Fabrication of a silicon-based superfluid oscillator

We have constructed an integrated superfluid oscillator using various silicon processing techniques, including micromachining and electron beam lithography. This device has the advantage of a very small internal volume (0.72 mm³). This makes it insensitive to spurious external acoustic noise which has limited the performance of larger experiments. We have tested the performance of this device in two configurations, one with a single micro-aperture and another with an additional fine tube. Both configurations demonstrate macroscopic quantum phenomena in superfluid ⁴He at low temperatures (0.25 K < T < 2.2 K) and have been used to study these effects in detail.