In early 2017, a research collaboration led by Leibniz University Hannover launched the MAIUS-1 research rocket. During its flight, researchers studied Bose-Einstein condensation and matter wave optics in more than 100 unique experiments in space. Initial results of the mission have now been published in the renowned scientific journal "Nature".
In the paper, the authors describe their observations of the so-called Bose-Einstein condensation, an extreme state close to absolute zero, in which matter forms a macroscopic wave. "We achieved this with an even larger number of atoms than previously anticipated", says Maike Lachmann from the Institute of Quantum Optics at Leibniz University Hannover. The physicist is part of the team that planned and conducted the complex experiments. The large amount of atoms, as well as the substantial number of experiments was achieved by using an atom chip. Apart from producing Bose-Einstein condensates, researchers used the chip to guide, shape, and study the behaviour of occurring matter waves in free fall. Undisturbed by gravity, researchers conducted the experiments in space, subsequently comparing them with theoretical models. These models will enable them to optimise similar experiments on the ground in a more efficient manner. "We don''t want to launch 20 rockets", adds project leader Professor Ernst Rasel with a smile.
Only a small fraction of the results have been analysed and published so far. Presently, researchers focus on experiments regarding matter-wave interferometry, which measures how several waves overlap. Using interferometers with Bose-Einstein condensates in space is currently considered the most promising approach for measurements with unmatched accuracy, as the sensitivity of the measurement increases with the duration of the free fall. This procedure will enable researchers to measure the earth''s gravitational field with particular precision or to develop more accurate and satellite-independent navigation devices. The researchers also aim to verify fundamental questions of physics, such as Albert Einstein''s theory of relativity.
To date, this was considered unfeasible due to the complexity of the experiments and the extreme conditions prevailing during a rocket launch, as well as in space. "Therefore, these missions are met with a great deal of scepticism. Even most experts questioned whether our approach would be feasible or not", remembers Rasel. With the help of the atom chip, the research team succeeded in miniaturising the original experimental set-up, which normally fills a whole room, so that it fitted into the research rocket.
The NASA has also expressed interest in the published results. In May, the US space agency brought the Cold Atom Lab to the International Space Station (ISS) in order to conduct similar experiments there. "The NASA team is very interested in our findings. We are pleased about the collaboration", explains Rasel. The cooperation will now be expanded to include a joint project. Based on the findings of the MAIUS mission and the Cold Atom Lab, researchers will investigate ultracold atoms and Bose-Einstein condensates in long-term experiments on the ISS.
The new applications of atom chips are not only relevant for experiments in outer space; meanwhile, many sceptics are opening up to the idea of using atom chips and Bose-Einstein condensates for interferometry in quantum sensor technology. The latter are key elements for future technologies, such as earth observation by means of quantum gravimeters or gyroscopes.
The MAIUS-1 research rocket mission is a collaborative project led by Leibniz University Hannover. Also involved are Humboldt University and Ferdinand Braun research institute in Berlin, the Center of Applied Space Technology and Microgravity in Bremen, Johannes Gutenberg University Mainz, Hamburg University, Ulm University, Technische Universität Darmstadt, as well as the German Aerospace Center. The mission is funded by the Federal Ministry for Economic Affairs and Energy.
Background information on Bose-Einstein condensates
In order to produce a Bose-Einstein condensate, a cloud of atoms is gradually cooled down to almost absolute zero, so that the movement of the atoms virtually comes to a standstill. The atoms reach a state of aggregation that is difficult to imagine for non-physicists and which can no longer be described by using conventional parameters such as solid, liquid, or gaseous. They become indistinguishable and assume a macroscopic wave state similar to laser radiation in electromagnetic waves. Bose-Einstein condensates possess several extraordinary properties, such as superfluidity. In the 1920s, Nathan Bose and Albert Einstein theoretically predicted this property; however, it was only experimentally validated in cold gases in 1995.
Original publication
D. Becker, M. D. Lachmann, S. T. Seidel, H. Ahlers, A. N. Dinkelaker, J. Grosse, O. Hellmig, H. Müntinga, V. Schkolnik, T. Wendrich, A. Wenzlawski, B. Weps, R. Corgier, D. Lüdtke, T. Franz, N. Gaaloul, W. Herr, M. Popp, S. Amri, H. Duncker, M. Erbe, A. Kohfeldt, A. Kubelka-Lange, C. Braxmaier, E. Charron, W. Ertmer, M. Krutzik, C. Lämmerzahl, A. Peters, W. P. Schleich, K. Sengstock, R. Walser, A. Wicht, P. Windpassinger, E. M. Rasel: Space-borne Bose-Einstein condensation for precision interferometry, Nature 562, 391-395 (2018), DOI: https://doi.org/10.1038/s41586-018-0605-1
Note to editors:
For further information, please contact Professor Ernst M. Rasel, Institute of Quantum Optics at Leibniz University Hannover (Tel. +49 511 762 19203, Email rasel@iqo.uni-hannover.de).
