  In many-body systems governed by pairwise contact interactions, a wide range
of observables is linked by a single parameter, the two-body contact, which
quantifies two-particle correlations. This profound insight has transformed our
understanding of strongly interacting Fermi gases. Here, using Ramsey
interferometry, we study coherent evolution of the resonantly interacting Bose
gas, and show that it cannot be explained by only pairwise correlations. Our
experiments reveal the crucial role of three-body correlations arising from
Efimov physics, and provide a direct measurement of the associated three-body
contact.
