Microscopic origins of noise in cryogenic semiconductor amplifiers

Alexander Choi, Peishi Cheng, Sander Weinreb, Austin Minnich

California Institute of Technology

In the frequency band of interest for QC readout, cryogenic HEMT amplifiers induce noise at five to ten times the standard quantum limit. The noise floor for these devices is set by a combination of hot-electron noise and by self-heating phenomena. This talk will highlight our efforts to understand the dominant noise mechanisms in semiconductor devices, including a first-principles treatment of hot-electron fluctuations and experimental investigation of self-heating in HEMT amplifiers.