Sven Hensler

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We report on the generation of a Bose-Einstein condensate in a gas of chromium atoms, which have an exceptionally large magnetic dipole moment and therefore underlie anisotropic long-range interactions. The preparation of the chromium condensate requires novel cooling strategies that are adapted to its special electronic and magnetic properties. The final(More)
We have observed Feshbach resonances in collisions between ultracold 52Cr atoms. This is the first observation of collisional Feshbach resonances in an atomic species with more than one valence electron. The zero nuclear spin of 52Cr and thus the absence of a Fermi-contact interaction leads to regularly spaced resonance sequences. By comparing resonance(More)
We have realized a scheme for continuous loading of a magnetic trap (MT). Cr atoms are continuously captured and cooled in a magneto-optical trap (MOT). Optical pumping to a metastable state decouples atoms from the cooling light. Due to their high magnetic moment (6 μB), low-field seeking metastable atoms are trapped in the magnetic quadrupole field(More)
We have investigated both theoretically and experimentally dipolar relaxation in a gas of magnetically trapped chromium atoms. We have found that the large magnetic moment of 6μB results in an event rate coefficient for dipolar relaxation processes of up to 3.2 · 10−11 cm3s−1 at a magnetic field of 44G. We present a theoretical model based on pure dipolar(More)
We present a robust continuous optical loading scheme for a IoffePritchard (IP) type magnetic trap. Atoms are cooled and trapped in a modified magneto-optical trap (MOT) consisting of a conventional 2D-MOT in radial direction and an axial molasses. The radial magnetic field gradient needed for the operation of the 2D-MOT is provided by the IP trap. A small(More)
We have measured the deca-triplet s-wave scattering length of the bosonic chromium isotopes 52Cr and 50Cr. From the time constants for cross-dimensional thermalization in ultracold atomic samples, we have determined the magnitudes |a(52Cr)|=(170+/-39)a(0) and |a(50Cr)|=(40+/-15)a(0), where a(0)=0.053 nm. By measuring the rethermalization rate of 52Cr over a(More)
We realize a combined trap for bosonic chromium (Cr) and rubidium (Rb) atoms. First experiments focus on exploring a suitable loading scheme for the combined trap and on studies of new trap loss mechanisms originating from simultaneous trapping of two species. By comparing the trap loss from the Rb magneto-optical trap (MOT) in absence and presence of(More)
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