In the past, many studies have focused on studying the interactions of particles close to each other. "In contrast, we are working with strongly magnetic atoms, which can also interact over long distances," explains co-author Manfred Mark. For their experiment the physicists prepared an ultracold gas of erbium atoms – a Bose-Einstein condensate – in a three dimensional optical lattice of laser beams. In this simulated 'crystal', the particles were arranged similar to eggs in a carton. The distance between the particles was seven times their wave function. "By using a magnetic field we are able to directly change the direction of the mini magnets and precisely control how the particles interact – attracting or repelling each other," says first author Simon Baier.
"Our collaboration with Zoller, Cai Zi and Mikhail Baranov was indispensable for understanding our measurement results comprehensively," underlines Francesca Ferlaino. "Our work is another important step towards a better understanding of quantum matter of dipolar atoms because their nature is a lot more complex than the atoms used for ultracold quantum gases in other experiments."
The research results lay the groundwork for future studies of novel exotic many-body quantum phases like 'checkerboard' and 'stripe phases', which might be created by long-range interactions. "Our study opens the door to finally being able to measure these type of phases," hopes Simon Baier. "In principle, we should be able to do this in our experiments as well, but we will need to cool the atoms even further from currently 70nK to approximately 2nK."
The research is supported by the Austrian Science Fund FWF and the European Research Council ERC, among others.
(© University of Innsbruck, AcademiaNet)