Hannover 2013 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 30: Quantum effects

Q 30.1: Group Report

Tuesday, March 19, 2013, 14:00–14:30, F 128

Coherent delocalisation and transport efficiency in disordered, noisy networks — •Federico Levi, Björn Witt, and Florian Mintert — Freiburg Institute for Advanced Studies (FRIAS), Albert-Ludwigs-Universität Freiburg, Alberstr.19, 79104 Freiburg

We investigate the role of quantum coherence in excitation transport across noisy, disordered networks. Our goal is to understand the impact of constructive multi-path interference on the transport efficiency. Necessary condition for multi-path interference is the coherent delocalisation of the excitation over multiple network sites; to characterise the spatial extent of this delocalisation we introduce a notion of coherence length for discrete systems and present techniques to characterise it for mixed states. More specifically we construct a hierarchy of criteria which provide a sufficient condition for coherent delocalisation of an excitation over a given number of sites. With these tools we consider in particular the case of networks driven incoherently by a thermal light field, for which we quantify the excitation flux in a stationary state. Although those states are strongly mixed we can verify enhanced coherent delocalisation in networks that yield highly efficient transport.