Yudu - Nanotimes May/June 2011

11-05 :: May/June 2011

nanotimes News in Brief

An ultra-cold cloud of atoms (yellow) is trapped in a magnetic trap and scanned across a nanostruc- tured surface. In “contact mode” a loss of atoms from the cloud can be measured, which depends on the surface topography. In the “dynamical mode” the frequency and amplitude of the cloud’s cen-tre-of-mass oscillation changes depending on the surface structure. Both methods allow the surface topography to be imaged.

pendicular to the surface, and observed how the frequency and size of these oscillations changed, depending on the topography of the nanostructured sample. In this way they were able to obtain a well resolved image of the surface. The researchers write that this method has an advantage because no atoms are loss from the cloud. This could be helpful in cases where atoms that are adsorbed on the sample might influence subsequent measurements.

The researchers conclude: “the extreme purity of the probe tip and quantum control over the atomic states in a Bose-Einstein condensate open up new possibili- ties of scanning probe microscopy with non-classical probe tips”. Beyond this, the researchers hope to develop new applications from the demonstrated coupling between ultra-cold quantum gases and nanostructures.

The study was done within the framework of the BMBF programme “NanoFutur” and in collaboration with several groups from the Center for Collective Quantum Phenomena (CQ) Tübingen, to which vari- ous research groups from the Faculty of Mathematics and Natural Science belong.

researchers, future improvements to the cold-atom scanning probe microscope could, in theory, increase the current resolution of about eight micrometres by a factor of a thousand.

The microscope also functions in the so-called “dynamical mode”. The researchers again created a Bose-Einstein condensate close to the nanotubes. They then allowed the condensate to oscillate per-

M. Gierling, P. Schneeweiss, G. Visanescu, P. Federsel, M. Häffner, D. P. Kern, T. E. Judd, A. Günther & J. Fortágh: Cold-atom scanning probe microscopy, In: Nature Nanotechnology AOP, May 29, 2011, DOI:10.1038/nna- no.2011.80:

http://dx.doi.org/10.1038/nnano.2011.80 http://www.physik.uni-tuebingen.de/fortagh/