Fig. 2: Schematic of the Penning trap set-up.
a, Sectional view of the trap tower consisting of cylindrical electrodes and spatial variation of the magnetic field inside the trap tower along the z axis. The insulation rings between the electrodes are depicted in blue, the copper electrodes in yellow and the nickel electrode in grey. All electrodes are gold plated. The microwaves for driving spin-flips are introduced into the trap using the copper coils on the side of the trap and through a waveguide from the top of the trap (white arrow) in the case of the 4 GHz and 150 GHz transitions, respectively. The second white arrow on the left side represents electrons from a field emission point used to ionize the atoms emitted by the 3He-filled glass sphere. The magnetic inhomogeneity in the analysis trap is spatially separated from the very homogeneous field in the precision trap by transport electrodes. b, Axial frequency νz measured in the AT after resonantly driving the electronic transition \(|1\rangle \leftrightarrow |3\rangle \). The dashed line serves to guide the eye. The frequency is higher by 22 Hz when the ion is in state \(|1\rangle \) compared to state \(|3\rangle \). The same axial frequency shift can be observed when transitioning between states \(|2\rangle \) and \(|4\rangle \).
