We present theoretical findings on the spin collective modes of a two-species Fermi liquid, prepared alternatively in a polarized equilibrium or a polarized nonequilibrium state. We explore the effects on these modes of a diverging $s$ -wave scattering length, as occurs near a Feshbach resonance in a fermionic atomic gas. We compare these atomic gas modes with those of the conventional $^{3}\mathrm{He}$ system, and we find that they differ from the conventional systems, and that the gap and spin stiffness are tunable via the Feshbach resonance.We present theoretical findings on the spin collective modes of a two-species Fermi liquid, prepared alternatively in a polarized equilibrium or a polarized nonequilibrium state. We explore the effects on these modes of a diverging $s$-wave scattering length, as occurs near a Feshbach resonance in a fermionic atomic gas. We compare these atomic gas modes with those of the conventional $^{3}\mathrm{He}$ system, and we find that they differ from the conventional systems, and that the gap and spin stiffness are tunable via the Feshbach resonance.

arXiv:0807.0018Physical Review ASep 3, 20083 citations

Interactions and collective excitations in a SU(N) Fermi gas

Zejian Ren, Bo Song, Chengdong He +5 more

Ultracold fermions with SU(N >2) symmetry offer a unique opportunity to study quantum dynamics and interaction effects in the large spin systems that have no analogue in condensed matter physics. In this poster, we present a set of experiments on the measurement of contact parameters and collective excitations with a SU(N) Fermi gas of 173Yb atoms. First, we explore the short-range interaction effect via Tan’s contact parameters in a multi-component Fermi gas with SU(N >2) symmetry. The s-wave contact parameter is experimentally measured by recording the high-momentum tail of weakly interacting fermions. For a tunable number of spin component N with a fixed number of atoms per component, we verify the linear increase in the contact with N providing experimental confirmation of SU(N) interactions. Furthermore, we explore the momentum distribution of SU(N) fermions at the low momentum regime. Next, we measure collective excitations of a harmonically trapped twodimensional SU(N) Fermi gas. Various collective modes are investigated with a tunable number of spin component N showing a decrease in the ratio of quadruple and dipole mode with N. Our work will pave the way for the experimental study of interacting SU(N) Fermi gases with large spin.Ultracold fermions with SU(N >2) symmetry offer a unique opportunity to study quantum dynamics and interaction effects in the large spin systems that have no analogue in condensed matter physics. In this poster, we present a set of experiments on the measurement of contact parameters and collective excitations with a SU(N) Fermi gas of 173Yb atoms. First, we explore the short-range interaction effect via Tan’s contact parameters in a multi-component Fermi gas with SU(N >2) symmetry. The s-wave contact parameter is experimentally measured by recording the high-momentum tail of weakly interacting fermions. For a tunable number of spin component N with a fixed number of atoms per component, we verify the linear increase in the contact with N providing experimental confirmation of SU(N) interactions. Furthermore, we explore the momentum distribution of SU(N) fermions at the low momentum regime. Next, we measure collective excitations of a harmonically trapped twodimensional SU(N) Fermi gas. Various collective modes are investigated with a tunable number of spin component N showing a decrease in the ratio of quadruple and dipole mode with N. Our work will pave the way for the experimental study of interacting SU(N) Fermi gases with large spin.

APS Division of Atomic, Molecular and Optical Physics Meeting AbstractsMay 1, 20190 citations

COLLECTIVE SPIN MODES IN FERMI LIQUIDS WITH SPIN-ORBIT COUPLING

Журнал Экспериментальной и Теоретической ФизикиOct 1, 20220 citations

Observation of Collective Atomic Recoil Motion in a Degenerate Fermion Gas

Pengjun Wang, L. Deng, E. W. Hagley +3 more

We demonstrate collective atomic recoil motion with a dilute, ultracold, degenerate fermion gas in a single spin state. By utilizing an adiabatically decompressed magnetic trap with an aspect ratio different from that of the initial trap, a momentum-squeezed fermion cloud is achieved. With a single pump pulse of the proper polarization, we observe, for the first time, multiple wave-mixing processes that result in distinct collective atomic recoil motion modes in a degenerate fermion cloud. Contrary to the case with Bose condensates, no pump-laser detuning asymmetry is present.We demonstrate collective atomic recoil motion with a dilute, ultracold, degenerate fermion gas in a single spin state. By utilizing an adiabatically decompressed magnetic trap with an aspect ratio different from that of the initial trap, a momentum-squeezed fermion cloud is achieved. With a single pump pulse of the proper polarization, we observe, for the first time, multiple wave-mixing processes that result in distinct collective atomic recoil motion modes in a degenerate fermion cloud. Contrary to the case with Bose condensates, no pump-laser detuning asymmetry is present.

arXiv:1006.3250Physical Review LettersMay 23, 201131 citations

s

-wave scattering length, as occurs near a Feshbach resonance in a fermionic atomic gas. We compare these atomic gas modes with those of the conventional

^{3}\mathrm{He}

system, and we find that they differ from the conventional systems, and that the gap and spin stiffness are tunable via the Feshbach resonance.