SU(N) spin symmetry and optical atomic clocks*

The state-of-the-art precision of a Sr optical lattice clock was used to measure SU(N) symmetrical interactions among 10 nuclear spin states in fermionic ⁸⁷Sr, providing a convenient platform to observe non-equilibrium spin-orbital dynamics in SU(N) magnetism [1].  Meanwhile, by creating arrays of isolated few-body systems of ⁸⁷Sr in a 3D optical lattice, high resolution clock spectroscopy revealed the onset of both elastic and inelastic multi-body interactions, highlighting the emergence of multi-body interactions in two-orbital high-spin fermions with SU(N) symmetry [2].  SU(N) symmetry also represents an untapped resource for cooling due to large s-wave collision rates and absence of spin loss, allowing us to produce deeply degenerate Fermi gases in just 0.6 s after initial laser cooling [3]. While this provides a precise study of the thermodynamics of a deeply degenerate Fermi gas with SU(N)-symmetric interactions, the fast preparation of quantum matter is also crucial for the advancement of 3D optical lattice clocks and has facilitated our recent observation of Pauli blocking of spontaneous radiative decay [4].

 

[1] X. Zhang et al., “Spectroscopic observation of SU(N)-symmetric interactions in Sr orbital magnetism,” Science 345, 1467 – 1473 (2014). 

[2] A. Goban et al., “Emergence of multi-body interactions in a fermionic lattice clock,” Nature 563, 369 – 373 (2018).

[3] L. Sonderhouse et al., “Thermodynamics of a deeply degenerate SU(N)-symmetric Fermi gas,” Nature Phys. 16, 1216 – 1221 (2020).

[4] C. Sanner et al., “Pauli blocking of atomic spontaneous decay,” arXiv:2103.02216 (2021).