  We recently pointed out that power measurements of single quasiparticle
devices can be used to detect dark matter. These devices have the lowest known
energy thresholds, far surpassing standard direct detection experiments,
requiring energy deposition above only about an meV. We calculate dark matter
induced quasiparticle densities in transmon qubits, and use the latest transmon
qubit measurements that provide one of the strongest existing lab-based bounds
on dark matter-nucleon scattering below about 100 MeV. We strongly constrain
sub-component dark matter, using both a dark matter population thermalized in
the Earth as well as the dark matter wind from the Galactic halo. We
demonstrate future potential sensitivities using devices with low quasiparticle
densities.
