Assembling a MEMS-based Calibration System for Dark Matter Detectors and Qubits

I will describe work I did this summer to help characterize a novel microelectromechanical (MEMS)-based, fiber optics-coupled calibration system designed to operate efficiently at the mixing chamber stage of a dilution refrigerator. The system provides accurate energy calibration as a function of position for advanced dark matter detectors and quantum information sensors, including qubit-based structures, at sub-Kelvin temperatures. The cryogenic system can be used to steer a monochromatic optical beam of a wide range of wavelengths over the entire area of a ~ cm^2-scale device under test. Besides its utility as an energy calibration and detector characterization tool, the system also can be used to precisely measure impact ionization effects in semiconductor- and superconductor-based devices. This summer, a second-generation MEMS-based system was built and optimized in the Dark Matter and Quantum Information Sensor (DMQIS) Group at SLAC National Accelerator Laboratory. This second-generation system was designed to be more compact than the first, in order to fit within custom magnetic shielding cans made from Cryoperm and/or superconducting materials.