Three-Dimensional Matter-Wave Interferometry of a Trapped Single Ion

We report on a demonstration of Ramsey interferometry by three-dimensional motion with a trapped $^{171}{\mathrm{Yb}}^{+}$ ion. We applied a momentum kick to the ion in a direction diagonal to the trap axes to initiate three-dimensional motion using a mode-locked pulse laser. The interference signal was analyzed theoretically to demonstrate three-dimensional matter-wave interference. This work paves the way to realizing matter-wave interferometry using trapped ions.