Arrays of nanometer sized apertures connecting two reservoirs of superfluid helium exhibit properties similar to Josephson weak links in superconductors. We have discovered numerous phenomena related to these devices including oscillating currents driven by static pressure heads, the so called "quantum whistle". This lecture will include descriptions of the underlying physics, the novel techniques developed and some of the new discoveries. The new physics leads to the development of a superfluid neutral matter interferometer. This device can be used as a sensitive gyroscope for geodesy or a novel probe of quantum phenomena. The talk will be understandable at the advanced undergraduate level.