Coherent Manipulation of Three-Atom Entangled States Near Förster Resonance

We recently demonstrated coherent excitation of entangled states of three Rydberg atoms near a Förster resonance in ⁸⁵Rb. Here, we characterize the coherence time using Ramsey Interferometry and observe a correlation between coherence time and dipole-dipole interaction strength. We also investigate the effects of inhomogeneous dephasing using spin echo. Our three-particle states show robust coherence, given that they are excited from an unstructured bulk gas. Therefore, they may find use in applications of three-atom entanglement to quantum protocols in simple atomic systems.