Related papers: Precise Feshbach resonance spectroscopy using tigh…
We use the dressed potentials obtained in the adiabatic representation of two coupled channels to calculate s-wave Feshbach resonances in a 3D spherically symmetric potential with an open channel interacting with a closed channel. Analytic…
We report on a two-particle matter wave interferometer realized with pairs of trapped 87Rb atoms. Each pair of atoms is confined at a single site of an optical lattice potential. The interferometer is realized by first creating a coherent…
In the absence of inelastic scattering, Feshbach resonances produce poles in scattering lengths and very large peaks in elastic cross sections. However, inelastic scattering removes the poles. Whenever the resonant state is coupled…
Experimental studies with ultracold atoms have enabled major breakthroughs in understanding three-body physics, historically a fundamental yet challenging problem. This is because the interactions among ultracold atoms can be precisely…
We experimentally demonstrate optical spectroscopy of magnetically trapped atoms on an atom chip. High resolution optical spectra of individual trapped clouds are recorded within a few hundred milliseconds. Detection sensitivities close to…
We produce Bose-Einstein condensates of two different species, $^{87}$Rb and $^{41}$K, in an optical dipole trap in proximity of interspecies Feshbach resonances. We discover and characterize two Feshbach resonances, located around 35 and…
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…
In Penning traps electromagnetic forces are used to confine charged particles under well-controlled conditions for virtually unlimited time. Sensitive detection methods have been developed to allow observation of single stored ions. Various…
We report on observations and modeling of interspecies magnetic Feshbach resonances in dilute ultracold mixtures of open-shell alkali-metal $^6$Li and closed-shell $^{173}$Yb atoms with temperatures just above quantum degeneracy for both…
We discuss the atom-atom scattering problem across a Feshbach resonance in a two-dimensional dilute Bose gas at zero temperature, in the limit where the s-wave scattering length exceeds the width of the vertical confinement. We determine a…
We present an analytic model to calculate the atomic scattering length near a Feshbach resonance from data on the molecular binding energy. Our approach considers finite-range square-well potentials and can be applied near broad, narrow, or…
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…
In an atomic gas near a Feshbach resonance, the energy of two colliding atoms is close to the energy of a bound state, i.e., a molecular state, in a closed channel that is coupled to the incoming open channel. Due to the different spin…
We discuss a recently demonstrated type of microwave spectroscopy of trapped ultra-cold atoms known as "echo spectroscopy" [M.F. Andersen et. al., Phys. Rev. Lett., in press (2002)]. Echo spectroscopy can serve as an extremely sensitive…
We have observed condensation of fermionic atom pairs in the BCS-BEC crossover regime. A trapped gas of fermionic 40K atoms is evaporatively cooled to quantum degeneracy and then a magnetic-field Feshbach resonance is used to control the…
In recent experiments on Na Bose-Einstein condensates [S. Inouye et al, Nature 392, 151 (1998); J. Stenger et al, Phys. Rev. Lett. 82, 2422 (1999)], large loss rates were observed when a time-varying magnetic field was used to tune a…
We use laser light near-resonant with a molecular bound-to-bound transition to control a magnetic Feshbach resonance in ultracold Fermi gases of $^{40}$K atoms. The spectrum of excited molecular states is measured by applying a laser field…
We model the formation of stable heteronuclear molecules via pulsed Raman photoassociation of a two-component Bose-Einstein condensate near a strong Feshbach resonance, for both counterintuitive and intuitive pulse sequencing. Compared to…
We present 17 experimentally confirmed Feshbach resonances in optically trapped 85Rb. Seven of the resonances are in the ground-state channel (f,m_f) = (2,+2)+(2,+2), and nine are in the excited-state channel (2,-2)+(2,-2). We find a wide…
It is demonstrated that elastic collisions of ultracold atoms forming a heteronuclear collision complex can be manipulated by laboratory practicable dc electric fields. The mechanism of electric field control is based on the interaction of…