20 research outputs found
Fast production of Bose-Einstein condensates of metastable Helium
We report on the Bose-Einstein condensation of metastable Helium-4 atoms
using a hybrid approach, consisting of a magnetic quadrupole and a crossed
optical dipole trap. In our setup we cross the phase transition with 2x10^6
atoms, and we obtain pure condensates of 5x10^5 atoms in the optical trap. This
novel approach to cooling Helium-4 provides enhanced cycle stability, large
optical access to the atoms and results in production of a condensate every 6
seconds - a factor 3 faster than the state-of-the-art. This speed-up will
dramatically reduce the data acquisition time needed for the measurement of
many particle correlations, made possible by the ability of metastable Helium
to be detected individually
Contactless nonlinear optics mediated by long-range Rydberg interactions
In conventional nonlinear optics, linear quantum optics1, 2, and cavity quantum electrodynamics3, 4 to create effective photon–photon interactions photons must have, at one time, interacted with matter inside a common medium. In contrast, in Rydberg quantum optics5, 6, 7, 8, 9, 10, optical photons are coherently and reversibly mapped onto collective atomic Rydberg excitations11, giving rise to dipole-mediated effective photon–photon interactions that are long range12, 13. Consequently, a spatial overlap between the light modes is no longer required. We demonstrate such a contactless coupling between photons stored as collective Rydberg excitations in spatially separate optical media. The potential induced by each photon modifies the retrieval mode of its neighbour7, 9, 14, 15, leading to correlations between them. We measure these correlations as a function of interaction strength, distance and storage time, demonstrating an effective interaction between photons separated by 15 times their wavelength. Contactless effective photon–photon interactions16 are relevant for scalable multichannel photonic devices15, 17 and the study of strongly correlated many-body dynamics using light18