Erlangen 2018 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 18: Quantum Gases (Bosons) II
Q 18.8: Talk
Monday, March 5, 2018, 15:45–16:00, K 2.020
Excitation transport in networks with an energy gradient, modelled after photosynthetic systems — Hlér Kristjánsson1,2, Jonathan Brugger1, Gabriel Dufour1, •Christian Scheppach1, and Andreas Buchleitner1 — 1Physikalisches Institut, Albert-Ludwigs-Universität Freiburg i. Br., Germany — 2Department of Physics, Imperial College London, U.K.
In photosynthesis, a photon is absorbed by a light-harvesting antenna, and the energy excitation is transported along several chlorophylls to a reaction centre. Recently, there has been much discussion whether a quantum mechanically coherent description of the transport process is necessary to understand it. This motivates our theoretical study of excitation transport through networks of two-level systems. To account for the limited experimental knowledge of the parameters, as well as the natural variability in biological systems, we study statistical ensembles of networks and look for design principles ensuring efficient transport. When the input and output site of the network have the same energy, ``centrosymmetry'' of the Hamiltonian and a ``dominant doublet'' are design principles enhancing the probability of efficient transport. In the more realistic case of an energy difference between the input and output site, external vibrations can bridge the gap, and are treated with Floquet theory. Here, one can demand a ``dominant Floquet doublet'', and ``anticentrosymmetry'' can be imposed in the extended Floquet-Hilbert space.