Dr. Joel Ullom leads the NIST Quantum Sensors Division. He is also a Lecturer in the Department of Physics at the University of Colorado Boulder. Dr. Ullom has worked in the fields of low temperature sensors, quantum electronics, and cryogenic systems since 1994. During this time, he has done research to understand and improve the performance of superconducting transition-edge sensors. He has also worked to develop different types of refrigerators including microcoolers based on quantum tunneling and macrocoolers that reduce the need for liquid cryogens. Dr. Ullom has developed and disseminated a variety of instruments based on multiplexed arrays of cryogenic sensors.