Phonon Landau\nQuantization and Enhanced Lifetime in\nDeformed Graphene

The pseudomagnetic field effect may offer unique opportunities\nfor the emergence of intriguing phenomena. To date, investigations\ninto pseudomagnetic field effects on phonons have been limited to\nsound waves in metamaterials. The revelation of this exotic effect\non the atomic vibration of natural materials remains elusive. Our\nsimulations of twisted graphene nanoribbons reveal well-defined Landau\nspectra and sublattice polarization of phonon states, mimicking the\nbehavior of Dirac Fermions in magnetic fields. Both valley-specified\nhelical edge currents and snake orbits are obtained. Analysis of dynamics\nindicates that phonon Landau states have extended lifetimes, which\nare crucial for the realization of Landau-level lasing. Our findings\ndemonstrate the occurrence of the phonon pseudomagnetic field effect\nin natural materials, which has important implications for the mechanical\ntuning of phonon quantum states at the atomic scale.