idea. An optical analog of the Josephson junction is discussed. An ex- perimental

A Josephson gyroscope using superfluidsR. Y. Chiao and A. A. MoulthropDepartment of Physics, University of California, Berkeley, CA 94720M. T. LevinsenPhysics Laboratory I, H. C. orsted Institute, University of CopenhagenUniversitetsparken 5, DK -2100 Copenhagen 0, DenmarkAbstractThe Sagnac effect using matter (de Broglie) waves is considered for gyroscopic applica-tions. Superfluid helium in a torus with a Josephson junction interupting it would be anembodiment of this idea. An optical analog of the Josephson junction is discussed. An ex-perimental search for the Sagnac effect in superfluid helium (isotope 4) is presented.IntroductionIn this workshop, we have seen that the optical ring gyroscope, which is based on theSagnac effect, is now a successful device. Here we will present some new ideas for Sagnacgyroscopes, and an experimental attempt to carry out these ideas using the Josephson effectin superfluid helium (He II). The basic physics here is the Sagnac effect of matter waves,i.e. de Broglie waves. One may ask: Why use de Broglie waves? The answer is that the Sagnacphase shift is much larger than for light. A second question is: Why use superfluids?The answer is that, like lasers, the superfluid possesses a coherent, macroscopic wave,which should lead to a more intense interference signal. A third question is: Why use theJosephson junction? The answer is that it is a potentially sensitive way to detect the in-terference, as will be shown below.Sagnac interference using matter waves: previous experimentsHere we would like to briefly discuss previous experimental work on the Sagnac effectusing de Broglie waves. First, we will discuss the interference of neutron waves[. The in-terferometer was constructed using a cylindrical boule of single -crystal silicon, out ofthe upper half of which were carved semi- circular beam splitters Ml, M2, and M3 (see Fig-ure 1).incomingneutrons