Exact two-body solutions and Quantum defect theory of two dimensional dipolar quantum gas

In this paper, we provide the two-body exact solutions of two dimensional (2D) Schr\"{o}dinger equation with isotropic $\pm 1/r^3$ interactions. Analytic quantum defect theory are constructed base on these solutions and are applied to investigate the scattering properties as well as two-body bound states of ultracold polar molecules confined in a quasi-2D geometry. Interestingly, we find that for the attractive case, the scattering resonance happens simultaneously in all partial waves which has not been observed in other systems. The effect of this feature on the scattering phase shift across such resonances is also illustrated.