Study of Open Systems with Molecules in Isotropic Liquids

We are interested in dynamics of a system in an environment, or an open system. Such phenomena like {\it crossover} from Markovian to non-Markovian relaxation and {\it thermal equilibration} are of our interest. Open systems have experimentally been studied with ultra cold atoms, ions in traps, optics, and cold electric circuits because well isolated systems can be prepared here and thus the effects of environments can be controlled. We point out that some molecules solved in isotropic liquid are well isolated and thus they can also be employed for studying open systems in Nuclear Magnetic Resonance (NMR) experiments. First, we provide a short review on related phenomena of open systems that helps readers to understand our motivation. We, then, present two experiments as examples of our approach with molecules in isotropic liquids. Crossover from Markovian to non-Markovian relaxation was realized in one NMR experiment, while relaxation like phenomena were observed in approximately isolated systems in the other.