Uniaxial modulation and the Berezinskii-Kosterlitz-Thouless transition

We present a theoretical study of the Berezinskii-Kosterlitz-Thouless transition of a two-dimensional superfluid in the presence of an externally imposed density modulation along a single axis. The subject is investigated in the context of the |psi |4 classical field theory, by means of analytical and numerical techniques. We show that, as the amplitude of the modulation increases, the physics of the system approaches that of the anisotropic x-y model, with a suppressed superfluid transition temperature and an anisotropic response, but with no dimensional crossover.