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 5×10³ molecules for almost 2 s at a temperature of 70(8) μK and a density of 1.2×10⁵ cm^-3. We measure the state-specific loss rate due to collisions with background helium.