  In 1989 Cabrera and Tate reported an anomalous excess of mass of the Cooper
pairs in rotating thin Niobium rings. So far, this experimental result never
received a proper theoretical explanation in the context of superconductor's
physics. In the present work we argue that what Cabrera and Tate interpreted as
an anomalous excess of mass can also be associated with a deviation from the
classical gravitomagnetic Larmor theorem due to the presence of dark energy in
the superconductor, as well as with the discrete structure of the area of the
superconducting Niobium ring as predicted by Loop Quantum Gravity. From Cabrera
and Tate measurements we deduce that the quantization of spacetime in
superconducting circular rings occurs at the Planck-Einstein scale $l_{PE} =
(\hbar G/c^3 \Lambda)^{1/4}\sim 3.77\times 10 ^{-5} m$, instead of the Planck
scale $l_{P} =(\hbar G / c^3)^{1/2}=1.61 \times 10 ^{-35} m$, with an Immirzi
parameter which depends on the specific critical temperature of the
superconducting material and on the area of the ring. The stephan-Boltzmann law
for quantized areas delimited by superconducting rings is predicted, and an
experimental concept based on the electromagnetic black-body radiation emitted
by this surfaces, is proposed to test loop quantum gravity and electromagnetic
dark energy in superconductors.
