A microfabricated superfluid ⁴He "RF Squid"

We have developed an apparatus which is the superfluid analog of the RF SQUID and exhibits the characteristic "staircase" response. This device is of the type demonstrated by O. Avenel and E. Varoquaux. The superfluid Helmholtz resonator is constructed from Silicon using microfabrication techniques and has an internal volume of only 5.0 mm³. The staircase pattern can be reliably reproduced in each new cell constructed by this technique. This device can, in principle, be used to detect absolute rotation. Numerical calculations of the flow field for our particular geometry predict sufficient sensitivity to detect the rotation of the Earth with s/n~100. An ongoing search is being performed to observe the rotation effects.