We report a new kind of experiment in which we take an array of nanoscale apertures that form a superfluid ${}^4\mathrm{He}$ Josephson junction and apply quantum phase gradients directly along the array. We observe collective coherent behaviors from aperture elements, leading to quantum interference. Connections to superconducting and Bose-Einstein condensate Josephson junctions as well as phase coherence among the superfluid aperture array are discussed.

• Received 9 November 2010

DOI:https://doi.org/10.1103/PhysRevLett.106.055302