Adiabatically compressing p-orbital Bose-Einstein condensates into lowest Landau level states

There has been much experimental progress in controlling p-orbital degrees of freedom in optical lattices, with lattice shaking, sublattice swapping, and lattice potential programming. Here, we present a protocol of preparing lowest Landau level (LLL) states of cold atoms by adiabatically compressing p-orbital Bose-Einstein condensates confined in two-dimensional array of tubes. The system starts from a chiral p+ip state carrying spontaneous angular momentum, which has been achieved in recent experiments. By adiabatically adjusting the lattice potential from a three-dimensional lattice confinement into a two-dimensional confinement, we find the orbital degrees of freedom morph into the LLL states. This process is enforced by the discrete rotation symmetry of the lattice potential. The final quantum many-body state is shown to acquire large angular momentum—one quantized unit per particle. We further discuss the properties of the ground state on LLL in presence of a repulsive contact interaction, which leads to an exotic gapped Bose-Einstein condensate state. Our scheme is accessible to the current optical lattice experiments.