How to Test Atom and Neutron Neutrality with Atom Interferometry

We propose an atom-interferometry experiment based on the scalar Aharonov-Bohm effect which detects an atom charge at the ${10}^{-28}e$ level, and improves the current laboratory limits by 8 orders of magnitude. This setup independently probes neutron charges down to ${10}^{-28}e$, 7 orders of magnitude below current bounds.

Figure 1

The experimental setup including particle trajectories. The upper and lower electrode tubes are operated at potentials $V/2$ and $-V/2$ respectively, as described in the text.

Figure 2

The atom wave-function trajectories as a function of time. The areas in dark and light gray indicate when the fast and slow atom wave functions are traveling in a region of voltage $V/2$ and $-V/2$, respectively. Below are shown the trajectories for a second atom cloud launched at the same time, in order to control systematics from laser phase noise.