High resolution imaging of an ultracold quantum gas
Tatjana Gericke (Universität Mainz)

<p> Ultracold atoms in optical lattices have demonstrated to be an interesting system to study quantum phenomena such as quantum phase transitions and strongly correlated many-body systems. The lattice spacing in these systems ranges from 400 nm to 600 nm. Although many different detection schemes have been developed, a high resolution in situ imaging system that is single atom sensitive is lacking. </p>

<p> We describe a new detection and manipulation technique based on scanning electron microscopy which allows for the detection of single atoms in a quantum gas with a spatial resolution of better than 150 nm. A focused electron beam with a FWHM of 100 nm is moved over the atom cloud and ionizes atoms by means of electron impact ionization. The produced ions are subsequently extracted and detected with the aid of ion optics. </p>

<p> Our 87Rb condensate consists of around 100,000 atoms, trapped in a single beam optical dipole trap formed by a focused CO2 laser beam. We have implemented a two-dimensional optical lattice with 600 nm lattice spacing to study quantum gases in periodic potentials. Our imaging technique enables us not only to resolve single lattice sites but also to remove atoms from selected sites without affecting neighboring sites. Therefore our technique offers a versatile experimental platform for the in situ study of ultracold quantum gases in various arbitrary patterns. </p>