Contact-induced decoherence in nanodevices

摘要

The active region of a ballistic nanodevice is an open system, evolving nonunitarily due to the coupling with contacts. In this work, a simple theoretical description of the contact-induced decoherence is presented. The active region-contact interaction Hamiltonian introduced here captures the continuous spectrum of a nanostructure's active region and models carrier injection through the open boundaries. Markovian nonunitary evolution of the active region's many-body statistical operator is derived by coarse-graining of the exact non-Markovian short-time dynamics over the energy relaxation time of the bulk-like contacts. On the example of a resonant-tunneling diode, the nonequilibrium steady-state populations of the forward and backward propagating states are obtained at any given bias by using the Markovian evolution, and the resulting Ⅰ-Ⅴ curve exhibits all the prominent resonant features.