Two-Component Dimers of Ultracold Atoms with Center-of-Mass-Momentum Dependent Interaction

In a previous work [Phys. Rev. A 95, 060701(R) (2017)] we show that a new type of twobody interaction, which depends on the center of mass (CoM) momentum, can be realized for ultracold atoms via laser-modulated magnetic Feshbach resonance (MFR). Further studies (e.g., L. He et. al., Phys. Rev. Lett. 120, 045302 (2018)) show that various interesting phenomena, such as Fulde-Ferrell superfluids, can be induced by the scattering between ultracold atoms with this interaction. In this work we investigate the shallow bound states of two ultracold atoms with this type of interaction. We show that when the magnetic field B is below the MFR point B0, two shallow bound states can appear in this system. Namely, a “two-component dimer” or a dimer with pseudo-spin 1/2 can be formed by two atoms. Furthermore, the dispersion curve of the dimer may has either single or double minimums in the CoM momentum space. The latter case can be explained as a result from significant pseudo-spin-orbital coupling (SOC) effects. Our results show that the ultracold gases with CoM momentum dependent interaction may be a candidate for quantum simulations with ultracold two-component molecules, especially the molecule gases with SOC.