Coupling optical and electrical gating for electronic read-out of quantum dot dynamics

We explore the coherent transfer of electronic signatures from a strongly correlated, optically gated nanoscale quantum dot to a weakly interacting, electrically backgated microscale channel. In this unique side-coupled `T geometry for transport, we predict a novel mechanism for detecting Rabi oscillations induced in the dot through quantum, rather than electrostatic means. This detection shows up as a field-tunable split in the Fano lineshape arising due to interference between the dipole coupled dot states and the channel continuum. The split is further modified by the Coulomb interactions within the dot that influence the detuning of the Rabi oscillations. Furthermore, time-resolving the signal we see clear beats when the Rabi frequencies approach the intrinsic Bohr frequencies in the dot. Capturing these coupled dynamics, including memory effects and quantum interference in the channel and the many-body effects in the dot requires coupling a Fock-space master equation for the dot dynamics with the phase-coherent, non-Markovian time-dependent non-equilibrium Greens function (TDNEGF) transport formalism in the channel through a properly evaluated self-energy and a Coulomb integral. The strength of the interactions can further be modulated using a backgate that controls the degree of hybridization and charge polarization at the transistor surface.

Controlling transistor threshold voltages using molecular dipoles

We develop a theoretical model for how organic molecules can control the electronic and transport properties of an underlying transistor channel to whose surface they are chemically bonded. The influence arises from a combination of long-ranged dipolar electrostatics due to the molecular head-groups, as well as short-ranged charge transfer and interfacial dipole driven by equilibrium band-alignment between the molecular backbone and the reconstructed semiconductor surface atoms.