We explore the limits of atomic coherence and measurement precision in a 87Sr optical lattice clock. We
perform a detailed characterization of key effects, including lattice Raman scattering and atomic collisions
in a shallow lattice configuration, determining a 174(28) s 3P0 clock state lifetime. Investigation of atomic
coherence across a range of lattice depths and atomic densities reveals decoherence mechanisms related to
photon scattering and atomic interaction. At a reduced density, we observe a coherence time of 118(9) s,
approaching the fundamental limit set by spontaneous emission. Guided by this coherence understanding,
we demonstrate a clock instability for an atomic ensemble of 1.5 × 10−18 at 1 s in fractional frequency
units. Our results are important for further advancing the state of the art of an optical lattice clock for
fundamental physics applications.
We explore the limits of atomic coherence and measurement precision in a 87Sr optical lattice clock. We
perform a detailed characterization of key effects, including lattice Raman scattering and atomic collisions
in a shallow lattice configuration, determining a 174(28) s 3P0 clock state lifetime. Investigation of atomic
coherence across a range of lattice depths and atomic densities reveals decoherence mechanisms related to
photon scattering and atomic interaction. At a reduced density, we observe a coherence time of 118(9) s,
approaching the fundamental limit set by spontaneous emission. Guided by this coherence understanding,
we demonstrate a clock instability for an atomic ensemble of 1.5 × 10−18 at 1 s in fractional frequency
units. Our results are important for further advancing the state of the art of an optical lattice clock for
fundamental physics applications.