QUANTUS Bose-Einstein Condensation in Microgravity
 

Scientists develop a robust apparatus to create matter waves

Scientists from the QUANTUS project (Quantengase unter Schwerelosigkeit) have succeeded in developing an apparatus to create Bose-Einstein condensates under conditions of weightlessness. According to the latest issue of the journal “Science”, this apparatus enables scientists to generate an atomic wave packet in free fall and follow its expansion to a millimetre-sized object over a period of one second. With this, the scientists have developed a promising and very robust source of matter waves, which can in future be applied in high precision measuring devices, so-called atom interferometers. The device was tested in the 146 meter high drop tower at ZARM (Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation) in Bremen. With seven German and two international institutions as participants, QUANTUS is coordinated at the Institute of Quantum Optics at Leibniz Universität Hannover.

Interferometry with matter waves opens up whole new approaches for precision measurements in the fields of metrology and fundamental physics. Bose-Einstein condensates are a promising source for interferometry. Atoms in this state lose their identity and can be described by a single wave function. This state of matter shows a great similarity to laser and distinguishes itself by high coherence and quality. Sources of Bose-Einstein condensates are therefore often described as atom lasers. Atom lasers are an important key to improving the sensitivity and precision of future atom interferometers in extended free fall. The sensitivity of the interferometers increases quadratically to the duration of the free fall.

In the experiments in the Bremen drop tower, scientists succeeded in creating a macroscopic wave packet with an extension of several millimetres and in following its evolution over a period of one second. Thanks to its laser-like properties, this matter-wave packet, in which more than 10,000 atoms were delocalised, could be depicted with the help of its shadow. With more than 180 drops, QUANTUS is the most complex and at the same time most stable experiment that has ever been conducted in the Bremen drop tower. The results of the research form the foundation for future experiments where the evolution of such a quantum object is to be observed with the aid of an atom interferometer and its potential as an inertial sensor is to be investigated.

Future areas of application of atom interferometers range from interdisciplinary applications in measuring the Earth’s gravity field to quantum tests of the weak equivalence principle. The weak equivalence principle is one of the cornerstones of general relativity theory. As far as matter waves are concerned, the weak equivalence principle states that in a gravitational field, matter waves fall in the same way, independent of their composition. Tests of the equivalence principle with quantum objects is thus a promising approach to checking Einstein’s relativity theory with the help of Bose-Einstein condensates.

QUANTUS is a joint project of German and European research facilities, including Leibniz Universität Hannover, Universität Ulm, Humboldt Universität zu Berlin, Universität Hamburg, the Max Planck Institute for Quantum Optics, Universität Darmstadt, Ecole Normale Superieure de Paris, Midlands Ultracold Atom Research Centre in Birmingham, the German Aerospace Centre (DLR) and the Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation (ZARM) in Bremen. The project was financed by the German Space Agency (DLR) with funds from the Ministry of Economics and Technology and by the Cluster of Excellence QUEST (Centre for Quantum Engineering and Space-Time Research) at Leibniz Universität Hannover.
The article "Bose-Einstein Condensation in Microgravity” appeared on 18th June 2010 in the journal Science.

For further information on QUANTUS see: www.iqo.uni-hannover.de/quantus.html

For further information on QUEST see: www.quest.uni-hannover.de

Meldung vom 26.08.2010