flat plateaus, whose position and spacing reflect the intrinsic features of the mixed quantum state and directly depend on $\omega _{\mathrm{R}}$ and $\Delta $. Thus, measuring RFAT allows an immediate observation of RF right in the I-V curves, thus improving the versatility and accuracy of many applications in the broad frequency range.