"Field-Induced Dipole-Dipole Interaction for the Condensation of Spin-Orbital Coupled Polar Molecules" Dr. Gary Liu

Field-Induced Dipole-Dipole Interaction for the Condensation of Spin-Orbital Coupled Polar Molecules
I-Kang Liu and Shih-Chuan Gou

Department of Physics and Graduate Institute of Photonics,
National Changhua University of Education, Changhua, Taiwan

    We theoretically investigate the behaviour of a two-dimensional ultra-cold polar molecule gas in the condensate phase with Raman-type coupled two rotational states, in which such spin-orbital coupling induces an effective dipole-dipole interaction [1, 2]. The induced dipole moments are considered to align to the out-of-plane direction of the two-dimensional setup, and this effectively non-local interaction between them features conducts with the spatial coherence between the coupled states. The condensate phase of the molecular gas presents two convention-type of solutions [3] when the interaction strength is small and favours Stoner-type ferromagnetic states [4] when the interaction is dominant. The Stoner-type phase exhibits periodic ±π/2 phase jump in the relative phase between coupled states, suggesting the feature of dark soliton array. The phase diagram is probed by variational ansatz and examined by the numerical solutions of the Gross-Pitaevskii equation. We also discuss the stability of the Stoner-type states and our preliminary results on its Bogouliubov-de-Gennes excitations.

1. A. Micheli,* G. Pupillo, H. P. Büchler, and P. Zoller, Phys. Rev. A 76, 043604 (2007).
2. N. R. Cooper and G.V. Shlyapnikov, Phys. Rev. Lett. 103, 155302 (2009).
3. Yun Li, Lev P Pitaevskii, Sandro Stringari, Phys. Rev. Lett. 108, 225301 (2012).
4. J.-H. Zheng, B. Xiong, G. Juzeliunas and D.-W. Wang, Phys. Rev. A 92, 013604 (2015).