Magnetic Trapping and Coherent Control of Laser-Cooled Molecules

We demonstrate coherent microwave control of the rotational, hyperfine, and Zeeman states of ultracold CaF molecules, and the magnetic trapping of these molecules in a single, selectable quantum state. We trap about 5 x 10(3) molecules for almost 2 s at a temperature of 70(8) mu K and a density of 1.2 x 10(5) cm(-3). We measure the state-specific loss rate due to collisions with background helium.