  With great interest from the quantum computing community, an immense amount
of R&D effort has been invested into improving superconducting qubits. The
technologies developed for the design and fabrication of these qubits can be
directly applied to applications for ultra-low threshold particle detectors,
e.g. low-mass dark matter and far-IR photon sensing. We propose a novel sensor
based on the transmon qubit architecture combined with a signal-enhancing
superconducting quasiparticle amplification stage. We refer to these sensors as
SQUATs: Superconducting Quasiparticle-Amplifying Transmons. We detail the
operating principle and design of this new sensor and predict that with minimal
R&D effort, solid-state based detectors patterned with these sensors can
achieve sensitivity to single THz photons, and sensitivity to $1\,\mathrm{meV}$
phonons in the detector absorber substrate on the $\mu\mathrm{s}$ timescale.
