Collective mode evidence of high-spin bosonization in a trapped one-dimensional atomic Fermi gas with tunable spin

Abstract: We calculate the frequency of collective modes of a one-dimensional repulsively interacting Fermi gas with high-spin symmetry confined in harmonic traps at zero temperature. This is a system realizable with fermionic alkaline-earth-metal atoms such as $^{173}$Yb, which displays an exact SU($\kappa$) spin symmetry with $\kappa\geqslant2$ and behaves like a spinless interacting Bose gas in the limit of infinite spin components $\kappa\rightarrow\infty$, namely high-spin bosonization. We solve the homogeneous equation of state of the high-spin Fermi system by using Bethe ansatz technique and obtain the density distribution in harmonic traps based on local density approximation. The frequency of collective modes is calculated by exactly solving the zero-temperature hydrodynamic equation. In the limit of large number of spin-components, we show that the mode frequency of the system approaches to that of a one-dimensional spinless interacting Bose gas, as a result of high-spin bosonization. Our prediction of collective modes is in excellent agreement with a very recent measurement for a Fermi gas of $^{173}$Yb atoms with tunable spin confined in a two-dimensional tight optical lattice.