Speaker
Description
Increasing sensitivity of low-threshold detectors is revealing long-lived, history-dependent processes in cryogenic materials. Recent measurements increasingly identify preparation and material-state variables behind these effects: low-energy event rates can depend strongly on cooldown history and relax as power laws over long times; athermal phonon-burst populations can originate in detector substrates or deliberately created lattice damage; and mechanical stress and vibration can strongly modify event rates. Superconducting quantum devices show related phenomenology, including phonon-mediated quasiparticle bursts, correlated errors, and long relaxation following cooldown or mechanical perturbations.
These observations need not share a single microscopic mechanism. Together, however, they point to a broader nonequilibrium-materials problem: how energy, charge, stress, and other excitations accumulate in low-temperature materials and interfaces; how metastable configurations and defects interact; and how the resulting material state evolves through intermittent energy release or gradual local parameter drift. In rare-event detectors these processes can appear as excess backgrounds and changing detector response, while in quantum devices they can contribute to decoherence, correlated errors, and parameter drift.
We propose closer collaboration between HEP detector programs and BES materials science to develop controlled perturbation experiments, time-resolved diagnostics, and common benchmarks for history dependence, relaxation, spatial and temporal correlations, and recovery. Combining advanced detectors with qubits, resonators, and complementary phonon, photon, charge, strain, or other material-state sensors could help identify energy pathways and metastable states, establish conditions under which correlated relaxation develops, and guide mitigation in both rare-event detectors and scalable quantum systems.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-2024690