Related papers: Controlling spin motion and interactions in a one-…
Combining the measured binding energies of four of the most weakly bound rovibrational levels of the $^{87}$Rb$_2$ molecule with the results of two other recent high-precision rubidium experiments, we obtain exceptionally strong constraints…
We study a spin-polarized degenerate Fermi gas interacting via a p-wave Feshbach resonance in an optical lattice. The strong confinement available in this system allows us to realize one- and two-dimensional gases and therefore to restrict…
Inelastic collision rates for ultracold $^{85}$Rb atoms in the F=2 m$_{f}$=-2 state have been measured as a function of magnetic field. Dramatic change in the vicinity of a Feshbach resonance at 155 G was observed. Similar to the elastic…
Spatio-temporal scaling dynamics connected to non-thermal fixed points has been suggested as a universal framework to describe the relaxation of isolated far-from-equilibrium systems. Experimental studies in weakly-interacting cold atom…
A Feshbach resonance in the s-wave scattering length occurs if the energy of the two atoms in the incoming open channel is close to the energy of a bound state in a coupled closed channel. Starting from the microscopic hamiltonian that…
We consider a one-dimensional gas of cold atoms with strong contact interactions and construct an effective spin-chain Hamiltonian for a two-component system. The resulting Heisenberg spin model can be engineered by manipulating the shape…
This PhD tutorial article is a review of our experiments on heteronuclear quantum gas mixtures at the University of Hamburg. We introduce basic properties of trapped Fermi-Bose mixtures and demonstrate the achievement of large quantum…
Low dimensional behavior of two ultra-cold atoms trapped in two-and one-dimensional waveguides is investigated in the vicinity of a magnetic Feshbach resonance. A quantitative two-channel model for the Feshbach mechanism is used allowing an…
We have loaded an ultracold gas of fermionic atoms into a far off resonance optical dipole trap and precisely controlled the spin composition of the trapped gas. We have measured a magnetic-field Feshbach resonance between atoms in the two…
We have measured a p-wave Feshbach resonance in a single-component, ultracold Fermi gas of potassium atoms. We have used this resonance to enhance the normally suppressed p-wave collision cross-section to values larger than the background…
We predict the presence of several magnetic Feshbach resonances in selected Zeeman sublevels of the isotopic pairs K(40)-Rb(87) and K(41)-Rb(87) at magnetic fields up to 1000 G. Positions and widths are determined combining a new…
We use a two-channel model to investigate an interacting Bose gas across a narrow Feshbach resonance within a field path integral approach. The ground state properties show strong deviation from that of a broad Feshbach resonance or a…
We theoretically investigate the equation of state and Tan's contact of a non-degenerate three dimensional Bose gas near a broad Feshbach resonance, within the framework of large-$N$ expansion. Our results agree with the path-integral Monte…
Quantum gas systems provide a unique experimental platform to study a fundamental paradigm of quantum many-body physics: the crossover between Bose-Einstein condensed (BEC) molecular pairs and Bardeen Cooper Schrieffer (BCS) superfluidity.…
Magnetic Feshbach resonances play a central role in experimental research of atomic gases at ultracold temperatures, as they allow one to control the microscopic interactions between ultracold atoms by tuning an applied magnetic field.…
We investigate magnetically tunable Feshbach resonances between ultracold europium atoms and between europium and alkali-metal atoms using multichannel quantum scattering calculations. For ultracold gases of europium atoms both homonuclear…
We report on the observation of controllable spatial separation in a dual-species Bose-Einstein condensate (BEC) with $^{85}$Rb and $^{87}$Rb. Interparticle interactions between the different components can change the miscibility of the two…
We present a theory of spin waves in a non-condensed gas of spin-1 bosons: providing both analytic calculations of the linear theory, and full numerical simulations of the nonlinear response. We highlight the role of spin-dependent contact…
Revealing the quantum properties of matter requires a high degree of experimental control accompanied by a profound theoretical understanding. At ultracold temperatures, quantities that appear continuous in everyday life, such as the…
We calculate the critical temperature for Bose-Einstein condensation in a gas of bosonic atoms across a Feshbach resonance, and show how medium effects at negative scattering lengths give rise to pairs reminiscent of the ones responsible…