First measurement of correlated charge noise in superconducting qubits underground

The goals of HEP detector development and of QIS systems development are in many ways complementary. Qubits and other quantum devices offer an appealing path towards low-threshold dark matter detectors. And conversely, the facilities and methodologies of HEP detector development offer new insights into fundamental questions of QIS device coherence. We discuss this complementarity in the context of our recent results, operating four superconducting qubits underground in a "low-background" facility with well-characterized and controllable sources of ionizing radiation. We observe correlated charge noise between all four qubits. This correlated noise scales with the flux of ionizing radiation on the qubit package, as characterized by a series of independent measurements on another energy-resolving detector operating simultaneously in the same cryostat with the qubits. These measurements give some indication of the way various sources of ionizing radiation impact qubit coherence. Furthermore, we operate four qubits for over 22 consecutive hours with zero correlated charge jumps at length scales above three millimeters. Finally, we will discuss the implications of this result for the development of dark matter detectors.