  We propose the use of superconducting nanowires as both target and sensor for
direct detection of sub-GeV dark matter. With excellent sensitivity to small
energy deposits on electrons, and demonstrated low dark counts, such devices
could be used to probe electron recoils from dark matter scattering and
absorption processes. We demonstrate the feasibility of this idea using
measurements of an existing fabricated tungsten-silicide nanowire prototype
with 0.8 eV energy threshold and 4.3 nanograms with 10 thousand seconds of
exposure, which showed no dark counts. The results from this device already
place meaningful bounds on dark matter-electron interactions, including the
strongest terrestrial bounds on sub-eV dark photon absorption to date. Future
expected fabrication on larger scales and with lower thresholds should enable
probing new territory in the direct detection landscape, establishing the
complementarity of this approach to other existing proposals.

High Energy Physics - Phenomenology;Superconductivity;High Energy Physics - Experiment;Quantum Physics