Cooling molecules down to the limit of quantum degeneracy poses enormous challenge with the internal degrees of freedom such as rotation and vibration precluding a straightforward application of laser cooling. Despite the large efforts no general molecular cooling method has been demonstrated so far.

We demonstrate the first trapping of molecular oxygen in a magnetic trap. The starting point of our experiments is a supersonic beam of oxygen molecules, which is an excellent and versatile source for high-flux cold atomic and molecular beams. Although the molecular beam is >1K cold, it has a high velocity in the laboratory frame. We decelerate the molecular ensemble in a moving magnetic trap decelerator with 3D magnetic confinement. Our method is applicable to both paramagnetic atoms and molecules.

After deceleration oxygen molecules are loaded into a static trap, generated by two permanent magnets with opposite magnetizations. The trap’s lifetime is on the order of several hundred milli-seconds, which raises the possibility of applying other cooling techniques to molecules.

Following the demonstration of simultaneous co-deceleration of both atoms and molecules by our group, the current effort is concentrated on exploring ways to entrain lithium atoms inside the beam and simultaneously decelerating them with the oxygen molecules. We will attempt sympathetic cooling of the molecular oxygen using laser cooled lithium atoms.