68th CEMS Colloquium

講演タイトル

イッテルビウム光格子量子シミュレーターによるSU(N)量子磁性の研究

講演概要

A system of ultracold atoms in an optical lattice is an ideal quantum simulator of a strongly correlated quantum many-body system due to the high controllability of system parameters. In this talk, I will report our recent experiments using ultracold fermions of ytterbium (Yb) in an optical lattice.

One of the unique properties of Fermi gases of two-electron atoms is a high spin symmetry of SU(N=2I+1) of nuclear spin I, which will show novel quantum magnetism. By using a 173Yb Fermi gas with SU(N) symmetry, we develop a technique for optically inducing a nuclear spin singlet-triplet oscillation with a spin-dependent potential gradient for measuring nearest-neighbor anti-ferromagnetic spin correlations. The straightforward comparison between the cases of SU(2) and SU(4) loaded in an optical dimerized lattice reveals the enhanced antiferromagnetic correlation for the SU(4) spin system compared with SU(2) as a consequence of a Pomeranchuk cooling effect [1]. In addition, we successfully observe the formation of nearest-neighbor antiferromagnetic spin correlations for SU(6) Fermi gases in 1D , 2D , and 3D optical lattices as well as a dimerized lattice. In addition, we successfully create a novel SU(4) singlet state in a plaquette configuration. This work is an important step towards the observation of novel SU(N) quantum magnetism.

Other researches using Yb gases such as the experiments towards the quantum simulation of the Kondo effect will be also reported [2].

Reference
[1] H. Ozawa et al, Phys. Rev. Lett. 121, 225303 (2018)
[2] K. Ono et al, arXiv:1810.00536.