Cover Picture: ZAMM 4/2009

The cover page of 2009 shows high‐resolution interference “quantum carpet” patterns for the momentum wave function of an interacting Bose‐Einstein condensate (BEC). As time progresses (from back to front), the many‐body mean field interaction of the BEC first leads to a broadening of the wave function, but then also to a time‐varying interference structure by inducing site‐dependent nonlinear phase shifts when the BEC is confined in a spatially periodic potential. Imaging the wave function in momentum space for different times leads to a pattern that one reminds of a carefully woven carpet and is hence termed “quantum carpet”. Quantum carpets beautifully demonstrate the surprisingly high matter wave coherence of particle‐particle interactions in the zero‐temperature limit.