High-Resolution Displacement Sensor Using SQUID Array Amplifier

We describe the design and operation principle of a new displacement sensor with a substantial improvement in resolution over what is currently possible. The potential for significant improvement in the measurement of displacement has profound implications for several high-impact gravitational physics and particle physics projects: the detection of gravitational waves, the test of the equivalence principle, the search for the postulated “axion” particle, and the test of the inverse square law of gravity, all of which rely on the detection of small displacements. If the new displacement sensof is sensitive enough to observe the quantum mechanical zero-point motion of a test mass, it will be possible to make a direct examination of the Heisenberg uncertainty principle. Based on our calculations, the achievable resolution ( to 10-22ml&) is high enough to reach the quantum limit. Investigations of these world-class science issues will reqvire the low vibration environment offered by free fall to achieve its ultimate sensitivity. * Tel: +1-818-354-3104; fax: +1-818-393-3707. E-maiZ address: Talso.C.Chui @ipl.nasa.gov (T.C.P. Chui)