Cold-collision-shift cancellation and inelastic scattering in a Yb optical lattice clock

Recently, p-wave cold collisions were shown to dominate the density-dependent shift of the clock transition frequency in a 171Yb optical lattice clock. Here we demonstrate that by operating such a system at the proper excitation fraction, the cold-collision shift is canceled below the 5 × 10−18 fractional frequency level. We report inelastic two-body loss rates for P0 -P0 and S0 -P0 scattering. We also measure interaction shifts in an unpolarized atomic sample. Collision measurements for this spin-1/2 171Yb system are relevant for high-performance optical clocks as well as strongly interacting systems for quantum information and quantum simulation applications.