Precision measurement based on quantum matter

The progress of optical lattice clock to the accuracy of 2 x 10$^{\mathrm{-18}}$ has benefited greatly from the understanding of atomic interactions [1,2]. The precision of clock spectroscopy greatly facilitates the exploration of many-body spin interactions [3], including SU($N)$ symmetry [4] and spin-orbit coupling [5]. Building on this combined front of quantum metrology and many-body physics, we have realized a Fermi degenerate three-dimensional optical lattice clock, which represents a scalable solution with a high, correlated density of a degenerate Fermi gas guarding against on-site interaction-related clock shifts [6]. We demonstrate atom-light coherence time of 10 s and clock measurement precision at 3 x 10$^{\mathrm{-19}}$. [1] B. J. Bloom, \textit{et al}., An optical lattice clock with accuracy and stability at the 10$^{\mathrm{-18}}$ level. Nature \textbf{506}, 71 (2014). [2] T. L. Nicholson, \textit{et al}., Systematic evaluation of an atomic clock at 2 \texttimes 10$^{\mathrm{-18}}$ total uncertainty. Nature Comm.\textbf{ 6}, 6896 (2015). [3] M. J. Martin, \textit{et al}., A quantum many-body spin system in an optical lattice clock. Science \textbf{341}, 632 (2013). [4] X. Zhang, \textit{et al}., Spectroscopic observation of SU($N)$-symmetric interactions in Sr orbital magnetism. Science \textbf{345}, 1467 (2014). [5] S. Kolkowitz, \textit{et al}., Spin-orbit coupled fermions in an optical lattice clock, Nature \textbf{542}, 66 (2017). [6] S. L. Campbell, \textit{et al}., A Fermi-degenerate 3D optical lattice clock, Science, in press (2017).