By cooling the atoms down to near-zero temperatures, Harvard researchers have created a system capable of detecting individual atoms. As described in their recent submission to Nature, the team of researchers led by Markus Greiner cooled rubidium down to approximately 5 billionth of one Kelvin. At this temperature, ordinary materials begin to behave quite strangely -- superconductivity and superfluidity are two interesting examples. In this case, the rubidium behaves as a quantum gas, tunneling between neighboring cells of the lattice. By combining the projection of this lattice with a high-powered microscope, the researchers were able to detect thousands of individual rubidium atoms -- a truly remarkable feat.

Read more at http://www.nature.com/nature/journal/v462/n7269/full/nature08482.html
http://news.harvard.edu/gazette/story/2009/11/quantum-gas-microscope-cre...