Berlin 2014 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 70: Quantum gases: Lattices IV

Q 70.8: Vortrag

Freitag, 21. März 2014, 18:15–18:30, UDL HS2002

Veselago lensing with ultracold atoms in an optical lattice — •Martin Leder, Christopher Grossert, and Martin Weitz — Institute of Applied Physics, University of Bonn, Germany

In 1968 Veselago pointed out that electromagnetic wave theory allows for materials with a negative index of refraction, in which most known optical phenomena would be reversed [1]. A slab of such a material can focus light by negative refraction, an imaging technique strikingly different from conventional positive refractive index optics, where curved surfaces bend the rays to form an image of an object. Veselago lensing has also been proposed for electrons in graphene material [2] and cold atoms in dark state media [3], but so far no experimental realization has been reported. Here we demonstrate Veselago lensing for matter waves, using ultracold atoms in an optical lattice. A relativistic, i.e. photon-like, dispersion relation for rubidium atoms is realized with a bichromatic optical lattice potential. We rely on a Raman π-pulse technique to transfer atoms between two different branches of the dispersion relation, converting a spatially diverging atom flow to a spatially converging one, and resulting in a focusing completely analogous to the effect described by Veselago for light waves. We study negative refraction and Veselago lensing both in a one-dimensional geometry and perform a ray-tracing simulation of a two-dimensional Veselago lens.

[1] Veselago, V.G., Sov. Phys. Usp. 10, 509 (1968).

[2] Cheianov, V.V. et al., Science 315, 1252 (2007).

[3] Juzeliūnas, G. et al., Phys. Rev. A 77, 011802 (2008).