Hurl an atomic cloud from a tower into an interferometer and you get an exquisite sensor of gravity and rotation. More compact alternatives that allow for long interrogation times without the skyscrapers are atom chips — miniature devices for trapping and controlling Bose–Einstein condensates. Some interferometer designs need to be able to shuttle atoms around, but moving quantum objects isn’t easy. Any perturbation may heat up the cloud and disrupt its coherence and potential for precision measurements.
Saurabh Pandey and co-workers have now managed to create a smooth enough ring-shaped trap to send their condensate on a hypersonic ride, reaching speeds of up to Mach 16 over distances of 15 cm, all while preserving the cloud’s coherent properties. Such an engineering feat required a combination of magnetic fields applied at three different timescales, as well as control techniques that compensated the tug felt by the atoms as the trap began to move around the ring — a feeling familiar to anyone who has been on a rollercoaster.
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Levi, F. Atomic rollercoaster. Nat. Phys. 15, 622 (2019). https://doi.org/10.1038/s41567-019-0588-3