Many-body quantum systems can exhibit a striking degree of symmetry unparallelled in their classical counterparts. In real materials SU(N) symmetry is an idealization, but this symmetry is pristinely realized in fully controllable ultracold alkaline-earth atomic gases. Here, we study an SU(N)-symmetric Fermi liquid of ⁸⁷Sr atoms, where N can be tuned to be as large as 10. In the deeply degenerate regime, we show through precise measurements of density fluctuations and expansion dynamics that the large N of spin states under SU(N) symmetry leads to pronounced interaction effects in a system with a nominally negligible interaction parameter. Accounting for these effects, we demonstrate thermometry accurate to 1% of the Fermi energy. We also demonstrate record speed for preparing degenerate Fermi seas enabled by the SU(N)-symmetric interactions, reaching T/T_F = 0.22 with 10 nuclear spin states in 0.6 s working with a laser-cooled sample. This, along with the introduction of a new spin polarizing method, enables the operation of a three-dimensional optical lattice clock in the band insulating regime.

多体量子系统可以表现出其经典对等体中无与伦比的对称性。在实际材料中，SU（N）对称性是一种理想化，但是这种对称性是在完全可控的超冷碱土原子气体中原始实现的。在这里，我们研究了一个具有^87个Sr原子的SU（N）对称费米液体，其中N可以调整为最大10。在深度退化的情况下，我们通过对密度波动和膨胀动力学的精确测量表明：ñ SU下自旋态（ñ）对称性会导致相互作用参数在名义上可忽略的系统中产生明显的相互作用效应。考虑到这些影响，我们证明了测温精确到费米能量的1％。我们还证明了制备简并费米海域记录速度由SU（启用Ñ） -对称相互作用，达到Ť / Ť _˚F  = 0.22用10核自旋态在0.6秒的工作用激光冷却样品。这连同新的自旋偏振方法的引入，使得能够在带绝缘状态下操作三维光学晶格时钟。