Ultracold molecules are a promising material for quantum computing, but assembling them into a neat array, like eggs in a carton, is no easy feat. A method has been proposed to load molecules one by one into optical tweezers or lattices directly from a gas. The molecules immediately end up in the calmest state of motion.
The secret lies in the strong repulsion between molecules shielded by microwaves. Thanks to this, two molecules cannot end up in the same trap — the spot is taken, and the second one cannot squeeze in. The success probability exceeds 99% for small traps and polar molecules.
This approach opens the door to large ordered arrays of polar molecules for quantum computing, simulation, and ultra-precise measurements.
Polar molecules, like tiny magnets, interact strongly with each other: this both prevents them from sharing a trap and helps in quantum tasks.