Single-photon detection enabled by negative differential conductivity in moiré superlattices

Detecting individual light quanta is essential for quantum information, space exploration, advanced machine vision, and fundamental science. In this work, we introduce a single-photon detection mechanism using highly photosensitive nonequilibrium electron phases in moiré materials. Using tunable bands in bilayer graphene/hexagonal boron nitride superlattices, we engineer negative differential conductance and a sensitive bistable state capable of detecting single photons. Operating in this regime, we demonstrate single-photon counting at mid-infrared (11.3 micrometers) and visible wavelengths (675 nanometers) and temperatures up to 25 kelvin. This detector offers prospects for broadband, high-temperature quantum technologies with complementary metal-oxide semiconductor compatibility and seamless integration into photonic-integrated circuits. Our analysis suggests that the underlying mechanism originates from superlattice-induced negative differential velocity.