Precision quantization of zero-field fractional Hall states in graphene
In plain words
In a true fractional quantum Hall state the sideways resistance equals an exact fraction of a natural constant and the forward resistance vanishes, and early graphene data fell short of both.
Precise statement
In rhombohedral multilayer graphene/hBN at $B=0$, determine whether the FQAH states at $\nu=2/3,\ 3/5$ and others reach $R_{xy}=h/(\nu e^{2})$ within 1e-3 with $R_{xx}\to0$ as $T\to0$, and extract their activation gaps. Early (2024) data had $R_{xx}$ of order kilo-ohms. An answer gives quantization accuracy and gap for each state.
What would settle it
Transport at electron temperatures below 20 mK on several devices with independent contact and geometry checks.
Status in the literature
Unverified note
2025 measurements below $40\,\mathrm{mK}$ found smaller $R_{xx}$ and new FQAH states; a September 2026 preprint (arXiv:2609.09422) reports fractional quantized anomalous Hall insulators, pending independent confirmation.