Record-Low 1/f Noise at 4 K in Cryogenic InGaAs HEMTs for Quantum Computing via Quantum Well Heterostructure Engineering

In this work, we report the first systematic study of low- frequency 1/f noise (LFN) at 4 K in cryogenic InGaAs HEMTs used in quantum computing low-noise amplifiers and interfaces. We show how the quantum well heterostructure can be engineered to suppress cryogenic LFN, and demonstrate the lowest ever reported transistor LFN at 4 K. LFN in cryogenic transistors is a key bottleneck for quantum computing as it degrades the signal-to- noise ratio of readout amplifiers and phase/frequency noise in control lines, reducing qubit coherence and readout fidelity. In contrast to other metrics, LFN performance tends to degrade from 300 to 4 K. Here, we show non-monotonic 1/f noise T-dependence with a minimum at 200 K, indicating additional disorder-induced noise mechanisms beyond the carrier number fluctuation model at 4 K. By comparing several quantum well designs, we identify channel-barrier interface disorder as the dominant origin of excess cryogenic LFN, and show that heterostructure engineering can suppress 4 K 1/f noise by two orders of magnitude. The resulting HEMTs show a combination of both record lowest reported noise indication factor, 0.14 ඥ ή Ȁ , and flat band voltage noise < 1x10-12 V2/Hz.