Developments over the last decade have pushed the search for particle dark matter to new frontiers, from just below the proton mass down to the keV-scale lower mass limit for thermally-produced dark matter. Galactic DM near the top of this mass range is kinematically better matched to electron scattering than nuclear scattering. We have developed single-charge-counting detectors based on Transition-Edge Sensors (TES) that have shown the best energy resolution for this type of detectors to date. For dark matter searches near the lowest masses, the energy deposited nears that needed to break a Cooper pair in common superconductors (~meV). Quantum sensors such as superconducting qubits can have sensitivity to these broken Cooper pairs, and can potentially be exploited as low-threshold detectors for particle-like DM scattering. On the other hand, excitations that break Cooper pairs in qubits can lead to lower T1 times and catastrophic correlated errors in quantum computers. The coupling between excitations in qubit substrates and qubit performance lies at the intersection of quantum sensing and quantum computing. In this talk I will overview some of our work on TES-based detectors as part of the SuperCDMS collaboration, and the research program being conducted by the Quantum Science Center group at Fermilab as part of a broad effort in quantum sensing and computing, focusing on the interaction of qubits with their environment.
