Oral: Quantum Sensing Abundant Jain Sequence Fractional Chern Insulators

Fractional quantum anomalous Hall (FQAH) effects are recently observed in twisted MoTe₂ homobilayer (tMoTe₂) and rhombohedral multilayer graphene. These first examples of zero-field fractional Chern insulators (FCIs) have opened a new frontier in researching correlated topological effects. Rapid progress has revealed several FCI states, among which the -2/3 state appears to be the most robust one. However, the missing of the presumed -1/3 state in both tMoTe₂ and multilayer graphene stands as an outstanding puzzle. Here, we report the observation of an ideal Jain sequence of the FCI states, including the missing -1/3 state, in ~3.1° twisted MoTe₂ bilayer. We engineer quantum confined potential traps for optically excited trions, i.e. optically active quantum dots, which have a spectral linewidth ~4 times smaller than that of free trions. This narrow and spatially localized spectral feature enables highly sensitive probe of the impressibility of adjacent bulk states. By performing optically detected fan diagram, we observe a Jain sequence of FCI states, including -2/3, -3/5, -4/7, -3/7, -2/5, and -1/3. Our results provide key information in understanding the nature of the FQAH and its connection to FQH and create a new measurement approach – quantum dot sensing of the topological quantum many-body systems, a viable path towards measuring zero-field fractional charges and anyons.