| Is the 1D Bose gas superfluid? |
June, 7 (2006) at 4pm Alexander Cherny While the one-dimensional Bose gas appears to exhibit a superfluid response under certain conditions, it fails the Landau criterion for superfluidity, according to the elementary excitation spectrum. The apparent riddle is solved by calculating the dynamic structure factor (DSF) of the exactly solvable Lieb-Liniger model for the 1D Bose gas. To solve the problem, we map strongly interacting bosons into weakly interacting fermions, which are treated in the Hartree-Fock and generalized random-phase approximations. By means of the analytical expression for the DSF, the drag force acting on a heavy impurity is analysed for arbitrary values of velocity of the impurity. The magnitude of the energy dissipation caused by the moving impurity provides us with the criterion for superfluidity. The predicted behaviour of the DSF can be directly observable by Bragg scattering in current experiments. |