Vortex formation in a stirred Bose-Einstein condensate

Using a focused laser beam we stir a Bose-Einstein condensate of 87Rb confined in a magnetic trap and observe the formation of a vortex for a stirring frequency exceeding a critical value. At larger rotation frequencies we produce states of the condensate for which up to four vortices are simultaneously present. We have also measured the lifetime of the single vortex state after turning off the stirring laser beam.Comment: 4 pages, 3 figure

An empirical analysis of the distribution of overshoots in a stationary Gaussian stochastic process

The frequency distribution of overshoots in a stationary Gaussian stochastic process is analyzed. The primary processes involved in this analysis are computer simulation and statistical estimation. Computer simulation is used to simulate stationary Gaussian stochastic processes that have selected autocorrelation functions. An analysis of the simulation results reveals a frequency distribution for overshoots with a functional dependence on the mean and variance of the process. Statistical estimation is then used to estimate the mean and variance of a process. It is shown that for an autocorrelation function, the mean and the variance for the number of overshoots, a frequency distribution for overshoots can be estimated

An Atom Faucet

We have constructed and modeled a simple and efficient source of slow atoms. From a background vapour loaded magneto-optical trap, a thin laser beam extracts a continuous jet of cold rubidium atoms. In this setup, the extraction column that is typical to leaking MOT systems is created without any optical parts placed inside the vacuum chamber. For detailed analysis, we present a simple 3D numerical simulation of the atomic motion in the presence of multiple saturating laser fields combined with an inhomogeneous magnetic field. At a pressure of $P_{\rm Rb87}=1 \times 10^{-8}$ mbar, the moderate laser power of 10 mW per beam generates a jet of flux $\Phi =1.3\times 10^8$ atoms/s with a mean velocity of 14 m/s and a divergence of $<20$ mrad.Comment: Submitted to EPJD. 1 TeX file (EPJ format), 7 picture

Transforming a 4th year Modern Optics Course Using a Deliberate Practice Framework

We present a study of active learning pedagogies in an upper division physics course. This work was guided by the principle of deliberate practice for the development of expertise, and this principle was used in the design of the materials and the orchestration of the classroom activities of the students. We present our process for efficiently converting a traditional lecture course based on instructor notes into activities for such a course with active learning methods. Ninety percent of the same material was covered and scores on common exam problems showed a 15 % improvement with an effect size greater than 1 after the transformation. We observe that the improvement and the associated effect size is sustained after handing off the materials to a second instructor. Because the improvement on exam questions was independent of specific problem topics and because the material tested was so mathematically advanced and broad (including linear algebra, Fourier Transforms, partial differential equations, vector calculus), we expect the transformation process could be applied to most upper division physics courses having a similar mathematical base.Comment: 31 page

Feshbach resonances in ultracold 85Rb-87Rb and 6Li-87Rb mixtures

We present an analysis of experimentally accessible magnetic Feshbach resonances in ultra-cold hetero-nuclear 85Rb-87Rb and 6Li-87Rb mixtures. Using recent experimental measurements of the triplet scattering lengths for 6Li-87Rb and 7Li-87Rb mixtures and Feshbach resonances for one combination of atomic states, we create model potential curves and fine tune them to reproduce the measured resonances and to predict the location of several experimentally relevant resonances in Li-Rb collisions. To model 85Rb-87Rb collisions, we use accurate Rb_2 potentials obtained previously from the analysis of experiments on 87Rb-87Rb collisions. We find resonances that occur at very low magnetic fields, below 10 G, which may be useful for entanglement generation in optical lattices or atom chip magnetic traps.Comment: 8 pages, 5 figure