Two-component dimers of ultracold atoms with center-of-mass-momentum dependent interactions

Abstract

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.