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Quantum field theory approach to quantum transport in macromolecules

Joint ECT*-BEC-LISC seminars
Pietro Faccioli (LISC)
06 Mar 2013 - 14:00
Villa Tambosi 2nd Floor, Seminar Room

The investigation of the quantum propagation of electrons, holes or excitons across biological or organic macromolecules is a fast growing field, due to its many implications in biophysics (e.g. in the understanding of DNA repair processes, and of light-harvesting and energy transfer mechanisms in photo-synthetic systems) and its possible applications in nano-bioelectronics (designing (bio-)polymer based electronic devices such as bio-transistors and molecular quantum wires).
In order to describe these processes, one needs to account for the coupling of the propagating quantum excitation with the molecular vibrational modes and with surrounding heat-bath, which provides fluctuation-dissipation effects. The development of computationally viable microscopic theories, in which these effects are rigorously and consistently taken into account remains an open challenge.
In this talk, we present our recent development of a rigorous framework which is based on the Feynman-Venron path integral formalism for open quantum systems. By resorting on quantum fields to describe the quantum excitation dynamics and taking the classical limit for the molecular degrees of freedom, we are able to analytically perform the path integral over the heat-bath and olecular vibrations. As a result, the matrix elements of the density matrix are described by an effective field theory for the quantum degrees of freedom only, and can be computed in perturbation theory, using appropriate Feynman rules. Extension to non-perturbative approximative approaches is alsodiscussed. As an illustrative example, we will apply this approach to study quantum transport and de-coherence in a simple model for an organic conjugate polymer.