Microscopic Modeling of Solid-State Quantum Devices

Semiconductor-based optoelectronic quantum devices are new-generation nanosystems in which the carrier dynamics shows purely quantum-mechanical or phase-coherence phenomena. The latter result from a proper combination of quantum-confinement effects and ultrafast intra- and/or interband optical excitations. A cohesive theoretical treatment of transport versus optical properties is both the key-tool for the microscopic investigation of such nanosystems and the essential prerequisite for the modeling and optimization of customized device designs. Diverse simulation strategies, ranging from semiclassical to fully quantum-mechanical approaches, may be devised each with its own validity limits. More specifically, one has to distinguish between ultrafast and steady-state properties of the system, in the linear as well as in the non-linear response regime, thus identifying the corresponding levels of description. The most severe problem in quantum-device modelling is the microscopic treatment of a quantum system with spatial open boundaries. Any solid state electronic nanodevice is an intrinsically open quantum system, exchanging both energy with the host material and carriers with connected reservoirs. Its out-of-equilibrium behavior is determined by a complex interplay between electronic dissipation and decoherence induced by inelastic processes within the device, as well as by the coupling of the latter to metallic electrodes.