Abstract
We have measured the ratio of Planck’s constant h to the observable mass m’ of a Cooper pair in a superconductor, using a rotating superconducting ring. The flux through such a ring of area S is zero for a set of rotation frequencies evenly spaced by Δν and h/2πm’=2SΔν. Our measurements of S and Δν enable us to quote a value of m’/2 for niobium of 1.000 084 (21). This result disagrees with predictions from currently available theories.
- Received 31 May 1990
DOI:https://doi.org/10.1103/PhysRevB.42.7885
©1990 American Physical Society