Faraday patterns in two-dimensional dipolar Bose-Einstein condensates

We analyze the physics of Faraday patterns in dipolar Bose-Einstein condensates. Faraday patterns can be induced in Bose-Einstein condensates by a periodic modulation of the system nonlinearity. We show that these patterns are remarkably different in dipolar gases with a roton-maxon excitation spectrum. Whereas for nondipolar gases the pattern size decreases monotonously with the driving frequency, patterns in dipolar gases present, even for shallow roton minima, a highly nontrivial frequency dependence characterized by abrupt pattern size transitions, which are especially pronounced when the dipolar interaction is modulated. Faraday patterns constitute, hence, an excellent tool for revealing the onset of the roton minimum, a key feature of dipolar gases.