Title: Qubit-based particle detectors

One of the challenges in exploring promising novel materials for dark matter searches is the detection of sub-eV energy excitations from light-dark matter interaction with a target material. Dark matter interaction can excite sub-eV optical phonon modes in polar materials like sapphire. We are developing a superconducting qubit-based detector for the energy deposited in the target material. The energy deposited into the qubit’s substrate excites phonons, a fraction of which end up in the superconductor film and break Cooper pairs in the superconductor, releasing quasiparticles. As the quasiparticles tunnel across the Josephson junction, the charge parity of the qubit changes. Measuring the parity switching rate to probe the quasiparticle density near the qubit's Josephson junction will provide a way to detect the energy deposited. This presentation describes our ongoing attempt to build such a prototype detector.