A German group of scientists at the University of Tübingen has produced a Bose-Einstein condensate in a magnetic trap just a few microns in size. The trap consists of seven copper wires with diameters of only a few microns, through which a strong electric current flows. The magnetic field generated thereby holds the condensate in its spatial position and can also transport it along the ladder. This is reported in the journal Applied Physics Letters (issue of July 29). The magnetic surface trap for Bose-Einstein condensates produced by the scientists around Claus Zimmermann is the smallest of its kind so far: The copper wires used are arranged in a grid-like construction with a width of only a few micrometers and have a length of a few millimeters. The magnetic field generated by a strong current around the conductors can trap a Bose-Einstein condensate at a temperature just a few billionths of a degree above absolute zero. although the trap is only about 100 microns away from a base plate at room temperature.

Control over the current flowing through the conductors also allows the transport of condensate along the conductor assembly? in analogy to the optical waveguides in telecommunications. In further experiments, the researchers want to divide a condensate trapped in this way into several parts in order to carry out basic quantum experiments such as interference or teleportation.

The transport of Bose-Einstein condensates over long distances of up to several centimeters is a prerequisite for the production of atom lasers. The group of German Nobel laureate Wolfgang Ketterle at the Massachusetts Institute of Technology uses laser beams from optical tweezers to transport the condensates. However, these "optical" traps are much larger than the magnetic traps made by the scientists in Tübingen. These would therefore be particularly suitable for the production of integrated computer chips that work with Bose-Einstein condensates.

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