We report the first measurement of ground-state diamagnetism of isolated neutral atoms in an atomic beam. We realize this measurement using magnetic deflection of fringes in a long-baseline matter-wave interferometer. The observed diamagnetic susceptibilities of −5.8±0.2±0.4×10−9 m3/kg for barium and −7.0±0.3±0.7×10−9 m3/kg for strontium are in good agreement with the theoretical values and correspond to a measured force on the order of 10−26 N. The high force sensitivity also allows us to observe the isotope dependence of the interference visibility due to the nuclear permanent magnetic moment, thereby demonstrating a new method for neutral isotope selection. The universality of the technique allows the magnetism of a wide range of atoms and molecules to be studied in the gas phase.
Y.Y. Fein, A. Shayeghi, L. Mairhofer, F. Kialka, P. Rieser, P. Geyer, S. Gerlich, M. Arndt
Quantum-Assisted Measurement of Atomic Diamagnetism,
Phys. Rev. X 10, 011014 (2020). DOI 10.1103/PhysRevX.10.011014
