Showing papers by "N.J. van Druten published in 2017"

Rydberg dressing of a one-dimensional Bose-Einstein condensate

Abstract: We study the influence of Rydberg-dressed interactions in a one-dimensional (1D) Bose-Einstein condensate (BEC). We show that a 1D geometry offers several advantages over a three-dimensional geometry for observing BEC Rydberg dressing. The effects of dressing are studied by investigating collective BEC dynamics after a rapid switch-off of the Rydberg dressing interaction. The results can be interpreted as an effective modification of the s-wave scattering length. We include this modification in an analytical model for the 1D BEC and compare it to numerical calculations of Rydberg dressing under realistic experimental conditions.

Medium-finesse optical cavity for the stabilization of Rydberg lasers

Abstract: We describe the design, construction, and characterization of a medium-finesse Fabry–Perot cavity for simultaneous frequency stabilization of two lasers operating at 960 and 780 nm wavelengths, respectively. The lasers are applied in experiments with ultracold rubidium Rydberg atoms, for which a combined laser linewidth similar to the natural Rydberg linewidth (≈10 kHz) is desired. The cavity, with a finesse of ≈1500, is used to reduce the linewidth of the lasers to below this level. By using a spacer made of ultra low expansion (ULE) glass with active temperature stabilization, the residual frequency drift is limited to ≲1 MHz/day. The design optimizes for ease of construction, robustness, and affordability.

Characterizing the local vectorial electric field near an atom chip using Rydberg-state spectroscopy

Abstract: We use the sensitive response to electric fields of Rydberg atoms to characterize all three vector components of the local electric field close to an atom-chip surface. We measured Stark-Zeeman maps of $S$ and $D$ Rydberg states using an elongated cloud of ultracold rubidium atoms (temperature $T\ensuremath{\sim}2.5\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{K}$) trapped magnetically $100\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{m}$ from the chip surface. The spectroscopy of $S$ states yields a calibration for the generated local electric field at the position of the atoms. The values for different components of the field are extracted from the more complex response of $D$ states to the combined electric and magnetic fields. From the analysis we find residual fields in the two uncompensated directions of $0.0\ifmmode\pm\else\textpm\fi{}0.2$ and $1.98\ifmmode\pm\else\textpm\fi{}0.09$ V/cm. This method also allows us to extract a value for the relevant field gradient along the long axis of the cloud. The manipulation of electric fields and the magnetic trapping are both done using on-chip wires, making this setup a promising candidate to observe Rydberg-mediated interactions on a chip.