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Coauthored the fractional-charge experiment in which the crossover between shot noise and Johnson-Nyquist noise independently supported an effective carrier charge of $e/3$. ^[ref]

Coauthored the fractional-charge experiment using cross-correlation between amplifier outputs to isolate shot noise, yielding the $e/3$ carrier charge. ^[ref]

Coauthored a fractional quantum Hall effect experiment using shot noise to measure tunnelling carriers with electric charge $e/3$ at filling factor $1/3$. ^[ref]

Daniel Tsui, Horst Störmer and Arthur Gossard reported the effect in 1982. They grew gallium arsenide–aluminium gallium arsenide layers by molecular beam epitaxy, separating the two-dimensional electron gas from its semiconductor doping. They cut Hall bars and made indium contacts. Low-field measurements established number density and charge carrier mobility. A perpendicular magnetic field sweep measured transverse and longitudinal sheet resistivities at several temperatures. Cooling sharpened the plateau near $3h/e^2$ and the longitudinal minimum at filling factor $1/3$; integer plateaus provided an internal comparison. The longitudinal minimum remained finite at the lowest temperature: zero-temperature vanishing was unresolved. This established anomalous transport, without directly measuring excitation electric charge.^[ref]

The two readouts test different statements. A single intersection with $R_H=3R_K$ would also occur on the smooth classical relation $R_H=B/(n_{s}e)$ at $n_{s}h/(eB)=1/3$. A quantum Hall plateau instead persists over a magnetic field interval. Comparing transverse and longitudinal signals helps distinguish that plateau from a contact-placement artefact; the quantum Hall conductivity tensor inversion quantifies the contamination when longitudinal sheet resistivity is nonzero.

Later, 1997 shot noise measurements associated with quantum tunnelling at filling factor $1/3$ tested the excitation electric charge separately, finding $e/3$. That is a different observable from a Hall plateau.^[ref]

Coauthored the fractional quantum Hall effect experiment in a gallium arsenide electron system, using a quantum point contact to control the backscattered current and its shot noise. ^[ref]