Eur. Phys. J. B (2012) 85: 194
https://doi.org/10.1140/epjb/e2012-30151-x

Regular Article

Quantum phase transitions and coherent tunneling in a bilayer of ultracold atoms with dipole interactions

¹ Department of Physics, Captipal Normal University, Beijing 100048, P.R. China
² Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P.R. China
³ International Center for Quantum Materials, Peking University, Beijing 100871, P.R. China
⁴ Department of Physics, Oklahoma State University, Stillwater, 74078 Oklahoma, USA

^a e-mail: andrewjee@sina.com

Received: 20 February 2012
Received in final form: 24 April 2012
Published online: 12 June 2012

Abstract

We study the quantum phase transitions and coherent tunneling in bilayer ultracold bosonic atoms with dipolar interactions at total filling factor ν_T = 1/2. We demonstrate that, due to the unique characters of the dipole interactions, the ground state of the system may undergo paired quantum Hall state (PQH), dimer quantum-Hall state (DQH), and super-counter-fluidity phase (SCF) by tuning the dipole strength. The SCF state which breaks the easy-plane U(1) symmetry is of particular interest because it can exhibit interlayer coherent tuneling in the incompressible quantum-Hall (QH) state. We suggest that this coherent tunneling current could be observed directly in future experiments.