Scientists see fireworks from atoms at ultra-low temperatures November 7, 2017 by Louise Lerner Please Register or Log in to view the hidden image! Jets of atoms shoot off together like fireworks from a central disc in a new quantum phenomenon discovered by UChicago scientists (color added for illustration). Credit: Cheng et al./University of Chicago Scientists aren't normally treated to fireworks when they discover something about the universe. But a team of University of Chicago researchers found a show waiting for them at the atomic level—along with a new form of quantum behavior. "This is a very fundamental behavior that we have never been seen before; it was a great surprise to us," said study author and professor of physics Cheng Chin. Published Nov. 6 in Nature, the research details a curious phenomenon—seen in what was thought to be a well-understood system—that may someday be useful in quantum technology applications. Read more at: https://phys.org/news/2017-11-scientists-fireworks-atoms-ultra-low-temperatures.html#jCp >>>>>>>>>>>>>>>>>>>>>>>>> https://www.nature.com/articles/nature24272 Collective emission of matter-wave jets from driven Bose–Einstein condensates Abstract Scattering is used to probe matter and its interactions in all areas of physics. In ultracold atomic gases, control over pairwise interactions enables us to investigate scattering in quantum many-body systems. Previous experiments on colliding Bose–Einstein condensates have revealed matter–wave interference, haloes of scattered atoms, four-wave mixing and correlations between counter-propagating pairs. However, a regime with strong stimulation of spontaneous collisions analogous to superradiance has proved elusive. In this regime, the collisions rapidly produce highly correlated states with macroscopic population. Here we find that runaway stimulated collisions in Bose–Einstein condensates with periodically modulated interaction strength cause the collective emission of matter-wave jets that resemble fireworks. Jets appear only above a threshold modulation amplitude and their correlations are invariant even when the number of ejected atoms grows exponentially. Hence, we show that the structures and atom occupancies of the jets stem from the quantum fluctuations of the condensate. Our findings demonstrate the conditions required for runaway stimulated collisions and reveal the quantum nature of matter-wave emission.
