J. Stuhler

Bose-Einstein Condensation of Chromium

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 step to reach quantum degeneracy is forced evaporative cooling of 52Cr atoms within a crossed optical dipole trap. At a critical temperature of T(c) approximately 700 nK, we observe Bose-Einstein condensation by the appearance of a two-component velocity distribution. We are able to produce almost pure condensates with more than 50,000 condensed 52Cr atoms.

Observation of Dipole-Dipole Interaction in a Degenerate Quantum Gas

We have investigated the expansion of a Bose-Einstein condensate of strongly magnetic chromium atoms. The long-range and anisotropic magnetic dipole-dipole interaction leads to an anisotropic deformation of the expanding chromium condensate which depends on the orientation of the atomic dipole moments. Our measurements are consistent with the theory of dipolar quantum gases and show that a chromium condensate is an excellent model system to study dipolar interactions in such gases.

Observation of Feshbach Resonances in an Ultracold Gas of 52Cr

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 positions with multichannel scattering calculations we determine the s-wave scattering length of the lowest (2S+1)Sigma(+)(g) potentials to be 112(14) a(0), 58(6) a(0), and -7(20) a(0) for S=6, 4, and 2, respectively, where a(0)=0.0529 nm.

Continuous loading of a magnetic trap

We have realized a scheme for continuous loading of a magnetic trap (MT).

Expansion dynamics of a dipolar Bose-Einstein condensate

{}^{52}\mathrm{Cr}

Demagnetization cooling of a gas

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

Nanometerscale lithography with chromium atoms using light forces

(6 {\ensuremath{\mu}}_{B}),

Analog+digital phase and frequency detector for phase locking of diode lasers

low-field seeking metastable atoms are trapped in the magnetic quadrupole field provided by the MOT. Limited by inelastic collisions between atoms in the MOT and in the MT, we load

Development of a strontium optical lattice clock for the SOC mission on the ISS

{10}^{8}

The space optical clocks project: Development of high-performance transportable and breadboard optical clocks and advanced subsystems

metastable atoms at a rate of