Synchronizing Bloch-Oscillating Free Carriers in Moire Flat Bands

Achieving Bloch oscillations of free carriers under a direct current, a long-sought-after collective manybody behavior, has been challenging due to stringent constraints on the band properties. We argue that the flat bands in moire graphene fulfill the basic requirements for observing Bloch oscillations, offering an appealing alternative to the stacked quantum wells used in previous work aiming to access this regime. Bloch-oscillating moire superlattices emit a tomblike spectrum of incommensurate frequencies, a property of interest for converting direct currents into high-frequency currents and developing broadband amplifiers in terahertz domain. The oscillations can be synchronized through coupling to an oscillator mode in a photonic or plasmonic resonator. Phase-coherent collective oscillations in the resonant regime provide a realization of current-pumped terahertz lasing.