  It is well known that a rotating superconductor produces a magnetic field
proportional to its angular velocity. The authors conjectured earlier, that in
addition to this so-called London moment, also a large gravitomagnetic field
should appear to explain an apparent mass increase of Niobium Cooper-pairs.
This phenomenon was indeed observed and induced acceleration fields outside the
superconductor in the order of about 10^-4 g were found. The field appears to
be directly proportional to the applied angular acceleration of the
superconductor following our theoretical motivations. If confirmed, a
gravitomagnetic field of measurable magnitude was produced for the first time
in a laboratory environment. These results may open up a new experimental
window on testing general relativity and its consequences using coherent
matter.
