The ground-state properties of neutral hard-core bosons trapped in an optical two-leg ladder in the presence of an artificial magnetic field are studied. For a weak field, two separated peaks appear in the momentum distribution as a signature of the Meissner state in which bosons, carrying persistent currents on each leg, condense into finite-momentum states, while for a strong field, a central peak and tiny bumps associated with the vortex lattice structure indicate that the ground state is the vortex state.

• Received 13 September 2010

DOI:https://doi.org/10.1103/PhysRevA.83.055602