Heat Dissipation and the Lower Limits of Microwave Noise in High Electron Mobility Transistors

Microwave amplifiers based on high electron mobility transistors (HEMTs) are a key component of scientific instrumentation with applications ranging from radio observatories to quantum computers. Present devices operate around a factor of 5 above the standard quantum limit of noise, and lower noise amplifiers are an important technological component of future large-scale quantum computers. In this talk, I will present our experimental studies on the lower bounds of HEMT noise at cryogenic temperatures. I will show how self-heating sets a fundamental limit for the noise floor of HEMTs and discuss the implications for scientific instrumentation.