Detecting Ultralight Bosonic Dark Matter via Absorption in
  Superconductors
  Superconducting targets have recently been proposed for the direct detection
of dark matter as light as a keV, via elastic scattering off conduction
electrons in Cooper pairs. Detecting such light dark matter requires
sensitivity to energies as small as the superconducting gap of O(meV). Here we
show that these same superconducting devices can detect much lighter DM, of meV
to eV mass, via dark matter absorption on a conduction electron, followed by
emission of an athermal phonon. We demonstrate the power of this setup for
relic kinetically mixed hidden photons, pseudoscalars, and scalars, showing the
reach can exceed current astrophysical and terrestrial constraints with only a
moderate exposure.
