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Published April 10, 1997 | public
Journal Article

Detection of the Earth's rotation using superfluid phase coherence


It has long been recognized that the macroscopic quantum properties of superfluid helium could form the basis of a technique for measuring the state of absolute rotation of the containment vessel: circulation of superfluid helium is quantized, so providing a reference state of zero rotation with respect to inertial space. Here we provide experimental proof of this concept by detecting the rotation of the Earth using the spatial phase coherence of superfluid ^4He, thus providing independent corroboration of an earlier report that demonstrated the feasibility of making such a measurement. Our superfluid container is constructed on a centimetre-size silicon wafer, and has an essentially toroidal geometry but with the flow path interrupted by partition incorporating a sub-micrometre aperture. Rotation of the container induces a measurable flow velocity through the aperture in order to maintain coherence in the quantum phase of the super-fluid. Using this device, we determine the Earth's rotation rate to a precision of 0.5% with a measurement time of one hour, and argue that improvements in sensitivity of several orders of magnitude should be feasible.

Additional Information

© 1997 Nature Publishing Group. Received 12 December 1996; accepted 10 March 1997. We thank A. Amar, J.C. Davis, Yu. Mukharsky and J. Steinhauer for help with earlier versions of this experiment; A. Loshak for help with fabrication of the silicon device; S. Vitale, E. Varoquaux, O. Avenel and S. Backhaus for conversations; and R. Orr for preparing Fig. 1. This work was supported in part by the Air Force Office of Scientific Research, the Office of Naval Research, and the National Science Foundation.

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