  We searched for violations of the weak equivalence principle using a
cryogenic torsion balance with a pendulum comprised of superconducting niobium
and copper. We constrain the E\"otv\"os parameter with 95%-confidence to
$\eta_{\text{Nb*-Cu}}~\leq~2.0\times10^{-9}$ and
$\eta_{\text{CP-ee}}\leq6.9\times10^{-3}$ for superconducting niobium and
Cooper pairs, respectively.
