Due to their strong long-range dipole-dipole interactions and large number of internal states, polar molecules cooled to cold and ultracold temperatures enable fascinating applications ranging from controlled chemistry to investigation of dipolar quantum gases. However, gaining and maintaining control of the motional and internal degrees of freedom of polar molecules is a formidable challenge.
In my talk, I will present our multifaceted efforts to tame polar molecules. On the one hand, buffer gas cooling is a general technique to produce motionally and internally cold beams of molecules. Here, thermometry of the molecular beam exiting the buffer gas cell has given us new insight into the physics of buffer gas cooling. On the other hand, optoelectrical Sisyphus cooling has allowed us to cool molecules over many orders of magnitude to sub-millikelvin temperatures. We thereby obtain 300,000 formaldehyde molecules at a temperature of about 400uK. Our experiments provide an excellent starting point to investigate cold and ultracold collisions, perform precision spectroscopy, and investigate sympathetic or evaporative cooling.