AC-Stark shift and photoionization of Rydberg atoms in an optical dipole trap

2010

We have measured the AC-Stark shift of the $14D_{5/2}$ Rydberg state of rubidium 87 in an optical dipole trap formed by a focussed CO$_2$-laser. We find good quantitative agreement with the model of a free electron experiencing a ponderomotive potential in the light field. In order to reproduce the observed spectra we take into account the broadening of the Rydberg state due to photoionization. The extracted cross-section is compatible with previous measurements on neighboring Rydberg states.

Transport of Strongly Correlated Bosons in an Optical Lattice

2019

A Scanning Electron Microscope for Ultracold Atoms

2006

We propose a new technique for the detection of single atoms in ultracold quantum gases. The technique is based on scanning electron microscopy and employs the electron impact ionization of trapped atoms with a focussed electron probe. Subsequent detection of the resulting ions allows for the reconstruction of the atoms position. This technique is expected to achieve a much better spatial resolution compared to any optical detection method. In combination with the sensitivity to single atoms, it makes new in situ measurements of atomic correlations possible. The detection principle is also well suited for the addressing of individual sites in optical lattices.

Dissipation-induced coherent structures in Bose-Einstein condensates.

2008

We discuss how to engineer the phase and amplitude of a complex order parameter using localized dissipative perturbations. Our results are applied to generate and control various types of atomic nonlinear matter waves (solitons) by means of localized dissipative defects.

Experimental demonstration of single-site addressability in a two-dimensional optical lattice

2009

We demonstrate single site addressability in a two-dimensional optical lattice with 600 nm lattice spacing. After loading a Bose-Einstein condensate in the lattice potential we use a focused electron beam to remove atoms from selected sites. The patterned structure is subsequently imaged by means of scanning electron microscopy. This technique allows us to create arbitrary patterns of mesoscopic atomic ensembles. We find that the patterns are remarkably stable against tunneling diffusion. Such micro-engineered quantum gases are a versatile resource for applications in quantum simulation, quantum optics and quantum information processing with neutral atoms.

High-resolution scanning electron microscopy of an ultracold quantum gas

2008

Our knowledge of ultracold quantum gases is strongly influenced by our ability to probe these objects. In situ imaging combined with single-atom sensitivity is an especially appealing scenario, as it can provide direct information on the structure and the correlations of such systems. For a precise characterization a high spatial resolution is mandatory. In particular, the perspective to study quantum gases in optical lattices makes a resolution well below one micrometre highly desirable. Here, we report on a novel microscopy technique, which is based on scanning electron microscopy and allows for the detection of single atoms inside a quantum gas with a spatial resolution of better than 15…