Dynamic structure factor of one-dimensional Fermi superfluid with spin-orbit coupling

We theoretically calculate the density dynamic structure factor of one-dimensional Fermi superfluid with Raman-type spin-orbit coupling, and analyze its main dynamical character during phase transition between Bardeen-Cooper-Schrieffer superfluid and topological superfluid. Our theoretical results display four kinds of single-particle excitations induced by the two-branch structure of the single-particle spectrum, and the cross single-particle excitation is much easier to see in the spin dynamic structure factor at a small transferred momentum. Also we find a new rotonlike collective mode emerges at a fixed transferred momentum q similar or equal to 2(k)F, and it only appears once the system enters the topological superfluid state. The occurrence of this rotonlike excitation is related to the switch of the global minimum in the single-particle spectrum from k = 0 to k similar or equal to 2k(F).

Automated summary

We calculate the density dynamic structure factor of one-dimensional Fermi superfluid with Raman-type spin-orbit coupling and analyze its main dynamical characteristics during the phase transition between Bardeen-Cooper-Schrieffer superfluid and topological superfluid. Our results show four types of single-particle excitations induced by the two-branch structure of the single-particle spectrum, and the cross single-particle excitation is more easily observed in the spin dynamic structure factor at a small transferred momentum. Additionally, we observe a new rotonlike collective mode at a fixed transferred momentum q similar to 2(k)F, which only appears in the topological superfluid state.