Stable multi-level quantum conductance in an optically tunable ITO/MoS2-Ag/Pt memristor

While classical memristors demonstrate reliable binary switching, multi-level states remain constrained by scalability and mechanism variability. Quantum conductance memristors, with discrete quantized conductance steps, offer a promising alternative. However, achieving stable quantized states requires precise atomic-scale filament control and quantum state stability, posing even greater challenges. Here, we address these challenges by constructing a multilayer MoS2/MoS2:Ag structure that stably yields previously elusive conductance steps. Combined with a non-reset voltage scanning method and supported by a scattering center model, our approach markedly improves reproducibility. Moreover, we observe light-induced half-integer conductance states in a non-magnetic system. Such phenomena, previously reported only in oxygen-vacancy-based devices, are here realized for the first time in a cation-migration-based quantum conductance memristor. This arises from the strong photoresponse of MoS2 and the offset between the Ag work function and the MoS2 conduction band minimum, which together enable spin-selective transport. This finding surpasses classical multi-level limits and opens new paths for optoelectronic quantum conductance control.