A molecular synchrotron

Abstract

Many of the tools for manipulating the motion of neutral atoms and molecules take their inspiration from techniques developed for charged particles. Traps for atoms—akin to the Paul trap for ions¹—have paved the way for many exciting experiments, ranging from ultra-precise clocks² to creating quantum degenerate matter^3,4. Surprisingly, little attention has been paid to developing a neutral particle analogue of a synchrotron—arguably, the most celebrated tool of the charged-particle physicist^5,6. So far, the few experiments dealing with ring structures for neutral particles have used cylindrically symmetric designs^7,8,9; in these rings, no force is applied to the particles along the longitudinal direction and the stored particles are free to fill the entire ring. Here, we demonstrate a synchrotron for neutral polar molecules. A packet of ammonia molecules is accelerated, decelerated and focused along the longitudinal direction (‘bunched’) using the fringe fields between the two halves of a segmented hexapole ring. The stored bunch of cold molecules (T=0.5 mK) is confined to a 3 mm packet even after a flight distance of over 30 m (40 round trips). Furthermore, we show the injection of multiple packets into the ring.