Speaker: Prof. Kyle Sundqvist, Physics Department, SDSU
Topic: “Low-temperature detectors and instrumentation with semiconductors and superconductors“
Time: 2:00 p.m., Friday, September 8 (refreshments served at 1:45 p.m.)
Low-temperature physics, including effects found in semiconducting and superconducting devices, offers a host of phenomena for use in novel detectors and instrumentation. For instance, cryogenic detectors developed for rare-event particle searches measure athermal phonons created by particle interactions in intrinsic germanium and silicon crystals at millikelvin temperatures. The challenges associated with these detectors are unique, as extreme non-equilibrium charge transport phenomena dominate the detector physics. Carrier scattering is dominated by zero-point fluctuations of the lattice ions, and the charged state of localized impurities also departs drastically from equilibrium. Superconducting readout of these detectors is performed using Superconducting QUantum Interference Devices (SQUIDs), which have utility in other domains of physics such as quantum information. A SQUID under parametric excitation may act electrically with some component of negative resistance, affording gain. Superconductive devices may also demonstrate an effect known as memristance, which offers a unique and dynamic relationship between current and voltage, which we also explore.