Optically driven quantum networks: Applications in molecular electronics

Progress in nanostructuring tends to provide us with synthetic structures for which, for example, energy or time scales can be adjusted in such a way that quantum systems with unusual physical properties emerge. The challenge of molecular electronics is to make these properties represent computer functions. We investigate a quantum network model consisting of a modular array of localized few-level subsystems. When driven optically, a diagonal (energy renormalizing) interaction among these subsystems is shown to lead to a complex stochastic dynamics, which may be interpreted as a highly parallel Monte-Carlo-type simulation ‘‘programmed’’ by the external light field. A first application is demonstrated in terms of a two-dimensional kinetic Ising model with J(${\mathbf{R}}_{\mathit{n}}$-${\mathbf{R}}_{\mathit{m}}$)∼‖${\mathbf{R}}_{\mathit{n}}$-${\mathbf{R}}_{\mathit{m}}$${\mathrm{\Vert }}^{\mathrm{-}3}$. In another application the nonlocal nonlinear optical properties are exploited in specific pump and probe scenarios: Under certain conditions simple image processing tasks are performed. A possible realization of such quantum network models by an array of charge-transfer quantum dots is discussed.