Molecules in a complex environment
I explore the interface between molecules and condensed matter systems. The extended system forms a nanostructured environment that modifies molecular properties. Usually, the environment is considered as an uncontrollable complex system characterized by a minimal set of phenomenological parameters. I am interested in shifting this paradigm towards a “functionalized environment,” which can be optimized and tuned for specific applications.
Exciton dynamics in J-aggregates
Many fluorescent dyes can assemble in short-range-ordered structures, J-aggregates. J-aggregates are characterized by a strong intermolecular coupling which significantly modifies their spectra as compared to spectra of non-interacting molecules. Excitons in J-aggregates are delocalized over tens of molecules and possess a rather high mobility as compared to other organic materials. I study exciton transport in such systems. How exciton localization/delocalization affects the exciton-exciton interaction? How important are the effects of quantum coherence in the exciton transport? Can we observe correlated exciton dynamics in J-aggregates?
Entanglement of a quantum system with its environment, eventually, leads to the loss of quantum coherence effects. Can we control this process? It has been demonstrated decades ago that time evolution of spin systems can be reversed. But what are the natural boundaries for time reversibility in open quantum systems? I explore these limitations studying evolution of spin systems.
Coherent control of quantum systems
Single quantum systems can be controlled coherently by external fields. In this project I study the methods of adiabatic optical control for the quantum system dynamics. Adiabatically varying fields are less sensitive to imperfections in the control pulses. Thus, precise operations can be designed. For instance, spins in single or coupled semiconductor quantum dots can be rotated coherently using adiabatic optical pulses. However, to minimize free-evolution decohenrece the operation should be fast. How fast the adiabatic control can be? How it interferes with decoherence?