Improved ¹⁷¹Yb Optical Lattice Clock Performance Using Coherent Delocalization

We report on a quantum control technique in an ¹⁷¹Yb optical lattice clock aimed at decreasing the cold collision frequency shift and reducing two-body inelastic losses. Amplitude modulation of a vertically oriented 1D optical lattice realizes Bloch driven coherent delocalization of atoms along the lattice sites. Because Landau-Zener tunneling can be seen to cause sizeable atom loss at very low trap depths (where the tunneling rate is highest), we perform coherent delocalization with the n_z = 2 excited motional band to access higher tunneling rates with limited atom loss. We have observed delocalization that decreases the density of our atomic sample by 4.9(0.6) times. As a result, the cold collision systematic frequency shift is reduced by the same factor, and atom loss due to inelastic two-body loss in the ³P₀ excited state is negligible for our conditions. Higher atom numbers and reduced systematic frequency shifts in atomic clocks can aid in probing new physics for next-generation time and frequency metrology, and even for measuring earth’s gravitational potential.