Hannover 2013 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 56: Poster III
Q 56.51: Poster
Donnerstag, 21. März 2013, 16:00–18:30, Empore Lichthof
Controlled engineering of extended states in disordered systems — •Alberto Rodriguez1, Arunava Chakrabarti2, and Rudolf A. Römer3 — 1Physikalisches Institut, Albert-Ludwigs Universität Freiburg,Hermann-Herder Strasse 3, D-79104, Freiburg, Germany — 2Department of Physics, University of Kalyani, Kalyani, West Bengal-741 235, India — 3Department of Physics and Centre for Scientific Computing, University of Warwick, Coventry, CV4 7AL, United Kingdom
We describe how to engineer wavefunction delocalization in disordered systems modelled by tight-binding Hamiltonians in d>1 dimensions. We show analytically that a simple product structure for the random onsite potential energies, together with suitably chosen hopping strengths, allows a resonant scattering process leading to ballistic transport along one direction, and a controlled coexistence of extended Bloch states and anisotropically localized states in the spectrum. We demonstrate that these features persist in the thermodynamic limit for a continuous range of the system parameters. Numerical results support these findings and highlight the robustness of the extended regime with respect to deviations from the exact resonance condition for finite systems. The localization and transport properties of the system can be engineered almost at will and independently in each direction. This study gives rise to the possibility of designing disordered potentials that work as switching devices and band-pass filters for quantum waves, such as matter waves in optical lattices. [Phys. Rev. B 86, 085119 (2012)]