Spontaneous rotation in one-dimensional systems of cold atoms

We theoretically study harmonically trapped one-dimensional Bose gases (e.g., Li, Na, K, Rb, etc.) with multibands occupied, focusing on effects of higher-energy bands. Combining the Ginzburg-Landau theory with the bosonization techniques, we predict that the repulsive interaction between higher-band bosons and the quantum fluctuation can induce the ground state with a finite angular momentum around the trapped axis. In this state, the Z_2 reflection symmetry (clockwise or anticlockwise rotations) is spontaneously broken.