Control of molecular processes in contact with an environment – CoMoc

1- Scientific background and objectives The control of molecular processes in contact with an environment, such as the trapping and handling of molecules inside nanocages, opens important prospects. Among many intended applications we can highlight the design of nanomachines, miniaturized classical circuits, quantum computing, opto-electronics, and chemical sensors. Combining the complementary skills of the partners, this project aims to control theoretically and experimentally molecular processes by laser pulses, when the molecules are in contact with two types of environment: a collisional environment in the gas phase and a nanoporous solid adsorbing and trapping the molecules. Quantum systems in contact with an environment display important dissipative effects, which manifest e.g. as decoherence. Among the different types of decoherence effects, the most relevant ones in our context are the loss of phase coherence and incoherent population transfers. The control of such decohering processes involve a rich and complex dynamics --even for simple models-- which has been only little studied. Strategies of control of the rotational degrees of freedom in a collisional environment will be elaborated and tested experimentally, by combined short femtosecond and adiabatic nanosecond lasers. The field induced modifications of the collision processes will be studied, with the aim of inducing new types of dynamic effects hitherto unexplored. The control of the rotation of the molecules inside nanoporous solids (zeolites) will be studied theoretically and experimentally, with their consequences on the transport and thermodynamic properties. Effects such as the laser-controlled adsorption on surfaces of zeolites will be researched, with applications to chemical sensors. 2- Project plan and methodology. This project is based on combining the expertise of several multidisciplinary teams, in theoretical and experimental Physics, in Chemistry and in Mathematics: The Physics group in Dijon of the Institut Carnot de Bourgogne (ICB) involved in this project has a theoretical and experimental expertise in the control of molecular processes in the gas phase, such as the laser-induced alignment of molecules. The Chemistry group of Dijon, whose laboratory has very recently merged with the physics laboratory to form the ICB, is experienced in the field of molecular interactions with nanoporous solids and its dynamics. The group of Besançon has an expertise with atomic and molecular collisions. Specific nanoporous zeolites will be produced and characterized by the Mulhouse partner, to be used in the experiments of control by laser in Dijon. The fourth partner is a group of mathematicians of Dijon who developed general tools of optimal control techniques, that will be adapted to dissipative quantum processes. Robust strategies with respect to an imperfect knowledge (i) of the model of the quantum system and (ii) of the interaction with the field and the environment will be researched in the framework of the theory of geometric optimal control, and using adiabatic techniques as well. Aligning molecules efficiently with intense laser pulses in a collisional environment will allow us to make a spectroscopic study of the collisional parameters at relatively low temperatures, in particular the collisional relaxation parameters which have not been accessible with current techniques. This will allow us to set up, and validate experimentally, precise models of the effects of the collisional environment, which are essential for the design of an efficient control by lasers of the dissipative dynamics. Handling molecules in zeolites by laser pulses will be conducted experimentally, guided by our joint theoretical expertise using a combination of classical molecular dynamics for the environment aspect and quantum calculations for the molecular reactivity. In both types of environment, our original techniques of non-destructive measurement of the alignment developed in a non-dissipative context will be used and extended. 3- Expected results The control of molecular processes to design nanomachines can be functional if the molecules can be adsorbed or trapped in a solid, while keeping some degrees of freedom, such as rotation and translation. A control of such dissipative quantum systems by lasers is an emerging science promising to a wide range of applications in the quest for miniaturization, with particular hopes to find a way to preserve the coherence of the quantum systems. Our project is based on the control of physicochemical systems that are complex, but each of the basic ingredients is well defined. Combining the expertise of each group will allow us to make progress in this direction.