  The field of ultracold quantum matter has burgeoned over the last few
decades, thanks to the growing capabilities for atomic systems to be probed and
manipulated with exquisite control. Researchers can now precisely create and
study quantum many-body states that are effectively isolated from the external
environment. Much of the work in ultracold matter has focused on systems of
alkali or alkaline-earth atoms, mainly due to their ease of cooling. Extending
this precise control to molecules has seen rapidly increasing interest and
activity, as molecules possess additional degrees of freedom that make them
useful for tests of fundamental physics, studying ultracold chemistry and
collisions, and engineering qualitatively new types of quantum phases and
quantum many-body systems. Here, we review one particularly fruitful research
direction: the creation and manipulation of ultracold bialkali molecules. The
recent success in creating a quantum gas of polar molecules opens many exciting
research opportunities.
