Measuring gravitational constant using a planetary system constructed with levitated superconducting test masses

Abstract

Newton’s gravitational constant G is the least known fundamental constant of nature, partly because the gravity signal produced in the laboratory is extremely weak and difficult to measure accurately. There also seem to be unknown systematics in many G measurements. Since Cavendish made the first measurement of G with a torsion balance over two hundred years ago, torsion balances have been used in many G experiments, but uncorrected anelasticity of torsion fibers make the results questionable. We present a new method of G measurement by using a superconducting gravity gradiometer constructed with levitated test masses, which is free from the irregularities of mechanical suspension. The detector is rotated to null the gravity field from the source mass by centrifugal acceleration, forming an artificial planetary system. We show that this experiment can potentially measure G with accuracy better than 10 ppm.