Condensed Matter Theory   Universität Basel
Dr. Jörg Lehmann

Molecular wires acting as coherent quantum ratchets

J. Lehmann, S. Kohler, P. Hänggi, and A. Nitzan

Phys. Rev. Lett. 88, 228305 (2002)

Preprint: arXiv:cond-mat/0201480

The effect of laser fields on electron transport through a molecular wire weakly coupled to two leads is investigated. The molecular wire acts as a coherent quantum ratchet if the molecule is composed of periodically arranged, asymmetric chemical groups. This setup presents a quantum rectifier with a finite dc response in the absence of a static bias. The nonlinear current is evaluated in closed form within the Floquet basis of the isolated, driven wire. The current response reveals multiple current reversals together with a nonlinear dependence on the amplitude and the frequency of the laser field. The current saturates for long wires at a nonzero value, while it may change sign upon decreasing its length.

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Uni Basel » Department of Physics » Condensed Matter Theory
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