Description:

The continued absence of a conclusive detection of conventional, GeV-scale particle dark matter (DM) has recently increased focus on developing low-threshold detector technologies capable of sensing a variety of light (sub-GeV) and ultralight dark matter candidates. In many of these technologies, meV-scale phonons from a DM scatter are sensed via their ability to break Cooper pairs into quasiparticles in superconducting films. Recently, devices based on superconducting qubits acting in such a “pairbreaking” detection capacity have promised low thresholds for athermal phonon sensing that are competitive with traditional techniques. In this seminar, we will discuss the sensitivity of qubit-based detector architectures to in-chip energy depositions as estimated using first-principles modeling of phonon and quasiparticle dynamics in those architectures. We follow with an exploration of other novel detection techniques including quantum acoustics devices, in which the 2Δ phonon energy requirement to break a Cooper pair can be sidestepped to achieve a sensor threshold limited by thermal noise. We will close with a discussion of the Fermilab Quantum Science Center group’s current experimental efforts to develop, characterize, and further improve the performance of such low-threshold qubit-based detectors.

Ryan Linehan, Fermilab

Host: Adrian Thompson