Centrifugal quantum states of neutrons

The “whispering gallery” effect has been known since ancient times for sound waves in air, later in water and more recently for a broad range of electromagnetic waves from the radiofrequency region, through visible light to X-rays. It consists of wave localization in the vicinity of concave surfaces. For matter waves, it would include a new feature: a massive particle would be settled in quantum states, with parameters depending on its mass. Here, we present the first observation of such an effect as well as constraints for short-range forces that could be estimated from this first observation.