Excess noise of metrology-grade quantum Hall effect devices

Low-frequency excess noise serves as a sensitive probe of dissipation in quantum Hall effect (QHE) devices, providing an alternative path to verify the approach of the quantization condition. This work demonstrates the technical feasibility of performing low-frequency (100 mHz to tens of Hz) excess voltage noise measurements on metrology-grade GaAs and epitaxial graphene QHE devices within a cryogen-free dilution refrigerator, using a two-channel correlation spectrum analyzer. Outside the quantized regime, voltage spectra are dominated by flicker noise, which is strongly suppressed as the dissipationless state is established. Cross-correlation measurements between different voltage terminals provide data that can qualify physical models about the origin of $1/f$ 1 / f noise in graphene devices. The current setup achieves a quantization status assessment sensitivity of 10 −5 in relative deviation, highlighting its potential utility for assessing integrated circuits like quantum Hall array resistance standards, where direct access to the longitudinal resistance of the individual elements is unavailable.